import { __String, AccessExpression, AccessFlags, AccessorDeclaration, addRange, addRelatedInfo, addSyntheticLeadingComment, AliasDeclarationNode, AllAccessorDeclarations, AmbientModuleDeclaration, and, AnonymousType, AnyImportOrReExport, AnyImportSyntax, append, appendIfUnique, ArrayBindingPattern, arrayFrom, arrayIsHomogeneous, ArrayLiteralExpression, arrayOf, arraysEqual, arrayToMultiMap, ArrayTypeNode, ArrowFunction, AssertionExpression, AssignmentDeclarationKind, AssignmentKind, AssignmentPattern, AwaitExpression, BaseType, BigIntLiteral, BigIntLiteralType, BinaryExpression, BinaryOperatorToken, binarySearch, BindableObjectDefinePropertyCall, BindableStaticNameExpression, BindingElement, BindingElementGrandparent, BindingName, BindingPattern, bindSourceFile, Block, BreakOrContinueStatement, CallChain, CallExpression, CallLikeExpression, CallSignatureDeclaration, CancellationToken, canHaveDecorators, canHaveExportModifier, canHaveFlowNode, canHaveIllegalDecorators, canHaveIllegalModifiers, canHaveJSDoc, canHaveLocals, canHaveModifiers, canHaveSymbol, canUsePropertyAccess, cartesianProduct, CaseBlock, CaseClause, CaseOrDefaultClause, cast, chainDiagnosticMessages, CharacterCodes, CheckFlags, ClassDeclaration, ClassElement, classElementOrClassElementParameterIsDecorated, ClassExpression, ClassLikeDeclaration, classOrConstructorParameterIsDecorated, ClassStaticBlockDeclaration, clear, combinePaths, compareDiagnostics, comparePaths, compareValues, Comparison, CompilerOptions, ComputedPropertyName, concatenate, concatenateDiagnosticMessageChains, ConditionalExpression, ConditionalRoot, ConditionalType, ConditionalTypeNode, ConstructorDeclaration, ConstructorTypeNode, ConstructSignatureDeclaration, contains, containsParseError, ContextFlags, copyEntries, countWhere, createBinaryExpressionTrampoline, createCompilerDiagnostic, createDiagnosticCollection, createDiagnosticForFileFromMessageChain, createDiagnosticForNode, createDiagnosticForNodeArray, createDiagnosticForNodeArrayFromMessageChain, createDiagnosticForNodeFromMessageChain, createDiagnosticMessageChainFromDiagnostic, createEmptyExports, createFileDiagnostic, createGetCanonicalFileName, createGetSymbolWalker, createModeAwareCacheKey, createPrinterWithDefaults, createPrinterWithRemoveComments, createPrinterWithRemoveCommentsNeverAsciiEscape, createPrinterWithRemoveCommentsOmitTrailingSemicolon, createPropertyNameNodeForIdentifierOrLiteral, createSymbolTable, createTextWriter, createUnderscoreEscapedMultiMap, Debug, Declaration, DeclarationName, declarationNameToString, DeclarationStatement, DeclarationWithTypeParameterChildren, DeclarationWithTypeParameters, Decorator, deduplicate, DefaultClause, defaultMaximumTruncationLength, DeferredTypeReference, DeleteExpression, Diagnostic, DiagnosticCategory, DiagnosticMessage, DiagnosticMessageChain, DiagnosticRelatedInformation, Diagnostics, DiagnosticWithLocation, DoStatement, DynamicNamedDeclaration, ElementAccessChain, ElementAccessExpression, ElementFlags, EmitFlags, EmitHint, emitModuleKindIsNonNodeESM, EmitResolver, EmitTextWriter, emptyArray, endsWith, EntityName, EntityNameExpression, EntityNameOrEntityNameExpression, entityNameToString, EnumDeclaration, EnumMember, EnumType, equateValues, escapeLeadingUnderscores, escapeString, every, EvolvingArrayType, ExclamationToken, ExportAssignment, exportAssignmentIsAlias, ExportDeclaration, ExportSpecifier, Expression, expressionResultIsUnused, ExpressionStatement, ExpressionWithTypeArguments, Extension, ExternalEmitHelpers, externalHelpersModuleNameText, factory, fileExtensionIs, fileExtensionIsOneOf, filter, find, findAncestor, findBestPatternMatch, findIndex, findLast, findLastIndex, findUseStrictPrologue, first, firstDefined, firstIterator, firstOrUndefined, firstOrUndefinedIterator, flatMap, flatten, FlowArrayMutation, FlowAssignment, FlowCall, FlowCondition, FlowFlags, FlowLabel, FlowNode, FlowReduceLabel, FlowStart, FlowSwitchClause, FlowType, forEach, forEachChild, forEachChildRecursively, forEachEnclosingBlockScopeContainer, forEachEntry, forEachImportClauseDeclaration, forEachKey, forEachReturnStatement, forEachYieldExpression, ForInOrOfStatement, ForInStatement, formatMessage, ForOfStatement, ForStatement, FreshableIntrinsicType, FreshableType, FreshObjectLiteralType, FunctionDeclaration, FunctionExpression, FunctionFlags, FunctionLikeDeclaration, FunctionOrConstructorTypeNode, FunctionTypeNode, GenericType, GetAccessorDeclaration, getAliasDeclarationFromName, getAllAccessorDeclarations, getAllJSDocTags, getAllowSyntheticDefaultImports, getAncestor, getAssignedExpandoInitializer, getAssignmentDeclarationKind, getAssignmentDeclarationPropertyAccessKind, getAssignmentTargetKind, getCheckFlags, getClassExtendsHeritageElement, getClassLikeDeclarationOfSymbol, getCombinedLocalAndExportSymbolFlags, getCombinedModifierFlags, getCombinedNodeFlags, getContainingClass, getContainingFunction, getContainingFunctionOrClassStaticBlock, getDeclarationModifierFlagsFromSymbol, getDeclarationOfKind, getDeclarationsOfKind, getDeclaredExpandoInitializer, getDecorators, getDirectoryPath, getEffectiveBaseTypeNode, getEffectiveConstraintOfTypeParameter, getEffectiveContainerForJSDocTemplateTag, getEffectiveImplementsTypeNodes, getEffectiveInitializer, getEffectiveJSDocHost, getEffectiveModifierFlags, getEffectiveReturnTypeNode, getEffectiveSetAccessorTypeAnnotationNode, getEffectiveTypeAnnotationNode, getEffectiveTypeParameterDeclarations, getElementOrPropertyAccessName, getEmitDeclarations, getEmitModuleKind, getEmitModuleResolutionKind, getEmitScriptTarget, getEnclosingBlockScopeContainer, getEntityNameFromTypeNode, getErrorSpanForNode, getEscapedTextOfIdentifierOrLiteral, getESModuleInterop, getExpandoInitializer, getExportAssignmentExpression, getExternalModuleImportEqualsDeclarationExpression, getExternalModuleName, getExternalModuleRequireArgument, getFirstConstructorWithBody, getFirstIdentifier, getFunctionFlags, getHostSignatureFromJSDoc, getIdentifierGeneratedImportReference, getIdentifierTypeArguments, getImmediatelyInvokedFunctionExpression, getInitializerOfBinaryExpression, getInterfaceBaseTypeNodes, getInvokedExpression, getIsolatedModules, getJSDocClassTag, getJSDocDeprecatedTag, getJSDocEnumTag, getJSDocHost, getJSDocParameterTags, getJSDocRoot, getJSDocSatisfiesExpressionType, getJSDocTags, getJSDocThisTag, getJSDocType, getJSDocTypeAssertionType, getJSDocTypeParameterDeclarations, getJSDocTypeTag, getJSXImplicitImportBase, getJSXRuntimeImport, getJSXTransformEnabled, getLeftmostAccessExpression, getLineAndCharacterOfPosition, getLocalSymbolForExportDefault, getMembersOfDeclaration, getModeForUsageLocation, getModifiers, getModuleInstanceState, getNameFromIndexInfo, getNameOfDeclaration, getNameOfExpando, getNamespaceDeclarationNode, getNewTargetContainer, getNonAugmentationDeclaration, getNormalizedAbsolutePath, getObjectFlags, getOriginalNode, getOrUpdate, getParameterSymbolFromJSDoc, getParseTreeNode, getPropertyAssignmentAliasLikeExpression, getPropertyNameForPropertyNameNode, getResolutionDiagnostic, getResolutionModeOverrideForClause, getResolvedExternalModuleName, getResolvedModule, getResolveJsonModule, getRestParameterElementType, getRootDeclaration, getScriptTargetFeatures, getSelectedEffectiveModifierFlags, getSemanticJsxChildren, getSetAccessorValueParameter, getSingleVariableOfVariableStatement, getSourceFileOfModule, getSourceFileOfNode, getSpanOfTokenAtPosition, getSpellingSuggestion, getStrictOptionValue, getSuperContainer, getSymbolNameForPrivateIdentifier, getTextOfIdentifierOrLiteral, getTextOfJSDocComment, getTextOfNode, getTextOfPropertyName, getThisContainer, getThisParameter, getTrailingSemicolonDeferringWriter, getTypeParameterFromJsDoc, getTypesPackageName, getUseDefineForClassFields, group, hasAbstractModifier, hasAccessorModifier, hasAmbientModifier, hasContextSensitiveParameters, HasDecorators, hasDecorators, hasDynamicName, hasEffectiveModifier, hasEffectiveModifiers, hasEffectiveReadonlyModifier, HasExpressionInitializer, hasExtension, HasIllegalDecorators, HasIllegalModifiers, HasInitializer, hasInitializer, hasJSDocNodes, hasJSDocParameterTags, hasJsonModuleEmitEnabled, HasLocals, HasModifiers, hasOnlyExpressionInitializer, hasOverrideModifier, hasPossibleExternalModuleReference, hasQuestionToken, hasRestParameter, hasScopeMarker, hasStaticModifier, hasSyntacticModifier, hasSyntacticModifiers, hasType, HeritageClause, Identifier, identifierToKeywordKind, IdentifierTypePredicate, idText, IfStatement, ImportCall, ImportClause, ImportDeclaration, ImportEqualsDeclaration, ImportOrExportSpecifier, ImportsNotUsedAsValues, ImportSpecifier, ImportTypeAssertionContainer, ImportTypeNode, IndexedAccessType, IndexedAccessTypeNode, IndexInfo, IndexKind, indexOfNode, IndexSignatureDeclaration, IndexType, indicesOf, InferenceContext, InferenceFlags, InferenceInfo, InferencePriority, InferTypeNode, InstantiableType, InstantiationExpressionType, InterfaceDeclaration, InterfaceType, InterfaceTypeWithDeclaredMembers, InternalSymbolName, IntersectionType, IntersectionTypeNode, IntrinsicType, introducesArgumentsExoticObject, isAccessExpression, isAccessor, isAliasableExpression, isAmbientModule, isArray, isArrayBindingPattern, isArrayLiteralExpression, isArrowFunction, isAssertionExpression, isAssignmentDeclaration, isAssignmentExpression, isAssignmentOperator, isAssignmentPattern, isAssignmentTarget, isAsyncFunction, isAutoAccessorPropertyDeclaration, isAwaitExpression, isBinaryExpression, isBindableObjectDefinePropertyCall, isBindableStaticElementAccessExpression, isBindableStaticNameExpression, isBindingElement, isBindingElementOfBareOrAccessedRequire, isBindingPattern, isBlock, isBlockOrCatchScoped, isBlockScopedContainerTopLevel, isBooleanLiteral, isCallChain, isCallExpression, isCallLikeExpression, isCallOrNewExpression, isCallSignatureDeclaration, isCatchClause, isCatchClauseVariableDeclarationOrBindingElement, isCheckJsEnabledForFile, isChildOfNodeWithKind, isClassDeclaration, isClassElement, isClassExpression, isClassLike, isClassStaticBlockDeclaration, isCommaSequence, isCommonJsExportedExpression, isCommonJsExportPropertyAssignment, isComputedNonLiteralName, isComputedPropertyName, isConstructorDeclaration, isConstructorTypeNode, isConstructSignatureDeclaration, isConstTypeReference, isDeclaration, isDeclarationFileName, isDeclarationName, isDeclarationReadonly, isDecorator, isDefaultedExpandoInitializer, isDeleteTarget, isDottedName, isDynamicName, isEffectiveExternalModule, isElementAccessExpression, isEntityName, isEntityNameExpression, isEnumConst, isEnumDeclaration, isEnumMember, isExclusivelyTypeOnlyImportOrExport, isExportAssignment, isExportDeclaration, isExportsIdentifier, isExportSpecifier, isExpression, isExpressionNode, isExpressionOfOptionalChainRoot, isExpressionStatement, isExpressionWithTypeArguments, isExpressionWithTypeArgumentsInClassExtendsClause, isExternalModule, isExternalModuleAugmentation, isExternalModuleImportEqualsDeclaration, isExternalModuleIndicator, isExternalModuleNameRelative, isExternalModuleReference, isExternalOrCommonJsModule, isForInOrOfStatement, isForInStatement, isForOfStatement, isForStatement, isFunctionDeclaration, isFunctionExpression, isFunctionExpressionOrArrowFunction, isFunctionLike, isFunctionLikeDeclaration, isFunctionLikeOrClassStaticBlockDeclaration, isFunctionOrModuleBlock, isFunctionTypeNode, isGeneratedIdentifier, isGetAccessor, isGetAccessorDeclaration, isGetOrSetAccessorDeclaration, isGlobalScopeAugmentation, isHeritageClause, isIdentifier, isIdentifierText, isIdentifierTypePredicate, isIdentifierTypeReference, isIfStatement, isImportCall, isImportClause, isImportDeclaration, isImportEqualsDeclaration, isImportKeyword, isImportOrExportSpecifier, isImportSpecifier, isImportTypeNode, isIndexedAccessTypeNode, isInExpressionContext, isInfinityOrNaNString, isInitializedProperty, isInJSDoc, isInJSFile, isInJsonFile, isInterfaceDeclaration, isInternalModuleImportEqualsDeclaration, isInTopLevelContext, isIntrinsicJsxName, isIterationStatement, isJSDocAllType, isJSDocAugmentsTag, isJSDocCallbackTag, isJSDocConstructSignature, isJSDocFunctionType, isJSDocIndexSignature, isJSDocLinkLike, isJSDocMemberName, isJSDocNameReference, isJSDocNode, isJSDocNonNullableType, isJSDocNullableType, isJSDocOptionalParameter, isJSDocOptionalType, isJSDocOverloadTag, isJSDocParameterTag, isJSDocPropertyLikeTag, isJSDocPropertyTag, isJSDocReturnTag, isJSDocSatisfiesExpression, isJSDocSatisfiesTag, isJSDocSignature, isJSDocTemplateTag, isJSDocTypeAlias, isJSDocTypeAssertion, isJSDocTypedefTag, isJSDocTypeExpression, isJSDocTypeLiteral, isJSDocTypeTag, isJSDocUnknownType, isJSDocVariadicType, isJsonSourceFile, isJsxAttribute, isJsxAttributeLike, isJsxAttributes, isJsxElement, isJsxOpeningElement, isJsxOpeningFragment, isJsxOpeningLikeElement, isJsxSelfClosingElement, isJsxSpreadAttribute, isJSXTagName, isKnownSymbol, isLateVisibilityPaintedStatement, isLeftHandSideExpression, isLet, isLineBreak, isLiteralComputedPropertyDeclarationName, isLiteralExpression, isLiteralExpressionOfObject, isLiteralImportTypeNode, isLiteralTypeNode, isLogicalOrCoalescingBinaryExpression, isLogicalOrCoalescingBinaryOperator, isMetaProperty, isMethodDeclaration, isMethodSignature, isModifier, isModuleBlock, isModuleDeclaration, isModuleExportsAccessExpression, isModuleIdentifier, isModuleOrEnumDeclaration, isModuleWithStringLiteralName, isNamedDeclaration, isNamedEvaluationSource, isNamedExports, isNamedTupleMember, isNamespaceExport, isNamespaceExportDeclaration, isNamespaceReexportDeclaration, isNewExpression, isNightly, isNodeDescendantOf, isNonNullAccess, isNullishCoalesce, isNumericLiteral, isNumericLiteralName, isObjectBindingPattern, isObjectLiteralElementLike, isObjectLiteralExpression, isObjectLiteralMethod, isObjectLiteralOrClassExpressionMethodOrAccessor, isOmittedExpression, isOptionalChain, isOptionalChainRoot, isOptionalDeclaration, isOptionalJSDocPropertyLikeTag, isOptionalTypeNode, isOutermostOptionalChain, isParameter, isParameterDeclaration, isParameterOrCatchClauseVariable, isParameterPropertyDeclaration, isParenthesizedExpression, isParenthesizedTypeNode, isPartOfTypeNode, isPartOfTypeQuery, isPlainJsFile, isPrefixUnaryExpression, isPrivateIdentifier, isPrivateIdentifierClassElementDeclaration, isPrivateIdentifierPropertyAccessExpression, isPropertyAccessEntityNameExpression, isPropertyAccessExpression, isPropertyAccessOrQualifiedNameOrImportTypeNode, isPropertyAssignment, isPropertyDeclaration, isPropertyName, isPropertyNameLiteral, isPropertySignature, isPrototypeAccess, isPrototypePropertyAssignment, isPushOrUnshiftIdentifier, isQualifiedName, isRequireCall, isRestParameter, isRestTypeNode, isRightSideOfQualifiedNameOrPropertyAccess, isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName, isSameEntityName, isSetAccessor, isSetAccessorDeclaration, isShorthandAmbientModuleSymbol, isShorthandPropertyAssignment, isSingleOrDoubleQuote, isSourceFile, isSourceFileJS, isSpreadAssignment, isSpreadElement, isStatement, isStatementWithLocals, isStatic, isString, isStringANonContextualKeyword, isStringLiteral, isStringLiteralLike, isStringOrNumericLiteralLike, isSuperCall, isSuperProperty, isTaggedTemplateExpression, isTemplateSpan, isThisContainerOrFunctionBlock, isThisIdentifier, isThisInitializedDeclaration, isThisInitializedObjectBindingExpression, isThisInTypeQuery, isThisProperty, isThisTypeParameter, isTransientSymbol, isTupleTypeNode, isTypeAlias, isTypeAliasDeclaration, isTypeDeclaration, isTypeLiteralNode, isTypeNode, isTypeNodeKind, isTypeOfExpression, isTypeOnlyImportOrExportDeclaration, isTypeOperatorNode, isTypeParameterDeclaration, isTypePredicateNode, isTypeQueryNode, isTypeReferenceNode, isTypeReferenceType, isUMDExportSymbol, isValidBigIntString, isValidESSymbolDeclaration, isValidTypeOnlyAliasUseSite, isValueSignatureDeclaration, isVarConst, isVariableDeclaration, isVariableDeclarationInitializedToBareOrAccessedRequire, isVariableDeclarationInVariableStatement, isVariableDeclarationList, isVariableLike, isVariableLikeOrAccessor, isVariableStatement, isWriteAccess, isWriteOnlyAccess, IterableOrIteratorType, IterationTypes, JSDoc, JSDocAugmentsTag, JSDocCallbackTag, JSDocComment, JSDocEnumTag, JSDocFunctionType, JSDocImplementsTag, JSDocLink, JSDocLinkCode, JSDocLinkPlain, JSDocMemberName, JSDocNullableType, JSDocOptionalType, JSDocOverloadTag, JSDocParameterTag, JSDocPrivateTag, JSDocPropertyLikeTag, JSDocPropertyTag, JSDocProtectedTag, JSDocPublicTag, JSDocSatisfiesTag, JSDocSignature, JSDocTemplateTag, JSDocTypedefTag, JSDocTypeExpression, JSDocTypeLiteral, JSDocTypeReferencingNode, JSDocTypeTag, JSDocVariadicType, JsxAttribute, JsxAttributeLike, JsxAttributes, JsxChild, JsxClosingElement, JsxElement, JsxEmit, JsxExpression, JsxFlags, JsxFragment, JsxOpeningElement, JsxOpeningFragment, JsxOpeningLikeElement, JsxReferenceKind, JsxSelfClosingElement, JsxSpreadAttribute, JsxTagNameExpression, KeywordTypeNode, LabeledStatement, last, lastOrUndefined, LateBoundBinaryExpressionDeclaration, LateBoundDeclaration, LateBoundName, LateVisibilityPaintedStatement, LeftHandSideExpression, length, LiteralExpression, LiteralType, LiteralTypeNode, mangleScopedPackageName, map, mapDefined, MappedSymbol, MappedType, MappedTypeNode, MatchingKeys, maybeBind, MemberName, MemberOverrideStatus, memoize, MetaProperty, MethodDeclaration, MethodSignature, minAndMax, MinusToken, Modifier, ModifierFlags, modifiersToFlags, modifierToFlag, ModuleBlock, ModuleDeclaration, ModuleInstanceState, ModuleKind, ModuleResolutionKind, ModuleSpecifierResolutionHost, NamedDeclaration, NamedExports, NamedImportsOrExports, NamedTupleMember, NamespaceDeclaration, NamespaceExport, NamespaceExportDeclaration, NamespaceImport, needsScopeMarker, NewExpression, Node, NodeArray, NodeBuilderFlags, nodeCanBeDecorated, NodeCheckFlags, NodeFlags, nodeHasName, nodeIsDecorated, nodeIsMissing, nodeIsPresent, nodeIsSynthesized, NodeLinks, nodeModulesPathPart, nodeStartsNewLexicalEnvironment, NodeWithTypeArguments, NonNullChain, NonNullExpression, not, noTruncationMaximumTruncationLength, nullTransformationContext, NumberLiteralType, NumericLiteral, objectAllocator, ObjectBindingPattern, ObjectFlags, ObjectFlagsType, ObjectLiteralElementLike, ObjectLiteralExpression, ObjectType, OptionalChain, OptionalTypeNode, or, orderedRemoveItemAt, OuterExpressionKinds, outFile, ParameterDeclaration, parameterIsThisKeyword, ParameterPropertyDeclaration, ParenthesizedExpression, ParenthesizedTypeNode, parseIsolatedEntityName, parseNodeFactory, parsePseudoBigInt, parseValidBigInt, Path, pathIsRelative, PatternAmbientModule, PlusToken, PostfixUnaryExpression, PrefixUnaryExpression, PrivateIdentifier, Program, PromiseOrAwaitableType, PropertyAccessChain, PropertyAccessEntityNameExpression, PropertyAccessExpression, PropertyAssignment, PropertyDeclaration, PropertyName, PropertySignature, PseudoBigInt, pseudoBigIntToString, pushIfUnique, QualifiedName, QuestionToken, rangeEquals, rangeOfNode, rangeOfTypeParameters, ReadonlyKeyword, reduceLeft, RelationComparisonResult, relativeComplement, removeExtension, removePrefix, replaceElement, resolutionExtensionIsTSOrJson, ResolutionMode, ResolvedModuleFull, ResolvedType, resolveTripleslashReference, resolvingEmptyArray, RestTypeNode, ReturnStatement, ReverseMappedSymbol, ReverseMappedType, sameMap, SatisfiesExpression, scanTokenAtPosition, ScriptKind, ScriptTarget, SetAccessorDeclaration, setCommentRange, setEmitFlags, setIdentifierTypeArguments, setNodeFlags, setOriginalNode, setParent, setSyntheticLeadingComments, setTextRange, setTextRangePosEnd, setValueDeclaration, ShorthandPropertyAssignment, shouldAllowImportingTsExtension, shouldPreserveConstEnums, shouldResolveJsRequire, Signature, SignatureDeclaration, SignatureFlags, SignatureKind, singleElementArray, skipOuterExpressions, skipParentheses, skipTrivia, skipTypeChecking, some, SourceFile, SpreadAssignment, SpreadElement, startsWith, Statement, stringContains, StringLiteral, StringLiteralLike, StringLiteralType, StringMappingType, stripQuotes, StructuredType, SubstitutionType, SuperCall, SwitchStatement, Symbol, SymbolAccessibility, SymbolAccessibilityResult, SymbolFlags, SymbolFormatFlags, SymbolId, SymbolLinks, symbolName, SymbolTable, SymbolTracker, SymbolVisibilityResult, SyntaxKind, SyntheticDefaultModuleType, SyntheticExpression, TaggedTemplateExpression, TemplateExpression, TemplateLiteralType, TemplateLiteralTypeNode, Ternary, textRangeContainsPositionInclusive, TextSpan, textSpanContainsPosition, textSpanEnd, ThisExpression, ThisTypeNode, ThrowStatement, TokenFlags, tokenToString, tracing, TracingNode, TransientSymbol, TransientSymbolLinks, tryAddToSet, tryCast, tryExtractTSExtension, tryGetClassImplementingOrExtendingExpressionWithTypeArguments, tryGetExtensionFromPath, tryGetJSDocSatisfiesTypeNode, tryGetModuleSpecifierFromDeclaration, tryGetPropertyAccessOrIdentifierToString, TryStatement, TupleType, TupleTypeNode, TupleTypeReference, Type, TypeAliasDeclaration, TypeAssertion, TypeChecker, TypeCheckerHost, TypeComparer, TypeElement, TypeFlags, TypeFormatFlags, TypeId, TypeLiteralNode, TypeMapKind, TypeMapper, TypeNode, TypeNodeSyntaxKind, TypeOfExpression, TypeOnlyAliasDeclaration, TypeOnlyCompatibleAliasDeclaration, TypeOperatorNode, TypeParameter, TypeParameterDeclaration, TypePredicate, TypePredicateKind, TypePredicateNode, TypeQueryNode, TypeReference, TypeReferenceNode, TypeReferenceSerializationKind, TypeReferenceType, TypeVariable, UnaryExpression, UnderscoreEscapedMap, unescapeLeadingUnderscores, UnionOrIntersectionType, UnionOrIntersectionTypeNode, UnionReduction, UnionType, UnionTypeNode, UniqueESSymbolType, usingSingleLineStringWriter, VariableDeclaration, VariableDeclarationList, VariableLikeDeclaration, VariableStatement, VarianceFlags, visitEachChild, visitNode, visitNodes, Visitor, VisitResult, VoidExpression, walkUpBindingElementsAndPatterns, walkUpOuterExpressions, walkUpParenthesizedExpressions, walkUpParenthesizedTypes, walkUpParenthesizedTypesAndGetParentAndChild, WhileStatement, WideningContext, WithStatement, YieldExpression, } from "./_namespaces/ts"; import * as moduleSpecifiers from "./_namespaces/ts.moduleSpecifiers"; import * as performance from "./_namespaces/ts.performance"; const ambientModuleSymbolRegex = /^".+"$/; const anon = "(anonymous)" as __String & string; let nextSymbolId = 1; let nextNodeId = 1; let nextMergeId = 1; let nextFlowId = 1; const enum IterationUse { AllowsSyncIterablesFlag = 1 << 0, AllowsAsyncIterablesFlag = 1 << 1, AllowsStringInputFlag = 1 << 2, ForOfFlag = 1 << 3, YieldStarFlag = 1 << 4, SpreadFlag = 1 << 5, DestructuringFlag = 1 << 6, PossiblyOutOfBounds = 1 << 7, // Spread, Destructuring, Array element assignment Element = AllowsSyncIterablesFlag, Spread = AllowsSyncIterablesFlag | SpreadFlag, Destructuring = AllowsSyncIterablesFlag | DestructuringFlag, ForOf = AllowsSyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, ForAwaitOf = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, YieldStar = AllowsSyncIterablesFlag | YieldStarFlag, AsyncYieldStar = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | YieldStarFlag, GeneratorReturnType = AllowsSyncIterablesFlag, AsyncGeneratorReturnType = AllowsAsyncIterablesFlag, } const enum IterationTypeKind { Yield, Return, Next, } interface IterationTypesResolver { iterableCacheKey: "iterationTypesOfAsyncIterable" | "iterationTypesOfIterable"; iteratorCacheKey: "iterationTypesOfAsyncIterator" | "iterationTypesOfIterator"; iteratorSymbolName: "asyncIterator" | "iterator"; getGlobalIteratorType: (reportErrors: boolean) => GenericType; getGlobalIterableType: (reportErrors: boolean) => GenericType; getGlobalIterableIteratorType: (reportErrors: boolean) => GenericType; getGlobalGeneratorType: (reportErrors: boolean) => GenericType; resolveIterationType: (type: Type, errorNode: Node | undefined) => Type | undefined; mustHaveANextMethodDiagnostic: DiagnosticMessage; mustBeAMethodDiagnostic: DiagnosticMessage; mustHaveAValueDiagnostic: DiagnosticMessage; } const enum WideningKind { Normal, FunctionReturn, GeneratorNext, GeneratorYield, } /** @internal */ export const enum TypeFacts { None = 0, TypeofEQString = 1 << 0, // typeof x === "string" TypeofEQNumber = 1 << 1, // typeof x === "number" TypeofEQBigInt = 1 << 2, // typeof x === "bigint" TypeofEQBoolean = 1 << 3, // typeof x === "boolean" TypeofEQSymbol = 1 << 4, // typeof x === "symbol" TypeofEQObject = 1 << 5, // typeof x === "object" TypeofEQFunction = 1 << 6, // typeof x === "function" TypeofEQHostObject = 1 << 7, // typeof x === "xxx" TypeofNEString = 1 << 8, // typeof x !== "string" TypeofNENumber = 1 << 9, // typeof x !== "number" TypeofNEBigInt = 1 << 10, // typeof x !== "bigint" TypeofNEBoolean = 1 << 11, // typeof x !== "boolean" TypeofNESymbol = 1 << 12, // typeof x !== "symbol" TypeofNEObject = 1 << 13, // typeof x !== "object" TypeofNEFunction = 1 << 14, // typeof x !== "function" TypeofNEHostObject = 1 << 15, // typeof x !== "xxx" EQUndefined = 1 << 16, // x === undefined EQNull = 1 << 17, // x === null EQUndefinedOrNull = 1 << 18, // x === undefined / x === null NEUndefined = 1 << 19, // x !== undefined NENull = 1 << 20, // x !== null NEUndefinedOrNull = 1 << 21, // x != undefined / x != null Truthy = 1 << 22, // x Falsy = 1 << 23, // !x IsUndefined = 1 << 24, // Contains undefined or intersection with undefined IsNull = 1 << 25, // Contains null or intersection with null IsUndefinedOrNull = IsUndefined | IsNull, All = (1 << 27) - 1, // The following members encode facts about particular kinds of types for use in the getTypeFacts function. // The presence of a particular fact means that the given test is true for some (and possibly all) values // of that kind of type. BaseStringStrictFacts = TypeofEQString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, BaseStringFacts = BaseStringStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, StringStrictFacts = BaseStringStrictFacts | Truthy | Falsy, StringFacts = BaseStringFacts | Truthy, EmptyStringStrictFacts = BaseStringStrictFacts | Falsy, EmptyStringFacts = BaseStringFacts, NonEmptyStringStrictFacts = BaseStringStrictFacts | Truthy, NonEmptyStringFacts = BaseStringFacts | Truthy, BaseNumberStrictFacts = TypeofEQNumber | TypeofNEString | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, BaseNumberFacts = BaseNumberStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, NumberStrictFacts = BaseNumberStrictFacts | Truthy | Falsy, NumberFacts = BaseNumberFacts | Truthy, ZeroNumberStrictFacts = BaseNumberStrictFacts | Falsy, ZeroNumberFacts = BaseNumberFacts, NonZeroNumberStrictFacts = BaseNumberStrictFacts | Truthy, NonZeroNumberFacts = BaseNumberFacts | Truthy, BaseBigIntStrictFacts = TypeofEQBigInt | TypeofNEString | TypeofNENumber | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, BaseBigIntFacts = BaseBigIntStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, BigIntStrictFacts = BaseBigIntStrictFacts | Truthy | Falsy, BigIntFacts = BaseBigIntFacts | Truthy, ZeroBigIntStrictFacts = BaseBigIntStrictFacts | Falsy, ZeroBigIntFacts = BaseBigIntFacts, NonZeroBigIntStrictFacts = BaseBigIntStrictFacts | Truthy, NonZeroBigIntFacts = BaseBigIntFacts | Truthy, BaseBooleanStrictFacts = TypeofEQBoolean | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, BaseBooleanFacts = BaseBooleanStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, BooleanStrictFacts = BaseBooleanStrictFacts | Truthy | Falsy, BooleanFacts = BaseBooleanFacts | Truthy, FalseStrictFacts = BaseBooleanStrictFacts | Falsy, FalseFacts = BaseBooleanFacts, TrueStrictFacts = BaseBooleanStrictFacts | Truthy, TrueFacts = BaseBooleanFacts | Truthy, SymbolStrictFacts = TypeofEQSymbol | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, SymbolFacts = SymbolStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, ObjectStrictFacts = TypeofEQObject | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | NEUndefined | NENull | NEUndefinedOrNull | Truthy, ObjectFacts = ObjectStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, FunctionStrictFacts = TypeofEQFunction | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, FunctionFacts = FunctionStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, VoidFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy, UndefinedFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy | IsUndefined, NullFacts = TypeofEQObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | TypeofNEHostObject | EQNull | EQUndefinedOrNull | NEUndefined | Falsy | IsNull, EmptyObjectStrictFacts = All & ~(EQUndefined | EQNull | EQUndefinedOrNull | IsUndefinedOrNull), EmptyObjectFacts = All & ~IsUndefinedOrNull, UnknownFacts = All & ~IsUndefinedOrNull, AllTypeofNE = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | NEUndefined, // Masks OrFactsMask = TypeofEQFunction | TypeofNEObject, AndFactsMask = All & ~OrFactsMask, } const typeofNEFacts: ReadonlyMap = new Map(Object.entries({ string: TypeFacts.TypeofNEString, number: TypeFacts.TypeofNENumber, bigint: TypeFacts.TypeofNEBigInt, boolean: TypeFacts.TypeofNEBoolean, symbol: TypeFacts.TypeofNESymbol, undefined: TypeFacts.NEUndefined, object: TypeFacts.TypeofNEObject, function: TypeFacts.TypeofNEFunction })); type TypeSystemEntity = Node | Symbol | Type | Signature; const enum TypeSystemPropertyName { Type, ResolvedBaseConstructorType, DeclaredType, ResolvedReturnType, ImmediateBaseConstraint, EnumTagType, ResolvedTypeArguments, ResolvedBaseTypes, WriteType, ParameterInitializerContainsUndefined, } /** @internal */ export const enum CheckMode { Normal = 0, // Normal type checking Contextual = 1 << 0, // Explicitly assigned contextual type, therefore not cacheable Inferential = 1 << 1, // Inferential typing SkipContextSensitive = 1 << 2, // Skip context sensitive function expressions SkipGenericFunctions = 1 << 3, // Skip single signature generic functions IsForSignatureHelp = 1 << 4, // Call resolution for purposes of signature help IsForStringLiteralArgumentCompletions = 1 << 5, // Do not infer from the argument currently being typed RestBindingElement = 1 << 6, // Checking a type that is going to be used to determine the type of a rest binding element // e.g. in `const { a, ...rest } = foo`, when checking the type of `foo` to determine the type of `rest`, // we need to preserve generic types instead of substituting them for constraints } /** @internal */ export const enum SignatureCheckMode { None = 0, BivariantCallback = 1 << 0, StrictCallback = 1 << 1, IgnoreReturnTypes = 1 << 2, StrictArity = 1 << 3, StrictTopSignature = 1 << 4, Callback = BivariantCallback | StrictCallback, } const enum IntersectionState { None = 0, Source = 1 << 0, // Source type is a constituent of an outer intersection Target = 1 << 1, // Target type is a constituent of an outer intersection } const enum RecursionFlags { None = 0, Source = 1 << 0, Target = 1 << 1, Both = Source | Target, } const enum MappedTypeModifiers { IncludeReadonly = 1 << 0, ExcludeReadonly = 1 << 1, IncludeOptional = 1 << 2, ExcludeOptional = 1 << 3, } const enum ExpandingFlags { None = 0, Source = 1, Target = 1 << 1, Both = Source | Target, } const enum MembersOrExportsResolutionKind { resolvedExports = "resolvedExports", resolvedMembers = "resolvedMembers" } const enum UnusedKind { Local, Parameter, } /** @param containingNode Node to check for parse error */ type AddUnusedDiagnostic = (containingNode: Node, type: UnusedKind, diagnostic: DiagnosticWithLocation) => void; const isNotOverloadAndNotAccessor = and(isNotOverload, isNotAccessor); const enum DeclarationMeaning { GetAccessor = 1, SetAccessor = 2, PropertyAssignment = 4, Method = 8, PrivateStatic = 16, GetOrSetAccessor = GetAccessor | SetAccessor, PropertyAssignmentOrMethod = PropertyAssignment | Method, } const enum DeclarationSpaces { None = 0, ExportValue = 1 << 0, ExportType = 1 << 1, ExportNamespace = 1 << 2, } const enum MinArgumentCountFlags { None = 0, StrongArityForUntypedJS = 1 << 0, VoidIsNonOptional = 1 << 1, } const enum IntrinsicTypeKind { Uppercase, Lowercase, Capitalize, Uncapitalize } const intrinsicTypeKinds: ReadonlyMap = new Map(Object.entries({ Uppercase: IntrinsicTypeKind.Uppercase, Lowercase: IntrinsicTypeKind.Lowercase, Capitalize: IntrinsicTypeKind.Capitalize, Uncapitalize: IntrinsicTypeKind.Uncapitalize })); const SymbolLinks = class implements SymbolLinks { declare _symbolLinksBrand: any; }; function NodeLinks(this: NodeLinks) { this.flags = NodeCheckFlags.None; } /** @internal */ export function getNodeId(node: Node): number { if (!node.id) { node.id = nextNodeId; nextNodeId++; } return node.id; } /** @internal */ export function getSymbolId(symbol: Symbol): SymbolId { if (!symbol.id) { symbol.id = nextSymbolId; nextSymbolId++; } return symbol.id; } /** @internal */ export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums: boolean) { const moduleState = getModuleInstanceState(node); return moduleState === ModuleInstanceState.Instantiated || (preserveConstEnums && moduleState === ModuleInstanceState.ConstEnumOnly); } /** @internal */ export function createTypeChecker(host: TypeCheckerHost): TypeChecker { // Why var? It avoids TDZ checks in the runtime which can be costly. // See: https://github.com/microsoft/TypeScript/issues/52924 /* eslint-disable no-var */ var getPackagesMap = memoize(() => { // A package name maps to true when we detect it has .d.ts files. // This is useful as an approximation of whether a package bundles its own types. // Note: we only look at files already found by module resolution, // so there may be files we did not consider. var map = new Map(); host.getSourceFiles().forEach(sf => { if (!sf.resolvedModules) return; sf.resolvedModules.forEach(({ resolvedModule }) => { if (resolvedModule?.packageId) map.set(resolvedModule.packageId.name, resolvedModule.extension === Extension.Dts || !!map.get(resolvedModule.packageId.name)); }); }); return map; }); var deferredDiagnosticsCallbacks: (() => void)[] = []; var addLazyDiagnostic = (arg: () => void) => { deferredDiagnosticsCallbacks.push(arg); }; // Cancellation that controls whether or not we can cancel in the middle of type checking. // In general cancelling is *not* safe for the type checker. We might be in the middle of // computing something, and we will leave our internals in an inconsistent state. Callers // who set the cancellation token should catch if a cancellation exception occurs, and // should throw away and create a new TypeChecker. // // Currently we only support setting the cancellation token when getting diagnostics. This // is because diagnostics can be quite expensive, and we want to allow hosts to bail out if // they no longer need the information (for example, if the user started editing again). var cancellationToken: CancellationToken | undefined; var requestedExternalEmitHelperNames = new Set(); var requestedExternalEmitHelpers: ExternalEmitHelpers; var externalHelpersModule: Symbol; var Symbol = objectAllocator.getSymbolConstructor(); var Type = objectAllocator.getTypeConstructor(); var Signature = objectAllocator.getSignatureConstructor(); var typeCount = 0; var symbolCount = 0; var totalInstantiationCount = 0; var instantiationCount = 0; var instantiationDepth = 0; var inlineLevel = 0; var currentNode: Node | undefined; var varianceTypeParameter: TypeParameter | undefined; var isInferencePartiallyBlocked = false; var emptySymbols = createSymbolTable(); var arrayVariances = [VarianceFlags.Covariant]; var compilerOptions = host.getCompilerOptions(); var languageVersion = getEmitScriptTarget(compilerOptions); var moduleKind = getEmitModuleKind(compilerOptions); var legacyDecorators = !!compilerOptions.experimentalDecorators; var useDefineForClassFields = getUseDefineForClassFields(compilerOptions); var allowSyntheticDefaultImports = getAllowSyntheticDefaultImports(compilerOptions); var strictNullChecks = getStrictOptionValue(compilerOptions, "strictNullChecks"); var strictFunctionTypes = getStrictOptionValue(compilerOptions, "strictFunctionTypes"); var strictBindCallApply = getStrictOptionValue(compilerOptions, "strictBindCallApply"); var strictPropertyInitialization = getStrictOptionValue(compilerOptions, "strictPropertyInitialization"); var noImplicitAny = getStrictOptionValue(compilerOptions, "noImplicitAny"); var noImplicitThis = getStrictOptionValue(compilerOptions, "noImplicitThis"); var useUnknownInCatchVariables = getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables"); var keyofStringsOnly = !!compilerOptions.keyofStringsOnly; var freshObjectLiteralFlag = compilerOptions.suppressExcessPropertyErrors ? 0 : ObjectFlags.FreshLiteral; var exactOptionalPropertyTypes = compilerOptions.exactOptionalPropertyTypes; var checkBinaryExpression = createCheckBinaryExpression(); var emitResolver = createResolver(); var nodeBuilder = createNodeBuilder(); var globals = createSymbolTable(); var undefinedSymbol = createSymbol(SymbolFlags.Property, "undefined" as __String); undefinedSymbol.declarations = []; var globalThisSymbol = createSymbol(SymbolFlags.Module, "globalThis" as __String, CheckFlags.Readonly); globalThisSymbol.exports = globals; globalThisSymbol.declarations = []; globals.set(globalThisSymbol.escapedName, globalThisSymbol); var argumentsSymbol = createSymbol(SymbolFlags.Property, "arguments" as __String); var requireSymbol = createSymbol(SymbolFlags.Property, "require" as __String); var isolatedModulesLikeFlagName = compilerOptions.verbatimModuleSyntax ? "verbatimModuleSyntax" : "isolatedModules"; /** This will be set during calls to `getResolvedSignature` where services determines an apparent number of arguments greater than what is actually provided. */ var apparentArgumentCount: number | undefined; // for public members that accept a Node or one of its subtypes, we must guard against // synthetic nodes created during transformations by calling `getParseTreeNode`. // for most of these, we perform the guard only on `checker` to avoid any possible // extra cost of calling `getParseTreeNode` when calling these functions from inside the // checker. const checker: TypeChecker = { getNodeCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.nodeCount, 0), getIdentifierCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.identifierCount, 0), getSymbolCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.symbolCount, symbolCount), getTypeCount: () => typeCount, getInstantiationCount: () => totalInstantiationCount, getRelationCacheSizes: () => ({ assignable: assignableRelation.size, identity: identityRelation.size, subtype: subtypeRelation.size, strictSubtype: strictSubtypeRelation.size, }), isUndefinedSymbol: symbol => symbol === undefinedSymbol, isArgumentsSymbol: symbol => symbol === argumentsSymbol, isUnknownSymbol: symbol => symbol === unknownSymbol, getMergedSymbol, getDiagnostics, getGlobalDiagnostics, getRecursionIdentity, getUnmatchedProperties, getTypeOfSymbolAtLocation: (symbol, locationIn) => { const location = getParseTreeNode(locationIn); return location ? getTypeOfSymbolAtLocation(symbol, location) : errorType; }, getTypeOfSymbol, getSymbolsOfParameterPropertyDeclaration: (parameterIn, parameterName) => { const parameter = getParseTreeNode(parameterIn, isParameter); if (parameter === undefined) return Debug.fail("Cannot get symbols of a synthetic parameter that cannot be resolved to a parse-tree node."); Debug.assert(isParameterPropertyDeclaration(parameter, parameter.parent)); return getSymbolsOfParameterPropertyDeclaration(parameter, escapeLeadingUnderscores(parameterName)); }, getDeclaredTypeOfSymbol, getPropertiesOfType, getPropertyOfType: (type, name) => getPropertyOfType(type, escapeLeadingUnderscores(name)), getPrivateIdentifierPropertyOfType: (leftType: Type, name: string, location: Node) => { const node = getParseTreeNode(location); if (!node) { return undefined; } const propName = escapeLeadingUnderscores(name); const lexicallyScopedIdentifier = lookupSymbolForPrivateIdentifierDeclaration(propName, node); return lexicallyScopedIdentifier ? getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedIdentifier) : undefined; }, getTypeOfPropertyOfType: (type, name) => getTypeOfPropertyOfType(type, escapeLeadingUnderscores(name)), getIndexInfoOfType: (type, kind) => getIndexInfoOfType(type, kind === IndexKind.String ? stringType : numberType), getIndexInfosOfType, getIndexInfosOfIndexSymbol, getSignaturesOfType, getIndexTypeOfType: (type, kind) => getIndexTypeOfType(type, kind === IndexKind.String ? stringType : numberType), getIndexType: type => getIndexType(type), getBaseTypes, getBaseTypeOfLiteralType, getWidenedType, getTypeFromTypeNode: nodeIn => { const node = getParseTreeNode(nodeIn, isTypeNode); return node ? getTypeFromTypeNode(node) : errorType; }, getParameterType: getTypeAtPosition, getParameterIdentifierNameAtPosition, getPromisedTypeOfPromise, getAwaitedType: type => getAwaitedType(type), getReturnTypeOfSignature, isNullableType, getNullableType, getNonNullableType, getNonOptionalType: removeOptionalTypeMarker, getTypeArguments, typeToTypeNode: nodeBuilder.typeToTypeNode, indexInfoToIndexSignatureDeclaration: nodeBuilder.indexInfoToIndexSignatureDeclaration, signatureToSignatureDeclaration: nodeBuilder.signatureToSignatureDeclaration, symbolToEntityName: nodeBuilder.symbolToEntityName, symbolToExpression: nodeBuilder.symbolToExpression, symbolToNode: nodeBuilder.symbolToNode, symbolToTypeParameterDeclarations: nodeBuilder.symbolToTypeParameterDeclarations, symbolToParameterDeclaration: nodeBuilder.symbolToParameterDeclaration, typeParameterToDeclaration: nodeBuilder.typeParameterToDeclaration, getSymbolsInScope: (locationIn, meaning) => { const location = getParseTreeNode(locationIn); return location ? getSymbolsInScope(location, meaning) : []; }, getSymbolAtLocation: nodeIn => { const node = getParseTreeNode(nodeIn); // set ignoreErrors: true because any lookups invoked by the API shouldn't cause any new errors return node ? getSymbolAtLocation(node, /*ignoreErrors*/ true) : undefined; }, getIndexInfosAtLocation: nodeIn => { const node = getParseTreeNode(nodeIn); return node ? getIndexInfosAtLocation(node) : undefined; }, getShorthandAssignmentValueSymbol: nodeIn => { const node = getParseTreeNode(nodeIn); return node ? getShorthandAssignmentValueSymbol(node) : undefined; }, getExportSpecifierLocalTargetSymbol: nodeIn => { const node = getParseTreeNode(nodeIn, isExportSpecifier); return node ? getExportSpecifierLocalTargetSymbol(node) : undefined; }, getExportSymbolOfSymbol(symbol) { return getMergedSymbol(symbol.exportSymbol || symbol); }, getTypeAtLocation: nodeIn => { const node = getParseTreeNode(nodeIn); return node ? getTypeOfNode(node) : errorType; }, getTypeOfAssignmentPattern: nodeIn => { const node = getParseTreeNode(nodeIn, isAssignmentPattern); return node && getTypeOfAssignmentPattern(node) || errorType; }, getPropertySymbolOfDestructuringAssignment: locationIn => { const location = getParseTreeNode(locationIn, isIdentifier); return location ? getPropertySymbolOfDestructuringAssignment(location) : undefined; }, signatureToString: (signature, enclosingDeclaration, flags, kind) => { return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind); }, typeToString: (type, enclosingDeclaration, flags) => { return typeToString(type, getParseTreeNode(enclosingDeclaration), flags); }, symbolToString: (symbol, enclosingDeclaration, meaning, flags) => { return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags); }, typePredicateToString: (predicate, enclosingDeclaration, flags) => { return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags); }, writeSignature: (signature, enclosingDeclaration, flags, kind, writer) => { return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind, writer); }, writeType: (type, enclosingDeclaration, flags, writer) => { return typeToString(type, getParseTreeNode(enclosingDeclaration), flags, writer); }, writeSymbol: (symbol, enclosingDeclaration, meaning, flags, writer) => { return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags, writer); }, writeTypePredicate: (predicate, enclosingDeclaration, flags, writer) => { return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags, writer); }, getAugmentedPropertiesOfType, getRootSymbols, getSymbolOfExpando, getContextualType: (nodeIn: Expression, contextFlags?: ContextFlags) => { const node = getParseTreeNode(nodeIn, isExpression); if (!node) { return undefined; } if (contextFlags! & ContextFlags.Completions) { return runWithInferenceBlockedFromSourceNode(node, () => getContextualType(node, contextFlags)); } return getContextualType(node, contextFlags); }, getContextualTypeForObjectLiteralElement: nodeIn => { const node = getParseTreeNode(nodeIn, isObjectLiteralElementLike); return node ? getContextualTypeForObjectLiteralElement(node, /*contextFlags*/ undefined) : undefined; }, getContextualTypeForArgumentAtIndex: (nodeIn, argIndex) => { const node = getParseTreeNode(nodeIn, isCallLikeExpression); return node && getContextualTypeForArgumentAtIndex(node, argIndex); }, getContextualTypeForJsxAttribute: (nodeIn) => { const node = getParseTreeNode(nodeIn, isJsxAttributeLike); return node && getContextualTypeForJsxAttribute(node, /*contextFlags*/ undefined); }, isContextSensitive, getTypeOfPropertyOfContextualType, getFullyQualifiedName, getResolvedSignature: (node, candidatesOutArray, argumentCount) => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.Normal), getResolvedSignatureForStringLiteralCompletions: (call, editingArgument, candidatesOutArray) => runWithInferenceBlockedFromSourceNode(editingArgument, () => getResolvedSignatureWorker(call, candidatesOutArray, /*argumentCount*/ undefined, CheckMode.IsForStringLiteralArgumentCompletions)), getResolvedSignatureForSignatureHelp: (node, candidatesOutArray, argumentCount) => runWithoutResolvedSignatureCaching(node, () => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.IsForSignatureHelp)), getExpandedParameters, hasEffectiveRestParameter, containsArgumentsReference, getConstantValue: nodeIn => { const node = getParseTreeNode(nodeIn, canHaveConstantValue); return node ? getConstantValue(node) : undefined; }, isValidPropertyAccess: (nodeIn, propertyName) => { const node = getParseTreeNode(nodeIn, isPropertyAccessOrQualifiedNameOrImportTypeNode); return !!node && isValidPropertyAccess(node, escapeLeadingUnderscores(propertyName)); }, isValidPropertyAccessForCompletions: (nodeIn, type, property) => { const node = getParseTreeNode(nodeIn, isPropertyAccessExpression); return !!node && isValidPropertyAccessForCompletions(node, type, property); }, getSignatureFromDeclaration: declarationIn => { const declaration = getParseTreeNode(declarationIn, isFunctionLike); return declaration ? getSignatureFromDeclaration(declaration) : undefined; }, isImplementationOfOverload: nodeIn => { const node = getParseTreeNode(nodeIn, isFunctionLike); return node ? isImplementationOfOverload(node) : undefined; }, getImmediateAliasedSymbol, getAliasedSymbol: resolveAlias, getEmitResolver, getExportsOfModule: getExportsOfModuleAsArray, getExportsAndPropertiesOfModule, forEachExportAndPropertyOfModule, getSymbolWalker: createGetSymbolWalker( getRestTypeOfSignature, getTypePredicateOfSignature, getReturnTypeOfSignature, getBaseTypes, resolveStructuredTypeMembers, getTypeOfSymbol, getResolvedSymbol, getConstraintOfTypeParameter, getFirstIdentifier, getTypeArguments, ), getAmbientModules, getJsxIntrinsicTagNamesAt, isOptionalParameter: nodeIn => { const node = getParseTreeNode(nodeIn, isParameter); return node ? isOptionalParameter(node) : false; }, tryGetMemberInModuleExports: (name, symbol) => tryGetMemberInModuleExports(escapeLeadingUnderscores(name), symbol), tryGetMemberInModuleExportsAndProperties: (name, symbol) => tryGetMemberInModuleExportsAndProperties(escapeLeadingUnderscores(name), symbol), tryFindAmbientModule: moduleName => tryFindAmbientModule(moduleName, /*withAugmentations*/ true), tryFindAmbientModuleWithoutAugmentations: moduleName => { // we deliberately exclude augmentations // since we are only interested in declarations of the module itself return tryFindAmbientModule(moduleName, /*withAugmentations*/ false); }, getApparentType, getUnionType, isTypeAssignableTo, createAnonymousType, createSignature, createSymbol, createIndexInfo, getAnyType: () => anyType, getStringType: () => stringType, getNumberType: () => numberType, createPromiseType, createArrayType, getElementTypeOfArrayType, getBooleanType: () => booleanType, getFalseType: (fresh?) => fresh ? falseType : regularFalseType, getTrueType: (fresh?) => fresh ? trueType : regularTrueType, getVoidType: () => voidType, getUndefinedType: () => undefinedType, getNullType: () => nullType, getESSymbolType: () => esSymbolType, getNeverType: () => neverType, getOptionalType: () => optionalType, getPromiseType: () => getGlobalPromiseType(/*reportErrors*/ false), getPromiseLikeType: () => getGlobalPromiseLikeType(/*reportErrors*/ false), getAsyncIterableType: () => { const type = getGlobalAsyncIterableType(/*reportErrors*/ false); if (type === emptyGenericType) return undefined; return type; }, isSymbolAccessible, isArrayType, isTupleType, isArrayLikeType, isEmptyAnonymousObjectType, isTypeInvalidDueToUnionDiscriminant, getExactOptionalProperties, getAllPossiblePropertiesOfTypes, getSuggestedSymbolForNonexistentProperty, getSuggestionForNonexistentProperty, getSuggestedSymbolForNonexistentJSXAttribute, getSuggestedSymbolForNonexistentSymbol: (location, name, meaning) => getSuggestedSymbolForNonexistentSymbol(location, escapeLeadingUnderscores(name), meaning), getSuggestionForNonexistentSymbol: (location, name, meaning) => getSuggestionForNonexistentSymbol(location, escapeLeadingUnderscores(name), meaning), getSuggestedSymbolForNonexistentModule, getSuggestionForNonexistentExport, getSuggestedSymbolForNonexistentClassMember, getBaseConstraintOfType, getDefaultFromTypeParameter: type => type && type.flags & TypeFlags.TypeParameter ? getDefaultFromTypeParameter(type as TypeParameter) : undefined, resolveName(name, location, meaning, excludeGlobals) { return resolveName(location, escapeLeadingUnderscores(name), meaning, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ false, excludeGlobals); }, getJsxNamespace: n => unescapeLeadingUnderscores(getJsxNamespace(n)), getJsxFragmentFactory: n => { const jsxFragmentFactory = getJsxFragmentFactoryEntity(n); return jsxFragmentFactory && unescapeLeadingUnderscores(getFirstIdentifier(jsxFragmentFactory).escapedText); }, getAccessibleSymbolChain, getTypePredicateOfSignature, resolveExternalModuleName: moduleSpecifierIn => { const moduleSpecifier = getParseTreeNode(moduleSpecifierIn, isExpression); return moduleSpecifier && resolveExternalModuleName(moduleSpecifier, moduleSpecifier, /*ignoreErrors*/ true); }, resolveExternalModuleSymbol, tryGetThisTypeAt: (nodeIn, includeGlobalThis, container) => { const node = getParseTreeNode(nodeIn); return node && tryGetThisTypeAt(node, includeGlobalThis, container); }, getTypeArgumentConstraint: nodeIn => { const node = getParseTreeNode(nodeIn, isTypeNode); return node && getTypeArgumentConstraint(node); }, getSuggestionDiagnostics: (fileIn, ct) => { const file = getParseTreeNode(fileIn, isSourceFile) || Debug.fail("Could not determine parsed source file."); if (skipTypeChecking(file, compilerOptions, host)) { return emptyArray; } let diagnostics: DiagnosticWithLocation[] | undefined; try { // Record the cancellation token so it can be checked later on during checkSourceElement. // Do this in a finally block so we can ensure that it gets reset back to nothing after // this call is done. cancellationToken = ct; // Ensure file is type checked, with _eager_ diagnostic production, so identifiers are registered as potentially unused checkSourceFileWithEagerDiagnostics(file); Debug.assert(!!(getNodeLinks(file).flags & NodeCheckFlags.TypeChecked)); diagnostics = addRange(diagnostics, suggestionDiagnostics.getDiagnostics(file.fileName)); checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(file), (containingNode, kind, diag) => { if (!containsParseError(containingNode) && !unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { (diagnostics || (diagnostics = [])).push({ ...diag, category: DiagnosticCategory.Suggestion }); } }); return diagnostics || emptyArray; } finally { cancellationToken = undefined; } }, runWithCancellationToken: (token, callback) => { try { cancellationToken = token; return callback(checker); } finally { cancellationToken = undefined; } }, getLocalTypeParametersOfClassOrInterfaceOrTypeAlias, isDeclarationVisible, isPropertyAccessible, getTypeOnlyAliasDeclaration, getMemberOverrideModifierStatus, isTypeParameterPossiblyReferenced, typeHasCallOrConstructSignatures, }; function runWithoutResolvedSignatureCaching(node: Node | undefined, fn: () => T): T { const containingCall = findAncestor(node, isCallLikeExpression); const containingCallResolvedSignature = containingCall && getNodeLinks(containingCall).resolvedSignature; if (containingCall) { getNodeLinks(containingCall).resolvedSignature = undefined; } const result = fn(); if (containingCall) { getNodeLinks(containingCall).resolvedSignature = containingCallResolvedSignature; } return result; } function runWithInferenceBlockedFromSourceNode(node: Node | undefined, fn: () => T): T { const containingCall = findAncestor(node, isCallLikeExpression); if (containingCall) { let toMarkSkip = node!; do { getNodeLinks(toMarkSkip).skipDirectInference = true; toMarkSkip = toMarkSkip.parent; } while (toMarkSkip && toMarkSkip !== containingCall); } isInferencePartiallyBlocked = true; const result = runWithoutResolvedSignatureCaching(node, fn); isInferencePartiallyBlocked = false; if (containingCall) { let toMarkSkip = node!; do { getNodeLinks(toMarkSkip).skipDirectInference = undefined; toMarkSkip = toMarkSkip.parent; } while (toMarkSkip && toMarkSkip !== containingCall); } return result; } function getResolvedSignatureWorker(nodeIn: CallLikeExpression, candidatesOutArray: Signature[] | undefined, argumentCount: number | undefined, checkMode: CheckMode): Signature | undefined { const node = getParseTreeNode(nodeIn, isCallLikeExpression); apparentArgumentCount = argumentCount; const res = !node ? undefined : getResolvedSignature(node, candidatesOutArray, checkMode); apparentArgumentCount = undefined; return res; } var tupleTypes = new Map(); var unionTypes = new Map(); var intersectionTypes = new Map(); var stringLiteralTypes = new Map(); var numberLiteralTypes = new Map(); var bigIntLiteralTypes = new Map(); var enumLiteralTypes = new Map(); var indexedAccessTypes = new Map(); var templateLiteralTypes = new Map(); var stringMappingTypes = new Map(); var substitutionTypes = new Map(); var subtypeReductionCache = new Map(); var decoratorContextOverrideTypeCache = new Map(); var cachedTypes = new Map(); var evolvingArrayTypes: EvolvingArrayType[] = []; var undefinedProperties: SymbolTable = new Map(); var markerTypes = new Set(); var unknownSymbol = createSymbol(SymbolFlags.Property, "unknown" as __String); var resolvingSymbol = createSymbol(0, InternalSymbolName.Resolving); var unresolvedSymbols = new Map(); var errorTypes = new Map(); // We specifically create the `undefined` and `null` types before any other types that can occur in // unions such that they are given low type IDs and occur first in the sorted list of union constituents. // We can then just examine the first constituent(s) of a union to check for their presence. var anyType = createIntrinsicType(TypeFlags.Any, "any"); var autoType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.NonInferrableType); var wildcardType = createIntrinsicType(TypeFlags.Any, "any"); var errorType = createIntrinsicType(TypeFlags.Any, "error"); var unresolvedType = createIntrinsicType(TypeFlags.Any, "unresolved"); var nonInferrableAnyType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.ContainsWideningType); var intrinsicMarkerType = createIntrinsicType(TypeFlags.Any, "intrinsic"); var unknownType = createIntrinsicType(TypeFlags.Unknown, "unknown"); var nonNullUnknownType = createIntrinsicType(TypeFlags.Unknown, "unknown"); var undefinedType = createIntrinsicType(TypeFlags.Undefined, "undefined"); var undefinedWideningType = strictNullChecks ? undefinedType : createIntrinsicType(TypeFlags.Undefined, "undefined", ObjectFlags.ContainsWideningType); var missingType = createIntrinsicType(TypeFlags.Undefined, "undefined"); var undefinedOrMissingType = exactOptionalPropertyTypes ? missingType : undefinedType; var optionalType = createIntrinsicType(TypeFlags.Undefined, "undefined"); var nullType = createIntrinsicType(TypeFlags.Null, "null"); var nullWideningType = strictNullChecks ? nullType : createIntrinsicType(TypeFlags.Null, "null", ObjectFlags.ContainsWideningType); var stringType = createIntrinsicType(TypeFlags.String, "string"); var numberType = createIntrinsicType(TypeFlags.Number, "number"); var bigintType = createIntrinsicType(TypeFlags.BigInt, "bigint"); var falseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false") as FreshableIntrinsicType; var regularFalseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false") as FreshableIntrinsicType; var trueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true") as FreshableIntrinsicType; var regularTrueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true") as FreshableIntrinsicType; trueType.regularType = regularTrueType; trueType.freshType = trueType; regularTrueType.regularType = regularTrueType; regularTrueType.freshType = trueType; falseType.regularType = regularFalseType; falseType.freshType = falseType; regularFalseType.regularType = regularFalseType; regularFalseType.freshType = falseType; var booleanType = getUnionType([regularFalseType, regularTrueType]); var esSymbolType = createIntrinsicType(TypeFlags.ESSymbol, "symbol"); var voidType = createIntrinsicType(TypeFlags.Void, "void"); var neverType = createIntrinsicType(TypeFlags.Never, "never"); var silentNeverType = createIntrinsicType(TypeFlags.Never, "never", ObjectFlags.NonInferrableType); var implicitNeverType = createIntrinsicType(TypeFlags.Never, "never"); var unreachableNeverType = createIntrinsicType(TypeFlags.Never, "never"); var nonPrimitiveType = createIntrinsicType(TypeFlags.NonPrimitive, "object"); var stringOrNumberType = getUnionType([stringType, numberType]); var stringNumberSymbolType = getUnionType([stringType, numberType, esSymbolType]); var keyofConstraintType = keyofStringsOnly ? stringType : stringNumberSymbolType; var numberOrBigIntType = getUnionType([numberType, bigintType]); var templateConstraintType = getUnionType([stringType, numberType, booleanType, bigintType, nullType, undefinedType]) as UnionType; var numericStringType = getTemplateLiteralType(["", ""], [numberType]); // The `${number}` type var restrictiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? getRestrictiveTypeParameter(t as TypeParameter) : t, () => "(restrictive mapper)"); var permissiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? wildcardType : t, () => "(permissive mapper)"); var uniqueLiteralType = createIntrinsicType(TypeFlags.Never, "never"); // `uniqueLiteralType` is a special `never` flagged by union reduction to behave as a literal var uniqueLiteralMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? uniqueLiteralType : t, () => "(unique literal mapper)"); // replace all type parameters with the unique literal type (disregarding constraints) var outofbandVarianceMarkerHandler: ((onlyUnreliable: boolean) => void) | undefined; var reportUnreliableMapper = makeFunctionTypeMapper(t => { if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { outofbandVarianceMarkerHandler(/*onlyUnreliable*/ true); } return t; }, () => "(unmeasurable reporter)"); var reportUnmeasurableMapper = makeFunctionTypeMapper(t => { if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { outofbandVarianceMarkerHandler(/*onlyUnreliable*/ false); } return t; }, () => "(unreliable reporter)"); var emptyObjectType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); var emptyJsxObjectType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); emptyJsxObjectType.objectFlags |= ObjectFlags.JsxAttributes; var emptyTypeLiteralSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); emptyTypeLiteralSymbol.members = createSymbolTable(); var emptyTypeLiteralType = createAnonymousType(emptyTypeLiteralSymbol, emptySymbols, emptyArray, emptyArray, emptyArray); var unknownEmptyObjectType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); var unknownUnionType = strictNullChecks ? getUnionType([undefinedType, nullType, unknownEmptyObjectType]) : unknownType; var emptyGenericType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray) as ObjectType as GenericType; emptyGenericType.instantiations = new Map(); var anyFunctionType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); // The anyFunctionType contains the anyFunctionType by definition. The flag is further propagated // in getPropagatingFlagsOfTypes, and it is checked in inferFromTypes. anyFunctionType.objectFlags |= ObjectFlags.NonInferrableType; var noConstraintType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); var circularConstraintType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); var resolvingDefaultType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); var markerSuperType = createTypeParameter(); var markerSubType = createTypeParameter(); markerSubType.constraint = markerSuperType; var markerOtherType = createTypeParameter(); var markerSuperTypeForCheck = createTypeParameter(); var markerSubTypeForCheck = createTypeParameter(); markerSubTypeForCheck.constraint = markerSuperTypeForCheck; var noTypePredicate = createTypePredicate(TypePredicateKind.Identifier, "<>", 0, anyType); var anySignature = createSignature(undefined, undefined, undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); var unknownSignature = createSignature(undefined, undefined, undefined, emptyArray, errorType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); var resolvingSignature = createSignature(undefined, undefined, undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); var silentNeverSignature = createSignature(undefined, undefined, undefined, emptyArray, silentNeverType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); var enumNumberIndexInfo = createIndexInfo(numberType, stringType, /*isReadonly*/ true); var iterationTypesCache = new Map(); // cache for common IterationTypes instances var noIterationTypes: IterationTypes = { get yieldType(): Type { return Debug.fail("Not supported"); }, get returnType(): Type { return Debug.fail("Not supported"); }, get nextType(): Type { return Debug.fail("Not supported"); }, }; var anyIterationTypes = createIterationTypes(anyType, anyType, anyType); var anyIterationTypesExceptNext = createIterationTypes(anyType, anyType, unknownType); var defaultIterationTypes = createIterationTypes(neverType, anyType, undefinedType); // default iteration types for `Iterator`. var asyncIterationTypesResolver: IterationTypesResolver = { iterableCacheKey: "iterationTypesOfAsyncIterable", iteratorCacheKey: "iterationTypesOfAsyncIterator", iteratorSymbolName: "asyncIterator", getGlobalIteratorType: getGlobalAsyncIteratorType, getGlobalIterableType: getGlobalAsyncIterableType, getGlobalIterableIteratorType: getGlobalAsyncIterableIteratorType, getGlobalGeneratorType: getGlobalAsyncGeneratorType, resolveIterationType: getAwaitedType, mustHaveANextMethodDiagnostic: Diagnostics.An_async_iterator_must_have_a_next_method, mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_async_iterator_must_be_a_method, mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_async_iterator_must_be_a_promise_for_a_type_with_a_value_property, }; var syncIterationTypesResolver: IterationTypesResolver = { iterableCacheKey: "iterationTypesOfIterable", iteratorCacheKey: "iterationTypesOfIterator", iteratorSymbolName: "iterator", getGlobalIteratorType, getGlobalIterableType, getGlobalIterableIteratorType, getGlobalGeneratorType, resolveIterationType: (type, _errorNode) => type, mustHaveANextMethodDiagnostic: Diagnostics.An_iterator_must_have_a_next_method, mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_iterator_must_be_a_method, mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_iterator_must_have_a_value_property, }; interface DuplicateInfoForSymbol { readonly firstFileLocations: Declaration[]; readonly secondFileLocations: Declaration[]; readonly isBlockScoped: boolean; } interface DuplicateInfoForFiles { readonly firstFile: SourceFile; readonly secondFile: SourceFile; /** Key is symbol name. */ readonly conflictingSymbols: Map; } /** Key is "/path/to/a.ts|/path/to/b.ts". */ var amalgamatedDuplicates: Map | undefined; var reverseMappedCache = new Map(); var inInferTypeForHomomorphicMappedType = false; var ambientModulesCache: Symbol[] | undefined; /** * List of every ambient module with a "*" wildcard. * Unlike other ambient modules, these can't be stored in `globals` because symbol tables only deal with exact matches. * This is only used if there is no exact match. */ var patternAmbientModules: PatternAmbientModule[]; var patternAmbientModuleAugmentations: Map | undefined; var globalObjectType: ObjectType; var globalFunctionType: ObjectType; var globalCallableFunctionType: ObjectType; var globalNewableFunctionType: ObjectType; var globalArrayType: GenericType; var globalReadonlyArrayType: GenericType; var globalStringType: ObjectType; var globalNumberType: ObjectType; var globalBooleanType: ObjectType; var globalRegExpType: ObjectType; var globalThisType: GenericType; var anyArrayType: Type; var autoArrayType: Type; var anyReadonlyArrayType: Type; var deferredGlobalNonNullableTypeAlias: Symbol; // The library files are only loaded when the feature is used. // This allows users to just specify library files they want to used through --lib // and they will not get an error from not having unrelated library files var deferredGlobalESSymbolConstructorSymbol: Symbol | undefined; var deferredGlobalESSymbolConstructorTypeSymbol: Symbol | undefined; var deferredGlobalESSymbolType: ObjectType | undefined; var deferredGlobalTypedPropertyDescriptorType: GenericType; var deferredGlobalPromiseType: GenericType | undefined; var deferredGlobalPromiseLikeType: GenericType | undefined; var deferredGlobalPromiseConstructorSymbol: Symbol | undefined; var deferredGlobalPromiseConstructorLikeType: ObjectType | undefined; var deferredGlobalIterableType: GenericType | undefined; var deferredGlobalIteratorType: GenericType | undefined; var deferredGlobalIterableIteratorType: GenericType | undefined; var deferredGlobalGeneratorType: GenericType | undefined; var deferredGlobalIteratorYieldResultType: GenericType | undefined; var deferredGlobalIteratorReturnResultType: GenericType | undefined; var deferredGlobalAsyncIterableType: GenericType | undefined; var deferredGlobalAsyncIteratorType: GenericType | undefined; var deferredGlobalAsyncIterableIteratorType: GenericType | undefined; var deferredGlobalAsyncGeneratorType: GenericType | undefined; var deferredGlobalTemplateStringsArrayType: ObjectType | undefined; var deferredGlobalImportMetaType: ObjectType; var deferredGlobalImportMetaExpressionType: ObjectType; var deferredGlobalImportCallOptionsType: ObjectType | undefined; var deferredGlobalExtractSymbol: Symbol | undefined; var deferredGlobalOmitSymbol: Symbol | undefined; var deferredGlobalAwaitedSymbol: Symbol | undefined; var deferredGlobalBigIntType: ObjectType | undefined; var deferredGlobalNaNSymbol: Symbol | undefined; var deferredGlobalRecordSymbol: Symbol | undefined; var deferredGlobalClassDecoratorContextType: GenericType | undefined; var deferredGlobalClassMethodDecoratorContextType: GenericType | undefined; var deferredGlobalClassGetterDecoratorContextType: GenericType | undefined; var deferredGlobalClassSetterDecoratorContextType: GenericType | undefined; var deferredGlobalClassAccessorDecoratorContextType: GenericType | undefined; var deferredGlobalClassAccessorDecoratorTargetType: GenericType | undefined; var deferredGlobalClassAccessorDecoratorResultType: GenericType | undefined; var deferredGlobalClassFieldDecoratorContextType: GenericType | undefined; var allPotentiallyUnusedIdentifiers = new Map(); // key is file name var flowLoopStart = 0; var flowLoopCount = 0; var sharedFlowCount = 0; var flowAnalysisDisabled = false; var flowInvocationCount = 0; var lastFlowNode: FlowNode | undefined; var lastFlowNodeReachable: boolean; var flowTypeCache: Type[] | undefined; var contextualTypeNodes: Node[] = []; var contextualTypes: (Type | undefined)[] = []; var contextualIsCache: boolean[] = []; var contextualTypeCount = 0; var inferenceContextNodes: Node[] = []; var inferenceContexts: (InferenceContext | undefined)[] = []; var inferenceContextCount = 0; var emptyStringType = getStringLiteralType(""); var zeroType = getNumberLiteralType(0); var zeroBigIntType = getBigIntLiteralType({ negative: false, base10Value: "0" }); var resolutionTargets: TypeSystemEntity[] = []; var resolutionResults: boolean[] = []; var resolutionPropertyNames: TypeSystemPropertyName[] = []; var suggestionCount = 0; var maximumSuggestionCount = 10; var mergedSymbols: Symbol[] = []; var symbolLinks: SymbolLinks[] = []; var nodeLinks: NodeLinks[] = []; var flowLoopCaches: Map[] = []; var flowLoopNodes: FlowNode[] = []; var flowLoopKeys: string[] = []; var flowLoopTypes: Type[][] = []; var sharedFlowNodes: FlowNode[] = []; var sharedFlowTypes: FlowType[] = []; var flowNodeReachable: (boolean | undefined)[] = []; var flowNodePostSuper: (boolean | undefined)[] = []; var potentialThisCollisions: Node[] = []; var potentialNewTargetCollisions: Node[] = []; var potentialWeakMapSetCollisions: Node[] = []; var potentialReflectCollisions: Node[] = []; var potentialUnusedRenamedBindingElementsInTypes: BindingElement[] = []; var awaitedTypeStack: number[] = []; var diagnostics = createDiagnosticCollection(); var suggestionDiagnostics = createDiagnosticCollection(); var typeofType = createTypeofType(); var _jsxNamespace: __String; var _jsxFactoryEntity: EntityName | undefined; var subtypeRelation = new Map(); var strictSubtypeRelation = new Map(); var assignableRelation = new Map(); var comparableRelation = new Map(); var identityRelation = new Map(); var enumRelation = new Map(); var builtinGlobals = createSymbolTable(); builtinGlobals.set(undefinedSymbol.escapedName, undefinedSymbol); // Extensions suggested for path imports when module resolution is node16 or higher. // The first element of each tuple is the extension a file has. // The second element of each tuple is the extension that should be used in a path import. // e.g. if we want to import file `foo.mts`, we should write `import {} from "./foo.mjs". var suggestedExtensions: [string, string][] = [ [".mts", ".mjs"], [".ts", ".js"], [".cts", ".cjs"], [".mjs", ".mjs"], [".js", ".js"], [".cjs", ".cjs"], [".tsx", compilerOptions.jsx === JsxEmit.Preserve ? ".jsx" : ".js"], [".jsx", ".jsx"], [".json", ".json"], ]; /* eslint-enable no-var */ initializeTypeChecker(); return checker; function getCachedType(key: string | undefined) { return key ? cachedTypes.get(key) : undefined; } function setCachedType(key: string | undefined, type: Type) { if (key) cachedTypes.set(key, type); return type; } function getJsxNamespace(location: Node | undefined): __String { if (location) { const file = getSourceFileOfNode(location); if (file) { if (isJsxOpeningFragment(location)) { if (file.localJsxFragmentNamespace) { return file.localJsxFragmentNamespace; } const jsxFragmentPragma = file.pragmas.get("jsxfrag"); if (jsxFragmentPragma) { const chosenPragma = isArray(jsxFragmentPragma) ? jsxFragmentPragma[0] : jsxFragmentPragma; file.localJsxFragmentFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); visitNode(file.localJsxFragmentFactory, markAsSynthetic, isEntityName); if (file.localJsxFragmentFactory) { return file.localJsxFragmentNamespace = getFirstIdentifier(file.localJsxFragmentFactory).escapedText; } } const entity = getJsxFragmentFactoryEntity(location); if (entity) { file.localJsxFragmentFactory = entity; return file.localJsxFragmentNamespace = getFirstIdentifier(entity).escapedText; } } else { const localJsxNamespace = getLocalJsxNamespace(file); if (localJsxNamespace) { return file.localJsxNamespace = localJsxNamespace; } } } } if (!_jsxNamespace) { _jsxNamespace = "React" as __String; if (compilerOptions.jsxFactory) { _jsxFactoryEntity = parseIsolatedEntityName(compilerOptions.jsxFactory, languageVersion); visitNode(_jsxFactoryEntity, markAsSynthetic); if (_jsxFactoryEntity) { _jsxNamespace = getFirstIdentifier(_jsxFactoryEntity).escapedText; } } else if (compilerOptions.reactNamespace) { _jsxNamespace = escapeLeadingUnderscores(compilerOptions.reactNamespace); } } if (!_jsxFactoryEntity) { _jsxFactoryEntity = factory.createQualifiedName(factory.createIdentifier(unescapeLeadingUnderscores(_jsxNamespace)), "createElement"); } return _jsxNamespace; } function getLocalJsxNamespace(file: SourceFile): __String | undefined { if (file.localJsxNamespace) { return file.localJsxNamespace; } const jsxPragma = file.pragmas.get("jsx"); if (jsxPragma) { const chosenPragma = isArray(jsxPragma) ? jsxPragma[0] : jsxPragma; file.localJsxFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); visitNode(file.localJsxFactory, markAsSynthetic, isEntityName); if (file.localJsxFactory) { return file.localJsxNamespace = getFirstIdentifier(file.localJsxFactory).escapedText; } } } function markAsSynthetic(node: T): VisitResult { setTextRangePosEnd(node, -1, -1); return visitEachChild(node, markAsSynthetic, nullTransformationContext); } function getEmitResolver(sourceFile: SourceFile, cancellationToken: CancellationToken) { // Ensure we have all the type information in place for this file so that all the // emitter questions of this resolver will return the right information. getDiagnostics(sourceFile, cancellationToken); return emitResolver; } function lookupOrIssueError(location: Node | undefined, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic { const diagnostic = location ? createDiagnosticForNode(location, message, arg0, arg1, arg2, arg3) : createCompilerDiagnostic(message, arg0, arg1, arg2, arg3); const existing = diagnostics.lookup(diagnostic); if (existing) { return existing; } else { diagnostics.add(diagnostic); return diagnostic; } } function errorSkippedOn(key: keyof CompilerOptions, location: Node | undefined, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic { const diagnostic = error(location, message, arg0, arg1, arg2, arg3); diagnostic.skippedOn = key; return diagnostic; } function createError(location: Node | undefined, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic { return location ? createDiagnosticForNode(location, message, arg0, arg1, arg2, arg3) : createCompilerDiagnostic(message, arg0, arg1, arg2, arg3); } function error(location: Node | undefined, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic { const diagnostic = createError(location, message, arg0, arg1, arg2, arg3); diagnostics.add(diagnostic); return diagnostic; } function addErrorOrSuggestion(isError: boolean, diagnostic: Diagnostic) { if (isError) { diagnostics.add(diagnostic); } else { suggestionDiagnostics.add({ ...diagnostic, category: DiagnosticCategory.Suggestion }); } } function errorOrSuggestion(isError: boolean, location: Node, message: DiagnosticMessage | DiagnosticMessageChain, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): void { // Pseudo-synthesized input node if (location.pos < 0 || location.end < 0) { if (!isError) { return; // Drop suggestions (we have no span to suggest on) } // Issue errors globally const file = getSourceFileOfNode(location); addErrorOrSuggestion(isError, "message" in message ? createFileDiagnostic(file, 0, 0, message, arg0, arg1, arg2, arg3) : createDiagnosticForFileFromMessageChain(file, message)); // eslint-disable-line local/no-in-operator return; } addErrorOrSuggestion(isError, "message" in message ? createDiagnosticForNode(location, message, arg0, arg1, arg2, arg3) : createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(location), location, message)); // eslint-disable-line local/no-in-operator } function errorAndMaybeSuggestAwait( location: Node, maybeMissingAwait: boolean, message: DiagnosticMessage, arg0?: string | number | undefined, arg1?: string | number | undefined, arg2?: string | number | undefined, arg3?: string | number | undefined): Diagnostic { const diagnostic = error(location, message, arg0, arg1, arg2, arg3); if (maybeMissingAwait) { const related = createDiagnosticForNode(location, Diagnostics.Did_you_forget_to_use_await); addRelatedInfo(diagnostic, related); } return diagnostic; } function addDeprecatedSuggestionWorker(declarations: Node | Node[], diagnostic: DiagnosticWithLocation) { const deprecatedTag = Array.isArray(declarations) ? forEach(declarations, getJSDocDeprecatedTag) : getJSDocDeprecatedTag(declarations); if (deprecatedTag) { addRelatedInfo( diagnostic, createDiagnosticForNode(deprecatedTag, Diagnostics.The_declaration_was_marked_as_deprecated_here) ); } // We call `addRelatedInfo()` before adding the diagnostic to prevent duplicates. suggestionDiagnostics.add(diagnostic); return diagnostic; } function isDeprecatedSymbol(symbol: Symbol) { if (length(symbol.declarations) > 1) { const parentSymbol = getParentOfSymbol(symbol); if (parentSymbol && parentSymbol.flags & SymbolFlags.Interface) { return some(symbol.declarations, d => !!(getCombinedNodeFlags(d) & NodeFlags.Deprecated)); } } return !!(getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Deprecated); } function addDeprecatedSuggestion(location: Node, declarations: Node[], deprecatedEntity: string) { const diagnostic = createDiagnosticForNode(location, Diagnostics._0_is_deprecated, deprecatedEntity); return addDeprecatedSuggestionWorker(declarations, diagnostic); } function addDeprecatedSuggestionWithSignature(location: Node, declaration: Node, deprecatedEntity: string | undefined, signatureString: string) { const diagnostic = deprecatedEntity ? createDiagnosticForNode(location, Diagnostics.The_signature_0_of_1_is_deprecated, signatureString, deprecatedEntity) : createDiagnosticForNode(location, Diagnostics._0_is_deprecated, signatureString); return addDeprecatedSuggestionWorker(declaration, diagnostic); } function createSymbol(flags: SymbolFlags, name: __String, checkFlags?: CheckFlags) { symbolCount++; const symbol = new Symbol(flags | SymbolFlags.Transient, name) as TransientSymbol; symbol.links = new SymbolLinks() as TransientSymbolLinks; symbol.links.checkFlags = checkFlags || CheckFlags.None; return symbol; } function createParameter(name: __String, type: Type) { const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name); symbol.links.type = type; return symbol; } function createProperty(name: __String, type: Type) { const symbol = createSymbol(SymbolFlags.Property, name); symbol.links.type = type; return symbol; } function getExcludedSymbolFlags(flags: SymbolFlags): SymbolFlags { let result: SymbolFlags = 0; if (flags & SymbolFlags.BlockScopedVariable) result |= SymbolFlags.BlockScopedVariableExcludes; if (flags & SymbolFlags.FunctionScopedVariable) result |= SymbolFlags.FunctionScopedVariableExcludes; if (flags & SymbolFlags.Property) result |= SymbolFlags.PropertyExcludes; if (flags & SymbolFlags.EnumMember) result |= SymbolFlags.EnumMemberExcludes; if (flags & SymbolFlags.Function) result |= SymbolFlags.FunctionExcludes; if (flags & SymbolFlags.Class) result |= SymbolFlags.ClassExcludes; if (flags & SymbolFlags.Interface) result |= SymbolFlags.InterfaceExcludes; if (flags & SymbolFlags.RegularEnum) result |= SymbolFlags.RegularEnumExcludes; if (flags & SymbolFlags.ConstEnum) result |= SymbolFlags.ConstEnumExcludes; if (flags & SymbolFlags.ValueModule) result |= SymbolFlags.ValueModuleExcludes; if (flags & SymbolFlags.Method) result |= SymbolFlags.MethodExcludes; if (flags & SymbolFlags.GetAccessor) result |= SymbolFlags.GetAccessorExcludes; if (flags & SymbolFlags.SetAccessor) result |= SymbolFlags.SetAccessorExcludes; if (flags & SymbolFlags.TypeParameter) result |= SymbolFlags.TypeParameterExcludes; if (flags & SymbolFlags.TypeAlias) result |= SymbolFlags.TypeAliasExcludes; if (flags & SymbolFlags.Alias) result |= SymbolFlags.AliasExcludes; return result; } function recordMergedSymbol(target: Symbol, source: Symbol) { if (!source.mergeId) { source.mergeId = nextMergeId; nextMergeId++; } mergedSymbols[source.mergeId] = target; } function cloneSymbol(symbol: Symbol): TransientSymbol { const result = createSymbol(symbol.flags, symbol.escapedName); result.declarations = symbol.declarations ? symbol.declarations.slice() : []; result.parent = symbol.parent; if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; if (symbol.members) result.members = new Map(symbol.members); if (symbol.exports) result.exports = new Map(symbol.exports); recordMergedSymbol(result, symbol); return result; } /** * Note: if target is transient, then it is mutable, and mergeSymbol with both mutate and return it. * If target is not transient, mergeSymbol will produce a transient clone, mutate that and return it. */ function mergeSymbol(target: Symbol, source: Symbol, unidirectional = false): Symbol { if (!(target.flags & getExcludedSymbolFlags(source.flags)) || (source.flags | target.flags) & SymbolFlags.Assignment) { if (source === target) { // This can happen when an export assigned namespace exports something also erroneously exported at the top level // See `declarationFileNoCrashOnExtraExportModifier` for an example return target; } if (!(target.flags & SymbolFlags.Transient)) { const resolvedTarget = resolveSymbol(target); if (resolvedTarget === unknownSymbol) { return source; } target = cloneSymbol(resolvedTarget); } // Javascript static-property-assignment declarations always merge, even though they are also values if (source.flags & SymbolFlags.ValueModule && target.flags & SymbolFlags.ValueModule && target.constEnumOnlyModule && !source.constEnumOnlyModule) { // reset flag when merging instantiated module into value module that has only const enums target.constEnumOnlyModule = false; } target.flags |= source.flags; if (source.valueDeclaration) { setValueDeclaration(target, source.valueDeclaration); } addRange(target.declarations, source.declarations); if (source.members) { if (!target.members) target.members = createSymbolTable(); mergeSymbolTable(target.members, source.members, unidirectional); } if (source.exports) { if (!target.exports) target.exports = createSymbolTable(); mergeSymbolTable(target.exports, source.exports, unidirectional); } if (!unidirectional) { recordMergedSymbol(target, source); } } else if (target.flags & SymbolFlags.NamespaceModule) { // Do not report an error when merging `var globalThis` with the built-in `globalThis`, // as we will already report a "Declaration name conflicts..." error, and this error // won't make much sense. if (target !== globalThisSymbol) { error( source.declarations && getNameOfDeclaration(source.declarations[0]), Diagnostics.Cannot_augment_module_0_with_value_exports_because_it_resolves_to_a_non_module_entity, symbolToString(target)); } } else { // error const isEitherEnum = !!(target.flags & SymbolFlags.Enum || source.flags & SymbolFlags.Enum); const isEitherBlockScoped = !!(target.flags & SymbolFlags.BlockScopedVariable || source.flags & SymbolFlags.BlockScopedVariable); const message = isEitherEnum ? Diagnostics.Enum_declarations_can_only_merge_with_namespace_or_other_enum_declarations : isEitherBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 : Diagnostics.Duplicate_identifier_0; const sourceSymbolFile = source.declarations && getSourceFileOfNode(source.declarations[0]); const targetSymbolFile = target.declarations && getSourceFileOfNode(target.declarations[0]); const isSourcePlainJs = isPlainJsFile(sourceSymbolFile, compilerOptions.checkJs); const isTargetPlainJs = isPlainJsFile(targetSymbolFile, compilerOptions.checkJs); const symbolName = symbolToString(source); // Collect top-level duplicate identifier errors into one mapping, so we can then merge their diagnostics if there are a bunch if (sourceSymbolFile && targetSymbolFile && amalgamatedDuplicates && !isEitherEnum && sourceSymbolFile !== targetSymbolFile) { const firstFile = comparePaths(sourceSymbolFile.path, targetSymbolFile.path) === Comparison.LessThan ? sourceSymbolFile : targetSymbolFile; const secondFile = firstFile === sourceSymbolFile ? targetSymbolFile : sourceSymbolFile; const filesDuplicates = getOrUpdate(amalgamatedDuplicates, `${firstFile.path}|${secondFile.path}`, (): DuplicateInfoForFiles => ({ firstFile, secondFile, conflictingSymbols: new Map() })); const conflictingSymbolInfo = getOrUpdate(filesDuplicates.conflictingSymbols, symbolName, (): DuplicateInfoForSymbol => ({ isBlockScoped: isEitherBlockScoped, firstFileLocations: [], secondFileLocations: [] })); if (!isSourcePlainJs) addDuplicateLocations(conflictingSymbolInfo.firstFileLocations, source); if (!isTargetPlainJs) addDuplicateLocations(conflictingSymbolInfo.secondFileLocations, target); } else { if (!isSourcePlainJs) addDuplicateDeclarationErrorsForSymbols(source, message, symbolName, target); if (!isTargetPlainJs) addDuplicateDeclarationErrorsForSymbols(target, message, symbolName, source); } } return target; function addDuplicateLocations(locs: Declaration[], symbol: Symbol): void { if (symbol.declarations) { for (const decl of symbol.declarations) { pushIfUnique(locs, decl); } } } } function addDuplicateDeclarationErrorsForSymbols(target: Symbol, message: DiagnosticMessage, symbolName: string, source: Symbol) { forEach(target.declarations, node => { addDuplicateDeclarationError(node, message, symbolName, source.declarations); }); } function addDuplicateDeclarationError(node: Declaration, message: DiagnosticMessage, symbolName: string, relatedNodes: readonly Declaration[] | undefined) { const errorNode = (getExpandoInitializer(node, /*isPrototypeAssignment*/ false) ? getNameOfExpando(node) : getNameOfDeclaration(node)) || node; const err = lookupOrIssueError(errorNode, message, symbolName); for (const relatedNode of relatedNodes || emptyArray) { const adjustedNode = (getExpandoInitializer(relatedNode, /*isPrototypeAssignment*/ false) ? getNameOfExpando(relatedNode) : getNameOfDeclaration(relatedNode)) || relatedNode; if (adjustedNode === errorNode) continue; err.relatedInformation = err.relatedInformation || []; const leadingMessage = createDiagnosticForNode(adjustedNode, Diagnostics._0_was_also_declared_here, symbolName); const followOnMessage = createDiagnosticForNode(adjustedNode, Diagnostics.and_here); if (length(err.relatedInformation) >= 5 || some(err.relatedInformation, r => compareDiagnostics(r, followOnMessage) === Comparison.EqualTo || compareDiagnostics(r, leadingMessage) === Comparison.EqualTo)) continue; addRelatedInfo(err, !length(err.relatedInformation) ? leadingMessage : followOnMessage); } } function combineSymbolTables(first: SymbolTable | undefined, second: SymbolTable | undefined): SymbolTable | undefined { if (!first?.size) return second; if (!second?.size) return first; const combined = createSymbolTable(); mergeSymbolTable(combined, first); mergeSymbolTable(combined, second); return combined; } function mergeSymbolTable(target: SymbolTable, source: SymbolTable, unidirectional = false) { source.forEach((sourceSymbol, id) => { const targetSymbol = target.get(id); target.set(id, targetSymbol ? mergeSymbol(targetSymbol, sourceSymbol, unidirectional) : getMergedSymbol(sourceSymbol)); }); } function mergeModuleAugmentation(moduleName: StringLiteral | Identifier): void { const moduleAugmentation = moduleName.parent as ModuleDeclaration; if (moduleAugmentation.symbol.declarations?.[0] !== moduleAugmentation) { // this is a combined symbol for multiple augmentations within the same file. // its symbol already has accumulated information for all declarations // so we need to add it just once - do the work only for first declaration Debug.assert(moduleAugmentation.symbol.declarations!.length > 1); return; } if (isGlobalScopeAugmentation(moduleAugmentation)) { mergeSymbolTable(globals, moduleAugmentation.symbol.exports!); } else { // find a module that about to be augmented // do not validate names of augmentations that are defined in ambient context const moduleNotFoundError = !(moduleName.parent.parent.flags & NodeFlags.Ambient) ? Diagnostics.Invalid_module_name_in_augmentation_module_0_cannot_be_found : undefined; let mainModule = resolveExternalModuleNameWorker(moduleName, moduleName, moduleNotFoundError, /*isForAugmentation*/ true); if (!mainModule) { return; } // obtain item referenced by 'export=' mainModule = resolveExternalModuleSymbol(mainModule); if (mainModule.flags & SymbolFlags.Namespace) { // If we're merging an augmentation to a pattern ambient module, we want to // perform the merge unidirectionally from the augmentation ('a.foo') to // the pattern ('*.foo'), so that 'getMergedSymbol()' on a.foo gives you // all the exports both from the pattern and from the augmentation, but // 'getMergedSymbol()' on *.foo only gives you exports from *.foo. if (some(patternAmbientModules, module => mainModule === module.symbol)) { const merged = mergeSymbol(moduleAugmentation.symbol, mainModule, /*unidirectional*/ true); if (!patternAmbientModuleAugmentations) { patternAmbientModuleAugmentations = new Map(); } // moduleName will be a StringLiteral since this is not `declare global`. patternAmbientModuleAugmentations.set((moduleName as StringLiteral).text, merged); } else { if (mainModule.exports?.get(InternalSymbolName.ExportStar) && moduleAugmentation.symbol.exports?.size) { // We may need to merge the module augmentation's exports into the target symbols of the resolved exports const resolvedExports = getResolvedMembersOrExportsOfSymbol(mainModule, MembersOrExportsResolutionKind.resolvedExports); for (const [key, value] of arrayFrom(moduleAugmentation.symbol.exports.entries())) { if (resolvedExports.has(key) && !mainModule.exports.has(key)) { mergeSymbol(resolvedExports.get(key)!, value); } } } mergeSymbol(mainModule, moduleAugmentation.symbol); } } else { // moduleName will be a StringLiteral since this is not `declare global`. error(moduleName, Diagnostics.Cannot_augment_module_0_because_it_resolves_to_a_non_module_entity, (moduleName as StringLiteral).text); } } } function addToSymbolTable(target: SymbolTable, source: SymbolTable, message: DiagnosticMessage) { source.forEach((sourceSymbol, id) => { const targetSymbol = target.get(id); if (targetSymbol) { // Error on redeclarations forEach(targetSymbol.declarations, addDeclarationDiagnostic(unescapeLeadingUnderscores(id), message)); } else { target.set(id, sourceSymbol); } }); function addDeclarationDiagnostic(id: string, message: DiagnosticMessage) { return (declaration: Declaration) => diagnostics.add(createDiagnosticForNode(declaration, message, id)); } } function getSymbolLinks(symbol: Symbol): SymbolLinks { if (symbol.flags & SymbolFlags.Transient) return (symbol as TransientSymbol).links; const id = getSymbolId(symbol); return symbolLinks[id] ??= new SymbolLinks(); } function getNodeLinks(node: Node): NodeLinks { const nodeId = getNodeId(node); return nodeLinks[nodeId] || (nodeLinks[nodeId] = new (NodeLinks as any)()); } function isGlobalSourceFile(node: Node) { return node.kind === SyntaxKind.SourceFile && !isExternalOrCommonJsModule(node as SourceFile); } function getSymbol(symbols: SymbolTable, name: __String, meaning: SymbolFlags): Symbol | undefined { if (meaning) { const symbol = getMergedSymbol(symbols.get(name)); if (symbol) { Debug.assert((getCheckFlags(symbol) & CheckFlags.Instantiated) === 0, "Should never get an instantiated symbol here."); if (symbol.flags & meaning) { return symbol; } if (symbol.flags & SymbolFlags.Alias) { const targetFlags = getAllSymbolFlags(symbol); // `targetFlags` will be `SymbolFlags.All` if an error occurred in alias resolution; this avoids cascading errors if (targetFlags & meaning) { return symbol; } } } } // return undefined if we can't find a symbol. } /** * Get symbols that represent parameter-property-declaration as parameter and as property declaration * @param parameter a parameterDeclaration node * @param parameterName a name of the parameter to get the symbols for. * @return a tuple of two symbols */ function getSymbolsOfParameterPropertyDeclaration(parameter: ParameterPropertyDeclaration, parameterName: __String): [Symbol, Symbol] { const constructorDeclaration = parameter.parent; const classDeclaration = parameter.parent.parent; const parameterSymbol = getSymbol(constructorDeclaration.locals!, parameterName, SymbolFlags.Value); const propertySymbol = getSymbol(getMembersOfSymbol(classDeclaration.symbol), parameterName, SymbolFlags.Value); if (parameterSymbol && propertySymbol) { return [parameterSymbol, propertySymbol]; } return Debug.fail("There should exist two symbols, one as property declaration and one as parameter declaration"); } function isBlockScopedNameDeclaredBeforeUse(declaration: Declaration, usage: Node): boolean { const declarationFile = getSourceFileOfNode(declaration); const useFile = getSourceFileOfNode(usage); const declContainer = getEnclosingBlockScopeContainer(declaration); if (declarationFile !== useFile) { if ((moduleKind && (declarationFile.externalModuleIndicator || useFile.externalModuleIndicator)) || (!outFile(compilerOptions)) || isInTypeQuery(usage) || declaration.flags & NodeFlags.Ambient) { // nodes are in different files and order cannot be determined return true; } // declaration is after usage // can be legal if usage is deferred (i.e. inside function or in initializer of instance property) if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { return true; } const sourceFiles = host.getSourceFiles(); return sourceFiles.indexOf(declarationFile) <= sourceFiles.indexOf(useFile); } if (declaration.pos <= usage.pos && !(isPropertyDeclaration(declaration) && isThisProperty(usage.parent) && !declaration.initializer && !declaration.exclamationToken)) { // declaration is before usage if (declaration.kind === SyntaxKind.BindingElement) { // still might be illegal if declaration and usage are both binding elements (eg var [a = b, b = b] = [1, 2]) const errorBindingElement = getAncestor(usage, SyntaxKind.BindingElement) as BindingElement; if (errorBindingElement) { return findAncestor(errorBindingElement, isBindingElement) !== findAncestor(declaration, isBindingElement) || declaration.pos < errorBindingElement.pos; } // or it might be illegal if usage happens before parent variable is declared (eg var [a] = a) return isBlockScopedNameDeclaredBeforeUse(getAncestor(declaration, SyntaxKind.VariableDeclaration) as Declaration, usage); } else if (declaration.kind === SyntaxKind.VariableDeclaration) { // still might be illegal if usage is in the initializer of the variable declaration (eg var a = a) return !isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration as VariableDeclaration, usage); } else if (isClassDeclaration(declaration)) { // still might be illegal if the usage is within a computed property name in the class (eg class A { static p = "a"; [A.p]() {} }) return !findAncestor(usage, n => isComputedPropertyName(n) && n.parent.parent === declaration); } else if (isPropertyDeclaration(declaration)) { // still might be illegal if a self-referencing property initializer (eg private x = this.x) return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ false); } else if (isParameterPropertyDeclaration(declaration, declaration.parent)) { // foo = this.bar is illegal in esnext+useDefineForClassFields when bar is a parameter property return !(getEmitScriptTarget(compilerOptions) === ScriptTarget.ESNext && useDefineForClassFields && getContainingClass(declaration) === getContainingClass(usage) && isUsedInFunctionOrInstanceProperty(usage, declaration)); } return true; } // declaration is after usage, but it can still be legal if usage is deferred: // 1. inside an export specifier // 2. inside a function // 3. inside an instance property initializer, a reference to a non-instance property // (except when target: "esnext" and useDefineForClassFields: true and the reference is to a parameter property) // 4. inside a static property initializer, a reference to a static method in the same class // 5. inside a TS export= declaration (since we will move the export statement during emit to avoid TDZ) // or if usage is in a type context: // 1. inside a type query (typeof in type position) // 2. inside a jsdoc comment if (usage.parent.kind === SyntaxKind.ExportSpecifier || (usage.parent.kind === SyntaxKind.ExportAssignment && (usage.parent as ExportAssignment).isExportEquals)) { // export specifiers do not use the variable, they only make it available for use return true; } // When resolving symbols for exports, the `usage` location passed in can be the export site directly if (usage.kind === SyntaxKind.ExportAssignment && (usage as ExportAssignment).isExportEquals) { return true; } if (!!(usage.flags & NodeFlags.JSDoc) || isInTypeQuery(usage) || isInAmbientOrTypeNode(usage)) { return true; } if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { if (getEmitScriptTarget(compilerOptions) === ScriptTarget.ESNext && useDefineForClassFields && getContainingClass(declaration) && (isPropertyDeclaration(declaration) || isParameterPropertyDeclaration(declaration, declaration.parent))) { return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ true); } else { return true; } } return false; function isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration: VariableDeclaration, usage: Node): boolean { switch (declaration.parent.parent.kind) { case SyntaxKind.VariableStatement: case SyntaxKind.ForStatement: case SyntaxKind.ForOfStatement: // variable statement/for/for-of statement case, // use site should not be inside variable declaration (initializer of declaration or binding element) if (isSameScopeDescendentOf(usage, declaration, declContainer)) { return true; } break; } // ForIn/ForOf case - use site should not be used in expression part const grandparent = declaration.parent.parent; return isForInOrOfStatement(grandparent) && isSameScopeDescendentOf(usage, grandparent.expression, declContainer); } function isUsedInFunctionOrInstanceProperty(usage: Node, declaration: Node): boolean { return !!findAncestor(usage, current => { if (current === declContainer) { return "quit"; } if (isFunctionLike(current)) { return true; } if (isClassStaticBlockDeclaration(current)) { return declaration.pos < usage.pos; } const propertyDeclaration = tryCast(current.parent, isPropertyDeclaration); if (propertyDeclaration) { const initializerOfProperty = propertyDeclaration.initializer === current; if (initializerOfProperty) { if (isStatic(current.parent)) { if (declaration.kind === SyntaxKind.MethodDeclaration) { return true; } if (isPropertyDeclaration(declaration) && getContainingClass(usage) === getContainingClass(declaration)) { const propName = declaration.name; if (isIdentifier(propName) || isPrivateIdentifier(propName)) { const type = getTypeOfSymbol(getSymbolOfDeclaration(declaration)); const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); if (isPropertyInitializedInStaticBlocks(propName, type, staticBlocks, declaration.parent.pos, current.pos)) { return true; } } } } else { const isDeclarationInstanceProperty = declaration.kind === SyntaxKind.PropertyDeclaration && !isStatic(declaration); if (!isDeclarationInstanceProperty || getContainingClass(usage) !== getContainingClass(declaration)) { return true; } } } } return false; }); } /** stopAtAnyPropertyDeclaration is used for detecting ES-standard class field use-before-def errors */ function isPropertyImmediatelyReferencedWithinDeclaration(declaration: PropertyDeclaration | ParameterPropertyDeclaration, usage: Node, stopAtAnyPropertyDeclaration: boolean) { // always legal if usage is after declaration if (usage.end > declaration.end) { return false; } // still might be legal if usage is deferred (e.g. x: any = () => this.x) // otherwise illegal if immediately referenced within the declaration (e.g. x: any = this.x) const ancestorChangingReferenceScope = findAncestor(usage, (node: Node) => { if (node === declaration) { return "quit"; } switch (node.kind) { case SyntaxKind.ArrowFunction: return true; case SyntaxKind.PropertyDeclaration: // even when stopping at any property declaration, they need to come from the same class return stopAtAnyPropertyDeclaration && (isPropertyDeclaration(declaration) && node.parent === declaration.parent || isParameterPropertyDeclaration(declaration, declaration.parent) && node.parent === declaration.parent.parent) ? "quit": true; case SyntaxKind.Block: switch (node.parent.kind) { case SyntaxKind.GetAccessor: case SyntaxKind.MethodDeclaration: case SyntaxKind.SetAccessor: return true; default: return false; } default: return false; } }); return ancestorChangingReferenceScope === undefined; } } function useOuterVariableScopeInParameter(result: Symbol, location: Node, lastLocation: Node) { const target = getEmitScriptTarget(compilerOptions); const functionLocation = location as FunctionLikeDeclaration; if (isParameter(lastLocation) && functionLocation.body && result.valueDeclaration && result.valueDeclaration.pos >= functionLocation.body.pos && result.valueDeclaration.end <= functionLocation.body.end) { // check for several cases where we introduce temporaries that require moving the name/initializer of the parameter to the body // - static field in a class expression // - optional chaining pre-es2020 // - nullish coalesce pre-es2020 // - spread assignment in binding pattern pre-es2017 if (target >= ScriptTarget.ES2015) { const links = getNodeLinks(functionLocation); if (links.declarationRequiresScopeChange === undefined) { links.declarationRequiresScopeChange = forEach(functionLocation.parameters, requiresScopeChange) || false; } return !links.declarationRequiresScopeChange; } } return false; function requiresScopeChange(node: ParameterDeclaration): boolean { return requiresScopeChangeWorker(node.name) || !!node.initializer && requiresScopeChangeWorker(node.initializer); } function requiresScopeChangeWorker(node: Node): boolean { switch (node.kind) { case SyntaxKind.ArrowFunction: case SyntaxKind.FunctionExpression: case SyntaxKind.FunctionDeclaration: case SyntaxKind.Constructor: // do not descend into these return false; case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.PropertyAssignment: return requiresScopeChangeWorker((node as MethodDeclaration | AccessorDeclaration | PropertyAssignment).name); case SyntaxKind.PropertyDeclaration: // static properties in classes introduce temporary variables if (hasStaticModifier(node)) { return target < ScriptTarget.ESNext || !useDefineForClassFields; } return requiresScopeChangeWorker((node as PropertyDeclaration).name); default: // null coalesce and optional chain pre-es2020 produce temporary variables if (isNullishCoalesce(node) || isOptionalChain(node)) { return target < ScriptTarget.ES2020; } if (isBindingElement(node) && node.dotDotDotToken && isObjectBindingPattern(node.parent)) { return target < ScriptTarget.ES2017; } if (isTypeNode(node)) return false; return forEachChild(node, requiresScopeChangeWorker) || false; } } } function isConstAssertion(location: Node) { return (isAssertionExpression(location) && isConstTypeReference(location.type)) || (isJSDocTypeTag(location) && isConstTypeReference(location.typeExpression)); } /** * Resolve a given name for a given meaning at a given location. An error is reported if the name was not found and * the nameNotFoundMessage argument is not undefined. Returns the resolved symbol, or undefined if no symbol with * the given name can be found. * * @param nameNotFoundMessage If defined, we will report errors found during resolve. * @param isUse If true, this will count towards --noUnusedLocals / --noUnusedParameters. */ function resolveName( location: Node | undefined, name: __String, meaning: SymbolFlags, nameNotFoundMessage: DiagnosticMessage | undefined, nameArg: __String | Identifier | undefined, isUse: boolean, excludeGlobals = false, getSpellingSuggestions = true): Symbol | undefined { return resolveNameHelper(location, name, meaning, nameNotFoundMessage, nameArg, isUse, excludeGlobals, getSpellingSuggestions, getSymbol); } function resolveNameHelper( location: Node | undefined, name: __String, meaning: SymbolFlags, nameNotFoundMessage: DiagnosticMessage | undefined, nameArg: __String | Identifier | undefined, isUse: boolean, excludeGlobals: boolean, getSpellingSuggestions: boolean, lookup: typeof getSymbol): Symbol | undefined { const originalLocation = location; // needed for did-you-mean error reporting, which gathers candidates starting from the original location let result: Symbol | undefined; let lastLocation: Node | undefined; let lastSelfReferenceLocation: Declaration | undefined; let propertyWithInvalidInitializer: PropertyDeclaration | undefined; let associatedDeclarationForContainingInitializerOrBindingName: ParameterDeclaration | BindingElement | undefined; let withinDeferredContext = false; const errorLocation = location; let grandparent: Node; let isInExternalModule = false; loop: while (location) { if (name === "const" && isConstAssertion(location)) { // `const` in an `as const` has no symbol, but issues no error because there is no *actual* lookup of the type // (it refers to the constant type of the expression instead) return undefined; } // Locals of a source file are not in scope (because they get merged into the global symbol table) if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { if (result = lookup(location.locals, name, meaning)) { let useResult = true; if (isFunctionLike(location) && lastLocation && lastLocation !== (location as FunctionLikeDeclaration).body) { // symbol lookup restrictions for function-like declarations // - Type parameters of a function are in scope in the entire function declaration, including the parameter // list and return type. However, local types are only in scope in the function body. // - parameters are only in the scope of function body // This restriction does not apply to JSDoc comment types because they are parented // at a higher level than type parameters would normally be if (meaning & result.flags & SymbolFlags.Type && lastLocation.kind !== SyntaxKind.JSDoc) { useResult = result.flags & SymbolFlags.TypeParameter // type parameters are visible in parameter list, return type and type parameter list ? lastLocation === (location as FunctionLikeDeclaration).type || lastLocation.kind === SyntaxKind.Parameter || lastLocation.kind === SyntaxKind.JSDocParameterTag || lastLocation.kind === SyntaxKind.JSDocReturnTag || lastLocation.kind === SyntaxKind.TypeParameter // local types not visible outside the function body : false; } if (meaning & result.flags & SymbolFlags.Variable) { // expression inside parameter will lookup as normal variable scope when targeting es2015+ if (useOuterVariableScopeInParameter(result, location, lastLocation)) { useResult = false; } else if (result.flags & SymbolFlags.FunctionScopedVariable) { // parameters are visible only inside function body, parameter list and return type // technically for parameter list case here we might mix parameters and variables declared in function, // however it is detected separately when checking initializers of parameters // to make sure that they reference no variables declared after them. useResult = lastLocation.kind === SyntaxKind.Parameter || ( lastLocation === (location as FunctionLikeDeclaration).type && !!findAncestor(result.valueDeclaration, isParameter) ); } } } else if (location.kind === SyntaxKind.ConditionalType) { // A type parameter declared using 'infer T' in a conditional type is visible only in // the true branch of the conditional type. useResult = lastLocation === (location as ConditionalTypeNode).trueType; } if (useResult) { break loop; } else { result = undefined; } } } withinDeferredContext = withinDeferredContext || getIsDeferredContext(location, lastLocation); switch (location.kind) { case SyntaxKind.SourceFile: if (!isExternalOrCommonJsModule(location as SourceFile)) break; isInExternalModule = true; // falls through case SyntaxKind.ModuleDeclaration: const moduleExports = getSymbolOfDeclaration(location as SourceFile | ModuleDeclaration)?.exports || emptySymbols; if (location.kind === SyntaxKind.SourceFile || (isModuleDeclaration(location) && location.flags & NodeFlags.Ambient && !isGlobalScopeAugmentation(location))) { // It's an external module. First see if the module has an export default and if the local // name of that export default matches. if (result = moduleExports.get(InternalSymbolName.Default)) { const localSymbol = getLocalSymbolForExportDefault(result); if (localSymbol && (result.flags & meaning) && localSymbol.escapedName === name) { break loop; } result = undefined; } // Because of module/namespace merging, a module's exports are in scope, // yet we never want to treat an export specifier as putting a member in scope. // Therefore, if the name we find is purely an export specifier, it is not actually considered in scope. // Two things to note about this: // 1. We have to check this without calling getSymbol. The problem with calling getSymbol // on an export specifier is that it might find the export specifier itself, and try to // resolve it as an alias. This will cause the checker to consider the export specifier // a circular alias reference when it might not be. // 2. We check === SymbolFlags.Alias in order to check that the symbol is *purely* // an alias. If we used &, we'd be throwing out symbols that have non alias aspects, // which is not the desired behavior. const moduleExport = moduleExports.get(name); if (moduleExport && moduleExport.flags === SymbolFlags.Alias && (getDeclarationOfKind(moduleExport, SyntaxKind.ExportSpecifier) || getDeclarationOfKind(moduleExport, SyntaxKind.NamespaceExport))) { break; } } // ES6 exports are also visible locally (except for 'default'), but commonjs exports are not (except typedefs) if (name !== InternalSymbolName.Default && (result = lookup(moduleExports, name, meaning & SymbolFlags.ModuleMember))) { if (isSourceFile(location) && location.commonJsModuleIndicator && !result.declarations?.some(isJSDocTypeAlias)) { result = undefined; } else { break loop; } } break; case SyntaxKind.EnumDeclaration: if (result = lookup(getSymbolOfDeclaration(location as EnumDeclaration)?.exports || emptySymbols, name, meaning & SymbolFlags.EnumMember)) { if (nameNotFoundMessage && getIsolatedModules(compilerOptions) && !(location.flags & NodeFlags.Ambient) && getSourceFileOfNode(location) !== getSourceFileOfNode(result.valueDeclaration)) { error( errorLocation, Diagnostics.Cannot_access_0_from_another_file_without_qualification_when_1_is_enabled_Use_2_instead, unescapeLeadingUnderscores(name), isolatedModulesLikeFlagName, `${unescapeLeadingUnderscores(getSymbolOfNode(location)!.escapedName)}.${unescapeLeadingUnderscores(name)}`); } break loop; } break; case SyntaxKind.PropertyDeclaration: // TypeScript 1.0 spec (April 2014): 8.4.1 // Initializer expressions for instance member variables are evaluated in the scope // of the class constructor body but are not permitted to reference parameters or // local variables of the constructor. This effectively means that entities from outer scopes // by the same name as a constructor parameter or local variable are inaccessible // in initializer expressions for instance member variables. if (!isStatic(location)) { const ctor = findConstructorDeclaration(location.parent as ClassLikeDeclaration); if (ctor && ctor.locals) { if (lookup(ctor.locals, name, meaning & SymbolFlags.Value)) { // Remember the property node, it will be used later to report appropriate error Debug.assertNode(location, isPropertyDeclaration); propertyWithInvalidInitializer = location; } } } break; case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: case SyntaxKind.InterfaceDeclaration: // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would // trigger resolving late-bound names, which we may already be in the process of doing while we're here! if (result = lookup(getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols, name, meaning & SymbolFlags.Type)) { if (!isTypeParameterSymbolDeclaredInContainer(result, location)) { // ignore type parameters not declared in this container result = undefined; break; } if (lastLocation && isStatic(lastLocation)) { // TypeScript 1.0 spec (April 2014): 3.4.1 // The scope of a type parameter extends over the entire declaration with which the type // parameter list is associated, with the exception of static member declarations in classes. if (nameNotFoundMessage) { error(errorLocation, Diagnostics.Static_members_cannot_reference_class_type_parameters); } return undefined; } break loop; } if (isClassExpression(location) && meaning & SymbolFlags.Class) { const className = location.name; if (className && name === className.escapedText) { result = location.symbol; break loop; } } break; case SyntaxKind.ExpressionWithTypeArguments: // The type parameters of a class are not in scope in the base class expression. if (lastLocation === (location as ExpressionWithTypeArguments).expression && (location.parent as HeritageClause).token === SyntaxKind.ExtendsKeyword) { const container = location.parent.parent; if (isClassLike(container) && (result = lookup(getSymbolOfDeclaration(container).members!, name, meaning & SymbolFlags.Type))) { if (nameNotFoundMessage) { error(errorLocation, Diagnostics.Base_class_expressions_cannot_reference_class_type_parameters); } return undefined; } } break; // It is not legal to reference a class's own type parameters from a computed property name that // belongs to the class. For example: // // function foo() { return '' } // class C { // <-- Class's own type parameter T // [foo()]() { } // <-- Reference to T from class's own computed property // } // case SyntaxKind.ComputedPropertyName: grandparent = location.parent.parent; if (isClassLike(grandparent) || grandparent.kind === SyntaxKind.InterfaceDeclaration) { // A reference to this grandparent's type parameters would be an error if (result = lookup(getSymbolOfDeclaration(grandparent as ClassLikeDeclaration | InterfaceDeclaration).members!, name, meaning & SymbolFlags.Type)) { if (nameNotFoundMessage) { error(errorLocation, Diagnostics.A_computed_property_name_cannot_reference_a_type_parameter_from_its_containing_type); } return undefined; } } break; case SyntaxKind.ArrowFunction: // when targeting ES6 or higher there is no 'arguments' in an arrow function // for lower compile targets the resolved symbol is used to emit an error if (getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2015) { break; } // falls through case SyntaxKind.MethodDeclaration: case SyntaxKind.Constructor: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.FunctionDeclaration: if (meaning & SymbolFlags.Variable && name === "arguments") { result = argumentsSymbol; break loop; } break; case SyntaxKind.FunctionExpression: if (meaning & SymbolFlags.Variable && name === "arguments") { result = argumentsSymbol; break loop; } if (meaning & SymbolFlags.Function) { const functionName = (location as FunctionExpression).name; if (functionName && name === functionName.escapedText) { result = (location as FunctionExpression).symbol; break loop; } } break; case SyntaxKind.Decorator: // Decorators are resolved at the class declaration. Resolving at the parameter // or member would result in looking up locals in the method. // // function y() {} // class C { // method(@y x, y) {} // <-- decorator y should be resolved at the class declaration, not the parameter. // } // if (location.parent && location.parent.kind === SyntaxKind.Parameter) { location = location.parent; } // // function y() {} // class C { // @y method(x, y) {} // <-- decorator y should be resolved at the class declaration, not the method. // } // // class Decorators are resolved outside of the class to avoid referencing type parameters of that class. // // type T = number; // declare function y(x: T): any; // @param(1 as T) // <-- T should resolve to the type alias outside of class C // class C {} if (location.parent && (isClassElement(location.parent) || location.parent.kind === SyntaxKind.ClassDeclaration)) { location = location.parent; } break; case SyntaxKind.JSDocTypedefTag: case SyntaxKind.JSDocCallbackTag: case SyntaxKind.JSDocEnumTag: // js type aliases do not resolve names from their host, so skip past it const root = getJSDocRoot(location); if (root) { location = root.parent; } break; case SyntaxKind.Parameter: if (lastLocation && ( lastLocation === (location as ParameterDeclaration).initializer || lastLocation === (location as ParameterDeclaration).name && isBindingPattern(lastLocation))) { if (!associatedDeclarationForContainingInitializerOrBindingName) { associatedDeclarationForContainingInitializerOrBindingName = location as ParameterDeclaration; } } break; case SyntaxKind.BindingElement: if (lastLocation && ( lastLocation === (location as BindingElement).initializer || lastLocation === (location as BindingElement).name && isBindingPattern(lastLocation))) { if (isParameterDeclaration(location as BindingElement) && !associatedDeclarationForContainingInitializerOrBindingName) { associatedDeclarationForContainingInitializerOrBindingName = location as BindingElement; } } break; case SyntaxKind.InferType: if (meaning & SymbolFlags.TypeParameter) { const parameterName = (location as InferTypeNode).typeParameter.name; if (parameterName && name === parameterName.escapedText) { result = (location as InferTypeNode).typeParameter.symbol; break loop; } } break; } if (isSelfReferenceLocation(location)) { lastSelfReferenceLocation = location; } lastLocation = location; location = isJSDocTemplateTag(location) ? getEffectiveContainerForJSDocTemplateTag(location) || location.parent : isJSDocParameterTag(location) || isJSDocReturnTag(location) ? getHostSignatureFromJSDoc(location) || location.parent : location.parent; } // We just climbed up parents looking for the name, meaning that we started in a descendant node of `lastLocation`. // If `result === lastSelfReferenceLocation.symbol`, that means that we are somewhere inside `lastSelfReferenceLocation` looking up a name, and resolving to `lastLocation` itself. // That means that this is a self-reference of `lastLocation`, and shouldn't count this when considering whether `lastLocation` is used. if (isUse && result && (!lastSelfReferenceLocation || result !== lastSelfReferenceLocation.symbol)) { result.isReferenced! |= meaning; } if (!result) { if (lastLocation) { Debug.assertNode(lastLocation, isSourceFile); if (lastLocation.commonJsModuleIndicator && name === "exports" && meaning & lastLocation.symbol.flags) { return lastLocation.symbol; } } if (!excludeGlobals) { result = lookup(globals, name, meaning); } } if (!result) { if (originalLocation && isInJSFile(originalLocation) && originalLocation.parent) { if (isRequireCall(originalLocation.parent, /*checkArgumentIsStringLiteralLike*/ false)) { return requireSymbol; } } } // The invalid initializer error is needed in two situation: // 1. When result is undefined, after checking for a missing "this." // 2. When result is defined function checkAndReportErrorForInvalidInitializer() { if (propertyWithInvalidInitializer && !(useDefineForClassFields && getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2022)) { // We have a match, but the reference occurred within a property initializer and the identifier also binds // to a local variable in the constructor where the code will be emitted. Note that this is actually allowed // with ESNext+useDefineForClassFields because the scope semantics are different. error(errorLocation, errorLocation && propertyWithInvalidInitializer.type && textRangeContainsPositionInclusive(propertyWithInvalidInitializer.type, errorLocation.pos) ? Diagnostics.Type_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor : Diagnostics.Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor, declarationNameToString(propertyWithInvalidInitializer.name), diagnosticName(nameArg!)); return true; } return false; } if (!result) { if (nameNotFoundMessage) { addLazyDiagnostic(() => { if (!errorLocation || !checkAndReportErrorForMissingPrefix(errorLocation, name, nameArg!) && // TODO: GH#18217 !checkAndReportErrorForInvalidInitializer() && !checkAndReportErrorForExtendingInterface(errorLocation) && !checkAndReportErrorForUsingTypeAsNamespace(errorLocation, name, meaning) && !checkAndReportErrorForExportingPrimitiveType(errorLocation, name) && !checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation, name, meaning) && !checkAndReportErrorForUsingTypeAsValue(errorLocation, name, meaning) && !checkAndReportErrorForUsingValueAsType(errorLocation, name, meaning)) { let suggestion: Symbol | undefined; let suggestedLib: string | undefined; // Report missing lib first if (nameArg) { suggestedLib = getSuggestedLibForNonExistentName(nameArg); if (suggestedLib) { error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg), suggestedLib); } } // then spelling suggestions if (!suggestedLib && getSpellingSuggestions && suggestionCount < maximumSuggestionCount) { suggestion = getSuggestedSymbolForNonexistentSymbol(originalLocation, name, meaning); const isGlobalScopeAugmentationDeclaration = suggestion?.valueDeclaration && isAmbientModule(suggestion.valueDeclaration) && isGlobalScopeAugmentation(suggestion.valueDeclaration); if (isGlobalScopeAugmentationDeclaration) { suggestion = undefined; } if (suggestion) { const suggestionName = symbolToString(suggestion); const isUncheckedJS = isUncheckedJSSuggestion(originalLocation, suggestion, /*excludeClasses*/ false); const message = meaning === SymbolFlags.Namespace || nameArg && typeof nameArg !== "string" && nodeIsSynthesized(nameArg) ? Diagnostics.Cannot_find_namespace_0_Did_you_mean_1 : isUncheckedJS ? Diagnostics.Could_not_find_name_0_Did_you_mean_1 : Diagnostics.Cannot_find_name_0_Did_you_mean_1; const diagnostic = createError(errorLocation, message, diagnosticName(nameArg!), suggestionName); addErrorOrSuggestion(!isUncheckedJS, diagnostic); if (suggestion.valueDeclaration) { addRelatedInfo( diagnostic, createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName) ); } } } // And then fall back to unspecified "not found" if (!suggestion && !suggestedLib && nameArg) { error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg)); } suggestionCount++; } }); } return undefined; } else if (nameNotFoundMessage && checkAndReportErrorForInvalidInitializer()) { return undefined; } // Perform extra checks only if error reporting was requested if (nameNotFoundMessage) { addLazyDiagnostic(() => { // Only check for block-scoped variable if we have an error location and are looking for the // name with variable meaning // For example, // declare module foo { // interface bar {} // } // const foo/*1*/: foo/*2*/.bar; // The foo at /*1*/ and /*2*/ will share same symbol with two meanings: // block-scoped variable and namespace module. However, only when we // try to resolve name in /*1*/ which is used in variable position, // we want to check for block-scoped if (errorLocation && (meaning & SymbolFlags.BlockScopedVariable || ((meaning & SymbolFlags.Class || meaning & SymbolFlags.Enum) && (meaning & SymbolFlags.Value) === SymbolFlags.Value))) { const exportOrLocalSymbol = getExportSymbolOfValueSymbolIfExported(result!); if (exportOrLocalSymbol.flags & SymbolFlags.BlockScopedVariable || exportOrLocalSymbol.flags & SymbolFlags.Class || exportOrLocalSymbol.flags & SymbolFlags.Enum) { checkResolvedBlockScopedVariable(exportOrLocalSymbol, errorLocation); } } // If we're in an external module, we can't reference value symbols created from UMD export declarations if (result && isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value && !(originalLocation!.flags & NodeFlags.JSDoc)) { const merged = getMergedSymbol(result); if (length(merged.declarations) && every(merged.declarations, d => isNamespaceExportDeclaration(d) || isSourceFile(d) && !!d.symbol.globalExports)) { errorOrSuggestion(!compilerOptions.allowUmdGlobalAccess, errorLocation!, Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead, unescapeLeadingUnderscores(name)); } } // If we're in a parameter initializer or binding name, we can't reference the values of the parameter whose initializer we're within or parameters to the right if (result && associatedDeclarationForContainingInitializerOrBindingName && !withinDeferredContext && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { const candidate = getMergedSymbol(getLateBoundSymbol(result)); const root = (getRootDeclaration(associatedDeclarationForContainingInitializerOrBindingName) as ParameterDeclaration); // A parameter initializer or binding pattern initializer within a parameter cannot refer to itself if (candidate === getSymbolOfDeclaration(associatedDeclarationForContainingInitializerOrBindingName)) { error(errorLocation, Diagnostics.Parameter_0_cannot_reference_itself, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name)); } // And it cannot refer to any declarations which come after it else if (candidate.valueDeclaration && candidate.valueDeclaration.pos > associatedDeclarationForContainingInitializerOrBindingName.pos && root.parent.locals && lookup(root.parent.locals, candidate.escapedName, meaning) === candidate) { error(errorLocation, Diagnostics.Parameter_0_cannot_reference_identifier_1_declared_after_it, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name), declarationNameToString(errorLocation as Identifier)); } } if (result && errorLocation && meaning & SymbolFlags.Value && result.flags & SymbolFlags.Alias && !(result.flags & SymbolFlags.Value) && !isValidTypeOnlyAliasUseSite(errorLocation)) { const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(result, SymbolFlags.Value); if (typeOnlyDeclaration) { const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type; const unescapedName = unescapeLeadingUnderscores(name); addTypeOnlyDeclarationRelatedInfo( error(errorLocation, message, unescapedName), typeOnlyDeclaration, unescapedName); } } }); } return result; } function addTypeOnlyDeclarationRelatedInfo(diagnostic: Diagnostic, typeOnlyDeclaration: TypeOnlyCompatibleAliasDeclaration | undefined, unescapedName: string) { if (!typeOnlyDeclaration) return diagnostic; return addRelatedInfo( diagnostic, createDiagnosticForNode( typeOnlyDeclaration, typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport ? Diagnostics._0_was_exported_here : Diagnostics._0_was_imported_here, unescapedName)); } function getIsDeferredContext(location: Node, lastLocation: Node | undefined): boolean { if (location.kind !== SyntaxKind.ArrowFunction && location.kind !== SyntaxKind.FunctionExpression) { // initializers in instance property declaration of class like entities are executed in constructor and thus deferred return isTypeQueryNode(location) || (( isFunctionLikeDeclaration(location) || (location.kind === SyntaxKind.PropertyDeclaration && !isStatic(location)) ) && (!lastLocation || lastLocation !== (location as SignatureDeclaration | PropertyDeclaration).name)); // A name is evaluated within the enclosing scope - so it shouldn't count as deferred } if (lastLocation && lastLocation === (location as FunctionExpression | ArrowFunction).name) { return false; } // generator functions and async functions are not inlined in control flow when immediately invoked if ((location as FunctionExpression | ArrowFunction).asteriskToken || hasSyntacticModifier(location, ModifierFlags.Async)) { return true; } return !getImmediatelyInvokedFunctionExpression(location); } type SelfReferenceLocation = | FunctionDeclaration | ClassDeclaration | InterfaceDeclaration | EnumDeclaration | TypeAliasDeclaration | ModuleDeclaration ; function isSelfReferenceLocation(node: Node): node is SelfReferenceLocation { switch (node.kind) { case SyntaxKind.FunctionDeclaration: case SyntaxKind.ClassDeclaration: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.EnumDeclaration: case SyntaxKind.TypeAliasDeclaration: case SyntaxKind.ModuleDeclaration: // For `namespace N { N; }` return true; default: return false; } } function diagnosticName(nameArg: __String | Identifier | PrivateIdentifier) { return isString(nameArg) ? unescapeLeadingUnderscores(nameArg as __String) : declarationNameToString(nameArg as Identifier); } function isTypeParameterSymbolDeclaredInContainer(symbol: Symbol, container: Node) { if (symbol.declarations) { for (const decl of symbol.declarations) { if (decl.kind === SyntaxKind.TypeParameter) { const parent = isJSDocTemplateTag(decl.parent) ? getJSDocHost(decl.parent) : decl.parent; if (parent === container) { return !(isJSDocTemplateTag(decl.parent) && find((decl.parent.parent as JSDoc).tags, isJSDocTypeAlias)); } } } } return false; } function checkAndReportErrorForMissingPrefix(errorLocation: Node, name: __String, nameArg: __String | Identifier): boolean { if (!isIdentifier(errorLocation) || errorLocation.escapedText !== name || isTypeReferenceIdentifier(errorLocation) || isInTypeQuery(errorLocation)) { return false; } const container = getThisContainer(errorLocation, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); let location: Node = container; while (location) { if (isClassLike(location.parent)) { const classSymbol = getSymbolOfDeclaration(location.parent); if (!classSymbol) { break; } // Check to see if a static member exists. const constructorType = getTypeOfSymbol(classSymbol); if (getPropertyOfType(constructorType, name)) { error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_static_member_1_0, diagnosticName(nameArg), symbolToString(classSymbol)); return true; } // No static member is present. // Check if we're in an instance method and look for a relevant instance member. if (location === container && !isStatic(location)) { const instanceType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType!; // TODO: GH#18217 if (getPropertyOfType(instanceType, name)) { error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_instance_member_this_0, diagnosticName(nameArg)); return true; } } } location = location.parent; } return false; } function checkAndReportErrorForExtendingInterface(errorLocation: Node): boolean { const expression = getEntityNameForExtendingInterface(errorLocation); if (expression && resolveEntityName(expression, SymbolFlags.Interface, /*ignoreErrors*/ true)) { error(errorLocation, Diagnostics.Cannot_extend_an_interface_0_Did_you_mean_implements, getTextOfNode(expression)); return true; } return false; } /** * Climbs up parents to an ExpressionWithTypeArguments, and returns its expression, * but returns undefined if that expression is not an EntityNameExpression. */ function getEntityNameForExtendingInterface(node: Node): EntityNameExpression | undefined { switch (node.kind) { case SyntaxKind.Identifier: case SyntaxKind.PropertyAccessExpression: return node.parent ? getEntityNameForExtendingInterface(node.parent) : undefined; case SyntaxKind.ExpressionWithTypeArguments: if (isEntityNameExpression((node as ExpressionWithTypeArguments).expression)) { return (node as ExpressionWithTypeArguments).expression as EntityNameExpression; } // falls through default: return undefined; } } function checkAndReportErrorForUsingTypeAsNamespace(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(errorLocation) ? SymbolFlags.Value : 0); if (meaning === namespaceMeaning) { const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~namespaceMeaning, /*nameNotFoundMessage*/undefined, /*nameArg*/ undefined, /*isUse*/ false)); const parent = errorLocation.parent; if (symbol) { if (isQualifiedName(parent)) { Debug.assert(parent.left === errorLocation, "Should only be resolving left side of qualified name as a namespace"); const propName = parent.right.escapedText; const propType = getPropertyOfType(getDeclaredTypeOfSymbol(symbol), propName); if (propType) { error( parent, Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, unescapeLeadingUnderscores(name), unescapeLeadingUnderscores(propName), ); return true; } } error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_namespace_here, unescapeLeadingUnderscores(name)); return true; } } return false; } function checkAndReportErrorForUsingValueAsType(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { if (meaning & (SymbolFlags.Type & ~SymbolFlags.Namespace)) { const symbol = resolveSymbol(resolveName(errorLocation, name, ~SymbolFlags.Type & SymbolFlags.Value, /*nameNotFoundMessage*/undefined, /*nameArg*/ undefined, /*isUse*/ false)); if (symbol && !(symbol.flags & SymbolFlags.Namespace)) { error(errorLocation, Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, unescapeLeadingUnderscores(name)); return true; } } return false; } function isPrimitiveTypeName(name: __String) { return name === "any" || name === "string" || name === "number" || name === "boolean" || name === "never" || name === "unknown"; } function checkAndReportErrorForExportingPrimitiveType(errorLocation: Node, name: __String): boolean { if (isPrimitiveTypeName(name) && errorLocation.parent.kind === SyntaxKind.ExportSpecifier) { error(errorLocation, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, name as string); return true; } return false; } function checkAndReportErrorForUsingTypeAsValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { if (meaning & SymbolFlags.Value) { if (isPrimitiveTypeName(name)) { if (isExtendedByInterface(errorLocation)) { error(errorLocation, Diagnostics.An_interface_cannot_extend_a_primitive_type_like_0_an_interface_can_only_extend_named_types_and_classes, unescapeLeadingUnderscores(name)); } else { error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, unescapeLeadingUnderscores(name)); } return true; } const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~SymbolFlags.Value, /*nameNotFoundMessage*/undefined, /*nameArg*/ undefined, /*isUse*/ false)); const allFlags = symbol && getAllSymbolFlags(symbol); if (symbol && allFlags !== undefined && !(allFlags & SymbolFlags.Value)) { const rawName = unescapeLeadingUnderscores(name); if (isES2015OrLaterConstructorName(name)) { error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_es2015_or_later, rawName); } else if (maybeMappedType(errorLocation, symbol)) { error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Did_you_mean_to_use_1_in_0, rawName, rawName === "K" ? "P" : "K"); } else { error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, rawName); } return true; } } return false; } function isExtendedByInterface(node: Node): boolean { const grandparent = node.parent.parent; const parentOfGrandparent = grandparent.parent; if(grandparent && parentOfGrandparent){ const isExtending = isHeritageClause(grandparent) && grandparent.token === SyntaxKind.ExtendsKeyword; const isInterface = isInterfaceDeclaration(parentOfGrandparent); return isExtending && isInterface; } return false; } function maybeMappedType(node: Node, symbol: Symbol) { const container = findAncestor(node.parent, n => isComputedPropertyName(n) || isPropertySignature(n) ? false : isTypeLiteralNode(n) || "quit") as TypeLiteralNode | undefined; if (container && container.members.length === 1) { const type = getDeclaredTypeOfSymbol(symbol); return !!(type.flags & TypeFlags.Union) && allTypesAssignableToKind(type, TypeFlags.StringOrNumberLiteral, /*strict*/ true); } return false; } function isES2015OrLaterConstructorName(n: __String) { switch (n) { case "Promise": case "Symbol": case "Map": case "WeakMap": case "Set": case "WeakSet": return true; } return false; } function checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { if (meaning & (SymbolFlags.Value & ~SymbolFlags.Type)) { const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.NamespaceModule, /*nameNotFoundMessage*/undefined, /*nameArg*/ undefined, /*isUse*/ false)); if (symbol) { error( errorLocation, Diagnostics.Cannot_use_namespace_0_as_a_value, unescapeLeadingUnderscores(name)); return true; } } else if (meaning & (SymbolFlags.Type & ~SymbolFlags.Value)) { const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Module, /*nameNotFoundMessage*/undefined, /*nameArg*/ undefined, /*isUse*/ false)); if (symbol) { error(errorLocation, Diagnostics.Cannot_use_namespace_0_as_a_type, unescapeLeadingUnderscores(name)); return true; } } return false; } function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void { Debug.assert(!!(result.flags & SymbolFlags.BlockScopedVariable || result.flags & SymbolFlags.Class || result.flags & SymbolFlags.Enum)); if (result.flags & (SymbolFlags.Function | SymbolFlags.FunctionScopedVariable | SymbolFlags.Assignment) && result.flags & SymbolFlags.Class) { // constructor functions aren't block scoped return; } // Block-scoped variables cannot be used before their definition const declaration = result.declarations?.find( d => isBlockOrCatchScoped(d) || isClassLike(d) || (d.kind === SyntaxKind.EnumDeclaration)); if (declaration === undefined) return Debug.fail("checkResolvedBlockScopedVariable could not find block-scoped declaration"); if (!(declaration.flags & NodeFlags.Ambient) && !isBlockScopedNameDeclaredBeforeUse(declaration, errorLocation)) { let diagnosticMessage; const declarationName = declarationNameToString(getNameOfDeclaration(declaration)); if (result.flags & SymbolFlags.BlockScopedVariable) { diagnosticMessage = error(errorLocation, Diagnostics.Block_scoped_variable_0_used_before_its_declaration, declarationName); } else if (result.flags & SymbolFlags.Class) { diagnosticMessage = error(errorLocation, Diagnostics.Class_0_used_before_its_declaration, declarationName); } else if (result.flags & SymbolFlags.RegularEnum) { diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); } else { Debug.assert(!!(result.flags & SymbolFlags.ConstEnum)); if (shouldPreserveConstEnums(compilerOptions)) { diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); } } if (diagnosticMessage) { addRelatedInfo(diagnosticMessage, createDiagnosticForNode(declaration, Diagnostics._0_is_declared_here, declarationName) ); } } } /* Starting from 'initial' node walk up the parent chain until 'stopAt' node is reached. * If at any point current node is equal to 'parent' node - return true. * If current node is an IIFE, continue walking up. * Return false if 'stopAt' node is reached or isFunctionLike(current) === true. */ function isSameScopeDescendentOf(initial: Node, parent: Node | undefined, stopAt: Node): boolean { return !!parent && !!findAncestor(initial, n => n === parent || (n === stopAt || isFunctionLike(n) && (!getImmediatelyInvokedFunctionExpression(n) || isAsyncFunction(n)) ? "quit" : false)); } function getAnyImportSyntax(node: Node): AnyImportSyntax | undefined { switch (node.kind) { case SyntaxKind.ImportEqualsDeclaration: return node as ImportEqualsDeclaration; case SyntaxKind.ImportClause: return (node as ImportClause).parent; case SyntaxKind.NamespaceImport: return (node as NamespaceImport).parent.parent; case SyntaxKind.ImportSpecifier: return (node as ImportSpecifier).parent.parent.parent; default: return undefined; } } function getDeclarationOfAliasSymbol(symbol: Symbol): Declaration | undefined { return symbol.declarations && findLast(symbol.declarations, isAliasSymbolDeclaration); } /** * An alias symbol is created by one of the following declarations: * import = ... * import from ... * import * as from ... * import { x as } from ... * export { x as } from ... * export * as ns from ... * export = * export default * module.exports = * {} * {name: } * const { x } = require ... */ function isAliasSymbolDeclaration(node: Node): boolean { return node.kind === SyntaxKind.ImportEqualsDeclaration || node.kind === SyntaxKind.NamespaceExportDeclaration || node.kind === SyntaxKind.ImportClause && !!(node as ImportClause).name || node.kind === SyntaxKind.NamespaceImport || node.kind === SyntaxKind.NamespaceExport || node.kind === SyntaxKind.ImportSpecifier || node.kind === SyntaxKind.ExportSpecifier || node.kind === SyntaxKind.ExportAssignment && exportAssignmentIsAlias(node as ExportAssignment) || isBinaryExpression(node) && getAssignmentDeclarationKind(node) === AssignmentDeclarationKind.ModuleExports && exportAssignmentIsAlias(node) || isAccessExpression(node) && isBinaryExpression(node.parent) && node.parent.left === node && node.parent.operatorToken.kind === SyntaxKind.EqualsToken && isAliasableOrJsExpression(node.parent.right) || node.kind === SyntaxKind.ShorthandPropertyAssignment || node.kind === SyntaxKind.PropertyAssignment && isAliasableOrJsExpression((node as PropertyAssignment).initializer) || node.kind === SyntaxKind.VariableDeclaration && isVariableDeclarationInitializedToBareOrAccessedRequire(node) || node.kind === SyntaxKind.BindingElement && isVariableDeclarationInitializedToBareOrAccessedRequire(node.parent.parent); } function isAliasableOrJsExpression(e: Expression) { return isAliasableExpression(e) || isFunctionExpression(e) && isJSConstructor(e); } function getTargetOfImportEqualsDeclaration(node: ImportEqualsDeclaration | VariableDeclaration, dontResolveAlias: boolean): Symbol | undefined { const commonJSPropertyAccess = getCommonJSPropertyAccess(node); if (commonJSPropertyAccess) { const name = (getLeftmostAccessExpression(commonJSPropertyAccess.expression) as CallExpression).arguments[0] as StringLiteral; return isIdentifier(commonJSPropertyAccess.name) ? resolveSymbol(getPropertyOfType(resolveExternalModuleTypeByLiteral(name), commonJSPropertyAccess.name.escapedText)) : undefined; } if (isVariableDeclaration(node) || node.moduleReference.kind === SyntaxKind.ExternalModuleReference) { const immediate = resolveExternalModuleName( node, getExternalModuleRequireArgument(node) || getExternalModuleImportEqualsDeclarationExpression(node)); const resolved = resolveExternalModuleSymbol(immediate); markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); return resolved; } const resolved = getSymbolOfPartOfRightHandSideOfImportEquals(node.moduleReference, dontResolveAlias); checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node, resolved); return resolved; } function checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node: ImportEqualsDeclaration, resolved: Symbol | undefined) { if (markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false) && !node.isTypeOnly) { const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(getSymbolOfDeclaration(node))!; const isExport = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration; const message = isExport ? Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_exported_using_export_type : Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_imported_using_import_type; const relatedMessage = isExport ? Diagnostics._0_was_exported_here : Diagnostics._0_was_imported_here; // TODO: how to get name for export *? const name = typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration ? "*" : unescapeLeadingUnderscores(typeOnlyDeclaration.name.escapedText); addRelatedInfo(error(node.moduleReference, message), createDiagnosticForNode(typeOnlyDeclaration, relatedMessage, name)); } } function resolveExportByName(moduleSymbol: Symbol, name: __String, sourceNode: TypeOnlyCompatibleAliasDeclaration | undefined, dontResolveAlias: boolean) { const exportValue = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); const exportSymbol = exportValue ? getPropertyOfType(getTypeOfSymbol(exportValue), name, /*skipObjectFunctionPropertyAugment*/ true) : moduleSymbol.exports!.get(name); const resolved = resolveSymbol(exportSymbol, dontResolveAlias); markSymbolOfAliasDeclarationIfTypeOnly(sourceNode, exportSymbol, resolved, /*overwriteEmpty*/ false); return resolved; } function isSyntacticDefault(node: Node) { return ((isExportAssignment(node) && !node.isExportEquals) || hasSyntacticModifier(node, ModifierFlags.Default) || isExportSpecifier(node)); } function getUsageModeForExpression(usage: Expression) { return isStringLiteralLike(usage) ? getModeForUsageLocation(getSourceFileOfNode(usage), usage) : undefined; } function isESMFormatImportImportingCommonjsFormatFile(usageMode: ResolutionMode, targetMode: ResolutionMode) { return usageMode === ModuleKind.ESNext && targetMode === ModuleKind.CommonJS; } function isOnlyImportedAsDefault(usage: Expression) { const usageMode = getUsageModeForExpression(usage); return usageMode === ModuleKind.ESNext && endsWith((usage as StringLiteralLike).text, Extension.Json); } function canHaveSyntheticDefault(file: SourceFile | undefined, moduleSymbol: Symbol, dontResolveAlias: boolean, usage: Expression) { const usageMode = file && getUsageModeForExpression(usage); if (file && usageMode !== undefined) { const result = isESMFormatImportImportingCommonjsFormatFile(usageMode, file.impliedNodeFormat); if (usageMode === ModuleKind.ESNext || result) { return result; } // fallthrough on cjs usages so we imply defaults for interop'd imports, too } if (!allowSyntheticDefaultImports) { return false; } // Declaration files (and ambient modules) if (!file || file.isDeclarationFile) { // Definitely cannot have a synthetic default if they have a syntactic default member specified const defaultExportSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, /*sourceNode*/ undefined, /*dontResolveAlias*/ true); // Dont resolve alias because we want the immediately exported symbol's declaration if (defaultExportSymbol && some(defaultExportSymbol.declarations, isSyntacticDefault)) { return false; } // It _might_ still be incorrect to assume there is no __esModule marker on the import at runtime, even if there is no `default` member // So we check a bit more, if (resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias)) { // If there is an `__esModule` specified in the declaration (meaning someone explicitly added it or wrote it in their code), // it definitely is a module and does not have a synthetic default return false; } // There are _many_ declaration files not written with esmodules in mind that still get compiled into a format with __esModule set // Meaning there may be no default at runtime - however to be on the permissive side, we allow access to a synthetic default member // as there is no marker to indicate if the accompanying JS has `__esModule` or not, or is even native esm return true; } // TypeScript files never have a synthetic default (as they are always emitted with an __esModule marker) _unless_ they contain an export= statement if (!isSourceFileJS(file)) { return hasExportAssignmentSymbol(moduleSymbol); } // JS files have a synthetic default if they do not contain ES2015+ module syntax (export = is not valid in js) _and_ do not have an __esModule marker return typeof file.externalModuleIndicator !== "object" && !resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias); } function getTargetOfImportClause(node: ImportClause, dontResolveAlias: boolean): Symbol | undefined { const moduleSymbol = resolveExternalModuleName(node, node.parent.moduleSpecifier); if (moduleSymbol) { return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); } } function getTargetofModuleDefault(moduleSymbol: Symbol, node: ImportClause | ImportOrExportSpecifier, dontResolveAlias: boolean) { let exportDefaultSymbol: Symbol | undefined; if (isShorthandAmbientModuleSymbol(moduleSymbol)) { exportDefaultSymbol = moduleSymbol; } else { exportDefaultSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, node, dontResolveAlias); } const file = moduleSymbol.declarations?.find(isSourceFile); const specifier = getModuleSpecifierForImportOrExport(node); if (!specifier) { return exportDefaultSymbol; } const hasDefaultOnly = isOnlyImportedAsDefault(specifier); const hasSyntheticDefault = canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, specifier); if (!exportDefaultSymbol && !hasSyntheticDefault && !hasDefaultOnly) { if (hasExportAssignmentSymbol(moduleSymbol) && !allowSyntheticDefaultImports) { const compilerOptionName = moduleKind >= ModuleKind.ES2015 ? "allowSyntheticDefaultImports" : "esModuleInterop"; const exportEqualsSymbol = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); const exportAssignment = exportEqualsSymbol!.valueDeclaration; const err = error(node.name, Diagnostics.Module_0_can_only_be_default_imported_using_the_1_flag, symbolToString(moduleSymbol), compilerOptionName); if (exportAssignment) { addRelatedInfo(err, createDiagnosticForNode( exportAssignment, Diagnostics.This_module_is_declared_with_export_and_can_only_be_used_with_a_default_import_when_using_the_0_flag, compilerOptionName )); } } else if (isImportClause(node)) { reportNonDefaultExport(moduleSymbol, node); } else { errorNoModuleMemberSymbol(moduleSymbol, moduleSymbol, node, isImportOrExportSpecifier(node) && node.propertyName || node.name); } } else if (hasSyntheticDefault || hasDefaultOnly) { // per emit behavior, a synthetic default overrides a "real" .default member if `__esModule` is not present const resolved = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); markSymbolOfAliasDeclarationIfTypeOnly(node, moduleSymbol, resolved, /*overwriteTypeOnly*/ false); return resolved; } markSymbolOfAliasDeclarationIfTypeOnly(node, exportDefaultSymbol, /*finalTarget*/ undefined, /*overwriteTypeOnly*/ false); return exportDefaultSymbol; } function getModuleSpecifierForImportOrExport(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportOrExportSpecifier): Expression | undefined { switch (node.kind) { case SyntaxKind.ImportClause: return node.parent.moduleSpecifier; case SyntaxKind.ImportEqualsDeclaration: return isExternalModuleReference(node.moduleReference) ? node.moduleReference.expression : undefined; case SyntaxKind.NamespaceImport: return node.parent.parent.moduleSpecifier; case SyntaxKind.ImportSpecifier: return node.parent.parent.parent.moduleSpecifier; case SyntaxKind.ExportSpecifier: return node.parent.parent.moduleSpecifier; default: return Debug.assertNever(node); } } function reportNonDefaultExport(moduleSymbol: Symbol, node: ImportClause) { if (moduleSymbol.exports?.has(node.symbol.escapedName)) { error( node.name, Diagnostics.Module_0_has_no_default_export_Did_you_mean_to_use_import_1_from_0_instead, symbolToString(moduleSymbol), symbolToString(node.symbol), ); } else { const diagnostic = error(node.name, Diagnostics.Module_0_has_no_default_export, symbolToString(moduleSymbol)); const exportStar = moduleSymbol.exports?.get(InternalSymbolName.ExportStar); if (exportStar) { const defaultExport = exportStar.declarations?.find(decl => !!( isExportDeclaration(decl) && decl.moduleSpecifier && resolveExternalModuleName(decl, decl.moduleSpecifier)?.exports?.has(InternalSymbolName.Default) )); if (defaultExport) { addRelatedInfo(diagnostic, createDiagnosticForNode(defaultExport, Diagnostics.export_Asterisk_does_not_re_export_a_default)); } } } } function getTargetOfNamespaceImport(node: NamespaceImport, dontResolveAlias: boolean): Symbol | undefined { const moduleSpecifier = node.parent.parent.moduleSpecifier; const immediate = resolveExternalModuleName(node, moduleSpecifier); const resolved = resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressUsageError*/ false); markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); return resolved; } function getTargetOfNamespaceExport(node: NamespaceExport, dontResolveAlias: boolean): Symbol | undefined { const moduleSpecifier = node.parent.moduleSpecifier; const immediate = moduleSpecifier && resolveExternalModuleName(node, moduleSpecifier); const resolved = moduleSpecifier && resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressUsageError*/ false); markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); return resolved; } // This function creates a synthetic symbol that combines the value side of one symbol with the // type/namespace side of another symbol. Consider this example: // // declare module graphics { // interface Point { // x: number; // y: number; // } // } // declare var graphics: { // Point: new (x: number, y: number) => graphics.Point; // } // declare module "graphics" { // export = graphics; // } // // An 'import { Point } from "graphics"' needs to create a symbol that combines the value side 'Point' // property with the type/namespace side interface 'Point'. function combineValueAndTypeSymbols(valueSymbol: Symbol, typeSymbol: Symbol): Symbol { if (valueSymbol === unknownSymbol && typeSymbol === unknownSymbol) { return unknownSymbol; } if (valueSymbol.flags & (SymbolFlags.Type | SymbolFlags.Namespace)) { return valueSymbol; } const result = createSymbol(valueSymbol.flags | typeSymbol.flags, valueSymbol.escapedName); Debug.assert(valueSymbol.declarations || typeSymbol.declarations); result.declarations = deduplicate(concatenate(valueSymbol.declarations!, typeSymbol.declarations), equateValues); result.parent = valueSymbol.parent || typeSymbol.parent; if (valueSymbol.valueDeclaration) result.valueDeclaration = valueSymbol.valueDeclaration; if (typeSymbol.members) result.members = new Map(typeSymbol.members); if (valueSymbol.exports) result.exports = new Map(valueSymbol.exports); return result; } function getExportOfModule(symbol: Symbol, name: Identifier, specifier: Declaration, dontResolveAlias: boolean): Symbol | undefined { if (symbol.flags & SymbolFlags.Module) { const exportSymbol = getExportsOfSymbol(symbol).get(name.escapedText); const resolved = resolveSymbol(exportSymbol, dontResolveAlias); const exportStarDeclaration = getSymbolLinks(symbol).typeOnlyExportStarMap?.get(name.escapedText); markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false, exportStarDeclaration, name.escapedText); return resolved; } } function getPropertyOfVariable(symbol: Symbol, name: __String): Symbol | undefined { if (symbol.flags & SymbolFlags.Variable) { const typeAnnotation = (symbol.valueDeclaration as VariableDeclaration).type; if (typeAnnotation) { return resolveSymbol(getPropertyOfType(getTypeFromTypeNode(typeAnnotation), name)); } } } function getExternalModuleMember(node: ImportDeclaration | ExportDeclaration | VariableDeclaration, specifier: ImportOrExportSpecifier | BindingElement | PropertyAccessExpression, dontResolveAlias = false): Symbol | undefined { const moduleSpecifier = getExternalModuleRequireArgument(node) || (node as ImportDeclaration | ExportDeclaration).moduleSpecifier!; const moduleSymbol = resolveExternalModuleName(node, moduleSpecifier)!; // TODO: GH#18217 const name = !isPropertyAccessExpression(specifier) && specifier.propertyName || specifier.name; if (!isIdentifier(name)) { return undefined; } const suppressInteropError = name.escapedText === InternalSymbolName.Default && allowSyntheticDefaultImports; const targetSymbol = resolveESModuleSymbol(moduleSymbol, moduleSpecifier, /*dontResolveAlias*/ false, suppressInteropError); if (targetSymbol) { if (name.escapedText) { if (isShorthandAmbientModuleSymbol(moduleSymbol)) { return moduleSymbol; } let symbolFromVariable: Symbol | undefined; // First check if module was specified with "export=". If so, get the member from the resolved type if (moduleSymbol && moduleSymbol.exports && moduleSymbol.exports.get(InternalSymbolName.ExportEquals)) { symbolFromVariable = getPropertyOfType(getTypeOfSymbol(targetSymbol), name.escapedText, /*skipObjectFunctionPropertyAugment*/ true); } else { symbolFromVariable = getPropertyOfVariable(targetSymbol, name.escapedText); } // if symbolFromVariable is export - get its final target symbolFromVariable = resolveSymbol(symbolFromVariable, dontResolveAlias); let symbolFromModule = getExportOfModule(targetSymbol, name, specifier, dontResolveAlias); if (symbolFromModule === undefined && name.escapedText === InternalSymbolName.Default) { const file = moduleSymbol.declarations?.find(isSourceFile); if (isOnlyImportedAsDefault(moduleSpecifier) || canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, moduleSpecifier)) { symbolFromModule = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); } } const symbol = symbolFromModule && symbolFromVariable && symbolFromModule !== symbolFromVariable ? combineValueAndTypeSymbols(symbolFromVariable, symbolFromModule) : symbolFromModule || symbolFromVariable; if (!symbol) { errorNoModuleMemberSymbol(moduleSymbol, targetSymbol, node, name); } return symbol; } } } function errorNoModuleMemberSymbol(moduleSymbol: Symbol, targetSymbol: Symbol, node: Node, name: Identifier) { const moduleName = getFullyQualifiedName(moduleSymbol, node); const declarationName = declarationNameToString(name); const suggestion = getSuggestedSymbolForNonexistentModule(name, targetSymbol); if (suggestion !== undefined) { const suggestionName = symbolToString(suggestion); const diagnostic = error(name, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, moduleName, declarationName, suggestionName); if (suggestion.valueDeclaration) { addRelatedInfo(diagnostic, createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName) ); } } else { if (moduleSymbol.exports?.has(InternalSymbolName.Default)) { error( name, Diagnostics.Module_0_has_no_exported_member_1_Did_you_mean_to_use_import_1_from_0_instead, moduleName, declarationName ); } else { reportNonExportedMember(node, name, declarationName, moduleSymbol, moduleName); } } } function reportNonExportedMember(node: Node, name: Identifier, declarationName: string, moduleSymbol: Symbol, moduleName: string): void { const localSymbol = tryCast(moduleSymbol.valueDeclaration, canHaveLocals)?.locals?.get(name.escapedText); const exports = moduleSymbol.exports; if (localSymbol) { const exportedEqualsSymbol = exports?.get(InternalSymbolName.ExportEquals); if (exportedEqualsSymbol) { getSymbolIfSameReference(exportedEqualsSymbol, localSymbol) ? reportInvalidImportEqualsExportMember(node, name, declarationName, moduleName) : error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); } else { const exportedSymbol = exports ? find(symbolsToArray(exports), symbol => !!getSymbolIfSameReference(symbol, localSymbol)) : undefined; const diagnostic = exportedSymbol ? error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_exported_as_2, moduleName, declarationName, symbolToString(exportedSymbol)) : error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_not_exported, moduleName, declarationName); if (localSymbol.declarations) { addRelatedInfo(diagnostic, ...map(localSymbol.declarations, (decl, index) => createDiagnosticForNode(decl, index === 0 ? Diagnostics._0_is_declared_here : Diagnostics.and_here, declarationName))); } } } else { error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); } } function reportInvalidImportEqualsExportMember(node: Node, name: Identifier, declarationName: string, moduleName: string) { if (moduleKind >= ModuleKind.ES2015) { const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_default_import : Diagnostics._0_can_only_be_imported_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; error(name, message, declarationName); } else { if (isInJSFile(node)) { const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_using_a_default_import : Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; error(name, message, declarationName); } else { const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_a_default_import : Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; error(name, message, declarationName, declarationName, moduleName); } } } function getTargetOfImportSpecifier(node: ImportSpecifier | BindingElement, dontResolveAlias: boolean): Symbol | undefined { if (isImportSpecifier(node) && idText(node.propertyName || node.name) === InternalSymbolName.Default) { const specifier = getModuleSpecifierForImportOrExport(node); const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); if (moduleSymbol) { return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); } } const root = isBindingElement(node) ? getRootDeclaration(node) as VariableDeclaration : node.parent.parent.parent; const commonJSPropertyAccess = getCommonJSPropertyAccess(root); const resolved = getExternalModuleMember(root, commonJSPropertyAccess || node, dontResolveAlias); const name = node.propertyName || node.name; if (commonJSPropertyAccess && resolved && isIdentifier(name)) { return resolveSymbol(getPropertyOfType(getTypeOfSymbol(resolved), name.escapedText), dontResolveAlias); } markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); return resolved; } function getCommonJSPropertyAccess(node: Node) { if (isVariableDeclaration(node) && node.initializer && isPropertyAccessExpression(node.initializer)) { return node.initializer; } } function getTargetOfNamespaceExportDeclaration(node: NamespaceExportDeclaration, dontResolveAlias: boolean): Symbol | undefined { if (canHaveSymbol(node.parent)) { const resolved = resolveExternalModuleSymbol(node.parent.symbol, dontResolveAlias); markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); return resolved; } } function getTargetOfExportSpecifier(node: ExportSpecifier, meaning: SymbolFlags, dontResolveAlias?: boolean) { if (idText(node.propertyName || node.name) === InternalSymbolName.Default) { const specifier = getModuleSpecifierForImportOrExport(node); const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); if (moduleSymbol) { return getTargetofModuleDefault(moduleSymbol, node, !!dontResolveAlias); } } const resolved = node.parent.parent.moduleSpecifier ? getExternalModuleMember(node.parent.parent, node, dontResolveAlias) : resolveEntityName(node.propertyName || node.name, meaning, /*ignoreErrors*/ false, dontResolveAlias); markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); return resolved; } function getTargetOfExportAssignment(node: ExportAssignment | BinaryExpression, dontResolveAlias: boolean): Symbol | undefined { const expression = isExportAssignment(node) ? node.expression : node.right; const resolved = getTargetOfAliasLikeExpression(expression, dontResolveAlias); markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); return resolved; } function getTargetOfAliasLikeExpression(expression: Expression, dontResolveAlias: boolean) { if (isClassExpression(expression)) { return checkExpressionCached(expression).symbol; } if (!isEntityName(expression) && !isEntityNameExpression(expression)) { return undefined; } const aliasLike = resolveEntityName(expression, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontResolveAlias); if (aliasLike) { return aliasLike; } checkExpressionCached(expression); return getNodeLinks(expression).resolvedSymbol; } function getTargetOfAccessExpression(node: AccessExpression, dontRecursivelyResolve: boolean): Symbol | undefined { if (!(isBinaryExpression(node.parent) && node.parent.left === node && node.parent.operatorToken.kind === SyntaxKind.EqualsToken)) { return undefined; } return getTargetOfAliasLikeExpression(node.parent.right, dontRecursivelyResolve); } function getTargetOfAliasDeclaration(node: Declaration, dontRecursivelyResolve = false): Symbol | undefined { switch (node.kind) { case SyntaxKind.ImportEqualsDeclaration: case SyntaxKind.VariableDeclaration: return getTargetOfImportEqualsDeclaration(node as ImportEqualsDeclaration | VariableDeclaration, dontRecursivelyResolve); case SyntaxKind.ImportClause: return getTargetOfImportClause(node as ImportClause, dontRecursivelyResolve); case SyntaxKind.NamespaceImport: return getTargetOfNamespaceImport(node as NamespaceImport, dontRecursivelyResolve); case SyntaxKind.NamespaceExport: return getTargetOfNamespaceExport(node as NamespaceExport, dontRecursivelyResolve); case SyntaxKind.ImportSpecifier: case SyntaxKind.BindingElement: return getTargetOfImportSpecifier(node as ImportSpecifier | BindingElement, dontRecursivelyResolve); case SyntaxKind.ExportSpecifier: return getTargetOfExportSpecifier(node as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, dontRecursivelyResolve); case SyntaxKind.ExportAssignment: case SyntaxKind.BinaryExpression: return getTargetOfExportAssignment((node as ExportAssignment | BinaryExpression), dontRecursivelyResolve); case SyntaxKind.NamespaceExportDeclaration: return getTargetOfNamespaceExportDeclaration(node as NamespaceExportDeclaration, dontRecursivelyResolve); case SyntaxKind.ShorthandPropertyAssignment: return resolveEntityName((node as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontRecursivelyResolve); case SyntaxKind.PropertyAssignment: return getTargetOfAliasLikeExpression((node as PropertyAssignment).initializer, dontRecursivelyResolve); case SyntaxKind.ElementAccessExpression: case SyntaxKind.PropertyAccessExpression: return getTargetOfAccessExpression(node as AccessExpression, dontRecursivelyResolve); default: return Debug.fail(); } } /** * Indicates that a symbol is an alias that does not merge with a local declaration. * OR Is a JSContainer which may merge an alias with a local declaration */ function isNonLocalAlias(symbol: Symbol | undefined, excludes = SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace): symbol is Symbol { if (!symbol) return false; return (symbol.flags & (SymbolFlags.Alias | excludes)) === SymbolFlags.Alias || !!(symbol.flags & SymbolFlags.Alias && symbol.flags & SymbolFlags.Assignment); } function resolveSymbol(symbol: Symbol, dontResolveAlias?: boolean): Symbol; function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { return !dontResolveAlias && isNonLocalAlias(symbol) ? resolveAlias(symbol) : symbol; } function resolveAlias(symbol: Symbol): Symbol { Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); const links = getSymbolLinks(symbol); if (!links.aliasTarget) { links.aliasTarget = resolvingSymbol; const node = getDeclarationOfAliasSymbol(symbol); if (!node) return Debug.fail(); const target = getTargetOfAliasDeclaration(node); if (links.aliasTarget === resolvingSymbol) { links.aliasTarget = target || unknownSymbol; } else { error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); } } else if (links.aliasTarget === resolvingSymbol) { links.aliasTarget = unknownSymbol; } return links.aliasTarget; } function tryResolveAlias(symbol: Symbol): Symbol | undefined { const links = getSymbolLinks(symbol); if (links.aliasTarget !== resolvingSymbol) { return resolveAlias(symbol); } return undefined; } /** * Gets combined flags of a `symbol` and all alias targets it resolves to. `resolveAlias` * is typically recursive over chains of aliases, but stops mid-chain if an alias is merged * with another exported symbol, e.g. * ```ts * // a.ts * export const a = 0; * // b.ts * export { a } from "./a"; * export type a = number; * // c.ts * import { a } from "./b"; * ``` * Calling `resolveAlias` on the `a` in c.ts would stop at the merged symbol exported * from b.ts, even though there is still more alias to resolve. Consequently, if we were * trying to determine if the `a` in c.ts has a value meaning, looking at the flags on * the local symbol and on the symbol returned by `resolveAlias` is not enough. * @returns SymbolFlags.All if `symbol` is an alias that ultimately resolves to `unknown`; * combined flags of all alias targets otherwise. */ function getAllSymbolFlags(symbol: Symbol): SymbolFlags { let flags = symbol.flags; let seenSymbols; while (symbol.flags & SymbolFlags.Alias) { const target = resolveAlias(symbol); if (target === unknownSymbol) { return SymbolFlags.All; } // Optimizations - try to avoid creating or adding to // `seenSymbols` if possible if (target === symbol || seenSymbols?.has(target)) { break; } if (target.flags & SymbolFlags.Alias) { if (seenSymbols) { seenSymbols.add(target); } else { seenSymbols = new Set([symbol, target]); } } flags |= target.flags; symbol = target; } return flags; } /** * Marks a symbol as type-only if its declaration is syntactically type-only. * If it is not itself marked type-only, but resolves to a type-only alias * somewhere in its resolution chain, save a reference to the type-only alias declaration * so the alias _not_ marked type-only can be identified as _transitively_ type-only. * * This function is called on each alias declaration that could be type-only or resolve to * another type-only alias during `resolveAlias`, so that later, when an alias is used in a * JS-emitting expression, we can quickly determine if that symbol is effectively type-only * and issue an error if so. * * @param aliasDeclaration The alias declaration not marked as type-only * @param immediateTarget The symbol to which the alias declaration immediately resolves * @param finalTarget The symbol to which the alias declaration ultimately resolves * @param overwriteEmpty Checks `resolvesToSymbol` for type-only declarations even if `aliasDeclaration` * has already been marked as not resolving to a type-only alias. Used when recursively resolving qualified * names of import aliases, e.g. `import C = a.b.C`. If namespace `a` is not found to be type-only, the * import declaration will initially be marked as not resolving to a type-only symbol. But, namespace `b` * must still be checked for a type-only marker, overwriting the previous negative result if found. */ function markSymbolOfAliasDeclarationIfTypeOnly( aliasDeclaration: Declaration | undefined, immediateTarget: Symbol | undefined, finalTarget: Symbol | undefined, overwriteEmpty: boolean, exportStarDeclaration?: ExportDeclaration & { readonly isTypeOnly: true }, exportStarName?: __String, ): boolean { if (!aliasDeclaration || isPropertyAccessExpression(aliasDeclaration)) return false; // If the declaration itself is type-only, mark it and return. // No need to check what it resolves to. const sourceSymbol = getSymbolOfDeclaration(aliasDeclaration); if (isTypeOnlyImportOrExportDeclaration(aliasDeclaration)) { const links = getSymbolLinks(sourceSymbol); links.typeOnlyDeclaration = aliasDeclaration; return true; } if (exportStarDeclaration) { const links = getSymbolLinks(sourceSymbol); links.typeOnlyDeclaration = exportStarDeclaration; if (sourceSymbol.escapedName !== exportStarName) { links.typeOnlyExportStarName = exportStarName; } return true; } const links = getSymbolLinks(sourceSymbol); return markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, immediateTarget, overwriteEmpty) || markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, finalTarget, overwriteEmpty); } function markSymbolOfAliasDeclarationIfTypeOnlyWorker(aliasDeclarationLinks: SymbolLinks, target: Symbol | undefined, overwriteEmpty: boolean): boolean { if (target && (aliasDeclarationLinks.typeOnlyDeclaration === undefined || overwriteEmpty && aliasDeclarationLinks.typeOnlyDeclaration === false)) { const exportSymbol = target.exports?.get(InternalSymbolName.ExportEquals) ?? target; const typeOnly = exportSymbol.declarations && find(exportSymbol.declarations, isTypeOnlyImportOrExportDeclaration); aliasDeclarationLinks.typeOnlyDeclaration = typeOnly ?? getSymbolLinks(exportSymbol).typeOnlyDeclaration ?? false; } return !!aliasDeclarationLinks.typeOnlyDeclaration; } /** Indicates that a symbol directly or indirectly resolves to a type-only import or export. */ function getTypeOnlyAliasDeclaration(symbol: Symbol, include?: SymbolFlags): TypeOnlyAliasDeclaration | undefined { if (!(symbol.flags & SymbolFlags.Alias)) { return undefined; } const links = getSymbolLinks(symbol); if (include === undefined) { return links.typeOnlyDeclaration || undefined; } if (links.typeOnlyDeclaration) { const resolved = links.typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration ? resolveSymbol(getExportsOfModule(links.typeOnlyDeclaration.symbol.parent!).get(links.typeOnlyExportStarName || symbol.escapedName))! : resolveAlias(links.typeOnlyDeclaration.symbol); return getAllSymbolFlags(resolved) & include ? links.typeOnlyDeclaration : undefined; } return undefined; } function markExportAsReferenced(node: ImportEqualsDeclaration | ExportSpecifier) { if (compilerOptions.verbatimModuleSyntax) { return; } const symbol = getSymbolOfDeclaration(node); const target = resolveAlias(symbol); if (target) { const markAlias = target === unknownSymbol || ((getAllSymbolFlags(target) & SymbolFlags.Value) && !isConstEnumOrConstEnumOnlyModule(target) && !getTypeOnlyAliasDeclaration(symbol, SymbolFlags.Value)); if (markAlias) { markAliasSymbolAsReferenced(symbol); } } } // When an alias symbol is referenced, we need to mark the entity it references as referenced and in turn repeat that until // we reach a non-alias or an exported entity (which is always considered referenced). We do this by checking the target of // the alias as an expression (which recursively takes us back here if the target references another alias). function markAliasSymbolAsReferenced(symbol: Symbol) { Debug.assert(!compilerOptions.verbatimModuleSyntax); const links = getSymbolLinks(symbol); if (!links.referenced) { links.referenced = true; const node = getDeclarationOfAliasSymbol(symbol); if (!node) return Debug.fail(); // We defer checking of the reference of an `import =` until the import itself is referenced, // This way a chain of imports can be elided if ultimately the final input is only used in a type // position. if (isInternalModuleImportEqualsDeclaration(node)) { if (getAllSymbolFlags(resolveSymbol(symbol)) & SymbolFlags.Value) { // import foo = checkExpressionCached(node.moduleReference as Expression); } } } } // Aliases that resolve to const enums are not marked as referenced because they are not emitted, // but their usage in value positions must be tracked to determine if the import can be type-only. function markConstEnumAliasAsReferenced(symbol: Symbol) { const links = getSymbolLinks(symbol); if (!links.constEnumReferenced) { links.constEnumReferenced = true; } } // This function is only for imports with entity names function getSymbolOfPartOfRightHandSideOfImportEquals(entityName: EntityName, dontResolveAlias?: boolean): Symbol | undefined { // There are three things we might try to look for. In the following examples, // the search term is enclosed in |...|: // // import a = |b|; // Namespace // import a = |b.c|; // Value, type, namespace // import a = |b.c|.d; // Namespace if (entityName.kind === SyntaxKind.Identifier && isRightSideOfQualifiedNameOrPropertyAccess(entityName)) { entityName = entityName.parent as QualifiedName; } // Check for case 1 and 3 in the above example if (entityName.kind === SyntaxKind.Identifier || entityName.parent.kind === SyntaxKind.QualifiedName) { return resolveEntityName(entityName, SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); } else { // Case 2 in above example // entityName.kind could be a QualifiedName or a Missing identifier Debug.assert(entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration); return resolveEntityName(entityName, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); } } function getFullyQualifiedName(symbol: Symbol, containingLocation?: Node): string { return symbol.parent ? getFullyQualifiedName(symbol.parent, containingLocation) + "." + symbolToString(symbol) : symbolToString(symbol, containingLocation, /*meaning*/ undefined, SymbolFormatFlags.DoNotIncludeSymbolChain | SymbolFormatFlags.AllowAnyNodeKind); } function getContainingQualifiedNameNode(node: QualifiedName) { while (isQualifiedName(node.parent)) { node = node.parent; } return node; } function tryGetQualifiedNameAsValue(node: QualifiedName) { let left: Identifier | QualifiedName = getFirstIdentifier(node); let symbol = resolveName(left, left.escapedText, SymbolFlags.Value, undefined, left, /*isUse*/ true); if (!symbol) { return undefined; } while (isQualifiedName(left.parent)) { const type = getTypeOfSymbol(symbol); symbol = getPropertyOfType(type, left.parent.right.escapedText); if (!symbol) { return undefined; } left = left.parent; } return symbol; } /** * Resolves a qualified name and any involved aliases. */ function resolveEntityName(name: EntityNameOrEntityNameExpression, meaning: SymbolFlags, ignoreErrors?: boolean, dontResolveAlias?: boolean, location?: Node): Symbol | undefined { if (nodeIsMissing(name)) { return undefined; } const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(name) ? meaning & SymbolFlags.Value : 0); let symbol: Symbol | undefined; if (name.kind === SyntaxKind.Identifier) { const message = meaning === namespaceMeaning || nodeIsSynthesized(name) ? Diagnostics.Cannot_find_namespace_0 : getCannotFindNameDiagnosticForName(getFirstIdentifier(name)); const symbolFromJSPrototype = isInJSFile(name) && !nodeIsSynthesized(name) ? resolveEntityNameFromAssignmentDeclaration(name, meaning) : undefined; symbol = getMergedSymbol(resolveName(location || name, name.escapedText, meaning, ignoreErrors || symbolFromJSPrototype ? undefined : message, name, /*isUse*/ true, false)); if (!symbol) { return getMergedSymbol(symbolFromJSPrototype); } } else if (name.kind === SyntaxKind.QualifiedName || name.kind === SyntaxKind.PropertyAccessExpression) { const left = name.kind === SyntaxKind.QualifiedName ? name.left : name.expression; const right = name.kind === SyntaxKind.QualifiedName ? name.right : name.name; let namespace = resolveEntityName(left, namespaceMeaning, ignoreErrors, /*dontResolveAlias*/ false, location); if (!namespace || nodeIsMissing(right)) { return undefined; } else if (namespace === unknownSymbol) { return namespace; } if ( namespace.valueDeclaration && isInJSFile(namespace.valueDeclaration) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Bundler && isVariableDeclaration(namespace.valueDeclaration) && namespace.valueDeclaration.initializer && isCommonJsRequire(namespace.valueDeclaration.initializer) ) { const moduleName = (namespace.valueDeclaration.initializer as CallExpression).arguments[0] as StringLiteral; const moduleSym = resolveExternalModuleName(moduleName, moduleName); if (moduleSym) { const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); if (resolvedModuleSymbol) { namespace = resolvedModuleSymbol; } } } symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, meaning)); if (!symbol) { if (!ignoreErrors) { const namespaceName = getFullyQualifiedName(namespace); const declarationName = declarationNameToString(right); const suggestionForNonexistentModule = getSuggestedSymbolForNonexistentModule(right, namespace); if (suggestionForNonexistentModule) { error(right, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, namespaceName, declarationName, symbolToString(suggestionForNonexistentModule)); return undefined; } const containingQualifiedName = isQualifiedName(name) && getContainingQualifiedNameNode(name); const canSuggestTypeof = globalObjectType // <-- can't pull on types if global types aren't initialized yet && (meaning & SymbolFlags.Type) && containingQualifiedName && !isTypeOfExpression(containingQualifiedName.parent) && tryGetQualifiedNameAsValue(containingQualifiedName); if (canSuggestTypeof) { error( containingQualifiedName, Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, entityNameToString(containingQualifiedName) ); return undefined; } if (meaning & SymbolFlags.Namespace && isQualifiedName(name.parent)) { const exportedTypeSymbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, SymbolFlags.Type)); if (exportedTypeSymbol) { error( name.parent.right, Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, symbolToString(exportedTypeSymbol), unescapeLeadingUnderscores(name.parent.right.escapedText) ); return undefined; } } error(right, Diagnostics.Namespace_0_has_no_exported_member_1, namespaceName, declarationName); } return undefined; } } else { throw Debug.assertNever(name, "Unknown entity name kind."); } Debug.assert((getCheckFlags(symbol) & CheckFlags.Instantiated) === 0, "Should never get an instantiated symbol here."); if (!nodeIsSynthesized(name) && isEntityName(name) && (symbol.flags & SymbolFlags.Alias || name.parent.kind === SyntaxKind.ExportAssignment)) { markSymbolOfAliasDeclarationIfTypeOnly(getAliasDeclarationFromName(name), symbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ true); } return (symbol.flags & meaning) || dontResolveAlias ? symbol : resolveAlias(symbol); } /** * 1. For prototype-property methods like `A.prototype.m = function () ...`, try to resolve names in the scope of `A` too. * Note that prototype-property assignment to locations outside the current file (eg globals) doesn't work, so * name resolution won't work either. * 2. For property assignments like `{ x: function f () { } }`, try to resolve names in the scope of `f` too. */ function resolveEntityNameFromAssignmentDeclaration(name: Identifier, meaning: SymbolFlags) { if (isJSDocTypeReference(name.parent)) { const secondaryLocation = getAssignmentDeclarationLocation(name.parent); if (secondaryLocation) { return resolveName(secondaryLocation, name.escapedText, meaning, /*nameNotFoundMessage*/ undefined, name, /*isUse*/ true); } } } function getAssignmentDeclarationLocation(node: TypeReferenceNode): Node | undefined { const typeAlias = findAncestor(node, node => !(isJSDocNode(node) || node.flags & NodeFlags.JSDoc) ? "quit" : isJSDocTypeAlias(node)); if (typeAlias) { return; } const host = getJSDocHost(node); if (host && isExpressionStatement(host) && isPrototypePropertyAssignment(host.expression)) { // /** @param {K} p */ X.prototype.m = function () { } <-- look for K on X's declaration const symbol = getSymbolOfDeclaration(host.expression.left); if (symbol) { return getDeclarationOfJSPrototypeContainer(symbol); } } if (host && isFunctionExpression(host) && isPrototypePropertyAssignment(host.parent) && isExpressionStatement(host.parent.parent)) { // X.prototype.m = /** @param {K} p */ function () { } <-- look for K on X's declaration const symbol = getSymbolOfDeclaration(host.parent.left); if (symbol) { return getDeclarationOfJSPrototypeContainer(symbol); } } if (host && (isObjectLiteralMethod(host) || isPropertyAssignment(host)) && isBinaryExpression(host.parent.parent) && getAssignmentDeclarationKind(host.parent.parent) === AssignmentDeclarationKind.Prototype) { // X.prototype = { /** @param {K} p */m() { } } <-- look for K on X's declaration const symbol = getSymbolOfDeclaration(host.parent.parent.left as BindableStaticNameExpression); if (symbol) { return getDeclarationOfJSPrototypeContainer(symbol); } } const sig = getEffectiveJSDocHost(node); if (sig && isFunctionLike(sig)) { const symbol = getSymbolOfDeclaration(sig); return symbol && symbol.valueDeclaration; } } function getDeclarationOfJSPrototypeContainer(symbol: Symbol) { const decl = symbol.parent!.valueDeclaration; if (!decl) { return undefined; } const initializer = isAssignmentDeclaration(decl) ? getAssignedExpandoInitializer(decl) : hasOnlyExpressionInitializer(decl) ? getDeclaredExpandoInitializer(decl) : undefined; return initializer || decl; } /** * Get the real symbol of a declaration with an expando initializer. * * Normally, declarations have an associated symbol, but when a declaration has an expando * initializer, the expando's symbol is the one that has all the members merged into it. */ function getExpandoSymbol(symbol: Symbol): Symbol | undefined { const decl = symbol.valueDeclaration; if (!decl || !isInJSFile(decl) || symbol.flags & SymbolFlags.TypeAlias || getExpandoInitializer(decl, /*isPrototypeAssignment*/ false)) { return undefined; } const init = isVariableDeclaration(decl) ? getDeclaredExpandoInitializer(decl) : getAssignedExpandoInitializer(decl); if (init) { const initSymbol = getSymbolOfNode(init); if (initSymbol) { return mergeJSSymbols(initSymbol, symbol); } } } function resolveExternalModuleName(location: Node, moduleReferenceExpression: Expression, ignoreErrors?: boolean): Symbol | undefined { const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; const errorMessage = isClassic? Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; return resolveExternalModuleNameWorker(location, moduleReferenceExpression, ignoreErrors ? undefined : errorMessage); } function resolveExternalModuleNameWorker(location: Node, moduleReferenceExpression: Expression, moduleNotFoundError: DiagnosticMessage | undefined, isForAugmentation = false): Symbol | undefined { return isStringLiteralLike(moduleReferenceExpression) ? resolveExternalModule(location, moduleReferenceExpression.text, moduleNotFoundError, moduleReferenceExpression, isForAugmentation) : undefined; } function resolveExternalModule(location: Node, moduleReference: string, moduleNotFoundError: DiagnosticMessage | undefined, errorNode: Node, isForAugmentation = false): Symbol | undefined { if (startsWith(moduleReference, "@types/")) { const diag = Diagnostics.Cannot_import_type_declaration_files_Consider_importing_0_instead_of_1; const withoutAtTypePrefix = removePrefix(moduleReference, "@types/"); error(errorNode, diag, withoutAtTypePrefix, moduleReference); } const ambientModule = tryFindAmbientModule(moduleReference, /*withAugmentations*/ true); if (ambientModule) { return ambientModule; } const currentSourceFile = getSourceFileOfNode(location); const contextSpecifier = isStringLiteralLike(location) ? location : findAncestor(location, isImportCall)?.arguments[0] || findAncestor(location, isImportDeclaration)?.moduleSpecifier || findAncestor(location, isExternalModuleImportEqualsDeclaration)?.moduleReference.expression || findAncestor(location, isExportDeclaration)?.moduleSpecifier || (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name || (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal; const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat; const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions); const resolvedModule = getResolvedModule(currentSourceFile, moduleReference, mode); const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule, currentSourceFile); const sourceFile = resolvedModule && (!resolutionDiagnostic || resolutionDiagnostic === Diagnostics.Module_0_was_resolved_to_1_but_jsx_is_not_set) && host.getSourceFile(resolvedModule.resolvedFileName); if (sourceFile) { // If there's a resolutionDiagnostic we need to report it even if a sourceFile is found. if (resolutionDiagnostic) { error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); } if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) { const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) { error( errorNode, Diagnostics.A_declaration_file_cannot_be_imported_without_import_type_Did_you_mean_to_import_an_implementation_file_0_instead, getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference)))); } } else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowImportingTsExtension(compilerOptions, currentSourceFile.fileName)) { const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference)); error(errorNode, Diagnostics.An_import_path_can_only_end_with_a_0_extension_when_allowImportingTsExtensions_is_enabled, tsExtension); } if (sourceFile.symbol) { if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) { errorOnImplicitAnyModule(/*isError*/ false, errorNode, currentSourceFile, mode, resolvedModule, moduleReference); } if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) { const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration); const overrideClauseHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined; const overrideClause = overrideClauseHost && isImportTypeNode(overrideClauseHost) ? overrideClauseHost.assertions?.assertClause : overrideClauseHost?.assertClause; // An override clause will take effect for type-only imports and import types, and allows importing the types across formats, regardless of // normal mode restrictions if (isSyncImport && sourceFile.impliedNodeFormat === ModuleKind.ESNext && !getResolutionModeOverrideForClause(overrideClause)) { if (findAncestor(location, isImportEqualsDeclaration)) { // ImportEquals in a ESM file resolving to another ESM file error(errorNode, Diagnostics.Module_0_cannot_be_imported_using_this_construct_The_specifier_only_resolves_to_an_ES_module_which_cannot_be_imported_with_require_Use_an_ECMAScript_import_instead, moduleReference); } else { // CJS file resolving to an ESM file let diagnosticDetails; const ext = tryGetExtensionFromPath(currentSourceFile.fileName); if (ext === Extension.Ts || ext === Extension.Js || ext === Extension.Tsx || ext === Extension.Jsx) { const scope = currentSourceFile.packageJsonScope; const targetExt = ext === Extension.Ts ? Extension.Mts : ext === Extension.Js ? Extension.Mjs : undefined; if (scope && !scope.contents.packageJsonContent.type) { if (targetExt) { diagnosticDetails = chainDiagnosticMessages( /*details*/ undefined, Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_add_the_field_type_Colon_module_to_1, targetExt, combinePaths(scope.packageDirectory, "package.json")); } else { diagnosticDetails = chainDiagnosticMessages( /*details*/ undefined, Diagnostics.To_convert_this_file_to_an_ECMAScript_module_add_the_field_type_Colon_module_to_0, combinePaths(scope.packageDirectory, "package.json")); } } else { if (targetExt) { diagnosticDetails = chainDiagnosticMessages( /*details*/ undefined, Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_create_a_local_package_json_file_with_type_Colon_module, targetExt); } else { diagnosticDetails = chainDiagnosticMessages( /*details*/ undefined, Diagnostics.To_convert_this_file_to_an_ECMAScript_module_create_a_local_package_json_file_with_type_Colon_module); } } } diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode), errorNode, chainDiagnosticMessages( diagnosticDetails, Diagnostics.The_current_file_is_a_CommonJS_module_whose_imports_will_produce_require_calls_however_the_referenced_file_is_an_ECMAScript_module_and_cannot_be_imported_with_require_Consider_writing_a_dynamic_import_0_call_instead, moduleReference))); } } } // merged symbol is module declaration symbol combined with all augmentations return getMergedSymbol(sourceFile.symbol); } if (moduleNotFoundError) { // report errors only if it was requested error(errorNode, Diagnostics.File_0_is_not_a_module, sourceFile.fileName); } return undefined; } if (patternAmbientModules) { const pattern = findBestPatternMatch(patternAmbientModules, _ => _.pattern, moduleReference); if (pattern) { // If the module reference matched a pattern ambient module ('*.foo') but there's also a // module augmentation by the specific name requested ('a.foo'), we store the merged symbol // by the augmentation name ('a.foo'), because asking for *.foo should not give you exports // from a.foo. const augmentation = patternAmbientModuleAugmentations && patternAmbientModuleAugmentations.get(moduleReference); if (augmentation) { return getMergedSymbol(augmentation); } return getMergedSymbol(pattern.symbol); } } // May be an untyped module. If so, ignore resolutionDiagnostic. if (resolvedModule && !resolutionExtensionIsTSOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) { if (isForAugmentation) { const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented; error(errorNode, diag, moduleReference, resolvedModule!.resolvedFileName); } else { errorOnImplicitAnyModule(/*isError*/ noImplicitAny && !!moduleNotFoundError, errorNode, currentSourceFile, mode, resolvedModule!, moduleReference); } // Failed imports and untyped modules are both treated in an untyped manner; only difference is whether we give a diagnostic first. return undefined; } if (moduleNotFoundError) { // See if this was possibly a projectReference redirect if (resolvedModule) { const redirect = host.getProjectReferenceRedirect(resolvedModule.resolvedFileName); if (redirect) { error(errorNode, Diagnostics.Output_file_0_has_not_been_built_from_source_file_1, redirect, resolvedModule.resolvedFileName); return undefined; } } if (resolutionDiagnostic) { error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); } else { const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference); const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext; if (!getResolveJsonModule(compilerOptions) && fileExtensionIs(moduleReference, Extension.Json) && moduleResolutionKind !== ModuleResolutionKind.Classic && hasJsonModuleEmitEnabled(compilerOptions)) { error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference); } else if (mode === ModuleKind.ESNext && resolutionIsNode16OrNext && isExtensionlessRelativePathImport) { const absoluteRef = getNormalizedAbsolutePath(moduleReference, getDirectoryPath(currentSourceFile.path)); const suggestedExt = suggestedExtensions.find(([actualExt, _importExt]) => host.fileExists(absoluteRef + actualExt))?.[1]; if (suggestedExt) { error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_EcmaScript_imports_when_moduleResolution_is_node16_or_nodenext_Did_you_mean_0, moduleReference + suggestedExt); } else { error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_EcmaScript_imports_when_moduleResolution_is_node16_or_nodenext_Consider_adding_an_extension_to_the_import_path); } } else { error(errorNode, moduleNotFoundError, moduleReference); } } } return undefined; function getSuggestedImportSource(tsExtension: string) { const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension); /** * Direct users to import source with .js extension if outputting an ES module. * @see https://github.com/microsoft/TypeScript/issues/42151 */ if (emitModuleKindIsNonNodeESM(moduleKind) || mode === ModuleKind.ESNext) { const preferTs = isDeclarationFileName(moduleReference) && shouldAllowImportingTsExtension(compilerOptions); const ext = tsExtension === Extension.Mts || tsExtension === Extension.Dmts ? preferTs ? ".mts" : ".mjs" : tsExtension === Extension.Cts || tsExtension === Extension.Dmts ? preferTs ? ".cts" : ".cjs" : preferTs ? ".ts" : ".js"; return importSourceWithoutExtension + ext; } return importSourceWithoutExtension; } } function errorOnImplicitAnyModule(isError: boolean, errorNode: Node, sourceFile: SourceFile, mode: ResolutionMode, { packageId, resolvedFileName }: ResolvedModuleFull, moduleReference: string): void { let errorInfo; if (!isExternalModuleNameRelative(moduleReference) && packageId) { const node10Result = sourceFile.resolvedModules?.get(moduleReference, mode)?.node10Result; errorInfo = node10Result ? chainDiagnosticMessages( /*details*/ undefined, Diagnostics.There_are_types_at_0_but_this_result_could_not_be_resolved_when_respecting_package_json_exports_The_1_library_may_need_to_update_its_package_json_or_typings, node10Result, node10Result.indexOf(nodeModulesPathPart + "@types/") > -1 ? `@types/${mangleScopedPackageName(packageId.name)}` : packageId.name) : typesPackageExists(packageId.name) ? chainDiagnosticMessages( /*details*/ undefined, Diagnostics.If_the_0_package_actually_exposes_this_module_consider_sending_a_pull_request_to_amend_https_Colon_Slash_Slashgithub_com_SlashDefinitelyTyped_SlashDefinitelyTyped_Slashtree_Slashmaster_Slashtypes_Slash_1, packageId.name, mangleScopedPackageName(packageId.name)) : packageBundlesTypes(packageId.name) ? chainDiagnosticMessages( /*details*/ undefined, Diagnostics.If_the_0_package_actually_exposes_this_module_try_adding_a_new_declaration_d_ts_file_containing_declare_module_1, packageId.name, moduleReference) : chainDiagnosticMessages( /*details*/ undefined, Diagnostics.Try_npm_i_save_dev_types_Slash_1_if_it_exists_or_add_a_new_declaration_d_ts_file_containing_declare_module_0, moduleReference, mangleScopedPackageName(packageId.name)); } errorOrSuggestion(isError, errorNode, chainDiagnosticMessages( errorInfo, Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type, moduleReference, resolvedFileName)); } function typesPackageExists(packageName: string): boolean { return getPackagesMap().has(getTypesPackageName(packageName)); } function packageBundlesTypes(packageName: string): boolean { return !!getPackagesMap().get(packageName); } function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol; function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { if (moduleSymbol?.exports) { const exportEquals = resolveSymbol(moduleSymbol.exports.get(InternalSymbolName.ExportEquals), dontResolveAlias); const exported = getCommonJsExportEquals(getMergedSymbol(exportEquals), getMergedSymbol(moduleSymbol)); return getMergedSymbol(exported) || moduleSymbol; } return undefined; } function getCommonJsExportEquals(exported: Symbol | undefined, moduleSymbol: Symbol): Symbol | undefined { if (!exported || exported === unknownSymbol || exported === moduleSymbol || moduleSymbol.exports!.size === 1 || exported.flags & SymbolFlags.Alias) { return exported; } const links = getSymbolLinks(exported); if (links.cjsExportMerged) { return links.cjsExportMerged; } const merged = exported.flags & SymbolFlags.Transient ? exported : cloneSymbol(exported); merged.flags = merged.flags | SymbolFlags.ValueModule; if (merged.exports === undefined) { merged.exports = createSymbolTable(); } moduleSymbol.exports!.forEach((s, name) => { if (name === InternalSymbolName.ExportEquals) return; merged.exports!.set(name, merged.exports!.has(name) ? mergeSymbol(merged.exports!.get(name)!, s) : s); }); getSymbolLinks(merged).cjsExportMerged = merged; return links.cjsExportMerged = merged; } // An external module with an 'export =' declaration may be referenced as an ES6 module provided the 'export =' // references a symbol that is at least declared as a module or a variable. The target of the 'export =' may // combine other declarations with the module or variable (e.g. a class/module, function/module, interface/variable). function resolveESModuleSymbol(moduleSymbol: Symbol | undefined, referencingLocation: Node, dontResolveAlias: boolean, suppressInteropError: boolean): Symbol | undefined { const symbol = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias); if (!dontResolveAlias && symbol) { if (!suppressInteropError && !(symbol.flags & (SymbolFlags.Module | SymbolFlags.Variable)) && !getDeclarationOfKind(symbol, SyntaxKind.SourceFile)) { const compilerOptionName = moduleKind >= ModuleKind.ES2015 ? "allowSyntheticDefaultImports" : "esModuleInterop"; error(referencingLocation, Diagnostics.This_module_can_only_be_referenced_with_ECMAScript_imports_Slashexports_by_turning_on_the_0_flag_and_referencing_its_default_export, compilerOptionName); return symbol; } const referenceParent = referencingLocation.parent; if ( (isImportDeclaration(referenceParent) && getNamespaceDeclarationNode(referenceParent)) || isImportCall(referenceParent) ) { const reference = isImportCall(referenceParent) ? referenceParent.arguments[0] : referenceParent.moduleSpecifier; const type = getTypeOfSymbol(symbol); const defaultOnlyType = getTypeWithSyntheticDefaultOnly(type, symbol, moduleSymbol!, reference); if (defaultOnlyType) { return cloneTypeAsModuleType(symbol, defaultOnlyType, referenceParent); } const targetFile = moduleSymbol?.declarations?.find(isSourceFile); const isEsmCjsRef = targetFile && isESMFormatImportImportingCommonjsFormatFile(getUsageModeForExpression(reference), targetFile.impliedNodeFormat); if (getESModuleInterop(compilerOptions) || isEsmCjsRef) { let sigs = getSignaturesOfStructuredType(type, SignatureKind.Call); if (!sigs || !sigs.length) { sigs = getSignaturesOfStructuredType(type, SignatureKind.Construct); } if ( (sigs && sigs.length) || getPropertyOfType(type, InternalSymbolName.Default, /*skipObjectFunctionPropertyAugment*/ true) || isEsmCjsRef ) { const moduleType = getTypeWithSyntheticDefaultImportType(type, symbol, moduleSymbol!, reference); return cloneTypeAsModuleType(symbol, moduleType, referenceParent); } } } } return symbol; } /** * Create a new symbol which has the module's type less the call and construct signatures */ function cloneTypeAsModuleType(symbol: Symbol, moduleType: Type, referenceParent: ImportDeclaration | ImportCall) { const result = createSymbol(symbol.flags, symbol.escapedName); result.declarations = symbol.declarations ? symbol.declarations.slice() : []; result.parent = symbol.parent; result.links.target = symbol; result.links.originatingImport = referenceParent; if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; if (symbol.members) result.members = new Map(symbol.members); if (symbol.exports) result.exports = new Map(symbol.exports); const resolvedModuleType = resolveStructuredTypeMembers(moduleType as StructuredType); // Should already be resolved from the signature checks above result.links.type = createAnonymousType(result, resolvedModuleType.members, emptyArray, emptyArray, resolvedModuleType.indexInfos); return result; } function hasExportAssignmentSymbol(moduleSymbol: Symbol): boolean { return moduleSymbol.exports!.get(InternalSymbolName.ExportEquals) !== undefined; } function getExportsOfModuleAsArray(moduleSymbol: Symbol): Symbol[] { return symbolsToArray(getExportsOfModule(moduleSymbol)); } function getExportsAndPropertiesOfModule(moduleSymbol: Symbol): Symbol[] { const exports = getExportsOfModuleAsArray(moduleSymbol); const exportEquals = resolveExternalModuleSymbol(moduleSymbol); if (exportEquals !== moduleSymbol) { const type = getTypeOfSymbol(exportEquals); if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { addRange(exports, getPropertiesOfType(type)); } } return exports; } function forEachExportAndPropertyOfModule(moduleSymbol: Symbol, cb: (symbol: Symbol, key: __String) => void): void { const exports = getExportsOfModule(moduleSymbol); exports.forEach((symbol, key) => { if (!isReservedMemberName(key)) { cb(symbol, key); } }); const exportEquals = resolveExternalModuleSymbol(moduleSymbol); if (exportEquals !== moduleSymbol) { const type = getTypeOfSymbol(exportEquals); if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { forEachPropertyOfType(type, (symbol, escapedName) => { cb(symbol, escapedName); }); } } } function tryGetMemberInModuleExports(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { const symbolTable = getExportsOfModule(moduleSymbol); if (symbolTable) { return symbolTable.get(memberName); } } function tryGetMemberInModuleExportsAndProperties(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { const symbol = tryGetMemberInModuleExports(memberName, moduleSymbol); if (symbol) { return symbol; } const exportEquals = resolveExternalModuleSymbol(moduleSymbol); if (exportEquals === moduleSymbol) { return undefined; } const type = getTypeOfSymbol(exportEquals); return shouldTreatPropertiesOfExternalModuleAsExports(type) ? getPropertyOfType(type, memberName) : undefined; } function shouldTreatPropertiesOfExternalModuleAsExports(resolvedExternalModuleType: Type) { return !(resolvedExternalModuleType.flags & TypeFlags.Primitive || getObjectFlags(resolvedExternalModuleType) & ObjectFlags.Class || // `isArrayOrTupleLikeType` is too expensive to use in this auto-imports hot path isArrayType(resolvedExternalModuleType) || isTupleType(resolvedExternalModuleType)); } function getExportsOfSymbol(symbol: Symbol): SymbolTable { return symbol.flags & SymbolFlags.LateBindingContainer ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedExports) : symbol.flags & SymbolFlags.Module ? getExportsOfModule(symbol) : symbol.exports || emptySymbols; } function getExportsOfModule(moduleSymbol: Symbol): SymbolTable { const links = getSymbolLinks(moduleSymbol); if (!links.resolvedExports) { const { exports, typeOnlyExportStarMap } = getExportsOfModuleWorker(moduleSymbol); links.resolvedExports = exports; links.typeOnlyExportStarMap = typeOnlyExportStarMap; } return links.resolvedExports; } interface ExportCollisionTracker { specifierText: string; exportsWithDuplicate?: ExportDeclaration[]; } type ExportCollisionTrackerTable = UnderscoreEscapedMap; /** * Extends one symbol table with another while collecting information on name collisions for error message generation into the `lookupTable` argument * Not passing `lookupTable` and `exportNode` disables this collection, and just extends the tables */ function extendExportSymbols(target: SymbolTable, source: SymbolTable | undefined, lookupTable?: ExportCollisionTrackerTable, exportNode?: ExportDeclaration) { if (!source) return; source.forEach((sourceSymbol, id) => { if (id === InternalSymbolName.Default) return; const targetSymbol = target.get(id); if (!targetSymbol) { target.set(id, sourceSymbol); if (lookupTable && exportNode) { lookupTable.set(id, { specifierText: getTextOfNode(exportNode.moduleSpecifier!) }); } } else if (lookupTable && exportNode && targetSymbol && resolveSymbol(targetSymbol) !== resolveSymbol(sourceSymbol)) { const collisionTracker = lookupTable.get(id)!; if (!collisionTracker.exportsWithDuplicate) { collisionTracker.exportsWithDuplicate = [exportNode]; } else { collisionTracker.exportsWithDuplicate.push(exportNode); } } }); } function getExportsOfModuleWorker(moduleSymbol: Symbol) { const visitedSymbols: Symbol[] = []; let typeOnlyExportStarMap: UnderscoreEscapedMap | undefined; const nonTypeOnlyNames = new Set<__String>(); // A module defined by an 'export=' consists of one export that needs to be resolved moduleSymbol = resolveExternalModuleSymbol(moduleSymbol); const exports = visit(moduleSymbol) || emptySymbols; if (typeOnlyExportStarMap) { nonTypeOnlyNames.forEach(name => typeOnlyExportStarMap!.delete(name)); } return { exports, typeOnlyExportStarMap, }; // The ES6 spec permits export * declarations in a module to circularly reference the module itself. For example, // module 'a' can 'export * from "b"' and 'b' can 'export * from "a"' without error. function visit(symbol: Symbol | undefined, exportStar?: ExportDeclaration, isTypeOnly?: boolean): SymbolTable | undefined { if (!isTypeOnly && symbol?.exports) { // Add non-type-only names before checking if we've visited this module, // because we might have visited it via an 'export type *', and visiting // again with 'export *' will override the type-onlyness of its exports. symbol.exports.forEach((_, name) => nonTypeOnlyNames.add(name)); } if (!(symbol && symbol.exports && pushIfUnique(visitedSymbols, symbol))) { return; } const symbols = new Map(symbol.exports); // All export * declarations are collected in an __export symbol by the binder const exportStars = symbol.exports.get(InternalSymbolName.ExportStar); if (exportStars) { const nestedSymbols = createSymbolTable(); const lookupTable: ExportCollisionTrackerTable = new Map(); if (exportStars.declarations) { for (const node of exportStars.declarations) { const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); const exportedSymbols = visit(resolvedModule, node as ExportDeclaration, isTypeOnly || (node as ExportDeclaration).isTypeOnly); extendExportSymbols( nestedSymbols, exportedSymbols, lookupTable, node as ExportDeclaration ); } } lookupTable.forEach(({ exportsWithDuplicate }, id) => { // It's not an error if the file with multiple `export *`s with duplicate names exports a member with that name itself if (id === "export=" || !(exportsWithDuplicate && exportsWithDuplicate.length) || symbols.has(id)) { return; } for (const node of exportsWithDuplicate) { diagnostics.add(createDiagnosticForNode( node, Diagnostics.Module_0_has_already_exported_a_member_named_1_Consider_explicitly_re_exporting_to_resolve_the_ambiguity, lookupTable.get(id)!.specifierText, unescapeLeadingUnderscores(id) )); } }); extendExportSymbols(symbols, nestedSymbols); } if (exportStar?.isTypeOnly) { typeOnlyExportStarMap ??= new Map(); symbols.forEach((_, escapedName) => typeOnlyExportStarMap!.set( escapedName, exportStar as ExportDeclaration & { readonly isTypeOnly: true })); } return symbols; } } function getMergedSymbol(symbol: Symbol): Symbol; function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined; function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined { let merged: Symbol; return symbol && symbol.mergeId && (merged = mergedSymbols[symbol.mergeId]) ? merged : symbol; } function getSymbolOfDeclaration(node: Declaration): Symbol { return getMergedSymbol(node.symbol && getLateBoundSymbol(node.symbol)); } /** * Get the merged symbol for a node. If you know the node is a `Declaration`, it is faster and more type safe to * use use `getSymbolOfDeclaration` instead. */ function getSymbolOfNode(node: Node): Symbol | undefined { return canHaveSymbol(node) ? getSymbolOfDeclaration(node) : undefined; } function getParentOfSymbol(symbol: Symbol): Symbol | undefined { return getMergedSymbol(symbol.parent && getLateBoundSymbol(symbol.parent)); } function getAlternativeContainingModules(symbol: Symbol, enclosingDeclaration: Node): Symbol[] { const containingFile = getSourceFileOfNode(enclosingDeclaration); const id = getNodeId(containingFile); const links = getSymbolLinks(symbol); let results: Symbol[] | undefined; if (links.extendedContainersByFile && (results = links.extendedContainersByFile.get(id))) { return results; } if (containingFile && containingFile.imports) { // Try to make an import using an import already in the enclosing file, if possible for (const importRef of containingFile.imports) { if (nodeIsSynthesized(importRef)) continue; // Synthetic names can't be resolved by `resolveExternalModuleName` - they'll cause a debug assert if they error const resolvedModule = resolveExternalModuleName(enclosingDeclaration, importRef, /*ignoreErrors*/ true); if (!resolvedModule) continue; const ref = getAliasForSymbolInContainer(resolvedModule, symbol); if (!ref) continue; results = append(results, resolvedModule); } if (length(results)) { (links.extendedContainersByFile || (links.extendedContainersByFile = new Map())).set(id, results!); return results!; } } if (links.extendedContainers) { return links.extendedContainers; } // No results from files already being imported by this file - expand search (expensive, but not location-specific, so cached) const otherFiles = host.getSourceFiles(); for (const file of otherFiles) { if (!isExternalModule(file)) continue; const sym = getSymbolOfDeclaration(file); const ref = getAliasForSymbolInContainer(sym, symbol); if (!ref) continue; results = append(results, sym); } return links.extendedContainers = results || emptyArray; } /** * Attempts to find the symbol corresponding to the container a symbol is in - usually this * is just its' `.parent`, but for locals, this value is `undefined` */ function getContainersOfSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): Symbol[] | undefined { const container = getParentOfSymbol(symbol); // Type parameters end up in the `members` lists but are not externally visible if (container && !(symbol.flags & SymbolFlags.TypeParameter)) { const additionalContainers = mapDefined(container.declarations, fileSymbolIfFileSymbolExportEqualsContainer); const reexportContainers = enclosingDeclaration && getAlternativeContainingModules(symbol, enclosingDeclaration); const objectLiteralContainer = getVariableDeclarationOfObjectLiteral(container, meaning); if ( enclosingDeclaration && container.flags & getQualifiedLeftMeaning(meaning) && getAccessibleSymbolChain(container, enclosingDeclaration, SymbolFlags.Namespace, /*externalOnly*/ false) ) { return append(concatenate(concatenate([container], additionalContainers), reexportContainers), objectLiteralContainer); // This order expresses a preference for the real container if it is in scope } // we potentially have a symbol which is a member of the instance side of something - look for a variable in scope with the container's type // which may be acting like a namespace (eg, `Symbol` acts like a namespace when looking up `Symbol.toStringTag`) const firstVariableMatch = !(container.flags & getQualifiedLeftMeaning(meaning)) && container.flags & SymbolFlags.Type && getDeclaredTypeOfSymbol(container).flags & TypeFlags.Object && meaning === SymbolFlags.Value ? forEachSymbolTableInScope(enclosingDeclaration, t => { return forEachEntry(t, s => { if (s.flags & getQualifiedLeftMeaning(meaning) && getTypeOfSymbol(s) === getDeclaredTypeOfSymbol(container)) { return s; } }); }) : undefined; let res = firstVariableMatch ? [firstVariableMatch, ...additionalContainers, container] : [...additionalContainers, container]; res = append(res, objectLiteralContainer); res = addRange(res, reexportContainers); return res; } const candidates = mapDefined(symbol.declarations, d => { if (!isAmbientModule(d) && d.parent){ // direct children of a module if (hasNonGlobalAugmentationExternalModuleSymbol(d.parent)) { return getSymbolOfDeclaration(d.parent as Declaration); } // export ='d member of an ambient module if (isModuleBlock(d.parent) && d.parent.parent && resolveExternalModuleSymbol(getSymbolOfDeclaration(d.parent.parent)) === symbol) { return getSymbolOfDeclaration(d.parent.parent); } } if (isClassExpression(d) && isBinaryExpression(d.parent) && d.parent.operatorToken.kind === SyntaxKind.EqualsToken && isAccessExpression(d.parent.left) && isEntityNameExpression(d.parent.left.expression)) { if (isModuleExportsAccessExpression(d.parent.left) || isExportsIdentifier(d.parent.left.expression)) { return getSymbolOfDeclaration(getSourceFileOfNode(d)); } checkExpressionCached(d.parent.left.expression); return getNodeLinks(d.parent.left.expression).resolvedSymbol; } }); if (!length(candidates)) { return undefined; } return mapDefined(candidates, candidate => getAliasForSymbolInContainer(candidate, symbol) ? candidate : undefined); function fileSymbolIfFileSymbolExportEqualsContainer(d: Declaration) { return container && getFileSymbolIfFileSymbolExportEqualsContainer(d, container); } } function getVariableDeclarationOfObjectLiteral(symbol: Symbol, meaning: SymbolFlags) { // If we're trying to reference some object literal in, eg `var a = { x: 1 }`, the symbol for the literal, `__object`, is distinct // from the symbol of the declaration it is being assigned to. Since we can use the declaration to refer to the literal, however, // we'd like to make that connection here - potentially causing us to paint the declaration's visibility, and therefore the literal. const firstDecl: Node | false = !!length(symbol.declarations) && first(symbol.declarations!); if (meaning & SymbolFlags.Value && firstDecl && firstDecl.parent && isVariableDeclaration(firstDecl.parent)) { if (isObjectLiteralExpression(firstDecl) && firstDecl === firstDecl.parent.initializer || isTypeLiteralNode(firstDecl) && firstDecl === firstDecl.parent.type) { return getSymbolOfDeclaration(firstDecl.parent); } } } function getFileSymbolIfFileSymbolExportEqualsContainer(d: Declaration, container: Symbol) { const fileSymbol = getExternalModuleContainer(d); const exported = fileSymbol && fileSymbol.exports && fileSymbol.exports.get(InternalSymbolName.ExportEquals); return exported && getSymbolIfSameReference(exported, container) ? fileSymbol : undefined; } function getAliasForSymbolInContainer(container: Symbol, symbol: Symbol) { if (container === getParentOfSymbol(symbol)) { // fast path, `symbol` is either already the alias or isn't aliased return symbol; } // Check if container is a thing with an `export=` which points directly at `symbol`, and if so, return // the container itself as the alias for the symbol const exportEquals = container.exports && container.exports.get(InternalSymbolName.ExportEquals); if (exportEquals && getSymbolIfSameReference(exportEquals, symbol)) { return container; } const exports = getExportsOfSymbol(container); const quick = exports.get(symbol.escapedName); if (quick && getSymbolIfSameReference(quick, symbol)) { return quick; } return forEachEntry(exports, exported => { if (getSymbolIfSameReference(exported, symbol)) { return exported; } }); } /** * Checks if two symbols, through aliasing and/or merging, refer to the same thing */ function getSymbolIfSameReference(s1: Symbol, s2: Symbol) { if (getMergedSymbol(resolveSymbol(getMergedSymbol(s1))) === getMergedSymbol(resolveSymbol(getMergedSymbol(s2)))) { return s1; } } function getExportSymbolOfValueSymbolIfExported(symbol: Symbol): Symbol; function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined; function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined { return getMergedSymbol(symbol && (symbol.flags & SymbolFlags.ExportValue) !== 0 && symbol.exportSymbol || symbol); } function symbolIsValue(symbol: Symbol, includeTypeOnlyMembers?: boolean): boolean { return !!( symbol.flags & SymbolFlags.Value || symbol.flags & SymbolFlags.Alias && getAllSymbolFlags(symbol) & SymbolFlags.Value && (includeTypeOnlyMembers || !getTypeOnlyAliasDeclaration(symbol))); } function findConstructorDeclaration(node: ClassLikeDeclaration): ConstructorDeclaration | undefined { const members = node.members; for (const member of members) { if (member.kind === SyntaxKind.Constructor && nodeIsPresent((member as ConstructorDeclaration).body)) { return member as ConstructorDeclaration; } } } function createType(flags: TypeFlags): Type { const result = new Type(checker, flags); typeCount++; result.id = typeCount; tracing?.recordType(result); return result; } function createTypeWithSymbol(flags: TypeFlags, symbol: Symbol): Type { const result = createType(flags); result.symbol = symbol; return result; } function createOriginType(flags: TypeFlags): Type { return new Type(checker, flags); } function createIntrinsicType(kind: TypeFlags, intrinsicName: string, objectFlags = ObjectFlags.None): IntrinsicType { const type = createType(kind) as IntrinsicType; type.intrinsicName = intrinsicName; type.objectFlags = objectFlags; return type; } function createObjectType(objectFlags: ObjectFlags, symbol?: Symbol): ObjectType { const type = createTypeWithSymbol(TypeFlags.Object, symbol!) as ObjectType; type.objectFlags = objectFlags; type.members = undefined; type.properties = undefined; type.callSignatures = undefined; type.constructSignatures = undefined; type.indexInfos = undefined; return type; } function createTypeofType() { return getUnionType(arrayFrom(typeofNEFacts.keys(), getStringLiteralType)); } function createTypeParameter(symbol?: Symbol) { return createTypeWithSymbol(TypeFlags.TypeParameter, symbol!) as TypeParameter; } // A reserved member name starts with two underscores, but the third character cannot be an underscore, // @, or #. A third underscore indicates an escaped form of an identifier that started // with at least two underscores. The @ character indicates that the name is denoted by a well known ES // Symbol instance and the # character indicates that the name is a PrivateIdentifier. function isReservedMemberName(name: __String) { return (name as string).charCodeAt(0) === CharacterCodes._ && (name as string).charCodeAt(1) === CharacterCodes._ && (name as string).charCodeAt(2) !== CharacterCodes._ && (name as string).charCodeAt(2) !== CharacterCodes.at && (name as string).charCodeAt(2) !== CharacterCodes.hash; } function getNamedMembers(members: SymbolTable): Symbol[] { let result: Symbol[] | undefined; members.forEach((symbol, id) => { if (isNamedMember(symbol, id)) { (result || (result = [])).push(symbol); } }); return result || emptyArray; } function isNamedMember(member: Symbol, escapedName: __String) { return !isReservedMemberName(escapedName) && symbolIsValue(member); } function getNamedOrIndexSignatureMembers(members: SymbolTable): Symbol[] { const result = getNamedMembers(members); const index = getIndexSymbolFromSymbolTable(members); return index ? concatenate(result, [index]) : result; } function setStructuredTypeMembers(type: StructuredType, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { const resolved = type as ResolvedType; resolved.members = members; resolved.properties = emptyArray; resolved.callSignatures = callSignatures; resolved.constructSignatures = constructSignatures; resolved.indexInfos = indexInfos; // This can loop back to getPropertyOfType() which would crash if `callSignatures` & `constructSignatures` are not initialized. if (members !== emptySymbols) resolved.properties = getNamedMembers(members); return resolved; } function createAnonymousType(symbol: Symbol | undefined, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { return setStructuredTypeMembers(createObjectType(ObjectFlags.Anonymous, symbol), members, callSignatures, constructSignatures, indexInfos); } function getResolvedTypeWithoutAbstractConstructSignatures(type: ResolvedType) { if (type.constructSignatures.length === 0) return type; if (type.objectTypeWithoutAbstractConstructSignatures) return type.objectTypeWithoutAbstractConstructSignatures; const constructSignatures = filter(type.constructSignatures, signature => !(signature.flags & SignatureFlags.Abstract)); if (type.constructSignatures === constructSignatures) return type; const typeCopy = createAnonymousType( type.symbol, type.members, type.callSignatures, some(constructSignatures) ? constructSignatures : emptyArray, type.indexInfos); type.objectTypeWithoutAbstractConstructSignatures = typeCopy; typeCopy.objectTypeWithoutAbstractConstructSignatures = typeCopy; return typeCopy; } function forEachSymbolTableInScope(enclosingDeclaration: Node | undefined, callback: (symbolTable: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean, scopeNode?: Node) => T): T { let result: T; for (let location = enclosingDeclaration; location; location = location.parent) { // Locals of a source file are not in scope (because they get merged into the global symbol table) if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { if (result = callback(location.locals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { return result; } } switch (location.kind) { case SyntaxKind.SourceFile: if (!isExternalOrCommonJsModule(location as SourceFile)) { break; } // falls through case SyntaxKind.ModuleDeclaration: const sym = getSymbolOfDeclaration(location as ModuleDeclaration); // `sym` may not have exports if this module declaration is backed by the symbol for a `const` that's being rewritten // into a namespace - in such cases, it's best to just let the namespace appear empty (the const members couldn't have referred // to one another anyway) if (result = callback(sym?.exports || emptySymbols, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { return result; } break; case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: case SyntaxKind.InterfaceDeclaration: // Type parameters are bound into `members` lists so they can merge across declarations // This is troublesome, since in all other respects, they behave like locals :cries: // TODO: the below is shared with similar code in `resolveName` - in fact, rephrasing all this symbol // lookup logic in terms of `resolveName` would be nice // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would // trigger resolving late-bound names, which we may already be in the process of doing while we're here! let table: UnderscoreEscapedMap | undefined; // TODO: Should this filtered table be cached in some way? (getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols).forEach((memberSymbol, key) => { if (memberSymbol.flags & (SymbolFlags.Type & ~SymbolFlags.Assignment)) { (table || (table = createSymbolTable())).set(key, memberSymbol); } }); if (table && (result = callback(table, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ false, location))) { return result; } break; } } return callback(globals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true); } function getQualifiedLeftMeaning(rightMeaning: SymbolFlags) { // If we are looking in value space, the parent meaning is value, other wise it is namespace return rightMeaning === SymbolFlags.Value ? SymbolFlags.Value : SymbolFlags.Namespace; } function getAccessibleSymbolChain(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean, visitedSymbolTablesMap: Map = new Map()): Symbol[] | undefined { if (!(symbol && !isPropertyOrMethodDeclarationSymbol(symbol))) { return undefined; } const links = getSymbolLinks(symbol); const cache = (links.accessibleChainCache ||= new Map()); // Go from enclosingDeclaration to the first scope we check, so the cache is keyed off the scope and thus shared more const firstRelevantLocation = forEachSymbolTableInScope(enclosingDeclaration, (_, __, ___, node) => node); const key = `${useOnlyExternalAliasing ? 0 : 1}|${firstRelevantLocation && getNodeId(firstRelevantLocation)}|${meaning}`; if (cache.has(key)) { return cache.get(key); } const id = getSymbolId(symbol); let visitedSymbolTables = visitedSymbolTablesMap.get(id); if (!visitedSymbolTables) { visitedSymbolTablesMap.set(id, visitedSymbolTables = []); } const result = forEachSymbolTableInScope(enclosingDeclaration, getAccessibleSymbolChainFromSymbolTable); cache.set(key, result); return result; /** * @param {ignoreQualification} boolean Set when a symbol is being looked for through the exports of another symbol (meaning we have a route to qualify it already) */ function getAccessibleSymbolChainFromSymbolTable(symbols: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean): Symbol[] | undefined { if (!pushIfUnique(visitedSymbolTables!, symbols)) { return undefined; } const result = trySymbolTable(symbols, ignoreQualification, isLocalNameLookup); visitedSymbolTables!.pop(); return result; } function canQualifySymbol(symbolFromSymbolTable: Symbol, meaning: SymbolFlags) { // If the symbol is equivalent and doesn't need further qualification, this symbol is accessible return !needsQualification(symbolFromSymbolTable, enclosingDeclaration, meaning) || // If symbol needs qualification, make sure that parent is accessible, if it is then this symbol is accessible too !!getAccessibleSymbolChain(symbolFromSymbolTable.parent, enclosingDeclaration, getQualifiedLeftMeaning(meaning), useOnlyExternalAliasing, visitedSymbolTablesMap); } function isAccessible(symbolFromSymbolTable: Symbol, resolvedAliasSymbol?: Symbol, ignoreQualification?: boolean) { return (symbol === (resolvedAliasSymbol || symbolFromSymbolTable) || getMergedSymbol(symbol) === getMergedSymbol(resolvedAliasSymbol || symbolFromSymbolTable)) && // if the symbolFromSymbolTable is not external module (it could be if it was determined as ambient external module and would be in globals table) // and if symbolFromSymbolTable or alias resolution matches the symbol, // check the symbol can be qualified, it is only then this symbol is accessible !some(symbolFromSymbolTable.declarations, hasNonGlobalAugmentationExternalModuleSymbol) && (ignoreQualification || canQualifySymbol(getMergedSymbol(symbolFromSymbolTable), meaning)); } function trySymbolTable(symbols: SymbolTable, ignoreQualification: boolean | undefined, isLocalNameLookup: boolean | undefined): Symbol[] | undefined { // If symbol is directly available by its name in the symbol table if (isAccessible(symbols.get(symbol!.escapedName)!, /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { return [symbol!]; } // Check if symbol is any of the aliases in scope const result = forEachEntry(symbols, symbolFromSymbolTable => { if (symbolFromSymbolTable.flags & SymbolFlags.Alias && symbolFromSymbolTable.escapedName !== InternalSymbolName.ExportEquals && symbolFromSymbolTable.escapedName !== InternalSymbolName.Default && !(isUMDExportSymbol(symbolFromSymbolTable) && enclosingDeclaration && isExternalModule(getSourceFileOfNode(enclosingDeclaration))) // If `!useOnlyExternalAliasing`, we can use any type of alias to get the name && (!useOnlyExternalAliasing || some(symbolFromSymbolTable.declarations, isExternalModuleImportEqualsDeclaration)) // If we're looking up a local name to reference directly, omit namespace reexports, otherwise when we're trawling through an export list to make a dotted name, we can keep it && (isLocalNameLookup ? !some(symbolFromSymbolTable.declarations, isNamespaceReexportDeclaration) : true) // While exports are generally considered to be in scope, export-specifier declared symbols are _not_ // See similar comment in `resolveName` for details && (ignoreQualification || !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier)) ) { const resolvedImportedSymbol = resolveAlias(symbolFromSymbolTable); const candidate = getCandidateListForSymbol(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification); if (candidate) { return candidate; } } if (symbolFromSymbolTable.escapedName === symbol!.escapedName && symbolFromSymbolTable.exportSymbol) { if (isAccessible(getMergedSymbol(symbolFromSymbolTable.exportSymbol), /*aliasSymbol*/ undefined, ignoreQualification)) { return [symbol!]; } } }); // If there's no result and we're looking at the global symbol table, treat `globalThis` like an alias and try to lookup thru that return result || (symbols === globals ? getCandidateListForSymbol(globalThisSymbol, globalThisSymbol, ignoreQualification) : undefined); } function getCandidateListForSymbol(symbolFromSymbolTable: Symbol, resolvedImportedSymbol: Symbol, ignoreQualification: boolean | undefined) { if (isAccessible(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification)) { return [symbolFromSymbolTable]; } // Look in the exported members, if we can find accessibleSymbolChain, symbol is accessible using this chain // but only if the symbolFromSymbolTable can be qualified const candidateTable = getExportsOfSymbol(resolvedImportedSymbol); const accessibleSymbolsFromExports = candidateTable && getAccessibleSymbolChainFromSymbolTable(candidateTable, /*ignoreQualification*/ true); if (accessibleSymbolsFromExports && canQualifySymbol(symbolFromSymbolTable, getQualifiedLeftMeaning(meaning))) { return [symbolFromSymbolTable].concat(accessibleSymbolsFromExports); } } } function needsQualification(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags) { let qualify = false; forEachSymbolTableInScope(enclosingDeclaration, symbolTable => { // If symbol of this name is not available in the symbol table we are ok let symbolFromSymbolTable = getMergedSymbol(symbolTable.get(symbol.escapedName)); if (!symbolFromSymbolTable) { // Continue to the next symbol table return false; } // If the symbol with this name is present it should refer to the symbol if (symbolFromSymbolTable === symbol) { // No need to qualify return true; } // Qualify if the symbol from symbol table has same meaning as expected const shouldResolveAlias = (symbolFromSymbolTable.flags & SymbolFlags.Alias && !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier)); symbolFromSymbolTable = shouldResolveAlias ? resolveAlias(symbolFromSymbolTable) : symbolFromSymbolTable; const flags = shouldResolveAlias ? getAllSymbolFlags(symbolFromSymbolTable) : symbolFromSymbolTable.flags; if (flags & meaning) { qualify = true; return true; } // Continue to the next symbol table return false; }); return qualify; } function isPropertyOrMethodDeclarationSymbol(symbol: Symbol) { if (symbol.declarations && symbol.declarations.length) { for (const declaration of symbol.declarations) { switch (declaration.kind) { case SyntaxKind.PropertyDeclaration: case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: continue; default: return false; } } return true; } return false; } function isTypeSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Type, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); return access.accessibility === SymbolAccessibility.Accessible; } function isValueSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Value, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); return access.accessibility === SymbolAccessibility.Accessible; } function isSymbolAccessibleByFlags(typeSymbol: Symbol, enclosingDeclaration: Node | undefined, flags: SymbolFlags): boolean { const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, flags, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ false); return access.accessibility === SymbolAccessibility.Accessible; } function isAnySymbolAccessible(symbols: Symbol[] | undefined, enclosingDeclaration: Node | undefined, initialSymbol: Symbol, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult | undefined { if (!length(symbols)) return; let hadAccessibleChain: Symbol | undefined; let earlyModuleBail = false; for (const symbol of symbols!) { // Symbol is accessible if it by itself is accessible const accessibleSymbolChain = getAccessibleSymbolChain(symbol, enclosingDeclaration, meaning, /*useOnlyExternalAliasing*/ false); if (accessibleSymbolChain) { hadAccessibleChain = symbol; const hasAccessibleDeclarations = hasVisibleDeclarations(accessibleSymbolChain[0], shouldComputeAliasesToMakeVisible); if (hasAccessibleDeclarations) { return hasAccessibleDeclarations; } } if (allowModules) { if (some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { if (shouldComputeAliasesToMakeVisible) { earlyModuleBail = true; // Generally speaking, we want to use the aliases that already exist to refer to a module, if present // In order to do so, we need to find those aliases in order to retain them in declaration emit; so // if we are in declaration emit, we cannot use the fast path for module visibility until we've exhausted // all other visibility options (in order to capture the possible aliases used to reference the module) continue; } // Any meaning of a module symbol is always accessible via an `import` type return { accessibility: SymbolAccessibility.Accessible }; } } // If we haven't got the accessible symbol, it doesn't mean the symbol is actually inaccessible. // It could be a qualified symbol and hence verify the path // e.g.: // module m { // export class c { // } // } // const x: typeof m.c // In the above example when we start with checking if typeof m.c symbol is accessible, // we are going to see if c can be accessed in scope directly. // But it can't, hence the accessible is going to be undefined, but that doesn't mean m.c is inaccessible // It is accessible if the parent m is accessible because then m.c can be accessed through qualification const containers = getContainersOfSymbol(symbol, enclosingDeclaration, meaning); const parentResult = isAnySymbolAccessible(containers, enclosingDeclaration, initialSymbol, initialSymbol === symbol ? getQualifiedLeftMeaning(meaning) : meaning, shouldComputeAliasesToMakeVisible, allowModules); if (parentResult) { return parentResult; } } if (earlyModuleBail) { return { accessibility: SymbolAccessibility.Accessible }; } if (hadAccessibleChain) { return { accessibility: SymbolAccessibility.NotAccessible, errorSymbolName: symbolToString(initialSymbol, enclosingDeclaration, meaning), errorModuleName: hadAccessibleChain !== initialSymbol ? symbolToString(hadAccessibleChain, enclosingDeclaration, SymbolFlags.Namespace) : undefined, }; } } /** * Check if the given symbol in given enclosing declaration is accessible and mark all associated alias to be visible if requested * * @param symbol a Symbol to check if accessible * @param enclosingDeclaration a Node containing reference to the symbol * @param meaning a SymbolFlags to check if such meaning of the symbol is accessible * @param shouldComputeAliasToMakeVisible a boolean value to indicate whether to return aliases to be mark visible in case the symbol is accessible */ function isSymbolAccessible(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean): SymbolAccessibilityResult { return isSymbolAccessibleWorker(symbol, enclosingDeclaration, meaning, shouldComputeAliasesToMakeVisible, /*allowModules*/ true); } function isSymbolAccessibleWorker(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult { if (symbol && enclosingDeclaration) { const result = isAnySymbolAccessible([symbol], enclosingDeclaration, symbol, meaning, shouldComputeAliasesToMakeVisible, allowModules); if (result) { return result; } // This could be a symbol that is not exported in the external module // or it could be a symbol from different external module that is not aliased and hence cannot be named const symbolExternalModule = forEach(symbol.declarations, getExternalModuleContainer); if (symbolExternalModule) { const enclosingExternalModule = getExternalModuleContainer(enclosingDeclaration); if (symbolExternalModule !== enclosingExternalModule) { // name from different external module that is not visible return { accessibility: SymbolAccessibility.CannotBeNamed, errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), errorModuleName: symbolToString(symbolExternalModule), errorNode: isInJSFile(enclosingDeclaration) ? enclosingDeclaration : undefined, }; } } // Just a local name that is not accessible return { accessibility: SymbolAccessibility.NotAccessible, errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), }; } return { accessibility: SymbolAccessibility.Accessible }; } function getExternalModuleContainer(declaration: Node) { const node = findAncestor(declaration, hasExternalModuleSymbol); return node && getSymbolOfDeclaration(node as AmbientModuleDeclaration | SourceFile); } function hasExternalModuleSymbol(declaration: Node) { return isAmbientModule(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); } function hasNonGlobalAugmentationExternalModuleSymbol(declaration: Node) { return isModuleWithStringLiteralName(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); } function hasVisibleDeclarations(symbol: Symbol, shouldComputeAliasToMakeVisible: boolean): SymbolVisibilityResult | undefined { let aliasesToMakeVisible: LateVisibilityPaintedStatement[] | undefined; if (!every(filter(symbol.declarations, d => d.kind !== SyntaxKind.Identifier), getIsDeclarationVisible)) { return undefined; } return { accessibility: SymbolAccessibility.Accessible, aliasesToMakeVisible }; function getIsDeclarationVisible(declaration: Declaration) { if (!isDeclarationVisible(declaration)) { // Mark the unexported alias as visible if its parent is visible // because these kind of aliases can be used to name types in declaration file const anyImportSyntax = getAnyImportSyntax(declaration); if (anyImportSyntax && !hasSyntacticModifier(anyImportSyntax, ModifierFlags.Export) && // import clause without export isDeclarationVisible(anyImportSyntax.parent)) { return addVisibleAlias(declaration, anyImportSyntax); } else if (isVariableDeclaration(declaration) && isVariableStatement(declaration.parent.parent) && !hasSyntacticModifier(declaration.parent.parent, ModifierFlags.Export) && // unexported variable statement isDeclarationVisible(declaration.parent.parent.parent)) { return addVisibleAlias(declaration, declaration.parent.parent); } else if (isLateVisibilityPaintedStatement(declaration) // unexported top-level statement && !hasSyntacticModifier(declaration, ModifierFlags.Export) && isDeclarationVisible(declaration.parent)) { return addVisibleAlias(declaration, declaration); } else if (isBindingElement(declaration)) { if (symbol.flags & SymbolFlags.Alias && isInJSFile(declaration) && declaration.parent?.parent // exported import-like top-level JS require statement && isVariableDeclaration(declaration.parent.parent) && declaration.parent.parent.parent?.parent && isVariableStatement(declaration.parent.parent.parent.parent) && !hasSyntacticModifier(declaration.parent.parent.parent.parent, ModifierFlags.Export) && declaration.parent.parent.parent.parent.parent // check if the thing containing the variable statement is visible (ie, the file) && isDeclarationVisible(declaration.parent.parent.parent.parent.parent)) { return addVisibleAlias(declaration, declaration.parent.parent.parent.parent); } else if (symbol.flags & SymbolFlags.BlockScopedVariable) { const variableStatement = findAncestor(declaration, isVariableStatement)!; if (hasSyntacticModifier(variableStatement, ModifierFlags.Export)) { return true; } if (!isDeclarationVisible(variableStatement.parent)) { return false; } return addVisibleAlias(declaration, variableStatement); } } // Declaration is not visible return false; } return true; } function addVisibleAlias(declaration: Declaration, aliasingStatement: LateVisibilityPaintedStatement) { // In function "buildTypeDisplay" where we decide whether to write type-alias or serialize types, // we want to just check if type- alias is accessible or not but we don't care about emitting those alias at that time // since we will do the emitting later in trackSymbol. if (shouldComputeAliasToMakeVisible) { getNodeLinks(declaration).isVisible = true; aliasesToMakeVisible = appendIfUnique(aliasesToMakeVisible, aliasingStatement); } return true; } } function isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node): SymbolVisibilityResult { // get symbol of the first identifier of the entityName let meaning: SymbolFlags; if (entityName.parent.kind === SyntaxKind.TypeQuery || entityName.parent.kind === SyntaxKind.ExpressionWithTypeArguments && !isPartOfTypeNode(entityName.parent) || entityName.parent.kind === SyntaxKind.ComputedPropertyName) { // Typeof value meaning = SymbolFlags.Value | SymbolFlags.ExportValue; } else if (entityName.kind === SyntaxKind.QualifiedName || entityName.kind === SyntaxKind.PropertyAccessExpression || entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration) { // Left identifier from type reference or TypeAlias // Entity name of the import declaration meaning = SymbolFlags.Namespace; } else { // Type Reference or TypeAlias entity = Identifier meaning = SymbolFlags.Type; } const firstIdentifier = getFirstIdentifier(entityName); const symbol = resolveName(enclosingDeclaration, firstIdentifier.escapedText, meaning, /*nodeNotFoundErrorMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ false); if (symbol && symbol.flags & SymbolFlags.TypeParameter && meaning & SymbolFlags.Type) { return { accessibility: SymbolAccessibility.Accessible }; } if (!symbol && isThisIdentifier(firstIdentifier) && isSymbolAccessible(getSymbolOfDeclaration(getThisContainer(firstIdentifier, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)), firstIdentifier, meaning, /*computeAliases*/ false).accessibility === SymbolAccessibility.Accessible) { return { accessibility: SymbolAccessibility.Accessible }; } // Verify if the symbol is accessible return (symbol && hasVisibleDeclarations(symbol, /*shouldComputeAliasToMakeVisible*/ true)) || { accessibility: SymbolAccessibility.NotAccessible, errorSymbolName: getTextOfNode(firstIdentifier), errorNode: firstIdentifier }; } function symbolToString(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags, flags: SymbolFormatFlags = SymbolFormatFlags.AllowAnyNodeKind, writer?: EmitTextWriter): string { let nodeFlags = NodeBuilderFlags.IgnoreErrors; if (flags & SymbolFormatFlags.UseOnlyExternalAliasing) { nodeFlags |= NodeBuilderFlags.UseOnlyExternalAliasing; } if (flags & SymbolFormatFlags.WriteTypeParametersOrArguments) { nodeFlags |= NodeBuilderFlags.WriteTypeParametersInQualifiedName; } if (flags & SymbolFormatFlags.UseAliasDefinedOutsideCurrentScope) { nodeFlags |= NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope; } if (flags & SymbolFormatFlags.DoNotIncludeSymbolChain) { nodeFlags |= NodeBuilderFlags.DoNotIncludeSymbolChain; } if (flags & SymbolFormatFlags.WriteComputedProps) { nodeFlags |= NodeBuilderFlags.WriteComputedProps; } const builder = flags & SymbolFormatFlags.AllowAnyNodeKind ? nodeBuilder.symbolToNode : nodeBuilder.symbolToEntityName; return writer ? symbolToStringWorker(writer).getText() : usingSingleLineStringWriter(symbolToStringWorker); function symbolToStringWorker(writer: EmitTextWriter) { const entity = builder(symbol, meaning!, enclosingDeclaration, nodeFlags)!; // TODO: GH#18217 // add neverAsciiEscape for GH#39027 const printer = enclosingDeclaration?.kind === SyntaxKind.SourceFile ? createPrinterWithRemoveCommentsNeverAsciiEscape() : createPrinterWithRemoveComments(); const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); printer.writeNode(EmitHint.Unspecified, entity, /*sourceFile*/ sourceFile, writer); return writer; } } function signatureToString(signature: Signature, enclosingDeclaration?: Node, flags = TypeFormatFlags.None, kind?: SignatureKind, writer?: EmitTextWriter): string { return writer ? signatureToStringWorker(writer).getText() : usingSingleLineStringWriter(signatureToStringWorker); function signatureToStringWorker(writer: EmitTextWriter) { let sigOutput: SyntaxKind; if (flags & TypeFormatFlags.WriteArrowStyleSignature) { sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructorType : SyntaxKind.FunctionType; } else { sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructSignature : SyntaxKind.CallSignature; } const sig = nodeBuilder.signatureToSignatureDeclaration(signature, sigOutput, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName); const printer = createPrinterWithRemoveCommentsOmitTrailingSemicolon(); const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); printer.writeNode(EmitHint.Unspecified, sig!, /*sourceFile*/ sourceFile, getTrailingSemicolonDeferringWriter(writer)); // TODO: GH#18217 return writer; } } function typeToString(type: Type, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.AllowUniqueESSymbolType | TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer: EmitTextWriter = createTextWriter("")): string { const noTruncation = compilerOptions.noErrorTruncation || flags & TypeFormatFlags.NoTruncation; const typeNode = nodeBuilder.typeToTypeNode(type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | (noTruncation ? NodeBuilderFlags.NoTruncation : 0)); if (typeNode === undefined) return Debug.fail("should always get typenode"); // The unresolved type gets a synthesized comment on `any` to hint to users that it's not a plain `any`. // Otherwise, we always strip comments out. const printer = type !== unresolvedType ? createPrinterWithRemoveComments() : createPrinterWithDefaults(); const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); printer.writeNode(EmitHint.Unspecified, typeNode, /*sourceFile*/ sourceFile, writer); const result = writer.getText(); const maxLength = noTruncation ? noTruncationMaximumTruncationLength * 2 : defaultMaximumTruncationLength * 2; if (maxLength && result && result.length >= maxLength) { return result.substr(0, maxLength - "...".length) + "..."; } return result; } function getTypeNamesForErrorDisplay(left: Type, right: Type): [string, string] { let leftStr = symbolValueDeclarationIsContextSensitive(left.symbol) ? typeToString(left, left.symbol.valueDeclaration) : typeToString(left); let rightStr = symbolValueDeclarationIsContextSensitive(right.symbol) ? typeToString(right, right.symbol.valueDeclaration) : typeToString(right); if (leftStr === rightStr) { leftStr = getTypeNameForErrorDisplay(left); rightStr = getTypeNameForErrorDisplay(right); } return [leftStr, rightStr]; } function getTypeNameForErrorDisplay(type: Type) { return typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType); } function symbolValueDeclarationIsContextSensitive(symbol: Symbol): boolean { return symbol && !!symbol.valueDeclaration && isExpression(symbol.valueDeclaration) && !isContextSensitive(symbol.valueDeclaration); } function toNodeBuilderFlags(flags = TypeFormatFlags.None): NodeBuilderFlags { return flags & TypeFormatFlags.NodeBuilderFlagsMask; } function isClassInstanceSide(type: Type) { return !!type.symbol && !!(type.symbol.flags & SymbolFlags.Class) && (type === getDeclaredTypeOfClassOrInterface(type.symbol) || (!!(type.flags & TypeFlags.Object) && !!(getObjectFlags(type) & ObjectFlags.IsClassInstanceClone))); } function createNodeBuilder() { return { typeToTypeNode: (type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeToTypeNodeHelper(type, context)), indexInfoToIndexSignatureDeclaration: (indexInfo: IndexInfo, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => indexInfoToIndexSignatureDeclarationHelper(indexInfo, context, /*typeNode*/ undefined)), signatureToSignatureDeclaration: (signature: Signature, kind: SignatureDeclaration["kind"], enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => signatureToSignatureDeclarationHelper(signature, kind, context)), symbolToEntityName: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToName(symbol, context, meaning, /*expectsIdentifier*/ false)), symbolToExpression: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToExpression(symbol, context, meaning)), symbolToTypeParameterDeclarations: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParametersToTypeParameterDeclarations(symbol, context)), symbolToParameterDeclaration: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToParameterDeclaration(symbol, context)), typeParameterToDeclaration: (parameter: TypeParameter, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParameterToDeclaration(parameter, context)), symbolTableToDeclarationStatements: (symbolTable: SymbolTable, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker, bundled?: boolean) => withContext(enclosingDeclaration, flags, tracker, context => symbolTableToDeclarationStatements(symbolTable, context, bundled)), symbolToNode: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToNode(symbol, context, meaning)), }; function symbolToNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { if (context.flags & NodeBuilderFlags.WriteComputedProps) { if (symbol.valueDeclaration) { const name = getNameOfDeclaration(symbol.valueDeclaration); if (name && isComputedPropertyName(name)) return name; } const nameType = getSymbolLinks(symbol).nameType; if (nameType && nameType.flags & (TypeFlags.EnumLiteral | TypeFlags.UniqueESSymbol)) { context.enclosingDeclaration = nameType.symbol.valueDeclaration; return factory.createComputedPropertyName(symbolToExpression(nameType.symbol, context, meaning)); } } return symbolToExpression(symbol, context, meaning); } function withContext(enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker: SymbolTracker | undefined, cb: (context: NodeBuilderContext) => T): T | undefined { Debug.assert(enclosingDeclaration === undefined || (enclosingDeclaration.flags & NodeFlags.Synthesized) === 0); const moduleResolverHost = tracker?.trackSymbol ? tracker.moduleResolverHost : flags! & NodeBuilderFlags.DoNotIncludeSymbolChain ? createBasicNodeBuilderModuleSpecifierResolutionHost(host) : undefined; const context: NodeBuilderContext = { enclosingDeclaration, flags: flags || NodeBuilderFlags.None, tracker: undefined!, encounteredError: false, reportedDiagnostic: false, visitedTypes: undefined, symbolDepth: undefined, inferTypeParameters: undefined, approximateLength: 0 }; context.tracker = new SymbolTrackerImpl(context, tracker, moduleResolverHost); const resultingNode = cb(context); if (context.truncating && context.flags & NodeBuilderFlags.NoTruncation) { context.tracker.reportTruncationError(); } return context.encounteredError ? undefined : resultingNode; } function checkTruncationLength(context: NodeBuilderContext): boolean { if (context.truncating) return context.truncating; return context.truncating = context.approximateLength > ((context.flags & NodeBuilderFlags.NoTruncation) ? noTruncationMaximumTruncationLength : defaultMaximumTruncationLength); } function typeToTypeNodeHelper(type: Type, context: NodeBuilderContext): TypeNode { const savedFlags = context.flags; const typeNode = typeToTypeNodeWorker(type, context); context.flags = savedFlags; return typeNode; } function typeToTypeNodeWorker(type: Type, context: NodeBuilderContext): TypeNode { if (cancellationToken && cancellationToken.throwIfCancellationRequested) { cancellationToken.throwIfCancellationRequested(); } const inTypeAlias = context.flags & NodeBuilderFlags.InTypeAlias; context.flags &= ~NodeBuilderFlags.InTypeAlias; if (!type) { if (!(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { context.encounteredError = true; return undefined!; // TODO: GH#18217 } context.approximateLength += 3; return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); } if (!(context.flags & NodeBuilderFlags.NoTypeReduction)) { type = getReducedType(type); } if (type.flags & TypeFlags.Any) { if (type.aliasSymbol) { return factory.createTypeReferenceNode(symbolToEntityNameNode(type.aliasSymbol), mapToTypeNodes(type.aliasTypeArguments, context)); } if (type === unresolvedType) { return addSyntheticLeadingComment(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), SyntaxKind.MultiLineCommentTrivia, "unresolved"); } context.approximateLength += 3; return factory.createKeywordTypeNode(type === intrinsicMarkerType ? SyntaxKind.IntrinsicKeyword : SyntaxKind.AnyKeyword); } if (type.flags & TypeFlags.Unknown) { return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); } if (type.flags & TypeFlags.String) { context.approximateLength += 6; return factory.createKeywordTypeNode(SyntaxKind.StringKeyword); } if (type.flags & TypeFlags.Number) { context.approximateLength += 6; return factory.createKeywordTypeNode(SyntaxKind.NumberKeyword); } if (type.flags & TypeFlags.BigInt) { context.approximateLength += 6; return factory.createKeywordTypeNode(SyntaxKind.BigIntKeyword); } if (type.flags & TypeFlags.Boolean && !type.aliasSymbol) { context.approximateLength += 7; return factory.createKeywordTypeNode(SyntaxKind.BooleanKeyword); } if (type.flags & TypeFlags.EnumLike) { if (type.symbol.flags & SymbolFlags.EnumMember) { const parentSymbol = getParentOfSymbol(type.symbol)!; const parentName = symbolToTypeNode(parentSymbol, context, SymbolFlags.Type); if (getDeclaredTypeOfSymbol(parentSymbol) === type) { return parentName; } const memberName = symbolName(type.symbol); if (isIdentifierText(memberName, ScriptTarget.ES3)) { return appendReferenceToType( parentName as TypeReferenceNode | ImportTypeNode, factory.createTypeReferenceNode(memberName, /*typeArguments*/ undefined) ); } if (isImportTypeNode(parentName)) { (parentName as any).isTypeOf = true; // mutably update, node is freshly manufactured anyhow return factory.createIndexedAccessTypeNode(parentName, factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); } else if (isTypeReferenceNode(parentName)) { return factory.createIndexedAccessTypeNode(factory.createTypeQueryNode(parentName.typeName), factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); } else { return Debug.fail("Unhandled type node kind returned from `symbolToTypeNode`."); } } return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); } if (type.flags & TypeFlags.StringLiteral) { context.approximateLength += ((type as StringLiteralType).value.length + 2); return factory.createLiteralTypeNode(setEmitFlags(factory.createStringLiteral((type as StringLiteralType).value, !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType)), EmitFlags.NoAsciiEscaping)); } if (type.flags & TypeFlags.NumberLiteral) { const value = (type as NumberLiteralType).value; context.approximateLength += ("" + value).length; return factory.createLiteralTypeNode(value < 0 ? factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-value)) : factory.createNumericLiteral(value)); } if (type.flags & TypeFlags.BigIntLiteral) { context.approximateLength += (pseudoBigIntToString((type as BigIntLiteralType).value).length) + 1; return factory.createLiteralTypeNode((factory.createBigIntLiteral((type as BigIntLiteralType).value))); } if (type.flags & TypeFlags.BooleanLiteral) { context.approximateLength += (type as IntrinsicType).intrinsicName.length; return factory.createLiteralTypeNode((type as IntrinsicType).intrinsicName === "true" ? factory.createTrue() : factory.createFalse()); } if (type.flags & TypeFlags.UniqueESSymbol) { if (!(context.flags & NodeBuilderFlags.AllowUniqueESSymbolType)) { if (isValueSymbolAccessible(type.symbol, context.enclosingDeclaration)) { context.approximateLength += 6; return symbolToTypeNode(type.symbol, context, SymbolFlags.Value); } if (context.tracker.reportInaccessibleUniqueSymbolError) { context.tracker.reportInaccessibleUniqueSymbolError(); } } context.approximateLength += 13; return factory.createTypeOperatorNode(SyntaxKind.UniqueKeyword, factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword)); } if (type.flags & TypeFlags.Void) { context.approximateLength += 4; return factory.createKeywordTypeNode(SyntaxKind.VoidKeyword); } if (type.flags & TypeFlags.Undefined) { context.approximateLength += 9; return factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword); } if (type.flags & TypeFlags.Null) { context.approximateLength += 4; return factory.createLiteralTypeNode(factory.createNull()); } if (type.flags & TypeFlags.Never) { context.approximateLength += 5; return factory.createKeywordTypeNode(SyntaxKind.NeverKeyword); } if (type.flags & TypeFlags.ESSymbol) { context.approximateLength += 6; return factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword); } if (type.flags & TypeFlags.NonPrimitive) { context.approximateLength += 6; return factory.createKeywordTypeNode(SyntaxKind.ObjectKeyword); } if (isThisTypeParameter(type)) { if (context.flags & NodeBuilderFlags.InObjectTypeLiteral) { if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowThisInObjectLiteral)) { context.encounteredError = true; } context.tracker.reportInaccessibleThisError?.(); } context.approximateLength += 4; return factory.createThisTypeNode(); } if (!inTypeAlias && type.aliasSymbol && (context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope || isTypeSymbolAccessible(type.aliasSymbol, context.enclosingDeclaration))) { const typeArgumentNodes = mapToTypeNodes(type.aliasTypeArguments, context); if (isReservedMemberName(type.aliasSymbol.escapedName) && !(type.aliasSymbol.flags & SymbolFlags.Class)) return factory.createTypeReferenceNode(factory.createIdentifier(""), typeArgumentNodes); if (length(typeArgumentNodes) === 1 && type.aliasSymbol === globalArrayType.symbol) { return factory.createArrayTypeNode(typeArgumentNodes![0]); } return symbolToTypeNode(type.aliasSymbol, context, SymbolFlags.Type, typeArgumentNodes); } const objectFlags = getObjectFlags(type); if (objectFlags & ObjectFlags.Reference) { Debug.assert(!!(type.flags & TypeFlags.Object)); return (type as TypeReference).node ? visitAndTransformType(type as TypeReference, typeReferenceToTypeNode) : typeReferenceToTypeNode(type as TypeReference); } if (type.flags & TypeFlags.TypeParameter || objectFlags & ObjectFlags.ClassOrInterface) { if (type.flags & TypeFlags.TypeParameter && contains(context.inferTypeParameters, type)) { context.approximateLength += (symbolName(type.symbol).length + 6); let constraintNode: TypeNode | undefined; const constraint = getConstraintOfTypeParameter(type as TypeParameter); if (constraint) { // If the infer type has a constraint that is not the same as the constraint // we would have normally inferred based on context, we emit the constraint // using `infer T extends ?`. We omit inferred constraints from type references // as they may be elided. const inferredConstraint = getInferredTypeParameterConstraint(type as TypeParameter, /*omitTypeReferences*/ true); if (!(inferredConstraint && isTypeIdenticalTo(constraint, inferredConstraint))) { context.approximateLength += 9; constraintNode = constraint && typeToTypeNodeHelper(constraint, context); } } return factory.createInferTypeNode(typeParameterToDeclarationWithConstraint(type as TypeParameter, context, constraintNode)); } if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && type.flags & TypeFlags.TypeParameter && !isTypeSymbolAccessible(type.symbol, context.enclosingDeclaration)) { const name = typeParameterToName(type, context); context.approximateLength += idText(name).length; return factory.createTypeReferenceNode(factory.createIdentifier(idText(name)), /*typeArguments*/ undefined); } // Ignore constraint/default when creating a usage (as opposed to declaration) of a type parameter. if (type.symbol) { return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); } const name = (type === markerSuperTypeForCheck || type === markerSubTypeForCheck) && varianceTypeParameter && varianceTypeParameter.symbol ? (type === markerSubTypeForCheck ? "sub-" : "super-") + symbolName(varianceTypeParameter.symbol) : "?"; return factory.createTypeReferenceNode(factory.createIdentifier(name), /*typeArguments*/ undefined); } if (type.flags & TypeFlags.Union && (type as UnionType).origin) { type = (type as UnionType).origin!; } if (type.flags & (TypeFlags.Union | TypeFlags.Intersection)) { const types = type.flags & TypeFlags.Union ? formatUnionTypes((type as UnionType).types) : (type as IntersectionType).types; if (length(types) === 1) { return typeToTypeNodeHelper(types[0], context); } const typeNodes = mapToTypeNodes(types, context, /*isBareList*/ true); if (typeNodes && typeNodes.length > 0) { return type.flags & TypeFlags.Union ? factory.createUnionTypeNode(typeNodes) : factory.createIntersectionTypeNode(typeNodes); } else { if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { context.encounteredError = true; } return undefined!; // TODO: GH#18217 } } if (objectFlags & (ObjectFlags.Anonymous | ObjectFlags.Mapped)) { Debug.assert(!!(type.flags & TypeFlags.Object)); // The type is an object literal type. return createAnonymousTypeNode(type as ObjectType); } if (type.flags & TypeFlags.Index) { const indexedType = (type as IndexType).type; context.approximateLength += 6; const indexTypeNode = typeToTypeNodeHelper(indexedType, context); return factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, indexTypeNode); } if (type.flags & TypeFlags.TemplateLiteral) { const texts = (type as TemplateLiteralType).texts; const types = (type as TemplateLiteralType).types; const templateHead = factory.createTemplateHead(texts[0]); const templateSpans = factory.createNodeArray( map(types, (t, i) => factory.createTemplateLiteralTypeSpan( typeToTypeNodeHelper(t, context), (i < types.length - 1 ? factory.createTemplateMiddle : factory.createTemplateTail)(texts[i + 1])))); context.approximateLength += 2; return factory.createTemplateLiteralType(templateHead, templateSpans); } if (type.flags & TypeFlags.StringMapping) { const typeNode = typeToTypeNodeHelper((type as StringMappingType).type, context); return symbolToTypeNode((type as StringMappingType).symbol, context, SymbolFlags.Type, [typeNode]); } if (type.flags & TypeFlags.IndexedAccess) { const objectTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).objectType, context); const indexTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).indexType, context); context.approximateLength += 2; return factory.createIndexedAccessTypeNode(objectTypeNode, indexTypeNode); } if (type.flags & TypeFlags.Conditional) { return visitAndTransformType(type, type => conditionalTypeToTypeNode(type as ConditionalType)); } if (type.flags & TypeFlags.Substitution) { return typeToTypeNodeHelper((type as SubstitutionType).baseType, context); } return Debug.fail("Should be unreachable."); function conditionalTypeToTypeNode(type: ConditionalType) { const checkTypeNode = typeToTypeNodeHelper(type.checkType, context); context.approximateLength += 15; if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && type.root.isDistributive && !(type.checkType.flags & TypeFlags.TypeParameter)) { const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); const name = typeParameterToName(newParam, context); const newTypeVariable = factory.createTypeReferenceNode(name); context.approximateLength += 37; // 15 each for two added conditionals, 7 for an added infer type const newMapper = prependTypeMapping(type.root.checkType, newParam, type.mapper); const saveInferTypeParameters = context.inferTypeParameters; context.inferTypeParameters = type.root.inferTypeParameters; const extendsTypeNode = typeToTypeNodeHelper(instantiateType(type.root.extendsType, newMapper), context); context.inferTypeParameters = saveInferTypeParameters; const trueTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(type.root.node.trueType), newMapper)); const falseTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(type.root.node.falseType), newMapper)); // outermost conditional makes `T` a type parameter, allowing the inner conditionals to be distributive // second conditional makes `T` have `T & checkType` substitution, so it is correctly usable as the checkType // inner conditional runs the check the user provided on the check type (distributively) and returns the result // checkType extends infer T ? T extends checkType ? T extends extendsType ? trueType : falseType : never : never; // this is potentially simplifiable to // checkType extends infer T ? T extends checkType & extendsType ? trueType : falseType : never; // but that may confuse users who read the output more. // On the other hand, // checkType extends infer T extends checkType ? T extends extendsType ? trueType : falseType : never; // may also work with `infer ... extends ...` in, but would produce declarations only compatible with the latest TS. return factory.createConditionalTypeNode( checkTypeNode, factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable.typeName) as Identifier)), factory.createConditionalTypeNode( factory.createTypeReferenceNode(factory.cloneNode(name)), typeToTypeNodeHelper(type.checkType, context), factory.createConditionalTypeNode(newTypeVariable, extendsTypeNode, trueTypeNode, falseTypeNode), factory.createKeywordTypeNode(SyntaxKind.NeverKeyword) ), factory.createKeywordTypeNode(SyntaxKind.NeverKeyword) ); } const saveInferTypeParameters = context.inferTypeParameters; context.inferTypeParameters = type.root.inferTypeParameters; const extendsTypeNode = typeToTypeNodeHelper(type.extendsType, context); context.inferTypeParameters = saveInferTypeParameters; const trueTypeNode = typeToTypeNodeOrCircularityElision(getTrueTypeFromConditionalType(type)); const falseTypeNode = typeToTypeNodeOrCircularityElision(getFalseTypeFromConditionalType(type)); return factory.createConditionalTypeNode(checkTypeNode, extendsTypeNode, trueTypeNode, falseTypeNode); } function typeToTypeNodeOrCircularityElision(type: Type) { if (type.flags & TypeFlags.Union) { if (context.visitedTypes?.has(getTypeId(type))) { if (!(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { context.encounteredError = true; context.tracker?.reportCyclicStructureError?.(); } return createElidedInformationPlaceholder(context); } return visitAndTransformType(type, type => typeToTypeNodeHelper(type, context)); } return typeToTypeNodeHelper(type, context); } function isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type: MappedType) { return isMappedTypeWithKeyofConstraintDeclaration(type) && !(getModifiersTypeFromMappedType(type).flags & TypeFlags.TypeParameter); } function createMappedTypeNodeFromType(type: MappedType) { Debug.assert(!!(type.flags & TypeFlags.Object)); const readonlyToken = type.declaration.readonlyToken ? factory.createToken(type.declaration.readonlyToken.kind) as ReadonlyKeyword | PlusToken | MinusToken : undefined; const questionToken = type.declaration.questionToken ? factory.createToken(type.declaration.questionToken.kind) as QuestionToken | PlusToken | MinusToken : undefined; let appropriateConstraintTypeNode: TypeNode; let newTypeVariable: TypeReferenceNode | undefined; if (isMappedTypeWithKeyofConstraintDeclaration(type)) { // We have a { [P in keyof T]: X } // We do this to ensure we retain the toplevel keyof-ness of the type which may be lost due to keyof distribution during `getConstraintTypeFromMappedType` if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); const name = typeParameterToName(newParam, context); newTypeVariable = factory.createTypeReferenceNode(name); } appropriateConstraintTypeNode = factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, newTypeVariable || typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)); } else { appropriateConstraintTypeNode = typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context); } const typeParameterNode = typeParameterToDeclarationWithConstraint(getTypeParameterFromMappedType(type), context, appropriateConstraintTypeNode); const nameTypeNode = type.declaration.nameType ? typeToTypeNodeHelper(getNameTypeFromMappedType(type)!, context) : undefined; const templateTypeNode = typeToTypeNodeHelper(removeMissingType(getTemplateTypeFromMappedType(type), !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), context); const mappedTypeNode = factory.createMappedTypeNode(readonlyToken, typeParameterNode, nameTypeNode, questionToken, templateTypeNode, /*members*/ undefined); context.approximateLength += 10; const result = setEmitFlags(mappedTypeNode, EmitFlags.SingleLine); if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { // homomorphic mapped type with a non-homomorphic naive inlining // wrap it with a conditional like `SomeModifiersType extends infer U ? {..the mapped type...} : never` to ensure the resulting // type stays homomorphic const originalConstraint = instantiateType(getConstraintOfTypeParameter(getTypeFromTypeNode((type.declaration.typeParameter.constraint! as TypeOperatorNode).type) as TypeParameter) || unknownType, type.mapper); return factory.createConditionalTypeNode( typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context), factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, originalConstraint.flags & TypeFlags.Unknown ? undefined : typeToTypeNodeHelper(originalConstraint, context))), result, factory.createKeywordTypeNode(SyntaxKind.NeverKeyword) ); } return result; } function createAnonymousTypeNode(type: ObjectType): TypeNode { const typeId = type.id; const symbol = type.symbol; if (symbol) { const isInstanceType = isClassInstanceSide(type) ? SymbolFlags.Type : SymbolFlags.Value; if (isJSConstructor(symbol.valueDeclaration)) { // Instance and static types share the same symbol; only add 'typeof' for the static side. return symbolToTypeNode(symbol, context, isInstanceType); } // Always use 'typeof T' for type of class, enum, and module objects else if (symbol.flags & SymbolFlags.Class && !getBaseTypeVariableOfClass(symbol) && !(symbol.valueDeclaration && isClassLike(symbol.valueDeclaration) && context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && (!isClassDeclaration(symbol.valueDeclaration) || isSymbolAccessible(symbol, context.enclosingDeclaration, isInstanceType, /*computeAliases*/ false).accessibility !== SymbolAccessibility.Accessible)) || symbol.flags & (SymbolFlags.Enum | SymbolFlags.ValueModule) || shouldWriteTypeOfFunctionSymbol()) { return symbolToTypeNode(symbol, context, isInstanceType); } else if (context.visitedTypes?.has(typeId)) { // If type is an anonymous type literal in a type alias declaration, use type alias name const typeAlias = getTypeAliasForTypeLiteral(type); if (typeAlias) { // The specified symbol flags need to be reinterpreted as type flags return symbolToTypeNode(typeAlias, context, SymbolFlags.Type); } else { return createElidedInformationPlaceholder(context); } } else { return visitAndTransformType(type, createTypeNodeFromObjectType); } } else { const isInstantiationExpressionType = !!(getObjectFlags(type) & ObjectFlags.InstantiationExpressionType); if (isInstantiationExpressionType) { const instantiationExpressionType = type as InstantiationExpressionType; if (isTypeQueryNode(instantiationExpressionType.node)) { const typeNode = serializeExistingTypeNode(context, instantiationExpressionType.node); if (typeNode) { return typeNode; } } if (context.visitedTypes?.has(typeId)) { return createElidedInformationPlaceholder(context); } return visitAndTransformType(type, createTypeNodeFromObjectType); } // Anonymous types without a symbol are never circular. return createTypeNodeFromObjectType(type); } function shouldWriteTypeOfFunctionSymbol() { const isStaticMethodSymbol = !!(symbol.flags & SymbolFlags.Method) && // typeof static method some(symbol.declarations, declaration => isStatic(declaration)); const isNonLocalFunctionSymbol = !!(symbol.flags & SymbolFlags.Function) && (symbol.parent || // is exported function symbol forEach(symbol.declarations, declaration => declaration.parent.kind === SyntaxKind.SourceFile || declaration.parent.kind === SyntaxKind.ModuleBlock)); if (isStaticMethodSymbol || isNonLocalFunctionSymbol) { // typeof is allowed only for static/non local functions return (!!(context.flags & NodeBuilderFlags.UseTypeOfFunction) || (context.visitedTypes?.has(typeId))) && // it is type of the symbol uses itself recursively (!(context.flags & NodeBuilderFlags.UseStructuralFallback) || isValueSymbolAccessible(symbol, context.enclosingDeclaration)); // And the build is going to succeed without visibility error or there is no structural fallback allowed } } } function visitAndTransformType(type: T, transform: (type: T) => TypeNode) { const typeId = type.id; const isConstructorObject = getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & SymbolFlags.Class; const id = getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference & T).node ? "N" + getNodeId((type as TypeReference & T).node!) : type.flags & TypeFlags.Conditional ? "N" + getNodeId((type as ConditionalType & T).root.node) : type.symbol ? (isConstructorObject ? "+" : "") + getSymbolId(type.symbol) : undefined; // Since instantiations of the same anonymous type have the same symbol, tracking symbols instead // of types allows us to catch circular references to instantiations of the same anonymous type if (!context.visitedTypes) { context.visitedTypes = new Set(); } if (id && !context.symbolDepth) { context.symbolDepth = new Map(); } const links = context.enclosingDeclaration && getNodeLinks(context.enclosingDeclaration); const key = `${getTypeId(type)}|${context.flags}`; if (links) { links.serializedTypes ||= new Map(); } const cachedResult = links?.serializedTypes?.get(key); if (cachedResult) { if (cachedResult.truncating) { context.truncating = true; } context.approximateLength += cachedResult.addedLength; return deepCloneOrReuseNode(cachedResult.node); } let depth: number | undefined; if (id) { depth = context.symbolDepth!.get(id) || 0; if (depth > 10) { return createElidedInformationPlaceholder(context); } context.symbolDepth!.set(id, depth + 1); } context.visitedTypes.add(typeId); const startLength = context.approximateLength; const result = transform(type); const addedLength = context.approximateLength - startLength; if (!context.reportedDiagnostic && !context.encounteredError) { links?.serializedTypes?.set(key, { node: result, truncating: context.truncating, addedLength }); } context.visitedTypes.delete(typeId); if (id) { context.symbolDepth!.set(id, depth!); } return result; function deepCloneOrReuseNode(node: T): T { if (!nodeIsSynthesized(node) && getParseTreeNode(node) === node) { return node; } return setTextRange(factory.cloneNode(visitEachChild(node, deepCloneOrReuseNode, nullTransformationContext, deepCloneOrReuseNodes)), node); } function deepCloneOrReuseNodes( nodes: NodeArray | undefined, visitor: Visitor, test?: (node: Node) => boolean, start?: number, count?: number, ): NodeArray | undefined { if (nodes && nodes.length === 0) { // Ensure we explicitly make a copy of an empty array; visitNodes will not do this unless the array has elements, // which can lead to us reusing the same empty NodeArray more than once within the same AST during type noding. return setTextRange(factory.createNodeArray(/*nodes*/ undefined, nodes.hasTrailingComma), nodes); } return visitNodes(nodes, visitor, test, start, count); } } function createTypeNodeFromObjectType(type: ObjectType): TypeNode { if (isGenericMappedType(type) || (type as MappedType).containsError) { return createMappedTypeNodeFromType(type as MappedType); } const resolved = resolveStructuredTypeMembers(type); if (!resolved.properties.length && !resolved.indexInfos.length) { if (!resolved.callSignatures.length && !resolved.constructSignatures.length) { context.approximateLength += 2; return setEmitFlags(factory.createTypeLiteralNode(/*members*/ undefined), EmitFlags.SingleLine); } if (resolved.callSignatures.length === 1 && !resolved.constructSignatures.length) { const signature = resolved.callSignatures[0]; const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.FunctionType, context) as FunctionTypeNode; return signatureNode; } if (resolved.constructSignatures.length === 1 && !resolved.callSignatures.length) { const signature = resolved.constructSignatures[0]; const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructorType, context) as ConstructorTypeNode; return signatureNode; } } const abstractSignatures = filter(resolved.constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract)); if (some(abstractSignatures)) { const types = map(abstractSignatures, getOrCreateTypeFromSignature); // count the number of type elements excluding abstract constructors const typeElementCount = resolved.callSignatures.length + (resolved.constructSignatures.length - abstractSignatures.length) + resolved.indexInfos.length + // exclude `prototype` when writing a class expression as a type literal, as per // the logic in `createTypeNodesFromResolvedType`. (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral ? countWhere(resolved.properties, p => !(p.flags & SymbolFlags.Prototype)) : length(resolved.properties)); // don't include an empty object literal if there were no other static-side // properties to write, i.e. `abstract class C { }` becomes `abstract new () => {}` // and not `(abstract new () => {}) & {}` if (typeElementCount) { // create a copy of the object type without any abstract construct signatures. types.push(getResolvedTypeWithoutAbstractConstructSignatures(resolved)); } return typeToTypeNodeHelper(getIntersectionType(types), context); } const savedFlags = context.flags; context.flags |= NodeBuilderFlags.InObjectTypeLiteral; const members = createTypeNodesFromResolvedType(resolved); context.flags = savedFlags; const typeLiteralNode = factory.createTypeLiteralNode(members); context.approximateLength += 2; setEmitFlags(typeLiteralNode, (context.flags & NodeBuilderFlags.MultilineObjectLiterals) ? 0 : EmitFlags.SingleLine); return typeLiteralNode; } function typeReferenceToTypeNode(type: TypeReference) { let typeArguments: readonly Type[] = getTypeArguments(type); if (type.target === globalArrayType || type.target === globalReadonlyArrayType) { if (context.flags & NodeBuilderFlags.WriteArrayAsGenericType) { const typeArgumentNode = typeToTypeNodeHelper(typeArguments[0], context); return factory.createTypeReferenceNode(type.target === globalArrayType ? "Array" : "ReadonlyArray", [typeArgumentNode]); } const elementType = typeToTypeNodeHelper(typeArguments[0], context); const arrayType = factory.createArrayTypeNode(elementType); return type.target === globalArrayType ? arrayType : factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, arrayType); } else if (type.target.objectFlags & ObjectFlags.Tuple) { typeArguments = sameMap(typeArguments, (t, i) => removeMissingType(t, !!((type.target as TupleType).elementFlags[i] & ElementFlags.Optional))); if (typeArguments.length > 0) { const arity = getTypeReferenceArity(type); const tupleConstituentNodes = mapToTypeNodes(typeArguments.slice(0, arity), context); if (tupleConstituentNodes) { if ((type.target as TupleType).labeledElementDeclarations) { for (let i = 0; i < tupleConstituentNodes.length; i++) { const flags = (type.target as TupleType).elementFlags[i]; tupleConstituentNodes[i] = factory.createNamedTupleMember( flags & ElementFlags.Variable ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined, factory.createIdentifier(unescapeLeadingUnderscores(getTupleElementLabel((type.target as TupleType).labeledElementDeclarations![i]))), flags & ElementFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : tupleConstituentNodes[i] ); } } else { for (let i = 0; i < Math.min(arity, tupleConstituentNodes.length); i++) { const flags = (type.target as TupleType).elementFlags[i]; tupleConstituentNodes[i] = flags & ElementFlags.Variable ? factory.createRestTypeNode(flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : tupleConstituentNodes[i]) : flags & ElementFlags.Optional ? factory.createOptionalTypeNode(tupleConstituentNodes[i]) : tupleConstituentNodes[i]; } } const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode(tupleConstituentNodes), EmitFlags.SingleLine); return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; } } if (context.encounteredError || (context.flags & NodeBuilderFlags.AllowEmptyTuple)) { const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode([]), EmitFlags.SingleLine); return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; } context.encounteredError = true; return undefined!; // TODO: GH#18217 } else if (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && type.symbol.valueDeclaration && isClassLike(type.symbol.valueDeclaration) && !isValueSymbolAccessible(type.symbol, context.enclosingDeclaration) ) { return createAnonymousTypeNode(type); } else { const outerTypeParameters = type.target.outerTypeParameters; let i = 0; let resultType: TypeReferenceNode | ImportTypeNode | undefined; if (outerTypeParameters) { const length = outerTypeParameters.length; while (i < length) { // Find group of type arguments for type parameters with the same declaring container. const start = i; const parent = getParentSymbolOfTypeParameter(outerTypeParameters[i])!; do { i++; } while (i < length && getParentSymbolOfTypeParameter(outerTypeParameters[i]) === parent); // When type parameters are their own type arguments for the whole group (i.e. we have // the default outer type arguments), we don't show the group. if (!rangeEquals(outerTypeParameters, typeArguments, start, i)) { const typeArgumentSlice = mapToTypeNodes(typeArguments.slice(start, i), context); const flags = context.flags; context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; const ref = symbolToTypeNode(parent, context, SymbolFlags.Type, typeArgumentSlice) as TypeReferenceNode | ImportTypeNode; context.flags = flags; resultType = !resultType ? ref : appendReferenceToType(resultType, ref as TypeReferenceNode); } } } let typeArgumentNodes: readonly TypeNode[] | undefined; if (typeArguments.length > 0) { const typeParameterCount = (type.target.typeParameters || emptyArray).length; typeArgumentNodes = mapToTypeNodes(typeArguments.slice(i, typeParameterCount), context); } const flags = context.flags; context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; const finalRef = symbolToTypeNode(type.symbol, context, SymbolFlags.Type, typeArgumentNodes); context.flags = flags; return !resultType ? finalRef : appendReferenceToType(resultType, finalRef as TypeReferenceNode); } } function appendReferenceToType(root: TypeReferenceNode | ImportTypeNode, ref: TypeReferenceNode): TypeReferenceNode | ImportTypeNode { if (isImportTypeNode(root)) { // first shift type arguments let typeArguments = root.typeArguments; let qualifier = root.qualifier; if (qualifier) { if (isIdentifier(qualifier)) { if (typeArguments !== getIdentifierTypeArguments(qualifier)) { qualifier = setIdentifierTypeArguments(factory.cloneNode(qualifier), typeArguments); } } else { if (typeArguments !== getIdentifierTypeArguments(qualifier.right)) { qualifier = factory.updateQualifiedName(qualifier, qualifier.left, setIdentifierTypeArguments(factory.cloneNode(qualifier.right), typeArguments)); } } } typeArguments = ref.typeArguments; // then move qualifiers const ids = getAccessStack(ref); for (const id of ids) { qualifier = qualifier ? factory.createQualifiedName(qualifier, id) : id; } return factory.updateImportTypeNode( root, root.argument, root.assertions, qualifier, typeArguments, root.isTypeOf); } else { // first shift type arguments let typeArguments = root.typeArguments; let typeName = root.typeName; if (isIdentifier(typeName)) { if (typeArguments !== getIdentifierTypeArguments(typeName)) { typeName = setIdentifierTypeArguments(factory.cloneNode(typeName), typeArguments); } } else { if (typeArguments !== getIdentifierTypeArguments(typeName.right)) { typeName = factory.updateQualifiedName(typeName, typeName.left, setIdentifierTypeArguments(factory.cloneNode(typeName.right), typeArguments)); } } typeArguments = ref.typeArguments; // then move qualifiers const ids = getAccessStack(ref); for (const id of ids) { typeName = factory.createQualifiedName(typeName, id); } return factory.updateTypeReferenceNode( root, typeName, typeArguments); } } function getAccessStack(ref: TypeReferenceNode): Identifier[] { let state = ref.typeName; const ids = []; while (!isIdentifier(state)) { ids.unshift(state.right); state = state.left; } ids.unshift(state); return ids; } function createTypeNodesFromResolvedType(resolvedType: ResolvedType): TypeElement[] | undefined { if (checkTruncationLength(context)) { return [factory.createPropertySignature(/*modifiers*/ undefined, "...", /*questionToken*/ undefined, /*type*/ undefined)]; } const typeElements: TypeElement[] = []; for (const signature of resolvedType.callSignatures) { typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.CallSignature, context) as CallSignatureDeclaration); } for (const signature of resolvedType.constructSignatures) { if (signature.flags & SignatureFlags.Abstract) continue; typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructSignature, context) as ConstructSignatureDeclaration); } for (const info of resolvedType.indexInfos) { typeElements.push(indexInfoToIndexSignatureDeclarationHelper(info, context, resolvedType.objectFlags & ObjectFlags.ReverseMapped ? createElidedInformationPlaceholder(context) : undefined)); } const properties = resolvedType.properties; if (!properties) { return typeElements; } let i = 0; for (const propertySymbol of properties) { i++; if (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral) { if (propertySymbol.flags & SymbolFlags.Prototype) { continue; } if (getDeclarationModifierFlagsFromSymbol(propertySymbol) & (ModifierFlags.Private | ModifierFlags.Protected) && context.tracker.reportPrivateInBaseOfClassExpression) { context.tracker.reportPrivateInBaseOfClassExpression(unescapeLeadingUnderscores(propertySymbol.escapedName)); } } if (checkTruncationLength(context) && (i + 2 < properties.length - 1)) { typeElements.push(factory.createPropertySignature(/*modifiers*/ undefined, `... ${properties.length - i} more ...`, /*questionToken*/ undefined, /*type*/ undefined)); addPropertyToElementList(properties[properties.length - 1], context, typeElements); break; } addPropertyToElementList(propertySymbol, context, typeElements); } return typeElements.length ? typeElements : undefined; } } function createElidedInformationPlaceholder(context: NodeBuilderContext) { context.approximateLength += 3; if (!(context.flags & NodeBuilderFlags.NoTruncation)) { return factory.createTypeReferenceNode(factory.createIdentifier("..."), /*typeArguments*/ undefined); } return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); } function shouldUsePlaceholderForProperty(propertySymbol: Symbol, context: NodeBuilderContext) { // Use placeholders for reverse mapped types we've either already descended into, or which // are nested reverse mappings within a mapping over a non-anonymous type. The later is a restriction mostly just to // reduce the blowup in printback size from doing, eg, a deep reverse mapping over `Window`. // Since anonymous types usually come from expressions, this allows us to preserve the output // for deep mappings which likely come from expressions, while truncating those parts which // come from mappings over library functions. return !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped) && ( contains(context.reverseMappedStack, propertySymbol as ReverseMappedSymbol) || ( context.reverseMappedStack?.[0] && !(getObjectFlags(last(context.reverseMappedStack).links.propertyType) & ObjectFlags.Anonymous) ) ); } function addPropertyToElementList(propertySymbol: Symbol, context: NodeBuilderContext, typeElements: TypeElement[]) { const propertyIsReverseMapped = !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped); const propertyType = shouldUsePlaceholderForProperty(propertySymbol, context) ? anyType : getNonMissingTypeOfSymbol(propertySymbol); const saveEnclosingDeclaration = context.enclosingDeclaration; context.enclosingDeclaration = undefined; if (context.tracker.canTrackSymbol && isLateBoundName(propertySymbol.escapedName)) { if (propertySymbol.declarations) { const decl = first(propertySymbol.declarations); if (hasLateBindableName(decl)) { if (isBinaryExpression(decl)) { const name = getNameOfDeclaration(decl); if (name && isElementAccessExpression(name) && isPropertyAccessEntityNameExpression(name.argumentExpression)) { trackComputedName(name.argumentExpression, saveEnclosingDeclaration, context); } } else { trackComputedName(decl.name.expression, saveEnclosingDeclaration, context); } } } else { context.tracker.reportNonSerializableProperty(symbolToString(propertySymbol)); } } context.enclosingDeclaration = propertySymbol.valueDeclaration || propertySymbol.declarations?.[0] || saveEnclosingDeclaration; const propertyName = getPropertyNameNodeForSymbol(propertySymbol, context); context.enclosingDeclaration = saveEnclosingDeclaration; context.approximateLength += (symbolName(propertySymbol).length + 1); const optionalToken = propertySymbol.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; if (propertySymbol.flags & (SymbolFlags.Function | SymbolFlags.Method) && !getPropertiesOfObjectType(propertyType).length && !isReadonlySymbol(propertySymbol)) { const signatures = getSignaturesOfType(filterType(propertyType, t => !(t.flags & TypeFlags.Undefined)), SignatureKind.Call); for (const signature of signatures) { const methodDeclaration = signatureToSignatureDeclarationHelper(signature, SyntaxKind.MethodSignature, context, { name: propertyName, questionToken: optionalToken }) as MethodSignature; typeElements.push(preserveCommentsOn(methodDeclaration)); } } else { let propertyTypeNode: TypeNode; if (shouldUsePlaceholderForProperty(propertySymbol, context)) { propertyTypeNode = createElidedInformationPlaceholder(context); } else { if (propertyIsReverseMapped) { context.reverseMappedStack ||= []; context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol); } propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, propertyType, propertySymbol, saveEnclosingDeclaration) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); if (propertyIsReverseMapped) { context.reverseMappedStack!.pop(); } } const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined; if (modifiers) { context.approximateLength += 9; } const propertySignature = factory.createPropertySignature( modifiers, propertyName, optionalToken, propertyTypeNode); typeElements.push(preserveCommentsOn(propertySignature)); } function preserveCommentsOn(node: T) { if (some(propertySymbol.declarations, d => d.kind === SyntaxKind.JSDocPropertyTag)) { const d = propertySymbol.declarations?.find(d => d.kind === SyntaxKind.JSDocPropertyTag)! as JSDocPropertyTag; const commentText = getTextOfJSDocComment(d.comment); if (commentText) { setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]); } } else if (propertySymbol.valueDeclaration) { // Copy comments to node for declaration emit setCommentRange(node, propertySymbol.valueDeclaration); } return node; } } function mapToTypeNodes(types: readonly Type[] | undefined, context: NodeBuilderContext, isBareList?: boolean): TypeNode[] | undefined { if (some(types)) { if (checkTruncationLength(context)) { if (!isBareList) { return [factory.createTypeReferenceNode("...", /*typeArguments*/ undefined)]; } else if (types.length > 2) { return [ typeToTypeNodeHelper(types[0], context), factory.createTypeReferenceNode(`... ${types.length - 2} more ...`, /*typeArguments*/ undefined), typeToTypeNodeHelper(types[types.length - 1], context) ]; } } const mayHaveNameCollisions = !(context.flags & NodeBuilderFlags.UseFullyQualifiedType); /** Map from type reference identifier text to [type, index in `result` where the type node is] */ const seenNames = mayHaveNameCollisions ? createUnderscoreEscapedMultiMap<[Type, number]>() : undefined; const result: TypeNode[] = []; let i = 0; for (const type of types) { i++; if (checkTruncationLength(context) && (i + 2 < types.length - 1)) { result.push(factory.createTypeReferenceNode(`... ${types.length - i} more ...`, /*typeArguments*/ undefined)); const typeNode = typeToTypeNodeHelper(types[types.length - 1], context); if (typeNode) { result.push(typeNode); } break; } context.approximateLength += 2; // Account for whitespace + separator const typeNode = typeToTypeNodeHelper(type, context); if (typeNode) { result.push(typeNode); if (seenNames && isIdentifierTypeReference(typeNode)) { seenNames.add(typeNode.typeName.escapedText, [type, result.length - 1]); } } } if (seenNames) { // To avoid printing types like `[Foo, Foo]` or `Bar & Bar` where // occurrences of the same name actually come from different // namespaces, go through the single-identifier type reference nodes // we just generated, and see if any names were generated more than // once while referring to different types. If so, regenerate the // type node for each entry by that name with the // `UseFullyQualifiedType` flag enabled. const saveContextFlags = context.flags; context.flags |= NodeBuilderFlags.UseFullyQualifiedType; seenNames.forEach(types => { if (!arrayIsHomogeneous(types, ([a], [b]) => typesAreSameReference(a, b))) { for (const [type, resultIndex] of types) { result[resultIndex] = typeToTypeNodeHelper(type, context); } } }); context.flags = saveContextFlags; } return result; } } function typesAreSameReference(a: Type, b: Type): boolean { return a === b || !!a.symbol && a.symbol === b.symbol || !!a.aliasSymbol && a.aliasSymbol === b.aliasSymbol; } function indexInfoToIndexSignatureDeclarationHelper(indexInfo: IndexInfo, context: NodeBuilderContext, typeNode: TypeNode | undefined): IndexSignatureDeclaration { const name = getNameFromIndexInfo(indexInfo) || "x"; const indexerTypeNode = typeToTypeNodeHelper(indexInfo.keyType, context); const indexingParameter = factory.createParameterDeclaration( /*modifiers*/ undefined, /*dotDotDotToken*/ undefined, name, /*questionToken*/ undefined, indexerTypeNode, /*initializer*/ undefined); if (!typeNode) { typeNode = typeToTypeNodeHelper(indexInfo.type || anyType, context); } if (!indexInfo.type && !(context.flags & NodeBuilderFlags.AllowEmptyIndexInfoType)) { context.encounteredError = true; } context.approximateLength += (name.length + 4); return factory.createIndexSignature( indexInfo.isReadonly ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined, [indexingParameter], typeNode); } interface SignatureToSignatureDeclarationOptions { modifiers?: readonly Modifier[]; name?: PropertyName; questionToken?: QuestionToken; privateSymbolVisitor?: (s: Symbol) => void; bundledImports?: boolean; } function signatureToSignatureDeclarationHelper(signature: Signature, kind: SignatureDeclaration["kind"], context: NodeBuilderContext, options?: SignatureToSignatureDeclarationOptions): SignatureDeclaration { const suppressAny = context.flags & NodeBuilderFlags.SuppressAnyReturnType; if (suppressAny) context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // suppress only toplevel `any`s context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum let typeParameters: TypeParameterDeclaration[] | undefined; let typeArguments: TypeNode[] | undefined; if (context.flags & NodeBuilderFlags.WriteTypeArgumentsOfSignature && signature.target && signature.mapper && signature.target.typeParameters) { typeArguments = signature.target.typeParameters.map(parameter => typeToTypeNodeHelper(instantiateType(parameter, signature.mapper), context)); } else { typeParameters = signature.typeParameters && signature.typeParameters.map(parameter => typeParameterToDeclaration(parameter, context)); } const expandedParams = getExpandedParameters(signature, /*skipUnionExpanding*/ true)[0]; // For regular function/method declarations, the enclosing declaration will already be signature.declaration, // so this is a no-op, but for arrow functions and function expressions, the enclosing declaration will be // the declaration that the arrow function / function expression is assigned to. // // If the parameters or return type include "typeof globalThis.paramName", using the wrong scope will lead // us to believe that we can emit "typeof paramName" instead, even though that would refer to the parameter, // not the global. Make sure we are in the right scope by changing the enclosingDeclaration to the function. // // We can't use the declaration directly; it may be in another file and so we may lose access to symbols // accessible to the current enclosing declaration, or gain access to symbols not accessible to the current // enclosing declaration. To keep this chain accurate, insert a fake scope into the chain which makes the // function's parameters visible. // // If the declaration is in a JS file, then we don't need to do this at all, as there are no annotations besides // JSDoc, which are always outside the function declaration, so are not in the parameter scope. let cleanup: (() => void) | undefined; if ( context.enclosingDeclaration && signature.declaration && signature.declaration !== context.enclosingDeclaration && !isInJSFile(signature.declaration) && some(expandedParams) ) { // As a performance optimization, reuse the same fake scope within this chain. // This is especially needed when we are working on an excessively deep type; // if we don't do this, then we spend all of our time adding more and more // scopes that need to be searched in isSymbolAccessible later. Since all we // really want to do is to mark certain names as unavailable, we can just keep // all of the names we're introducing in one large table and push/pop from it as // needed; isSymbolAccessible will walk upward and find the closest "fake" scope, // which will conveniently report on any and all faked scopes in the chain. // // It'd likely be better to store this somewhere else for isSymbolAccessible, but // since that API _only_ uses the enclosing declaration (and its parents), this is // seems like the best way to inject names into that search process. // // Note that we only check the most immediate enclosingDeclaration; the only place we // could potentially add another fake scope into the chain is right here, so we don't // traverse all ancestors. const existingFakeScope = getNodeLinks(context.enclosingDeclaration).fakeScopeForSignatureDeclaration ? context.enclosingDeclaration : undefined; Debug.assertOptionalNode(existingFakeScope, isBlock); const locals = existingFakeScope?.locals ?? createSymbolTable(); let newLocals: __String[] | undefined; for (const param of expandedParams) { if (!locals.has(param.escapedName)) { newLocals = append(newLocals, param.escapedName); locals.set(param.escapedName, param); } } if (newLocals) { function removeNewLocals() { forEach(newLocals, s => locals.delete(s)); } if (existingFakeScope) { cleanup = removeNewLocals; } else { // Use a Block for this; the type of the node doesn't matter so long as it // has locals, and this is cheaper/easier than using a function-ish Node. const fakeScope = parseNodeFactory.createBlock(emptyArray); getNodeLinks(fakeScope).fakeScopeForSignatureDeclaration = true; fakeScope.locals = locals; const saveEnclosingDeclaration = context.enclosingDeclaration; setParent(fakeScope, saveEnclosingDeclaration); context.enclosingDeclaration = fakeScope; cleanup = () => { context.enclosingDeclaration = saveEnclosingDeclaration; removeNewLocals(); }; } } } // If the expanded parameter list had a variadic in a non-trailing position, don't expand it const parameters = (some(expandedParams, p => p !== expandedParams[expandedParams.length - 1] && !!(getCheckFlags(p) & CheckFlags.RestParameter)) ? signature.parameters : expandedParams).map(parameter => symbolToParameterDeclaration(parameter, context, kind === SyntaxKind.Constructor, options?.privateSymbolVisitor, options?.bundledImports)); const thisParameter = context.flags & NodeBuilderFlags.OmitThisParameter ? undefined : tryGetThisParameterDeclaration(signature, context); if (thisParameter) { parameters.unshift(thisParameter); } let returnTypeNode: TypeNode | undefined; const typePredicate = getTypePredicateOfSignature(signature); if (typePredicate) { const assertsModifier = typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? factory.createToken(SyntaxKind.AssertsKeyword) : undefined; const parameterName = typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? setEmitFlags(factory.createIdentifier(typePredicate.parameterName), EmitFlags.NoAsciiEscaping) : factory.createThisTypeNode(); const typeNode = typePredicate.type && typeToTypeNodeHelper(typePredicate.type, context); returnTypeNode = factory.createTypePredicateNode(assertsModifier, parameterName, typeNode); } else { const returnType = getReturnTypeOfSignature(signature); if (returnType && !(suppressAny && isTypeAny(returnType))) { returnTypeNode = serializeReturnTypeForSignature(context, returnType, signature, options?.privateSymbolVisitor, options?.bundledImports); } else if (!suppressAny) { returnTypeNode = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); } } let modifiers = options?.modifiers; if ((kind === SyntaxKind.ConstructorType) && signature.flags & SignatureFlags.Abstract) { const flags = modifiersToFlags(modifiers); modifiers = factory.createModifiersFromModifierFlags(flags | ModifierFlags.Abstract); } const node = kind === SyntaxKind.CallSignature ? factory.createCallSignature(typeParameters, parameters, returnTypeNode) : kind === SyntaxKind.ConstructSignature ? factory.createConstructSignature(typeParameters, parameters, returnTypeNode) : kind === SyntaxKind.MethodSignature ? factory.createMethodSignature(modifiers, options?.name ?? factory.createIdentifier(""), options?.questionToken, typeParameters, parameters, returnTypeNode) : kind === SyntaxKind.MethodDeclaration ? factory.createMethodDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ?? factory.createIdentifier(""), /*questionToken*/ undefined, typeParameters, parameters, returnTypeNode, /*body*/ undefined) : kind === SyntaxKind.Constructor ? factory.createConstructorDeclaration(modifiers, parameters, /*body*/ undefined) : kind === SyntaxKind.GetAccessor ? factory.createGetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, returnTypeNode, /*body*/ undefined) : kind === SyntaxKind.SetAccessor ? factory.createSetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, /*body*/ undefined) : kind === SyntaxKind.IndexSignature ? factory.createIndexSignature(modifiers, parameters, returnTypeNode) : kind === SyntaxKind.JSDocFunctionType ? factory.createJSDocFunctionType(parameters, returnTypeNode) : kind === SyntaxKind.FunctionType ? factory.createFunctionTypeNode(typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : kind === SyntaxKind.ConstructorType ? factory.createConstructorTypeNode(modifiers, typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : kind === SyntaxKind.FunctionDeclaration ? factory.createFunctionDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, /*body*/ undefined) : kind === SyntaxKind.FunctionExpression ? factory.createFunctionExpression(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, factory.createBlock([])) : kind === SyntaxKind.ArrowFunction ? factory.createArrowFunction(modifiers, typeParameters, parameters, returnTypeNode, /*equalsGreaterThanToken*/ undefined, factory.createBlock([])) : Debug.assertNever(kind); if (typeArguments) { node.typeArguments = factory.createNodeArray(typeArguments); } cleanup?.(); return node; } function tryGetThisParameterDeclaration(signature: Signature, context: NodeBuilderContext) { if (signature.thisParameter) { return symbolToParameterDeclaration(signature.thisParameter, context); } if (signature.declaration && isInJSFile(signature.declaration)) { const thisTag = getJSDocThisTag(signature.declaration); if (thisTag && thisTag.typeExpression) { return factory.createParameterDeclaration( /* modifiers */ undefined, /* dotDotDotToken */ undefined, "this", /* questionToken */ undefined, typeToTypeNodeHelper(getTypeFromTypeNode(thisTag.typeExpression), context) ); } } } function typeParameterToDeclarationWithConstraint(type: TypeParameter, context: NodeBuilderContext, constraintNode: TypeNode | undefined): TypeParameterDeclaration { const savedContextFlags = context.flags; context.flags &= ~NodeBuilderFlags.WriteTypeParametersInQualifiedName; // Avoids potential infinite loop when building for a claimspace with a generic const modifiers = factory.createModifiersFromModifierFlags(getTypeParameterModifiers(type)); const name = typeParameterToName(type, context); const defaultParameter = getDefaultFromTypeParameter(type); const defaultParameterNode = defaultParameter && typeToTypeNodeHelper(defaultParameter, context); context.flags = savedContextFlags; return factory.createTypeParameterDeclaration(modifiers, name, constraintNode, defaultParameterNode); } function typeParameterToDeclaration(type: TypeParameter, context: NodeBuilderContext, constraint = getConstraintOfTypeParameter(type)): TypeParameterDeclaration { const constraintNode = constraint && typeToTypeNodeHelper(constraint, context); return typeParameterToDeclarationWithConstraint(type, context, constraintNode); } function symbolToParameterDeclaration(parameterSymbol: Symbol, context: NodeBuilderContext, preserveModifierFlags?: boolean, privateSymbolVisitor?: (s: Symbol) => void, bundledImports?: boolean): ParameterDeclaration { let parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined = getDeclarationOfKind(parameterSymbol, SyntaxKind.Parameter); if (!parameterDeclaration && !isTransientSymbol(parameterSymbol)) { parameterDeclaration = getDeclarationOfKind(parameterSymbol, SyntaxKind.JSDocParameterTag); } let parameterType = getTypeOfSymbol(parameterSymbol); if (parameterDeclaration && isRequiredInitializedParameter(parameterDeclaration)) { parameterType = getOptionalType(parameterType); } const parameterTypeNode = serializeTypeForDeclaration(context, parameterType, parameterSymbol, context.enclosingDeclaration, privateSymbolVisitor, bundledImports); const modifiers = !(context.flags & NodeBuilderFlags.OmitParameterModifiers) && preserveModifierFlags && parameterDeclaration && canHaveModifiers(parameterDeclaration) ? map(getModifiers(parameterDeclaration), factory.cloneNode) : undefined; const isRest = parameterDeclaration && isRestParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.RestParameter; const dotDotDotToken = isRest ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined; const name = parameterDeclaration ? parameterDeclaration.name ? parameterDeclaration.name.kind === SyntaxKind.Identifier ? setEmitFlags(factory.cloneNode(parameterDeclaration.name), EmitFlags.NoAsciiEscaping) : parameterDeclaration.name.kind === SyntaxKind.QualifiedName ? setEmitFlags(factory.cloneNode(parameterDeclaration.name.right), EmitFlags.NoAsciiEscaping) : cloneBindingName(parameterDeclaration.name) : symbolName(parameterSymbol) : symbolName(parameterSymbol); const isOptional = parameterDeclaration && isOptionalParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.OptionalParameter; const questionToken = isOptional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; const parameterNode = factory.createParameterDeclaration( modifiers, dotDotDotToken, name, questionToken, parameterTypeNode, /*initializer*/ undefined); context.approximateLength += symbolName(parameterSymbol).length + 3; return parameterNode; function cloneBindingName(node: BindingName): BindingName { return elideInitializerAndSetEmitFlags(node) as BindingName; function elideInitializerAndSetEmitFlags(node: Node): Node { if (context.tracker.canTrackSymbol && isComputedPropertyName(node) && isLateBindableName(node)) { trackComputedName(node.expression, context.enclosingDeclaration, context); } let visited = visitEachChild(node, elideInitializerAndSetEmitFlags, nullTransformationContext, /*nodesVisitor*/ undefined, elideInitializerAndSetEmitFlags)!; if (isBindingElement(visited)) { visited = factory.updateBindingElement( visited, visited.dotDotDotToken, visited.propertyName, visited.name, /*initializer*/ undefined); } if (!nodeIsSynthesized(visited)) { visited = factory.cloneNode(visited); } return setEmitFlags(visited, EmitFlags.SingleLine | EmitFlags.NoAsciiEscaping); } } } function trackComputedName(accessExpression: EntityNameOrEntityNameExpression, enclosingDeclaration: Node | undefined, context: NodeBuilderContext) { if (!context.tracker.canTrackSymbol) return; // get symbol of the first identifier of the entityName const firstIdentifier = getFirstIdentifier(accessExpression); const name = resolveName(firstIdentifier, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue, /*nodeNotFoundErrorMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ true); if (name) { context.tracker.trackSymbol(name, enclosingDeclaration, SymbolFlags.Value); } } function lookupSymbolChain(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { context.tracker.trackSymbol(symbol, context.enclosingDeclaration, meaning); return lookupSymbolChainWorker(symbol, context, meaning, yieldModuleSymbol); } function lookupSymbolChainWorker(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { // Try to get qualified name if the symbol is not a type parameter and there is an enclosing declaration. let chain: Symbol[]; const isTypeParameter = symbol.flags & SymbolFlags.TypeParameter; if (!isTypeParameter && (context.enclosingDeclaration || context.flags & NodeBuilderFlags.UseFullyQualifiedType) && !(context.flags & NodeBuilderFlags.DoNotIncludeSymbolChain)) { chain = Debug.checkDefined(getSymbolChain(symbol, meaning, /*endOfChain*/ true)); Debug.assert(chain && chain.length > 0); } else { chain = [symbol]; } return chain; /** @param endOfChain Set to false for recursive calls; non-recursive calls should always output something. */ function getSymbolChain(symbol: Symbol, meaning: SymbolFlags, endOfChain: boolean): Symbol[] | undefined { let accessibleSymbolChain = getAccessibleSymbolChain(symbol, context.enclosingDeclaration, meaning, !!(context.flags & NodeBuilderFlags.UseOnlyExternalAliasing)); let parentSpecifiers: (string | undefined)[]; if (!accessibleSymbolChain || needsQualification(accessibleSymbolChain[0], context.enclosingDeclaration, accessibleSymbolChain.length === 1 ? meaning : getQualifiedLeftMeaning(meaning))) { // Go up and add our parent. const parents = getContainersOfSymbol(accessibleSymbolChain ? accessibleSymbolChain[0] : symbol, context.enclosingDeclaration, meaning); if (length(parents)) { parentSpecifiers = parents!.map(symbol => some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol) ? getSpecifierForModuleSymbol(symbol, context) : undefined); const indices = parents!.map((_, i) => i); indices.sort(sortByBestName); const sortedParents = indices.map(i => parents![i]); for (const parent of sortedParents) { const parentChain = getSymbolChain(parent, getQualifiedLeftMeaning(meaning), /*endOfChain*/ false); if (parentChain) { if (parent.exports && parent.exports.get(InternalSymbolName.ExportEquals) && getSymbolIfSameReference(parent.exports.get(InternalSymbolName.ExportEquals)!, symbol)) { // parentChain root _is_ symbol - symbol is a module export=, so it kinda looks like it's own parent // No need to lookup an alias for the symbol in itself accessibleSymbolChain = parentChain; break; } accessibleSymbolChain = parentChain.concat(accessibleSymbolChain || [getAliasForSymbolInContainer(parent, symbol) || symbol]); break; } } } } if (accessibleSymbolChain) { return accessibleSymbolChain; } if ( // If this is the last part of outputting the symbol, always output. The cases apply only to parent symbols. endOfChain || // If a parent symbol is an anonymous type, don't write it. !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral))) { // If a parent symbol is an external module, don't write it. (We prefer just `x` vs `"foo/bar".x`.) if (!endOfChain && !yieldModuleSymbol && !!forEach(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { return; } return [symbol]; } function sortByBestName(a: number, b: number) { const specifierA = parentSpecifiers[a]; const specifierB = parentSpecifiers[b]; if (specifierA && specifierB) { const isBRelative = pathIsRelative(specifierB); if (pathIsRelative(specifierA) === isBRelative) { // Both relative or both non-relative, sort by number of parts return moduleSpecifiers.countPathComponents(specifierA) - moduleSpecifiers.countPathComponents(specifierB); } if (isBRelative) { // A is non-relative, B is relative: prefer A return -1; } // A is relative, B is non-relative: prefer B return 1; } return 0; } } } function typeParametersToTypeParameterDeclarations(symbol: Symbol, context: NodeBuilderContext) { let typeParameterNodes: NodeArray | undefined; const targetSymbol = getTargetSymbol(symbol); if (targetSymbol.flags & (SymbolFlags.Class | SymbolFlags.Interface | SymbolFlags.TypeAlias)) { typeParameterNodes = factory.createNodeArray(map(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol), tp => typeParameterToDeclaration(tp, context))); } return typeParameterNodes; } function lookupTypeParameterNodes(chain: Symbol[], index: number, context: NodeBuilderContext) { Debug.assert(chain && 0 <= index && index < chain.length); const symbol = chain[index]; const symbolId = getSymbolId(symbol); if (context.typeParameterSymbolList?.has(symbolId)) { return undefined; } (context.typeParameterSymbolList || (context.typeParameterSymbolList = new Set())).add(symbolId); let typeParameterNodes: readonly TypeNode[] | readonly TypeParameterDeclaration[] | undefined; if (context.flags & NodeBuilderFlags.WriteTypeParametersInQualifiedName && index < (chain.length - 1)) { const parentSymbol = symbol; const nextSymbol = chain[index + 1]; if (getCheckFlags(nextSymbol) & CheckFlags.Instantiated) { const params = getTypeParametersOfClassOrInterface( parentSymbol.flags & SymbolFlags.Alias ? resolveAlias(parentSymbol) : parentSymbol ); // NOTE: cast to TransientSymbol should be safe because only TransientSymbol can have CheckFlags.Instantiated typeParameterNodes = mapToTypeNodes(map(params, t => getMappedType(t, (nextSymbol as TransientSymbol).links.mapper!)), context); } else { typeParameterNodes = typeParametersToTypeParameterDeclarations(symbol, context); } } return typeParameterNodes; } /** * Given A[B][C][D], finds A[B] */ function getTopmostIndexedAccessType(top: IndexedAccessTypeNode): IndexedAccessTypeNode { if (isIndexedAccessTypeNode(top.objectType)) { return getTopmostIndexedAccessType(top.objectType); } return top; } function getSpecifierForModuleSymbol(symbol: Symbol, context: NodeBuilderContext, overrideImportMode?: ResolutionMode) { let file = getDeclarationOfKind(symbol, SyntaxKind.SourceFile); if (!file) { const equivalentFileSymbol = firstDefined(symbol.declarations, d => getFileSymbolIfFileSymbolExportEqualsContainer(d, symbol)); if (equivalentFileSymbol) { file = getDeclarationOfKind(equivalentFileSymbol, SyntaxKind.SourceFile); } } if (file && file.moduleName !== undefined) { // Use the amd name if it is available return file.moduleName; } if (!file) { if (context.tracker.trackReferencedAmbientModule) { const ambientDecls = filter(symbol.declarations, isAmbientModule); if (length(ambientDecls)) { for (const decl of ambientDecls!) { context.tracker.trackReferencedAmbientModule(decl, symbol); } } } if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); } } if (!context.enclosingDeclaration || !context.tracker.moduleResolverHost) { // If there's no context declaration, we can't lookup a non-ambient specifier, so we just use the symbol name if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); } return getSourceFileOfNode(getNonAugmentationDeclaration(symbol)!).fileName; // A resolver may not be provided for baselines and errors - in those cases we use the fileName in full } const contextFile = getSourceFileOfNode(getOriginalNode(context.enclosingDeclaration)); const resolutionMode = overrideImportMode || contextFile?.impliedNodeFormat; const cacheKey = createModeAwareCacheKey(contextFile.path, resolutionMode); const links = getSymbolLinks(symbol); let specifier = links.specifierCache && links.specifierCache.get(cacheKey); if (!specifier) { const isBundle = !!outFile(compilerOptions); // For declaration bundles, we need to generate absolute paths relative to the common source dir for imports, // just like how the declaration emitter does for the ambient module declarations - we can easily accomplish this // using the `baseUrl` compiler option (which we would otherwise never use in declaration emit) and a non-relative // specifier preference const { moduleResolverHost } = context.tracker; const specifierCompilerOptions = isBundle ? { ...compilerOptions, baseUrl: moduleResolverHost.getCommonSourceDirectory() } : compilerOptions; specifier = first(moduleSpecifiers.getModuleSpecifiers( symbol, checker, specifierCompilerOptions, contextFile, moduleResolverHost, { importModuleSpecifierPreference: isBundle ? "non-relative" : "project-relative", importModuleSpecifierEnding: isBundle ? "minimal" : resolutionMode === ModuleKind.ESNext ? "js" : undefined, }, { overrideImportMode } )); links.specifierCache ??= new Map(); links.specifierCache.set(cacheKey, specifier); } return specifier; } function symbolToEntityNameNode(symbol: Symbol): EntityName { const identifier = factory.createIdentifier(unescapeLeadingUnderscores(symbol.escapedName)); return symbol.parent ? factory.createQualifiedName(symbolToEntityNameNode(symbol.parent), identifier) : identifier; } function symbolToTypeNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, overrideTypeArguments?: readonly TypeNode[]): TypeNode { const chain = lookupSymbolChain(symbol, context, meaning, !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope)); // If we're using aliases outside the current scope, dont bother with the module const isTypeOf = meaning === SymbolFlags.Value; if (some(chain[0].declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { // module is root, must use `ImportTypeNode` const nonRootParts = chain.length > 1 ? createAccessFromSymbolChain(chain, chain.length - 1, 1) : undefined; const typeParameterNodes = overrideTypeArguments || lookupTypeParameterNodes(chain, 0, context); const contextFile = getSourceFileOfNode(getOriginalNode(context.enclosingDeclaration)); const targetFile = getSourceFileOfModule(chain[0]); let specifier: string | undefined; let assertion: ImportTypeAssertionContainer | undefined; if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { // An `import` type directed at an esm format file is only going to resolve in esm mode - set the esm mode assertion if (targetFile?.impliedNodeFormat === ModuleKind.ESNext && targetFile.impliedNodeFormat !== contextFile?.impliedNodeFormat) { specifier = getSpecifierForModuleSymbol(chain[0], context, ModuleKind.ESNext); assertion = factory.createImportTypeAssertionContainer(factory.createAssertClause(factory.createNodeArray([ factory.createAssertEntry( factory.createStringLiteral("resolution-mode"), factory.createStringLiteral("import") ) ]))); context.tracker.reportImportTypeNodeResolutionModeOverride?.(); } } if (!specifier) { specifier = getSpecifierForModuleSymbol(chain[0], context); } if (!(context.flags & NodeBuilderFlags.AllowNodeModulesRelativePaths) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Classic && specifier.indexOf("/node_modules/") >= 0) { const oldSpecifier = specifier; if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { // We might be able to write a portable import type using a mode override; try specifier generation again, but with a different mode set const swappedMode = contextFile?.impliedNodeFormat === ModuleKind.ESNext ? ModuleKind.CommonJS : ModuleKind.ESNext; specifier = getSpecifierForModuleSymbol(chain[0], context, swappedMode); if (specifier.indexOf("/node_modules/") >= 0) { // Still unreachable :( specifier = oldSpecifier; } else { assertion = factory.createImportTypeAssertionContainer(factory.createAssertClause(factory.createNodeArray([ factory.createAssertEntry( factory.createStringLiteral("resolution-mode"), factory.createStringLiteral(swappedMode === ModuleKind.ESNext ? "import" : "require") ) ]))); context.tracker.reportImportTypeNodeResolutionModeOverride?.(); } } if (!assertion) { // If ultimately we can only name the symbol with a reference that dives into a `node_modules` folder, we should error // since declaration files with these kinds of references are liable to fail when published :( context.encounteredError = true; if (context.tracker.reportLikelyUnsafeImportRequiredError) { context.tracker.reportLikelyUnsafeImportRequiredError(oldSpecifier); } } } const lit = factory.createLiteralTypeNode(factory.createStringLiteral(specifier)); if (context.tracker.trackExternalModuleSymbolOfImportTypeNode) context.tracker.trackExternalModuleSymbolOfImportTypeNode(chain[0]); context.approximateLength += specifier.length + 10; // specifier + import("") if (!nonRootParts || isEntityName(nonRootParts)) { if (nonRootParts) { const lastId = isIdentifier(nonRootParts) ? nonRootParts : nonRootParts.right; setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); } return factory.createImportTypeNode(lit, assertion, nonRootParts as EntityName, typeParameterNodes as readonly TypeNode[], isTypeOf); } else { const splitNode = getTopmostIndexedAccessType(nonRootParts); const qualifier = (splitNode.objectType as TypeReferenceNode).typeName; return factory.createIndexedAccessTypeNode(factory.createImportTypeNode(lit, assertion, qualifier, typeParameterNodes as readonly TypeNode[], isTypeOf), splitNode.indexType); } } const entityName = createAccessFromSymbolChain(chain, chain.length - 1, 0); if (isIndexedAccessTypeNode(entityName)) { return entityName; // Indexed accesses can never be `typeof` } if (isTypeOf) { return factory.createTypeQueryNode(entityName); } else { const lastId = isIdentifier(entityName) ? entityName : entityName.right; const lastTypeArgs = getIdentifierTypeArguments(lastId); setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); return factory.createTypeReferenceNode(entityName, lastTypeArgs as NodeArray); } function createAccessFromSymbolChain(chain: Symbol[], index: number, stopper: number): EntityName | IndexedAccessTypeNode { const typeParameterNodes = index === (chain.length - 1) ? overrideTypeArguments : lookupTypeParameterNodes(chain, index, context); const symbol = chain[index]; const parent = chain[index - 1]; let symbolName: string | undefined; if (index === 0) { context.flags |= NodeBuilderFlags.InInitialEntityName; symbolName = getNameOfSymbolAsWritten(symbol, context); context.approximateLength += (symbolName ? symbolName.length : 0) + 1; context.flags ^= NodeBuilderFlags.InInitialEntityName; } else { if (parent && getExportsOfSymbol(parent)) { const exports = getExportsOfSymbol(parent); forEachEntry(exports, (ex, name) => { if (getSymbolIfSameReference(ex, symbol) && !isLateBoundName(name) && name !== InternalSymbolName.ExportEquals) { symbolName = unescapeLeadingUnderscores(name); return true; } }); } } if (symbolName === undefined) { const name = firstDefined(symbol.declarations, getNameOfDeclaration); if (name && isComputedPropertyName(name) && isEntityName(name.expression)) { const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); if (isEntityName(LHS)) { return factory.createIndexedAccessTypeNode(factory.createParenthesizedType(factory.createTypeQueryNode(LHS)), factory.createTypeQueryNode(name.expression)); } return LHS; } symbolName = getNameOfSymbolAsWritten(symbol, context); } context.approximateLength += symbolName.length + 1; if (!(context.flags & NodeBuilderFlags.ForbidIndexedAccessSymbolReferences) && parent && getMembersOfSymbol(parent) && getMembersOfSymbol(parent).get(symbol.escapedName) && getSymbolIfSameReference(getMembersOfSymbol(parent).get(symbol.escapedName)!, symbol)) { // Should use an indexed access const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); if (isIndexedAccessTypeNode(LHS)) { return factory.createIndexedAccessTypeNode(LHS, factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); } else { return factory.createIndexedAccessTypeNode(factory.createTypeReferenceNode(LHS, typeParameterNodes as readonly TypeNode[]), factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); } } const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); identifier.symbol = symbol; if (index > stopper) { const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); if (!isEntityName(LHS)) { return Debug.fail("Impossible construct - an export of an indexed access cannot be reachable"); } return factory.createQualifiedName(LHS, identifier); } return identifier; } } function typeParameterShadowsNameInScope(escapedName: __String, context: NodeBuilderContext, type: TypeParameter) { const result = resolveName(context.enclosingDeclaration, escapedName, SymbolFlags.Type, /*nameNotFoundArg*/ undefined, escapedName, /*isUse*/ false); if (result) { if (result.flags & SymbolFlags.TypeParameter && result === type.symbol) { return false; } return true; } return false; } function typeParameterToName(type: TypeParameter, context: NodeBuilderContext) { if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && context.typeParameterNames) { const cached = context.typeParameterNames.get(getTypeId(type)); if (cached) { return cached; } } let result = symbolToName(type.symbol, context, SymbolFlags.Type, /*expectsIdentifier*/ true); if (!(result.kind & SyntaxKind.Identifier)) { return factory.createIdentifier("(Missing type parameter)"); } if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { const rawtext = result.escapedText as string; let i = context.typeParameterNamesByTextNextNameCount?.get(rawtext) || 0; let text = rawtext; while (context.typeParameterNamesByText?.has(text) || typeParameterShadowsNameInScope(text as __String, context, type)) { i++; text = `${rawtext}_${i}`; } if (text !== rawtext) { const typeArguments = getIdentifierTypeArguments(result); result = factory.createIdentifier(text); setIdentifierTypeArguments(result, typeArguments); } // avoiding iterations of the above loop turns out to be worth it when `i` starts to get large, so we cache the max // `i` we've used thus far, to save work later (context.typeParameterNamesByTextNextNameCount ||= new Map()).set(rawtext, i); (context.typeParameterNames ||= new Map()).set(getTypeId(type), result); (context.typeParameterNamesByText ||= new Set()).add(rawtext); } return result; } function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: true): Identifier; function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: false): EntityName; function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: boolean): EntityName { const chain = lookupSymbolChain(symbol, context, meaning); if (expectsIdentifier && chain.length !== 1 && !context.encounteredError && !(context.flags & NodeBuilderFlags.AllowQualifiedNameInPlaceOfIdentifier)) { context.encounteredError = true; } return createEntityNameFromSymbolChain(chain, chain.length - 1); function createEntityNameFromSymbolChain(chain: Symbol[], index: number): EntityName { const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); const symbol = chain[index]; if (index === 0) { context.flags |= NodeBuilderFlags.InInitialEntityName; } const symbolName = getNameOfSymbolAsWritten(symbol, context); if (index === 0) { context.flags ^= NodeBuilderFlags.InInitialEntityName; } const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); identifier.symbol = symbol; return index > 0 ? factory.createQualifiedName(createEntityNameFromSymbolChain(chain, index - 1), identifier) : identifier; } } function symbolToExpression(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { const chain = lookupSymbolChain(symbol, context, meaning); return createExpressionFromSymbolChain(chain, chain.length - 1); function createExpressionFromSymbolChain(chain: Symbol[], index: number): Expression { const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); const symbol = chain[index]; if (index === 0) { context.flags |= NodeBuilderFlags.InInitialEntityName; } let symbolName = getNameOfSymbolAsWritten(symbol, context); if (index === 0) { context.flags ^= NodeBuilderFlags.InInitialEntityName; } let firstChar = symbolName.charCodeAt(0); if (isSingleOrDoubleQuote(firstChar) && some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { return factory.createStringLiteral(getSpecifierForModuleSymbol(symbol, context)); } if (index === 0 || canUsePropertyAccess(symbolName, languageVersion)) { const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); identifier.symbol = symbol; return index > 0 ? factory.createPropertyAccessExpression(createExpressionFromSymbolChain(chain, index - 1), identifier) : identifier; } else { if (firstChar === CharacterCodes.openBracket) { symbolName = symbolName.substring(1, symbolName.length - 1); firstChar = symbolName.charCodeAt(0); } let expression: Expression | undefined; if (isSingleOrDoubleQuote(firstChar) && !(symbol.flags & SymbolFlags.EnumMember)) { expression = factory.createStringLiteral(stripQuotes(symbolName).replace(/\\./g, s => s.substring(1)), firstChar === CharacterCodes.singleQuote); } else if (("" + +symbolName) === symbolName) { expression = factory.createNumericLiteral(+symbolName); } if (!expression) { const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); identifier.symbol = symbol; expression = identifier; } return factory.createElementAccessExpression(createExpressionFromSymbolChain(chain, index - 1), expression); } } } function isStringNamed(d: Declaration) { const name = getNameOfDeclaration(d); return !!name && isStringLiteral(name); } function isSingleQuotedStringNamed(d: Declaration) { const name = getNameOfDeclaration(d); return !!(name && isStringLiteral(name) && (name.singleQuote || !nodeIsSynthesized(name) && startsWith(getTextOfNode(name, /*includeTrivia*/ false), "'"))); } function getPropertyNameNodeForSymbol(symbol: Symbol, context: NodeBuilderContext) { const stringNamed = !!length(symbol.declarations) && every(symbol.declarations, isStringNamed); const singleQuote = !!length(symbol.declarations) && every(symbol.declarations, isSingleQuotedStringNamed); const fromNameType = getPropertyNameNodeForSymbolFromNameType(symbol, context, singleQuote, stringNamed); if (fromNameType) { return fromNameType; } const rawName = unescapeLeadingUnderscores(symbol.escapedName); return createPropertyNameNodeForIdentifierOrLiteral(rawName, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed); } // See getNameForSymbolFromNameType for a stringy equivalent function getPropertyNameNodeForSymbolFromNameType(symbol: Symbol, context: NodeBuilderContext, singleQuote?: boolean, stringNamed?: boolean) { const nameType = getSymbolLinks(symbol).nameType; if (nameType) { if (nameType.flags & TypeFlags.StringOrNumberLiteral) { const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && (stringNamed || !isNumericLiteralName(name))) { return factory.createStringLiteral(name, !!singleQuote); } if (isNumericLiteralName(name) && startsWith(name, "-")) { return factory.createComputedPropertyName(factory.createNumericLiteral(+name)); } return createPropertyNameNodeForIdentifierOrLiteral(name, getEmitScriptTarget(compilerOptions)); } if (nameType.flags & TypeFlags.UniqueESSymbol) { return factory.createComputedPropertyName(symbolToExpression((nameType as UniqueESSymbolType).symbol, context, SymbolFlags.Value)); } } } function cloneNodeBuilderContext(context: NodeBuilderContext): NodeBuilderContext { const initial: NodeBuilderContext = { ...context }; // Make type parameters created within this context not consume the name outside this context // The symbol serializer ends up creating many sibling scopes that all need "separate" contexts when // it comes to naming things - within a normal `typeToTypeNode` call, the node builder only ever descends // through the type tree, so the only cases where we could have used distinct sibling scopes was when there // were multiple generic overloads with similar generated type parameter names // The effect: // When we write out // export const x: (x: T) => T // export const y: (x: T) => T // we write it out like that, rather than as // export const x: (x: T) => T // export const y: (x: T_1) => T_1 if (initial.typeParameterNames) { initial.typeParameterNames = new Map(initial.typeParameterNames); } if (initial.typeParameterNamesByText) { initial.typeParameterNamesByText = new Set(initial.typeParameterNamesByText); } if (initial.typeParameterSymbolList) { initial.typeParameterSymbolList = new Set(initial.typeParameterSymbolList); } initial.tracker = new SymbolTrackerImpl(initial, initial.tracker.inner, initial.tracker.moduleResolverHost); return initial; } function getDeclarationWithTypeAnnotation(symbol: Symbol, enclosingDeclaration: Node | undefined) { return symbol.declarations && find(symbol.declarations, s => !!getEffectiveTypeAnnotationNode(s) && (!enclosingDeclaration || !!findAncestor(s, n => n === enclosingDeclaration))); } function existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing: TypeNode, type: Type) { return !(getObjectFlags(type) & ObjectFlags.Reference) || !isTypeReferenceNode(existing) || length(existing.typeArguments) >= getMinTypeArgumentCount((type as TypeReference).target.typeParameters); } function getEnclosingDeclarationIgnoringFakeScope(enclosingDeclaration: Node) { return getNodeLinks(enclosingDeclaration).fakeScopeForSignatureDeclaration ? enclosingDeclaration.parent : enclosingDeclaration; } /** * Unlike `typeToTypeNodeHelper`, this handles setting up the `AllowUniqueESSymbolType` flag * so a `unique symbol` is returned when appropriate for the input symbol, rather than `typeof sym` */ function serializeTypeForDeclaration(context: NodeBuilderContext, type: Type, symbol: Symbol, enclosingDeclaration: Node | undefined, includePrivateSymbol?: (s: Symbol) => void, bundled?: boolean) { if (!isErrorType(type) && enclosingDeclaration) { const declWithExistingAnnotation = getDeclarationWithTypeAnnotation(symbol, getEnclosingDeclarationIgnoringFakeScope(enclosingDeclaration)); if (declWithExistingAnnotation && !isFunctionLikeDeclaration(declWithExistingAnnotation) && !isGetAccessorDeclaration(declWithExistingAnnotation)) { // try to reuse the existing annotation const existing = getEffectiveTypeAnnotationNode(declWithExistingAnnotation)!; if (typeNodeIsEquivalentToType(existing, declWithExistingAnnotation, type) && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type)) { const result = serializeExistingTypeNode(context, existing, includePrivateSymbol, bundled); if (result) { return result; } } } } const oldFlags = context.flags; if (type.flags & TypeFlags.UniqueESSymbol && type.symbol === symbol && (!context.enclosingDeclaration || some(symbol.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!)))) { context.flags |= NodeBuilderFlags.AllowUniqueESSymbolType; } const result = typeToTypeNodeHelper(type, context); context.flags = oldFlags; return result; } function typeNodeIsEquivalentToType(typeNode: TypeNode, annotatedDeclaration: Declaration, type: Type) { const typeFromTypeNode = getTypeFromTypeNode(typeNode); if (typeFromTypeNode === type) { return true; } if (isParameter(annotatedDeclaration) && annotatedDeclaration.questionToken) { return getTypeWithFacts(type, TypeFacts.NEUndefined) === typeFromTypeNode; } return false; } function serializeReturnTypeForSignature(context: NodeBuilderContext, type: Type, signature: Signature, includePrivateSymbol?: (s: Symbol) => void, bundled?: boolean) { if (!isErrorType(type) && context.enclosingDeclaration) { const annotation = signature.declaration && getEffectiveReturnTypeNode(signature.declaration); const enclosingDeclarationIgnoringFakeScope = getEnclosingDeclarationIgnoringFakeScope(context.enclosingDeclaration); if (!!findAncestor(annotation, n => n === enclosingDeclarationIgnoringFakeScope) && annotation) { const annotated = getTypeFromTypeNode(annotation); const thisInstantiated = annotated.flags & TypeFlags.TypeParameter && (annotated as TypeParameter).isThisType ? instantiateType(annotated, signature.mapper) : annotated; if (thisInstantiated === type && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(annotation, type)) { const result = serializeExistingTypeNode(context, annotation, includePrivateSymbol, bundled); if (result) { return result; } } } } return typeToTypeNodeHelper(type, context); } function trackExistingEntityName(node: T, context: NodeBuilderContext, includePrivateSymbol?: (s: Symbol) => void) { let introducesError = false; const leftmost = getFirstIdentifier(node); if (isInJSFile(node) && (isExportsIdentifier(leftmost) || isModuleExportsAccessExpression(leftmost.parent) || (isQualifiedName(leftmost.parent) && isModuleIdentifier(leftmost.parent.left) && isExportsIdentifier(leftmost.parent.right)))) { introducesError = true; return { introducesError, node }; } const sym = resolveEntityName(leftmost, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveALias*/ true); if (sym) { if (isSymbolAccessible(sym, context.enclosingDeclaration, SymbolFlags.All, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) { introducesError = true; } else { context.tracker.trackSymbol(sym, context.enclosingDeclaration, SymbolFlags.All); includePrivateSymbol?.(sym); } if (isIdentifier(node)) { const type = getDeclaredTypeOfSymbol(sym); const name = sym.flags & SymbolFlags.TypeParameter && !isTypeSymbolAccessible(type.symbol, context.enclosingDeclaration) ? typeParameterToName(type, context) : factory.cloneNode(node); name.symbol = sym; // for quickinfo, which uses identifier symbol information return { introducesError, node: setEmitFlags(setOriginalNode(name, node), EmitFlags.NoAsciiEscaping) }; } } return { introducesError, node }; } function serializeExistingTypeNode(context: NodeBuilderContext, existing: TypeNode, includePrivateSymbol?: (s: Symbol) => void, bundled?: boolean) { if (cancellationToken && cancellationToken.throwIfCancellationRequested) { cancellationToken.throwIfCancellationRequested(); } let hadError = false; const file = getSourceFileOfNode(existing); const transformed = visitNode(existing, visitExistingNodeTreeSymbols, isTypeNode); if (hadError) { return undefined; } return transformed === existing ? setTextRange(factory.cloneNode(existing), existing) : transformed; function visitExistingNodeTreeSymbols(node: Node): Node { // We don't _actually_ support jsdoc namepath types, emit `any` instead if (isJSDocAllType(node) || node.kind === SyntaxKind.JSDocNamepathType) { return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); } if (isJSDocUnknownType(node)) { return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); } if (isJSDocNullableType(node)) { return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode), factory.createLiteralTypeNode(factory.createNull())]); } if (isJSDocOptionalType(node)) { return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode), factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); } if (isJSDocNonNullableType(node)) { return visitNode(node.type, visitExistingNodeTreeSymbols); } if (isJSDocVariadicType(node)) { return factory.createArrayTypeNode(visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)); } if (isJSDocTypeLiteral(node)) { return factory.createTypeLiteralNode(map(node.jsDocPropertyTags, t => { const name = isIdentifier(t.name) ? t.name : t.name.right; const typeViaParent = getTypeOfPropertyOfType(getTypeFromTypeNode(node), name.escapedText); const overrideTypeNode = typeViaParent && t.typeExpression && getTypeFromTypeNode(t.typeExpression.type) !== typeViaParent ? typeToTypeNodeHelper(typeViaParent, context) : undefined; return factory.createPropertySignature( /*modifiers*/ undefined, name, t.isBracketed || t.typeExpression && isJSDocOptionalType(t.typeExpression.type) ? factory.createToken(SyntaxKind.QuestionToken) : undefined, overrideTypeNode || (t.typeExpression && visitNode(t.typeExpression.type, visitExistingNodeTreeSymbols, isTypeNode)) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword) ); })); } if (isTypeReferenceNode(node) && isIdentifier(node.typeName) && node.typeName.escapedText === "") { return setOriginalNode(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), node); } if ((isExpressionWithTypeArguments(node) || isTypeReferenceNode(node)) && isJSDocIndexSignature(node)) { return factory.createTypeLiteralNode([factory.createIndexSignature( /*modifiers*/ undefined, [factory.createParameterDeclaration( /*modifiers*/ undefined, /*dotdotdotToken*/ undefined, "x", /*questionToken*/ undefined, visitNode(node.typeArguments![0], visitExistingNodeTreeSymbols, isTypeNode) )], visitNode(node.typeArguments![1], visitExistingNodeTreeSymbols, isTypeNode) )]); } if (isJSDocFunctionType(node)) { if (isJSDocConstructSignature(node)) { let newTypeNode: TypeNode | undefined; return factory.createConstructorTypeNode( /*modifiers*/ undefined, visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), mapDefined(node.parameters, (p, i) => p.name && isIdentifier(p.name) && p.name.escapedText === "new" ? (newTypeNode = p.type, undefined) : factory.createParameterDeclaration( /*modifiers*/ undefined, getEffectiveDotDotDotForParameter(p), getNameForJSDocFunctionParameter(p, i), p.questionToken, visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), /*initializer*/ undefined )), visitNode(newTypeNode || node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword) ); } else { return factory.createFunctionTypeNode( visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), map(node.parameters, (p, i) => factory.createParameterDeclaration( /*modifiers*/ undefined, getEffectiveDotDotDotForParameter(p), getNameForJSDocFunctionParameter(p, i), p.questionToken, visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), /*initializer*/ undefined )), visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword) ); } } if (isTypeReferenceNode(node) && isInJSDoc(node) && (!existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(node, getTypeFromTypeNode(node)) || getIntendedTypeFromJSDocTypeReference(node) || unknownSymbol === resolveTypeReferenceName(node, SymbolFlags.Type, /*ignoreErrors*/ true))) { return setOriginalNode(typeToTypeNodeHelper(getTypeFromTypeNode(node), context), node); } if (isLiteralImportTypeNode(node)) { const nodeSymbol = getNodeLinks(node).resolvedSymbol; if (isInJSDoc(node) && nodeSymbol && ( // The import type resolved using jsdoc fallback logic (!node.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || // The import type had type arguments autofilled by js fallback logic !(length(node.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) ) ) { return setOriginalNode(typeToTypeNodeHelper(getTypeFromTypeNode(node), context), node); } return factory.updateImportTypeNode( node, factory.updateLiteralTypeNode(node.argument, rewriteModuleSpecifier(node, node.argument.literal)), node.assertions, node.qualifier, visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), node.isTypeOf ); } if (isEntityName(node) || isEntityNameExpression(node)) { const { introducesError, node: result } = trackExistingEntityName(node, context, includePrivateSymbol); hadError = hadError || introducesError; if (result !== node) { return result; } } if (file && isTupleTypeNode(node) && (getLineAndCharacterOfPosition(file, node.pos).line === getLineAndCharacterOfPosition(file, node.end).line)) { setEmitFlags(node, EmitFlags.SingleLine); } return visitEachChild(node, visitExistingNodeTreeSymbols, nullTransformationContext); function getEffectiveDotDotDotForParameter(p: ParameterDeclaration) { return p.dotDotDotToken || (p.type && isJSDocVariadicType(p.type) ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined); } /** Note that `new:T` parameters are not handled, but should be before calling this function. */ function getNameForJSDocFunctionParameter(p: ParameterDeclaration, index: number) { return p.name && isIdentifier(p.name) && p.name.escapedText === "this" ? "this" : getEffectiveDotDotDotForParameter(p) ? `args` : `arg${index}`; } function rewriteModuleSpecifier(parent: ImportTypeNode, lit: StringLiteral) { if (bundled) { if (context.tracker && context.tracker.moduleResolverHost) { const targetFile = getExternalModuleFileFromDeclaration(parent); if (targetFile) { const getCanonicalFileName = createGetCanonicalFileName(!!host.useCaseSensitiveFileNames); const resolverHost = { getCanonicalFileName, getCurrentDirectory: () => context.tracker.moduleResolverHost!.getCurrentDirectory(), getCommonSourceDirectory: () => context.tracker.moduleResolverHost!.getCommonSourceDirectory() }; const newName = getResolvedExternalModuleName(resolverHost, targetFile); return factory.createStringLiteral(newName); } } } else { if (context.tracker && context.tracker.trackExternalModuleSymbolOfImportTypeNode) { const moduleSym = resolveExternalModuleNameWorker(lit, lit, /*moduleNotFoundError*/ undefined); if (moduleSym) { context.tracker.trackExternalModuleSymbolOfImportTypeNode(moduleSym); } } } return lit; } } } function symbolTableToDeclarationStatements(symbolTable: SymbolTable, context: NodeBuilderContext, bundled?: boolean): Statement[] { const serializePropertySymbolForClass = makeSerializePropertySymbol(factory.createPropertyDeclaration, SyntaxKind.MethodDeclaration, /*useAcessors*/ true); const serializePropertySymbolForInterfaceWorker = makeSerializePropertySymbol((mods, name, question, type) => factory.createPropertySignature(mods, name, question, type), SyntaxKind.MethodSignature, /*useAcessors*/ false); // TODO: Use `setOriginalNode` on original declaration names where possible so these declarations see some kind of // declaration mapping // We save the enclosing declaration off here so it's not adjusted by well-meaning declaration // emit codepaths which want to apply more specific contexts (so we can still refer to the root real declaration // we're trying to emit from later on) const enclosingDeclaration = context.enclosingDeclaration!; let results: Statement[] = []; const visitedSymbols = new Set(); const deferredPrivatesStack: Map[] = []; const oldcontext = context; context = { ...oldcontext, usedSymbolNames: new Set(oldcontext.usedSymbolNames), remappedSymbolNames: new Map(), tracker: undefined!, }; const tracker: SymbolTracker = { ...oldcontext.tracker.inner, trackSymbol: (sym, decl, meaning) => { const accessibleResult = isSymbolAccessible(sym, decl, meaning, /*computeAliases*/ false); if (accessibleResult.accessibility === SymbolAccessibility.Accessible) { // Lookup the root symbol of the chain of refs we'll use to access it and serialize it const chain = lookupSymbolChainWorker(sym, context, meaning); if (!(sym.flags & SymbolFlags.Property)) { includePrivateSymbol(chain[0]); } } else if (oldcontext.tracker.inner?.trackSymbol) { return oldcontext.tracker.inner.trackSymbol(sym, decl, meaning); } return false; }, }; context.tracker = new SymbolTrackerImpl(context, tracker, oldcontext.tracker.moduleResolverHost); forEachEntry(symbolTable, (symbol, name) => { const baseName = unescapeLeadingUnderscores(name); void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames` }); let addingDeclare = !bundled; const exportEquals = symbolTable.get(InternalSymbolName.ExportEquals); if (exportEquals && symbolTable.size > 1 && exportEquals.flags & SymbolFlags.Alias) { symbolTable = createSymbolTable(); // Remove extraneous elements from root symbol table (they'll be mixed back in when the target of the `export=` is looked up) symbolTable.set(InternalSymbolName.ExportEquals, exportEquals); } visitSymbolTable(symbolTable); return mergeRedundantStatements(results); function isIdentifierAndNotUndefined(node: Node | undefined): node is Identifier { return !!node && node.kind === SyntaxKind.Identifier; } function getNamesOfDeclaration(statement: Statement): Identifier[] { if (isVariableStatement(statement)) { return filter(map(statement.declarationList.declarations, getNameOfDeclaration), isIdentifierAndNotUndefined); } return filter([getNameOfDeclaration(statement as DeclarationStatement)], isIdentifierAndNotUndefined); } function flattenExportAssignedNamespace(statements: Statement[]) { const exportAssignment = find(statements, isExportAssignment); const nsIndex = findIndex(statements, isModuleDeclaration); let ns = nsIndex !== -1 ? statements[nsIndex] as ModuleDeclaration : undefined; if (ns && exportAssignment && exportAssignment.isExportEquals && isIdentifier(exportAssignment.expression) && isIdentifier(ns.name) && idText(ns.name) === idText(exportAssignment.expression) && ns.body && isModuleBlock(ns.body)) { // Pass 0: Correct situations where a module has both an `export = ns` and multiple top-level exports by stripping the export modifiers from // the top-level exports and exporting them in the targeted ns, as can occur when a js file has both typedefs and `module.export` assignments const excessExports = filter(statements, s => !!(getEffectiveModifierFlags(s) & ModifierFlags.Export)); const name = ns.name; let body = ns.body; if (length(excessExports)) { ns = factory.updateModuleDeclaration( ns, ns.modifiers, ns.name, body = factory.updateModuleBlock( body, factory.createNodeArray([...ns.body.statements, factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports(map(flatMap(excessExports, e => getNamesOfDeclaration(e)), id => factory.createExportSpecifier(/*isTypeOnly*/ false, /*alias*/ undefined, id))), /*moduleSpecifier*/ undefined )]) ) ); statements = [...statements.slice(0, nsIndex), ns, ...statements.slice(nsIndex + 1)]; } // Pass 1: Flatten `export namespace _exports {} export = _exports;` so long as the `export=` only points at a single namespace declaration if (!find(statements, s => s !== ns && nodeHasName(s, name))) { results = []; // If the namespace contains no export assignments or declarations, and no declarations flagged with `export`, then _everything_ is exported - // to respect this as the top level, we need to add an `export` modifier to everything const mixinExportFlag = !some(body.statements, s => hasSyntacticModifier(s, ModifierFlags.Export) || isExportAssignment(s) || isExportDeclaration(s)); forEach(body.statements, s => { addResult(s, mixinExportFlag ? ModifierFlags.Export : ModifierFlags.None); // Recalculates the ambient (and export, if applicable from above) flag }); statements = [...filter(statements, s => s !== ns && s !== exportAssignment), ...results]; } } return statements; } function mergeExportDeclarations(statements: Statement[]) { // Pass 2: Combine all `export {}` declarations const exports = filter(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; if (length(exports) > 1) { const nonExports = filter(statements, d => !isExportDeclaration(d) || !!d.moduleSpecifier || !d.exportClause); statements = [...nonExports, factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports(flatMap(exports, e => cast(e.exportClause, isNamedExports).elements)), /*moduleSpecifier*/ undefined )]; } // Pass 2b: Also combine all `export {} from "..."` declarations as needed const reexports = filter(statements, d => isExportDeclaration(d) && !!d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; if (length(reexports) > 1) { const groups = group(reexports, decl => isStringLiteral(decl.moduleSpecifier!) ? ">" + decl.moduleSpecifier.text : ">"); if (groups.length !== reexports.length) { for (const group of groups) { if (group.length > 1) { // remove group members from statements and then merge group members and add back to statements statements = [ ...filter(statements, s => group.indexOf(s as ExportDeclaration) === -1), factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports(flatMap(group, e => cast(e.exportClause, isNamedExports).elements)), group[0].moduleSpecifier ) ]; } } } } return statements; } function inlineExportModifiers(statements: Statement[]) { // Pass 3: Move all `export {}`'s to `export` modifiers where possible const index = findIndex(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !d.assertClause && !!d.exportClause && isNamedExports(d.exportClause)); if (index >= 0) { const exportDecl = statements[index] as ExportDeclaration & { readonly exportClause: NamedExports }; const replacements = mapDefined(exportDecl.exportClause.elements, e => { if (!e.propertyName) { // export {name} - look thru `statements` for `name`, and if all results can take an `export` modifier, do so and filter it const indices = indicesOf(statements); const associatedIndices = filter(indices, i => nodeHasName(statements[i], e.name)); if (length(associatedIndices) && every(associatedIndices, i => canHaveExportModifier(statements[i]))) { for (const index of associatedIndices) { statements[index] = addExportModifier(statements[index] as Extract); } return undefined; } } return e; }); if (!length(replacements)) { // all clauses removed, remove the export declaration orderedRemoveItemAt(statements, index); } else { // some items filtered, others not - update the export declaration statements[index] = factory.updateExportDeclaration( exportDecl, exportDecl.modifiers, exportDecl.isTypeOnly, factory.updateNamedExports( exportDecl.exportClause, replacements ), exportDecl.moduleSpecifier, exportDecl.assertClause ); } } return statements; } function mergeRedundantStatements(statements: Statement[]) { statements = flattenExportAssignedNamespace(statements); statements = mergeExportDeclarations(statements); statements = inlineExportModifiers(statements); // Not a cleanup, but as a final step: If there is a mix of `export` and non-`export` declarations, but no `export =` or `export {}` add a `export {};` so // declaration privacy is respected. if (enclosingDeclaration && ((isSourceFile(enclosingDeclaration) && isExternalOrCommonJsModule(enclosingDeclaration)) || isModuleDeclaration(enclosingDeclaration)) && (!some(statements, isExternalModuleIndicator) || (!hasScopeMarker(statements) && some(statements, needsScopeMarker)))) { statements.push(createEmptyExports(factory)); } return statements; } function addExportModifier(node: Extract) { const flags = (getEffectiveModifierFlags(node) | ModifierFlags.Export) & ~ModifierFlags.Ambient; return factory.updateModifiers(node, flags); } function removeExportModifier(node: Extract) { const flags = getEffectiveModifierFlags(node) & ~ModifierFlags.Export; return factory.updateModifiers(node, flags); } function visitSymbolTable(symbolTable: SymbolTable, suppressNewPrivateContext?: boolean, propertyAsAlias?: boolean) { if (!suppressNewPrivateContext) { deferredPrivatesStack.push(new Map()); } symbolTable.forEach((symbol: Symbol) => { serializeSymbol(symbol, /*isPrivate*/ false, !!propertyAsAlias); }); if (!suppressNewPrivateContext) { // deferredPrivates will be filled up by visiting the symbol table // And will continue to iterate as elements are added while visited `deferredPrivates` // (As that's how a map iterator is defined to work) deferredPrivatesStack[deferredPrivatesStack.length - 1].forEach((symbol: Symbol) => { serializeSymbol(symbol, /*isPrivate*/ true, !!propertyAsAlias); }); deferredPrivatesStack.pop(); } } function serializeSymbol(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean): void { // cache visited list based on merged symbol, since we want to use the unmerged top-level symbol, but // still skip reserializing it if we encounter the merged product later on const visitedSym = getMergedSymbol(symbol); if (visitedSymbols.has(getSymbolId(visitedSym))) { return; // Already printed } visitedSymbols.add(getSymbolId(visitedSym)); // Only actually serialize symbols within the correct enclosing declaration, otherwise do nothing with the out-of-context symbol const skipMembershipCheck = !isPrivate; // We only call this on exported symbols when we know they're in the correct scope if (skipMembershipCheck || (!!length(symbol.declarations) && some(symbol.declarations, d => !!findAncestor(d, n => n === enclosingDeclaration)))) { const oldContext = context; context = cloneNodeBuilderContext(context); serializeSymbolWorker(symbol, isPrivate, propertyAsAlias); if (context.reportedDiagnostic) { oldcontext.reportedDiagnostic = context.reportedDiagnostic; // hoist diagnostic result into outer context } context = oldContext; } } // Synthesize declarations for a symbol - might be an Interface, a Class, a Namespace, a Type, a Variable (const, let, or var), an Alias // or a merge of some number of those. // An interesting challenge is ensuring that when classes merge with namespaces and interfaces, is keeping // each symbol in only one of the representations // Also, synthesizing a default export of some kind // If it's an alias: emit `export default ref` // If it's a property: emit `export default _default` with a `_default` prop // If it's a class/interface/function: emit a class/interface/function with a `default` modifier // These forms can merge, eg (`export default 12; export default interface A {}`) function serializeSymbolWorker(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean): void { const symbolName = unescapeLeadingUnderscores(symbol.escapedName); const isDefault = symbol.escapedName === InternalSymbolName.Default; if (isPrivate && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier) && isStringANonContextualKeyword(symbolName) && !isDefault) { // Oh no. We cannot use this symbol's name as it's name... It's likely some jsdoc had an invalid name like `export` or `default` :( context.encounteredError = true; // TODO: Issue error via symbol tracker? return; // If we need to emit a private with a keyword name, we're done for, since something else will try to refer to it by that name } let needsPostExportDefault = isDefault && !!( symbol.flags & SymbolFlags.ExportDoesNotSupportDefaultModifier || (symbol.flags & SymbolFlags.Function && length(getPropertiesOfType(getTypeOfSymbol(symbol)))) ) && !(symbol.flags & SymbolFlags.Alias); // An alias symbol should preclude needing to make an alias ourselves let needsExportDeclaration = !needsPostExportDefault && !isPrivate && isStringANonContextualKeyword(symbolName) && !isDefault; // `serializeVariableOrProperty` will handle adding the export declaration if it is run (since `getInternalSymbolName` will create the name mapping), so we need to ensuer we unset `needsExportDeclaration` if it is if (needsPostExportDefault || needsExportDeclaration) { isPrivate = true; } const modifierFlags = (!isPrivate ? ModifierFlags.Export : 0) | (isDefault && !needsPostExportDefault ? ModifierFlags.Default : 0); const isConstMergedWithNS = symbol.flags & SymbolFlags.Module && symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property) && symbol.escapedName !== InternalSymbolName.ExportEquals; const isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol); if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method) || isConstMergedWithNSPrintableAsSignatureMerge) { serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); } if (symbol.flags & SymbolFlags.TypeAlias) { serializeTypeAlias(symbol, symbolName, modifierFlags); } // Need to skip over export= symbols below - json source files get a single `Property` flagged // symbol of name `export=` which needs to be handled like an alias. It's not great, but it is what it is. if (symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property) && symbol.escapedName !== InternalSymbolName.ExportEquals && !(symbol.flags & SymbolFlags.Prototype) && !(symbol.flags & SymbolFlags.Class) && !(symbol.flags & SymbolFlags.Method) && !isConstMergedWithNSPrintableAsSignatureMerge) { if (propertyAsAlias) { const createdExport = serializeMaybeAliasAssignment(symbol); if (createdExport) { needsExportDeclaration = false; needsPostExportDefault = false; } } else { const type = getTypeOfSymbol(symbol); const localName = getInternalSymbolName(symbol, symbolName); if (!(symbol.flags & SymbolFlags.Function) && isTypeRepresentableAsFunctionNamespaceMerge(type, symbol)) { // If the type looks like a function declaration + ns could represent it, and it's type is sourced locally, rewrite it into a function declaration + ns serializeAsFunctionNamespaceMerge(type, symbol, localName, modifierFlags); } else { // A Class + Property merge is made for a `module.exports.Member = class {}`, and it doesn't serialize well as either a class _or_ a property symbol - in fact, _it behaves like an alias!_ // `var` is `FunctionScopedVariable`, `const` and `let` are `BlockScopedVariable`, and `module.exports.thing =` is `Property` const flags = !(symbol.flags & SymbolFlags.BlockScopedVariable) ? symbol.parent?.valueDeclaration && isSourceFile(symbol.parent?.valueDeclaration) ? NodeFlags.Const // exports are immutable in es6, which is what we emulate and check; so it's safe to mark all exports as `const` (there's no difference to consumers, but it allows unique symbol type declarations) : undefined : isConstVariable(symbol) ? NodeFlags.Const : NodeFlags.Let; const name = (needsPostExportDefault || !(symbol.flags & SymbolFlags.Property)) ? localName : getUnusedName(localName, symbol); let textRange: Node | undefined = symbol.declarations && find(symbol.declarations, d => isVariableDeclaration(d)); if (textRange && isVariableDeclarationList(textRange.parent) && textRange.parent.declarations.length === 1) { textRange = textRange.parent.parent; } const propertyAccessRequire = symbol.declarations?.find(isPropertyAccessExpression); if (propertyAccessRequire && isBinaryExpression(propertyAccessRequire.parent) && isIdentifier(propertyAccessRequire.parent.right) && type.symbol?.valueDeclaration && isSourceFile(type.symbol.valueDeclaration)) { const alias = localName === propertyAccessRequire.parent.right.escapedText ? undefined : propertyAccessRequire.parent.right; addResult( factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, alias, localName)]) ), ModifierFlags.None ); context.tracker.trackSymbol(type.symbol, context.enclosingDeclaration, SymbolFlags.Value); } else { const statement = setTextRange(factory.createVariableStatement(/*modifiers*/ undefined, factory.createVariableDeclarationList([ factory.createVariableDeclaration(name, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, type, symbol, enclosingDeclaration, includePrivateSymbol, bundled)) ], flags)), textRange); addResult(statement, name !== localName ? modifierFlags & ~ModifierFlags.Export : modifierFlags); if (name !== localName && !isPrivate) { // We rename the variable declaration we generate for Property symbols since they may have a name which // conflicts with a local declaration. For example, given input: // ``` // function g() {} // module.exports.g = g // ``` // In such a situation, we have a local variable named `g`, and a separate exported variable named `g`. // Naively, we would emit // ``` // function g() {} // export const g: typeof g; // ``` // That's obviously incorrect - the `g` in the type annotation needs to refer to the local `g`, but // the export declaration shadows it. // To work around that, we instead write // ``` // function g() {} // const g_1: typeof g; // export { g_1 as g }; // ``` // To create an export named `g` that does _not_ shadow the local `g` addResult( factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, name, localName)]) ), ModifierFlags.None ); needsExportDeclaration = false; needsPostExportDefault = false; } } } } } if (symbol.flags & SymbolFlags.Enum) { serializeEnum(symbol, symbolName, modifierFlags); } if (symbol.flags & SymbolFlags.Class) { if (symbol.flags & SymbolFlags.Property && symbol.valueDeclaration && isBinaryExpression(symbol.valueDeclaration.parent) && isClassExpression(symbol.valueDeclaration.parent.right)) { // Looks like a `module.exports.Sub = class {}` - if we serialize `symbol` as a class, the result will have no members, // since the classiness is actually from the target of the effective alias the symbol is. yes. A BlockScopedVariable|Class|Property // _really_ acts like an Alias, and none of a BlockScopedVariable, Class, or Property. This is the travesty of JS binding today. serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); } else { serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); } } if ((symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) { serializeModule(symbol, symbolName, modifierFlags); } // The class meaning serialization should handle serializing all interface members if (symbol.flags & SymbolFlags.Interface && !(symbol.flags & SymbolFlags.Class)) { serializeInterface(symbol, symbolName, modifierFlags); } if (symbol.flags & SymbolFlags.Alias) { serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); } if (symbol.flags & SymbolFlags.Property && symbol.escapedName === InternalSymbolName.ExportEquals) { serializeMaybeAliasAssignment(symbol); } if (symbol.flags & SymbolFlags.ExportStar) { // synthesize export * from "moduleReference" // Straightforward - only one thing to do - make an export declaration if (symbol.declarations) { for (const node of symbol.declarations) { const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); if (!resolvedModule) continue; addResult(factory.createExportDeclaration(/*modifiers*/ undefined, /*isTypeOnly*/ (node as ExportDeclaration).isTypeOnly, /*exportClause*/ undefined, factory.createStringLiteral(getSpecifierForModuleSymbol(resolvedModule, context))), ModifierFlags.None); } } } if (needsPostExportDefault) { addResult(factory.createExportAssignment(/*modifiers*/ undefined, /*isExportAssignment*/ false, factory.createIdentifier(getInternalSymbolName(symbol, symbolName))), ModifierFlags.None); } else if (needsExportDeclaration) { addResult(factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, getInternalSymbolName(symbol, symbolName), symbolName)]) ), ModifierFlags.None); } } function includePrivateSymbol(symbol: Symbol) { if (some(symbol.declarations, isParameterDeclaration)) return; Debug.assertIsDefined(deferredPrivatesStack[deferredPrivatesStack.length - 1]); getUnusedName(unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol // Blanket moving (import) aliases into the root private context should work, since imports are not valid within namespaces // (so they must have been in the root to begin with if they were real imports) cjs `require` aliases (an upcoming feature) // will throw a wrench in this, since those may have been nested, but we'll need to synthesize them in the outer scope // anyway, as that's the only place the import they translate to is valid. In such a case, we might need to use a unique name // for the moved import; which hopefully the above `getUnusedName` call should produce. const isExternalImportAlias = !!(symbol.flags & SymbolFlags.Alias) && !some(symbol.declarations, d => !!findAncestor(d, isExportDeclaration) || isNamespaceExport(d) || (isImportEqualsDeclaration(d) && !isExternalModuleReference(d.moduleReference)) ); deferredPrivatesStack[isExternalImportAlias ? 0 : (deferredPrivatesStack.length - 1)].set(getSymbolId(symbol), symbol); } function isExportingScope(enclosingDeclaration: Node) { return ((isSourceFile(enclosingDeclaration) && (isExternalOrCommonJsModule(enclosingDeclaration) || isJsonSourceFile(enclosingDeclaration))) || (isAmbientModule(enclosingDeclaration) && !isGlobalScopeAugmentation(enclosingDeclaration))); } // Prepends a `declare` and/or `export` modifier if the context requires it, and then adds `node` to `result` and returns `node` function addResult(node: Statement, additionalModifierFlags: ModifierFlags) { if (canHaveModifiers(node)) { let newModifierFlags: ModifierFlags = ModifierFlags.None; const enclosingDeclaration = context.enclosingDeclaration && (isJSDocTypeAlias(context.enclosingDeclaration) ? getSourceFileOfNode(context.enclosingDeclaration) : context.enclosingDeclaration); if (additionalModifierFlags & ModifierFlags.Export && enclosingDeclaration && (isExportingScope(enclosingDeclaration) || isModuleDeclaration(enclosingDeclaration)) && canHaveExportModifier(node) ) { // Classes, namespaces, variables, functions, interfaces, and types should all be `export`ed in a module context if not private newModifierFlags |= ModifierFlags.Export; } if (addingDeclare && !(newModifierFlags & ModifierFlags.Export) && (!enclosingDeclaration || !(enclosingDeclaration.flags & NodeFlags.Ambient)) && (isEnumDeclaration(node) || isVariableStatement(node) || isFunctionDeclaration(node) || isClassDeclaration(node) || isModuleDeclaration(node))) { // Classes, namespaces, variables, enums, and functions all need `declare` modifiers to be valid in a declaration file top-level scope newModifierFlags |= ModifierFlags.Ambient; } if ((additionalModifierFlags & ModifierFlags.Default) && (isClassDeclaration(node) || isInterfaceDeclaration(node) || isFunctionDeclaration(node))) { newModifierFlags |= ModifierFlags.Default; } if (newModifierFlags) { node = factory.updateModifiers(node, newModifierFlags | getEffectiveModifierFlags(node)); } } results.push(node); } function serializeTypeAlias(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { const aliasType = getDeclaredTypeOfTypeAlias(symbol); const typeParams = getSymbolLinks(symbol).typeParameters; const typeParamDecls = map(typeParams, p => typeParameterToDeclaration(p, context)); const jsdocAliasDecl = symbol.declarations?.find(isJSDocTypeAlias); const commentText = getTextOfJSDocComment(jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined); const oldFlags = context.flags; context.flags |= NodeBuilderFlags.InTypeAlias; const oldEnclosingDecl = context.enclosingDeclaration; context.enclosingDeclaration = jsdocAliasDecl; const typeNode = jsdocAliasDecl && jsdocAliasDecl.typeExpression && isJSDocTypeExpression(jsdocAliasDecl.typeExpression) && serializeExistingTypeNode(context, jsdocAliasDecl.typeExpression.type, includePrivateSymbol, bundled) || typeToTypeNodeHelper(aliasType, context); addResult(setSyntheticLeadingComments( factory.createTypeAliasDeclaration(/*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, typeNode), !commentText ? [] : [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }] ), modifierFlags); context.flags = oldFlags; context.enclosingDeclaration = oldEnclosingDecl; } function serializeInterface(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { const interfaceType = getDeclaredTypeOfClassOrInterface(symbol); const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); const baseTypes = getBaseTypes(interfaceType); const baseType = length(baseTypes) ? getIntersectionType(baseTypes) : undefined; const members = flatMap(getPropertiesOfType(interfaceType), p => serializePropertySymbolForInterface(p, baseType)); const callSignatures = serializeSignatures(SignatureKind.Call, interfaceType, baseType, SyntaxKind.CallSignature) as CallSignatureDeclaration[]; const constructSignatures = serializeSignatures(SignatureKind.Construct, interfaceType, baseType, SyntaxKind.ConstructSignature) as ConstructSignatureDeclaration[]; const indexSignatures = serializeIndexSignatures(interfaceType, baseType); const heritageClauses = !length(baseTypes) ? undefined : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, mapDefined(baseTypes, b => trySerializeAsTypeReference(b, SymbolFlags.Value)))]; addResult(factory.createInterfaceDeclaration( /*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, heritageClauses, [...indexSignatures, ...constructSignatures, ...callSignatures, ...members] ), modifierFlags); } function getNamespaceMembersForSerialization(symbol: Symbol) { return !symbol.exports ? [] : filter(arrayFrom(symbol.exports.values()), isNamespaceMember); } function isTypeOnlyNamespace(symbol: Symbol) { return every(getNamespaceMembersForSerialization(symbol), m => !(getAllSymbolFlags(resolveSymbol(m)) & SymbolFlags.Value)); } function serializeModule(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { const members = getNamespaceMembersForSerialization(symbol); // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging) const locationMap = arrayToMultiMap(members, m => m.parent && m.parent === symbol ? "real" : "merged"); const realMembers = locationMap.get("real") || emptyArray; const mergedMembers = locationMap.get("merged") || emptyArray; // TODO: `suppressNewPrivateContext` is questionable -we need to simply be emitting privates in whatever scope they were declared in, rather // than whatever scope we traverse to them in. That's a bit of a complex rewrite, since we're not _actually_ tracking privates at all in advance, // so we don't even have placeholders to fill in. if (length(realMembers)) { const localName = getInternalSymbolName(symbol, symbolName); serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (SymbolFlags.Function | SymbolFlags.Assignment))); } if (length(mergedMembers)) { const containingFile = getSourceFileOfNode(context.enclosingDeclaration); const localName = getInternalSymbolName(symbol, symbolName); const nsBody = factory.createModuleBlock([factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports(mapDefined(filter(mergedMembers, n => n.escapedName !== InternalSymbolName.ExportEquals), s => { const name = unescapeLeadingUnderscores(s.escapedName); const localName = getInternalSymbolName(s, name); const aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s); if (containingFile && (aliasDecl ? containingFile !== getSourceFileOfNode(aliasDecl) : !some(s.declarations, d => getSourceFileOfNode(d) === containingFile))) { context.tracker?.reportNonlocalAugmentation?.(containingFile, symbol, s); return undefined; } const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); includePrivateSymbol(target || s); const targetName = target ? getInternalSymbolName(target, unescapeLeadingUnderscores(target.escapedName)) : localName; return factory.createExportSpecifier(/*isTypeOnly*/ false, name === targetName ? undefined : targetName, name); })) )]); addResult(factory.createModuleDeclaration( /*modifiers*/ undefined, factory.createIdentifier(localName), nsBody, NodeFlags.Namespace ), ModifierFlags.None); } } function serializeEnum(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { addResult(factory.createEnumDeclaration( factory.createModifiersFromModifierFlags(isConstEnumSymbol(symbol) ? ModifierFlags.Const : 0), getInternalSymbolName(symbol, symbolName), map(filter(getPropertiesOfType(getTypeOfSymbol(symbol)), p => !!(p.flags & SymbolFlags.EnumMember)), p => { // TODO: Handle computed names // I hate that to get the initialized value we need to walk back to the declarations here; but there's no // other way to get the possible const value of an enum member that I'm aware of, as the value is cached // _on the declaration_, not on the declaration's symbol... const initializedValue = p.declarations && p.declarations[0] && isEnumMember(p.declarations[0]) ? getConstantValue(p.declarations[0]) : undefined; return factory.createEnumMember(unescapeLeadingUnderscores(p.escapedName), initializedValue === undefined ? undefined : typeof initializedValue === "string" ? factory.createStringLiteral(initializedValue) : factory.createNumericLiteral(initializedValue)); }) ), modifierFlags); } function serializeAsFunctionNamespaceMerge(type: Type, symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { const signatures = getSignaturesOfType(type, SignatureKind.Call); for (const sig of signatures) { // Each overload becomes a separate function declaration, in order const decl = signatureToSignatureDeclarationHelper(sig, SyntaxKind.FunctionDeclaration, context, { name: factory.createIdentifier(localName), privateSymbolVisitor: includePrivateSymbol, bundledImports: bundled }) as FunctionDeclaration; addResult(setTextRange(decl, getSignatureTextRangeLocation(sig)), modifierFlags); } // Module symbol emit will take care of module-y members, provided it has exports if (!(symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && !!symbol.exports && !!symbol.exports.size)) { const props = filter(getPropertiesOfType(type), isNamespaceMember); serializeAsNamespaceDeclaration(props, localName, modifierFlags, /*suppressNewPrivateContext*/ true); } } function getSignatureTextRangeLocation(signature: Signature) { if (signature.declaration && signature.declaration.parent) { if (isBinaryExpression(signature.declaration.parent) && getAssignmentDeclarationKind(signature.declaration.parent) === AssignmentDeclarationKind.Property) { return signature.declaration.parent; } // for expressions assigned to `var`s, use the `var` as the text range if (isVariableDeclaration(signature.declaration.parent) && signature.declaration.parent.parent) { return signature.declaration.parent.parent; } } return signature.declaration; } function serializeAsNamespaceDeclaration(props: readonly Symbol[], localName: string, modifierFlags: ModifierFlags, suppressNewPrivateContext: boolean) { if (length(props)) { const localVsRemoteMap = arrayToMultiMap(props, p => !length(p.declarations) || some(p.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!) ) ? "local" : "remote" ); const localProps = localVsRemoteMap.get("local") || emptyArray; // handle remote props first - we need to make an `import` declaration that points at the module containing each remote // prop in the outermost scope (TODO: a namespace within a namespace would need to be appropriately handled by this) // Example: // import Foo_1 = require("./exporter"); // export namespace ns { // import Foo = Foo_1.Foo; // export { Foo }; // export const c: number; // } // This is needed because in JS, statements like `const x = require("./f")` support both type and value lookup, even if they're // normally just value lookup (so it functions kinda like an alias even when it's not an alias) // _Usually_, we'll simply print the top-level as an alias instead of a `var` in such situations, however is is theoretically // possible to encounter a situation where a type has members from both the current file and other files - in those situations, // emit akin to the above would be needed. // Add a namespace // Create namespace as non-synthetic so it is usable as an enclosing declaration let fakespace = parseNodeFactory.createModuleDeclaration(/*modifiers*/ undefined, factory.createIdentifier(localName), factory.createModuleBlock([]), NodeFlags.Namespace); setParent(fakespace, enclosingDeclaration as SourceFile | NamespaceDeclaration); fakespace.locals = createSymbolTable(props); fakespace.symbol = props[0].parent!; const oldResults = results; results = []; const oldAddingDeclare = addingDeclare; addingDeclare = false; const subcontext = { ...context, enclosingDeclaration: fakespace }; const oldContext = context; context = subcontext; // TODO: implement handling for the localVsRemoteMap.get("remote") - should be difficult to trigger (see comment above), as only interesting cross-file js merges should make this possible visitSymbolTable(createSymbolTable(localProps), suppressNewPrivateContext, /*propertyAsAlias*/ true); context = oldContext; addingDeclare = oldAddingDeclare; const declarations = results; results = oldResults; // replace namespace with synthetic version const defaultReplaced = map(declarations, d => isExportAssignment(d) && !d.isExportEquals && isIdentifier(d.expression) ? factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, d.expression, factory.createIdentifier(InternalSymbolName.Default))]) ) : d); const exportModifierStripped = every(defaultReplaced, d => hasSyntacticModifier(d, ModifierFlags.Export)) ? map(defaultReplaced as Extract[], removeExportModifier) : defaultReplaced; fakespace = factory.updateModuleDeclaration( fakespace, fakespace.modifiers, fakespace.name, factory.createModuleBlock(exportModifierStripped)); addResult(fakespace, modifierFlags); // namespaces can never be default exported } } function isNamespaceMember(p: Symbol) { return !!(p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias)) || !(p.flags & SymbolFlags.Prototype || p.escapedName === "prototype" || p.valueDeclaration && isStatic(p.valueDeclaration) && isClassLike(p.valueDeclaration.parent)); } function sanitizeJSDocImplements(clauses: readonly ExpressionWithTypeArguments[]): ExpressionWithTypeArguments[] | undefined { const result = mapDefined(clauses, e => { const oldEnclosing = context.enclosingDeclaration; context.enclosingDeclaration = e; let expr = e.expression; if (isEntityNameExpression(expr)) { if (isIdentifier(expr) && idText(expr) === "") { return cleanup(/*result*/ undefined); // Empty heritage clause, should be an error, but prefer emitting no heritage clauses to reemitting the empty one } let introducesError: boolean; ({ introducesError, node: expr } = trackExistingEntityName(expr, context, includePrivateSymbol)); if (introducesError) { return cleanup(/*result*/ undefined); } } return cleanup(factory.createExpressionWithTypeArguments(expr, map(e.typeArguments, a => serializeExistingTypeNode(context, a, includePrivateSymbol, bundled) || typeToTypeNodeHelper(getTypeFromTypeNode(a), context) ) )); function cleanup(result: T): T { context.enclosingDeclaration = oldEnclosing; return result; } }); if (result.length === clauses.length) { return result; } return undefined; } function serializeAsClass(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { const originalDecl = symbol.declarations?.find(isClassLike); const oldEnclosing = context.enclosingDeclaration; context.enclosingDeclaration = originalDecl || oldEnclosing; const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); const classType = getDeclaredTypeOfClassOrInterface(symbol); const baseTypes = getBaseTypes(classType); const originalImplements = originalDecl && getEffectiveImplementsTypeNodes(originalDecl); const implementsExpressions = originalImplements && sanitizeJSDocImplements(originalImplements) || mapDefined(getImplementsTypes(classType), serializeImplementedType); const staticType = getTypeOfSymbol(symbol); const isClass = !!staticType.symbol?.valueDeclaration && isClassLike(staticType.symbol.valueDeclaration); const staticBaseType = isClass ? getBaseConstructorTypeOfClass(staticType as InterfaceType) : anyType; const heritageClauses = [ ...!length(baseTypes) ? [] : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, map(baseTypes, b => serializeBaseType(b, staticBaseType, localName)))], ...!length(implementsExpressions) ? [] : [factory.createHeritageClause(SyntaxKind.ImplementsKeyword, implementsExpressions)] ]; const symbolProps = getNonInheritedProperties(classType, baseTypes, getPropertiesOfType(classType)); const publicSymbolProps = filter(symbolProps, s => { // `valueDeclaration` could be undefined if inherited from // a union/intersection base type, but inherited properties // don't matter here. const valueDecl = s.valueDeclaration; return !!valueDecl && !(isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name)); }); const hasPrivateIdentifier = some(symbolProps, s => { // `valueDeclaration` could be undefined if inherited from // a union/intersection base type, but inherited properties // don't matter here. const valueDecl = s.valueDeclaration; return !!valueDecl && isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name); }); // Boil down all private properties into a single one. const privateProperties = hasPrivateIdentifier ? [factory.createPropertyDeclaration( /*modifiers*/ undefined, factory.createPrivateIdentifier("#private"), /*questionOrExclamationToken*/ undefined, /*type*/ undefined, /*initializer*/ undefined, )] : emptyArray; const publicProperties = flatMap(publicSymbolProps, p => serializePropertySymbolForClass(p, /*isStatic*/ false, baseTypes[0])); // Consider static members empty if symbol also has function or module meaning - function namespacey emit will handle statics const staticMembers = flatMap( filter(getPropertiesOfType(staticType), p => !(p.flags & SymbolFlags.Prototype) && p.escapedName !== "prototype" && !isNamespaceMember(p)), p => serializePropertySymbolForClass(p, /*isStatic*/ true, staticBaseType)); // When we encounter an `X.prototype.y` assignment in a JS file, we bind `X` as a class regardless as to whether // the value is ever initialized with a class or function-like value. For cases where `X` could never be // created via `new`, we will inject a `private constructor()` declaration to indicate it is not createable. const isNonConstructableClassLikeInJsFile = !isClass && !!symbol.valueDeclaration && isInJSFile(symbol.valueDeclaration) && !some(getSignaturesOfType(staticType, SignatureKind.Construct)); const constructors = isNonConstructableClassLikeInJsFile ? [factory.createConstructorDeclaration(factory.createModifiersFromModifierFlags(ModifierFlags.Private), [], /*body*/ undefined)] : serializeSignatures(SignatureKind.Construct, staticType, staticBaseType, SyntaxKind.Constructor) as ConstructorDeclaration[]; const indexSignatures = serializeIndexSignatures(classType, baseTypes[0]); context.enclosingDeclaration = oldEnclosing; addResult(setTextRange(factory.createClassDeclaration( /*modifiers*/ undefined, localName, typeParamDecls, heritageClauses, [...indexSignatures, ...staticMembers, ...constructors, ...publicProperties, ...privateProperties] ), symbol.declarations && filter(symbol.declarations, d => isClassDeclaration(d) || isClassExpression(d))[0]), modifierFlags); } function getSomeTargetNameFromDeclarations(declarations: Declaration[] | undefined) { return firstDefined(declarations, d => { if (isImportSpecifier(d) || isExportSpecifier(d)) { return idText(d.propertyName || d.name); } if (isBinaryExpression(d) || isExportAssignment(d)) { const expression = isExportAssignment(d) ? d.expression : d.right; if (isPropertyAccessExpression(expression)) { return idText(expression.name); } } if (isAliasSymbolDeclaration(d)) { // This is... heuristic, at best. But it's probably better than always printing the name of the shorthand ambient module. const name = getNameOfDeclaration(d); if (name && isIdentifier(name)) { return idText(name); } } return undefined; }); } function serializeAsAlias(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { // synthesize an alias, eg `export { symbolName as Name }` // need to mark the alias `symbol` points at // as something we need to serialize as a private declaration as well const node = getDeclarationOfAliasSymbol(symbol); if (!node) return Debug.fail(); const target = getMergedSymbol(getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true)); if (!target) { return; } // If `target` refers to a shorthand module symbol, the name we're trying to pull out isn;t recoverable from the target symbol // In such a scenario, we must fall back to looking for an alias declaration on `symbol` and pulling the target name from that let verbatimTargetName = isShorthandAmbientModuleSymbol(target) && getSomeTargetNameFromDeclarations(symbol.declarations) || unescapeLeadingUnderscores(target.escapedName); if (verbatimTargetName === InternalSymbolName.ExportEquals && allowSyntheticDefaultImports) { // target refers to an `export=` symbol that was hoisted into a synthetic default - rename here to match verbatimTargetName = InternalSymbolName.Default; } const targetName = getInternalSymbolName(target, verbatimTargetName); includePrivateSymbol(target); // the target may be within the same scope - attempt to serialize it first switch (node.kind) { case SyntaxKind.BindingElement: if (node.parent?.parent?.kind === SyntaxKind.VariableDeclaration) { // const { SomeClass } = require('./lib'); const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // './lib' const { propertyName } = node as BindingElement; addResult(factory.createImportDeclaration( /*modifiers*/ undefined, factory.createImportClause(/*isTypeOnly*/ false, /*name*/ undefined, factory.createNamedImports([factory.createImportSpecifier( /*isTypeOnly*/ false, propertyName && isIdentifier(propertyName) ? factory.createIdentifier(idText(propertyName)) : undefined, factory.createIdentifier(localName) )])), factory.createStringLiteral(specifier), /*importClause*/ undefined ), ModifierFlags.None); break; } // We don't know how to serialize this (nested?) binding element Debug.failBadSyntaxKind(node.parent?.parent || node, "Unhandled binding element grandparent kind in declaration serialization"); break; case SyntaxKind.ShorthandPropertyAssignment: if (node.parent?.parent?.kind === SyntaxKind.BinaryExpression) { // module.exports = { SomeClass } serializeExportSpecifier( unescapeLeadingUnderscores(symbol.escapedName), targetName ); } break; case SyntaxKind.VariableDeclaration: // commonjs require: const x = require('y') if (isPropertyAccessExpression((node as VariableDeclaration).initializer!)) { // const x = require('y').z const initializer = (node as VariableDeclaration).initializer! as PropertyAccessExpression; // require('y').z const uniqueName = factory.createUniqueName(localName); // _x const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // 'y' // import _x = require('y'); addResult(factory.createImportEqualsDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, uniqueName, factory.createExternalModuleReference(factory.createStringLiteral(specifier)) ), ModifierFlags.None); // import x = _x.z addResult(factory.createImportEqualsDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createIdentifier(localName), factory.createQualifiedName(uniqueName, initializer.name as Identifier), ), modifierFlags); break; } // else fall through and treat commonjs require just like import= case SyntaxKind.ImportEqualsDeclaration: // This _specifically_ only exists to handle json declarations - where we make aliases, but since // we emit no declarations for the json document, must not refer to it in the declarations if (target.escapedName === InternalSymbolName.ExportEquals && some(target.declarations, d => isSourceFile(d) && isJsonSourceFile(d))) { serializeMaybeAliasAssignment(symbol); break; } // Could be a local `import localName = ns.member` or // an external `import localName = require("whatever")` const isLocalImport = !(target.flags & SymbolFlags.ValueModule) && !isVariableDeclaration(node); addResult(factory.createImportEqualsDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createIdentifier(localName), isLocalImport ? symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false) : factory.createExternalModuleReference(factory.createStringLiteral(getSpecifierForModuleSymbol(target, context))) ), isLocalImport ? modifierFlags : ModifierFlags.None); break; case SyntaxKind.NamespaceExportDeclaration: // export as namespace foo // TODO: Not part of a file's local or export symbol tables // Is bound into file.symbol.globalExports instead, which we don't currently traverse addResult(factory.createNamespaceExportDeclaration(idText((node as NamespaceExportDeclaration).name)), ModifierFlags.None); break; case SyntaxKind.ImportClause: { const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects const specifier = bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportClause).parent.moduleSpecifier; addResult(factory.createImportDeclaration( /*modifiers*/ undefined, factory.createImportClause(/*isTypeOnly*/ false, factory.createIdentifier(localName), /*namedBindings*/ undefined), specifier, (node as ImportClause).parent.assertClause ), ModifierFlags.None); break; } case SyntaxKind.NamespaceImport: { const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects const specifier = bundled ? factory.createStringLiteral(generatedSpecifier) : (node as NamespaceImport).parent.parent.moduleSpecifier; addResult(factory.createImportDeclaration( /*modifiers*/ undefined, factory.createImportClause(/*isTypeOnly*/ false, /*importClause*/ undefined, factory.createNamespaceImport(factory.createIdentifier(localName))), specifier, (node as NamespaceImport).parent.parent.assertClause ), ModifierFlags.None); break; } case SyntaxKind.NamespaceExport: addResult(factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamespaceExport(factory.createIdentifier(localName)), factory.createStringLiteral(getSpecifierForModuleSymbol(target, context)) ), ModifierFlags.None); break; case SyntaxKind.ImportSpecifier: { const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects const specifier = bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportSpecifier).parent.parent.parent.moduleSpecifier; addResult(factory.createImportDeclaration( /*modifiers*/ undefined, factory.createImportClause( /*isTypeOnly*/ false, /*importClause*/ undefined, factory.createNamedImports([ factory.createImportSpecifier( /*isTypeOnly*/ false, localName !== verbatimTargetName ? factory.createIdentifier(verbatimTargetName) : undefined, factory.createIdentifier(localName) ) ])), specifier, (node as ImportSpecifier).parent.parent.parent.assertClause, ), ModifierFlags.None); break; } case SyntaxKind.ExportSpecifier: // does not use localName because the symbol name in this case refers to the name in the exports table, // which we must exactly preserve const specifier = (node.parent.parent as ExportDeclaration).moduleSpecifier; // targetName is only used when the target is local, as otherwise the target is an alias that points at // another file serializeExportSpecifier( unescapeLeadingUnderscores(symbol.escapedName), specifier ? verbatimTargetName : targetName, specifier && isStringLiteralLike(specifier) ? factory.createStringLiteral(specifier.text) : undefined ); break; case SyntaxKind.ExportAssignment: serializeMaybeAliasAssignment(symbol); break; case SyntaxKind.BinaryExpression: case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: // Could be best encoded as though an export specifier or as though an export assignment // If name is default or export=, do an export assignment // Otherwise do an export specifier if (symbol.escapedName === InternalSymbolName.Default || symbol.escapedName === InternalSymbolName.ExportEquals) { serializeMaybeAliasAssignment(symbol); } else { serializeExportSpecifier(localName, targetName); } break; default: return Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!"); } } function serializeExportSpecifier(localName: string, targetName: string, specifier?: Expression) { addResult(factory.createExportDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, localName !== targetName ? targetName : undefined, localName)]), specifier ), ModifierFlags.None); } /** * Returns `true` if an export assignment or declaration was produced for the symbol */ function serializeMaybeAliasAssignment(symbol: Symbol): boolean { if (symbol.flags & SymbolFlags.Prototype) { return false; } const name = unescapeLeadingUnderscores(symbol.escapedName); const isExportEquals = name === InternalSymbolName.ExportEquals; const isDefault = name === InternalSymbolName.Default; const isExportAssignmentCompatibleSymbolName = isExportEquals || isDefault; // synthesize export = ref // ref should refer to either be a locally scoped symbol which we need to emit, or // a reference to another namespace/module which we may need to emit an `import` statement for const aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol); // serialize what the alias points to, preserve the declaration's initializer const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const if (target && length(target.declarations) && some(target.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(enclosingDeclaration))) { // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it // eg, `namespace A { export class B {} }; exports = A.B;` // Technically, this is all that's required in the case where the assignment is an entity name expression const expr = aliasDecl && ((isExportAssignment(aliasDecl) || isBinaryExpression(aliasDecl)) ? getExportAssignmentExpression(aliasDecl) : getPropertyAssignmentAliasLikeExpression(aliasDecl as ShorthandPropertyAssignment | PropertyAssignment | PropertyAccessExpression)); const first = expr && isEntityNameExpression(expr) ? getFirstNonModuleExportsIdentifier(expr) : undefined; const referenced = first && resolveEntityName(first, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, enclosingDeclaration); if (referenced || target) { includePrivateSymbol(referenced || target); } // We disable the context's symbol tracker for the duration of this name serialization // as, by virtue of being here, the name is required to print something, and we don't want to // issue a visibility error on it. Only anonymous classes that an alias points at _would_ issue // a visibility error here (as they're not visible within any scope), but we want to hoist them // into the containing scope anyway, so we want to skip the visibility checks. const prevDisableTrackSymbol = context.tracker.disableTrackSymbol; context.tracker.disableTrackSymbol = true; if (isExportAssignmentCompatibleSymbolName) { results.push(factory.createExportAssignment( /*modifiers*/ undefined, isExportEquals, symbolToExpression(target, context, SymbolFlags.All) )); } else { if (first === expr && first) { // serialize as `export {target as name}` serializeExportSpecifier(name, idText(first)); } else if (expr && isClassExpression(expr)) { serializeExportSpecifier(name, getInternalSymbolName(target, symbolName(target))); } else { // serialize as `import _Ref = t.arg.et; export { _Ref as name }` const varName = getUnusedName(name, symbol); addResult(factory.createImportEqualsDeclaration( /*modifiers*/ undefined, /*isTypeOnly*/ false, factory.createIdentifier(varName), symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false) ), ModifierFlags.None); serializeExportSpecifier(name, varName); } } context.tracker.disableTrackSymbol = prevDisableTrackSymbol; return true; } else { // serialize as an anonymous property declaration const varName = getUnusedName(name, symbol); // We have to use `getWidenedType` here since the object within a json file is unwidened within the file // (Unwidened types can only exist in expression contexts and should never be serialized) const typeToSerialize = getWidenedType(getTypeOfSymbol(getMergedSymbol(symbol))); if (isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize, symbol)) { // If there are no index signatures and `typeToSerialize` is an object type, emit as a namespace instead of a const serializeAsFunctionNamespaceMerge(typeToSerialize, symbol, varName, isExportAssignmentCompatibleSymbolName ? ModifierFlags.None : ModifierFlags.Export); } else { const statement = factory.createVariableStatement(/*modifiers*/ undefined, factory.createVariableDeclarationList([ factory.createVariableDeclaration(varName, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, typeToSerialize, symbol, enclosingDeclaration, includePrivateSymbol, bundled)) ], NodeFlags.Const)); // Inlined JSON types exported with [module.]exports= will already emit an export=, so should use `declare`. // Otherwise, the type itself should be exported. addResult(statement, target && target.flags & SymbolFlags.Property && target.escapedName === InternalSymbolName.ExportEquals ? ModifierFlags.Ambient : name === varName ? ModifierFlags.Export : ModifierFlags.None); } if (isExportAssignmentCompatibleSymbolName) { results.push(factory.createExportAssignment( /*modifiers*/ undefined, isExportEquals, factory.createIdentifier(varName) )); return true; } else if (name !== varName) { serializeExportSpecifier(name, varName); return true; } return false; } } function isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize: Type, hostSymbol: Symbol) { // Only object types which are not constructable, or indexable, whose members all come from the // context source file, and whose property names are all valid identifiers and not late-bound, _and_ // whose input is not type annotated (if the input symbol has an annotation we can reuse, we should prefer it) const ctxSrc = getSourceFileOfNode(context.enclosingDeclaration); return getObjectFlags(typeToSerialize) & (ObjectFlags.Anonymous | ObjectFlags.Mapped) && !length(getIndexInfosOfType(typeToSerialize)) && !isClassInstanceSide(typeToSerialize) && // While a class instance is potentially representable as a NS, prefer printing a reference to the instance type and serializing the class !!(length(filter(getPropertiesOfType(typeToSerialize), isNamespaceMember)) || length(getSignaturesOfType(typeToSerialize, SignatureKind.Call))) && !length(getSignaturesOfType(typeToSerialize, SignatureKind.Construct)) && // TODO: could probably serialize as function + ns + class, now that that's OK !getDeclarationWithTypeAnnotation(hostSymbol, enclosingDeclaration) && !(typeToSerialize.symbol && some(typeToSerialize.symbol.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && !some(getPropertiesOfType(typeToSerialize), p => isLateBoundName(p.escapedName)) && !some(getPropertiesOfType(typeToSerialize), p => some(p.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && every(getPropertiesOfType(typeToSerialize), p => isIdentifierText(symbolName(p), languageVersion)); } function makeSerializePropertySymbol(createProperty: ( modifiers: readonly Modifier[] | undefined, name: string | PropertyName, questionOrExclamationToken: QuestionToken | undefined, type: TypeNode | undefined, initializer: Expression | undefined ) => T, methodKind: SignatureDeclaration["kind"], useAccessors: true): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => (T | AccessorDeclaration | (T | AccessorDeclaration)[]); function makeSerializePropertySymbol(createProperty: ( modifiers: readonly Modifier[] | undefined, name: string | PropertyName, questionOrExclamationToken: QuestionToken | undefined, type: TypeNode | undefined, initializer: Expression | undefined ) => T, methodKind: SignatureDeclaration["kind"], useAccessors: false): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => (T | T[]); function makeSerializePropertySymbol(createProperty: ( modifiers: readonly Modifier[] | undefined, name: string | PropertyName, questionOrExclamationToken: QuestionToken | undefined, type: TypeNode | undefined, initializer: Expression | undefined ) => T, methodKind: SignatureDeclaration["kind"], useAccessors: boolean): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => (T | AccessorDeclaration | (T | AccessorDeclaration)[]) { return function serializePropertySymbol(p: Symbol, isStatic: boolean, baseType: Type | undefined): (T | AccessorDeclaration | (T | AccessorDeclaration)[]) { const modifierFlags = getDeclarationModifierFlagsFromSymbol(p); const isPrivate = !!(modifierFlags & ModifierFlags.Private); if (isStatic && (p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias))) { // Only value-only-meaning symbols can be correctly encoded as class statics, type/namespace/alias meaning symbols // need to be merged namespace members return []; } if (p.flags & SymbolFlags.Prototype || (baseType && getPropertyOfType(baseType, p.escapedName) && isReadonlySymbol(getPropertyOfType(baseType, p.escapedName)!) === isReadonlySymbol(p) && (p.flags & SymbolFlags.Optional) === (getPropertyOfType(baseType, p.escapedName)!.flags & SymbolFlags.Optional) && isTypeIdenticalTo(getTypeOfSymbol(p), getTypeOfPropertyOfType(baseType, p.escapedName)!))) { return []; } const flag = (modifierFlags & ~ModifierFlags.Async) | (isStatic ? ModifierFlags.Static : 0); const name = getPropertyNameNodeForSymbol(p, context); const firstPropertyLikeDecl = p.declarations?.find(or(isPropertyDeclaration, isAccessor, isVariableDeclaration, isPropertySignature, isBinaryExpression, isPropertyAccessExpression)); if (p.flags & SymbolFlags.Accessor && useAccessors) { const result: AccessorDeclaration[] = []; if (p.flags & SymbolFlags.SetAccessor) { result.push(setTextRange(factory.createSetAccessorDeclaration( factory.createModifiersFromModifierFlags(flag), name, [factory.createParameterDeclaration( /*modifiers*/ undefined, /*dotDotDotToken*/ undefined, "arg", /*questionToken*/ undefined, isPrivate ? undefined : serializeTypeForDeclaration(context, getTypeOfSymbol(p), p, enclosingDeclaration, includePrivateSymbol, bundled) )], /*body*/ undefined ), p.declarations?.find(isSetAccessor) || firstPropertyLikeDecl)); } if (p.flags & SymbolFlags.GetAccessor) { const isPrivate = modifierFlags & ModifierFlags.Private; result.push(setTextRange(factory.createGetAccessorDeclaration( factory.createModifiersFromModifierFlags(flag), name, [], isPrivate ? undefined : serializeTypeForDeclaration(context, getTypeOfSymbol(p), p, enclosingDeclaration, includePrivateSymbol, bundled), /*body*/ undefined ), p.declarations?.find(isGetAccessor) || firstPropertyLikeDecl)); } return result; } // This is an else/if as accessors and properties can't merge in TS, but might in JS // If this happens, we assume the accessor takes priority, as it imposes more constraints else if (p.flags & (SymbolFlags.Property | SymbolFlags.Variable | SymbolFlags.Accessor)) { return setTextRange(createProperty( factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), name, p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, isPrivate ? undefined : serializeTypeForDeclaration(context, getWriteTypeOfSymbol(p), p, enclosingDeclaration, includePrivateSymbol, bundled), // TODO: https://github.com/microsoft/TypeScript/pull/32372#discussion_r328386357 // interface members can't have initializers, however class members _can_ /*initializer*/ undefined ), p.declarations?.find(or(isPropertyDeclaration, isVariableDeclaration)) || firstPropertyLikeDecl); } if (p.flags & (SymbolFlags.Method | SymbolFlags.Function)) { const type = getTypeOfSymbol(p); const signatures = getSignaturesOfType(type, SignatureKind.Call); if (flag & ModifierFlags.Private) { return setTextRange(createProperty( factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), name, p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, /*type*/ undefined, /*initializer*/ undefined ), p.declarations?.find(isFunctionLikeDeclaration) || signatures[0] && signatures[0].declaration || p.declarations && p.declarations[0]); } const results = []; for (const sig of signatures) { // Each overload becomes a separate method declaration, in order const decl = signatureToSignatureDeclarationHelper( sig, methodKind, context, { name, questionToken: p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, modifiers: flag ? factory.createModifiersFromModifierFlags(flag) : undefined } ); const location = sig.declaration && isPrototypePropertyAssignment(sig.declaration.parent) ? sig.declaration.parent : sig.declaration; results.push(setTextRange(decl, location)); } return results as unknown as T[]; } // The `Constructor`'s symbol isn't in the class's properties lists, obviously, since it's a signature on the static return Debug.fail(`Unhandled class member kind! ${(p as any).__debugFlags || p.flags}`); }; } function serializePropertySymbolForInterface(p: Symbol, baseType: Type | undefined) { return serializePropertySymbolForInterfaceWorker(p, /*isStatic*/ false, baseType); } function serializeSignatures(kind: SignatureKind, input: Type, baseType: Type | undefined, outputKind: SignatureDeclaration["kind"]) { const signatures = getSignaturesOfType(input, kind); if (kind === SignatureKind.Construct) { if (!baseType && every(signatures, s => length(s.parameters) === 0)) { return []; // No base type, every constructor is empty - elide the extraneous `constructor()` } if (baseType) { // If there is a base type, if every signature in the class is identical to a signature in the baseType, elide all the declarations const baseSigs = getSignaturesOfType(baseType, SignatureKind.Construct); if (!length(baseSigs) && every(signatures, s => length(s.parameters) === 0)) { return []; // Base had no explicit signatures, if all our signatures are also implicit, return an empty list } if (baseSigs.length === signatures.length) { let failed = false; for (let i = 0; i < baseSigs.length; i++) { if (!compareSignaturesIdentical(signatures[i], baseSigs[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { failed = true; break; } } if (!failed) { return []; // Every signature was identical - elide constructor list as it is inherited } } } let privateProtected: ModifierFlags = 0; for (const s of signatures) { if (s.declaration) { privateProtected |= getSelectedEffectiveModifierFlags(s.declaration, ModifierFlags.Private | ModifierFlags.Protected); } } if (privateProtected) { return [setTextRange(factory.createConstructorDeclaration( factory.createModifiersFromModifierFlags(privateProtected), /*parameters*/ [], /*body*/ undefined, ), signatures[0].declaration)]; } } const results = []; for (const sig of signatures) { // Each overload becomes a separate constructor declaration, in order const decl = signatureToSignatureDeclarationHelper(sig, outputKind, context); results.push(setTextRange(decl, sig.declaration)); } return results; } function serializeIndexSignatures(input: Type, baseType: Type | undefined) { const results: IndexSignatureDeclaration[] = []; for (const info of getIndexInfosOfType(input)) { if (baseType) { const baseInfo = getIndexInfoOfType(baseType, info.keyType); if (baseInfo) { if (isTypeIdenticalTo(info.type, baseInfo.type)) { continue; // elide identical index signatures } } } results.push(indexInfoToIndexSignatureDeclarationHelper(info, context, /*typeNode*/ undefined)); } return results; } function serializeBaseType(t: Type, staticType: Type, rootName: string) { const ref = trySerializeAsTypeReference(t, SymbolFlags.Value); if (ref) { return ref; } const tempName = getUnusedName(`${rootName}_base`); const statement = factory.createVariableStatement(/*modifiers*/ undefined, factory.createVariableDeclarationList([ factory.createVariableDeclaration(tempName, /*exclamationToken*/ undefined, typeToTypeNodeHelper(staticType, context)) ], NodeFlags.Const)); addResult(statement, ModifierFlags.None); return factory.createExpressionWithTypeArguments(factory.createIdentifier(tempName), /*typeArgs*/ undefined); } function trySerializeAsTypeReference(t: Type, flags: SymbolFlags) { let typeArgs: TypeNode[] | undefined; let reference: Expression | undefined; // We don't use `isValueSymbolAccessible` below. since that considers alternative containers (like modules) // which we can't write out in a syntactically valid way as an expression if ((t as TypeReference).target && isSymbolAccessibleByFlags((t as TypeReference).target.symbol, enclosingDeclaration, flags)) { typeArgs = map(getTypeArguments(t as TypeReference), t => typeToTypeNodeHelper(t, context)); reference = symbolToExpression((t as TypeReference).target.symbol, context, SymbolFlags.Type); } else if (t.symbol && isSymbolAccessibleByFlags(t.symbol, enclosingDeclaration, flags)) { reference = symbolToExpression(t.symbol, context, SymbolFlags.Type); } if (reference) { return factory.createExpressionWithTypeArguments(reference, typeArgs); } } function serializeImplementedType(t: Type) { const ref = trySerializeAsTypeReference(t, SymbolFlags.Type); if (ref) { return ref; } if (t.symbol) { return factory.createExpressionWithTypeArguments(symbolToExpression(t.symbol, context, SymbolFlags.Type), /*typeArgs*/ undefined); } } function getUnusedName(input: string, symbol?: Symbol): string { const id = symbol ? getSymbolId(symbol) : undefined; if (id) { if (context.remappedSymbolNames!.has(id)) { return context.remappedSymbolNames!.get(id)!; } } if (symbol) { input = getNameCandidateWorker(symbol, input); } let i = 0; const original = input; while (context.usedSymbolNames?.has(input)) { i++; input = `${original}_${i}`; } context.usedSymbolNames?.add(input); if (id) { context.remappedSymbolNames!.set(id, input); } return input; } function getNameCandidateWorker(symbol: Symbol, localName: string) { if (localName === InternalSymbolName.Default || localName === InternalSymbolName.Class || localName === InternalSymbolName.Function) { const flags = context.flags; context.flags |= NodeBuilderFlags.InInitialEntityName; const nameCandidate = getNameOfSymbolAsWritten(symbol, context); context.flags = flags; localName = nameCandidate.length > 0 && isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? stripQuotes(nameCandidate) : nameCandidate; } if (localName === InternalSymbolName.Default) { localName = "_default"; } else if (localName === InternalSymbolName.ExportEquals) { localName = "_exports"; } localName = isIdentifierText(localName, languageVersion) && !isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_"); return localName; } function getInternalSymbolName(symbol: Symbol, localName: string) { const id = getSymbolId(symbol); if (context.remappedSymbolNames!.has(id)) { return context.remappedSymbolNames!.get(id)!; } localName = getNameCandidateWorker(symbol, localName); // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up context.remappedSymbolNames!.set(id, localName); return localName; } } } function typePredicateToString(typePredicate: TypePredicate, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer?: EmitTextWriter): string { return writer ? typePredicateToStringWorker(writer).getText() : usingSingleLineStringWriter(typePredicateToStringWorker); function typePredicateToStringWorker(writer: EmitTextWriter) { const predicate = factory.createTypePredicateNode( typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? factory.createToken(SyntaxKind.AssertsKeyword) : undefined, typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? factory.createIdentifier(typePredicate.parameterName) : factory.createThisTypeNode(), typePredicate.type && nodeBuilder.typeToTypeNode(typePredicate.type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName)! // TODO: GH#18217 ); const printer = createPrinterWithRemoveComments(); const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); printer.writeNode(EmitHint.Unspecified, predicate, /*sourceFile*/ sourceFile, writer); return writer; } } function formatUnionTypes(types: readonly Type[]): Type[] { const result: Type[] = []; let flags = 0 as TypeFlags; for (let i = 0; i < types.length; i++) { const t = types[i]; flags |= t.flags; if (!(t.flags & TypeFlags.Nullable)) { if (t.flags & (TypeFlags.BooleanLiteral | TypeFlags.EnumLike)) { const baseType = t.flags & TypeFlags.BooleanLiteral ? booleanType : getBaseTypeOfEnumLikeType(t as LiteralType); if (baseType.flags & TypeFlags.Union) { const count = (baseType as UnionType).types.length; if (i + count <= types.length && getRegularTypeOfLiteralType(types[i + count - 1]) === getRegularTypeOfLiteralType((baseType as UnionType).types[count - 1])) { result.push(baseType); i += count - 1; continue; } } } result.push(t); } } if (flags & TypeFlags.Null) result.push(nullType); if (flags & TypeFlags.Undefined) result.push(undefinedType); return result || types; } function visibilityToString(flags: ModifierFlags): string | undefined { if (flags === ModifierFlags.Private) { return "private"; } if (flags === ModifierFlags.Protected) { return "protected"; } return "public"; } function getTypeAliasForTypeLiteral(type: Type): Symbol | undefined { if (type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && type.symbol.declarations) { const node = walkUpParenthesizedTypes(type.symbol.declarations[0].parent); if (isTypeAliasDeclaration(node)) { return getSymbolOfDeclaration(node); } } return undefined; } function isTopLevelInExternalModuleAugmentation(node: Node): boolean { return node && node.parent && node.parent.kind === SyntaxKind.ModuleBlock && isExternalModuleAugmentation(node.parent.parent); } function isDefaultBindingContext(location: Node) { return location.kind === SyntaxKind.SourceFile || isAmbientModule(location); } function getNameOfSymbolFromNameType(symbol: Symbol, context?: NodeBuilderContext) { const nameType = getSymbolLinks(symbol).nameType; if (nameType) { if (nameType.flags & TypeFlags.StringOrNumberLiteral) { const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && !isNumericLiteralName(name)) { return `"${escapeString(name, CharacterCodes.doubleQuote)}"`; } if (isNumericLiteralName(name) && startsWith(name, "-")) { return `[${name}]`; } return name; } if (nameType.flags & TypeFlags.UniqueESSymbol) { return `[${getNameOfSymbolAsWritten((nameType as UniqueESSymbolType).symbol, context)}]`; } } } /** * Gets a human-readable name for a symbol. * Should *not* be used for the right-hand side of a `.` -- use `symbolName(symbol)` for that instead. * * Unlike `symbolName(symbol)`, this will include quotes if the name is from a string literal. * It will also use a representation of a number as written instead of a decimal form, e.g. `0o11` instead of `9`. */ function getNameOfSymbolAsWritten(symbol: Symbol, context?: NodeBuilderContext): string { if (context && symbol.escapedName === InternalSymbolName.Default && !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope) && // If it's not the first part of an entity name, it must print as `default` (!(context.flags & NodeBuilderFlags.InInitialEntityName) || // if the symbol is synthesized, it will only be referenced externally it must print as `default` !symbol.declarations || // if not in the same binding context (source file, module declaration), it must print as `default` (context.enclosingDeclaration && findAncestor(symbol.declarations[0], isDefaultBindingContext) !== findAncestor(context.enclosingDeclaration, isDefaultBindingContext)))) { return "default"; } if (symbol.declarations && symbol.declarations.length) { let declaration = firstDefined(symbol.declarations, d => getNameOfDeclaration(d) ? d : undefined); // Try using a declaration with a name, first const name = declaration && getNameOfDeclaration(declaration); if (declaration && name) { if (isCallExpression(declaration) && isBindableObjectDefinePropertyCall(declaration)) { return symbolName(symbol); } if (isComputedPropertyName(name) && !(getCheckFlags(symbol) & CheckFlags.Late)) { const nameType = getSymbolLinks(symbol).nameType; if (nameType && nameType.flags & TypeFlags.StringOrNumberLiteral) { // Computed property name isn't late bound, but has a well-known name type - use name type to generate a symbol name const result = getNameOfSymbolFromNameType(symbol, context); if (result !== undefined) { return result; } } } return declarationNameToString(name); } if (!declaration) { declaration = symbol.declarations[0]; // Declaration may be nameless, but we'll try anyway } if (declaration.parent && declaration.parent.kind === SyntaxKind.VariableDeclaration) { return declarationNameToString((declaration.parent as VariableDeclaration).name); } switch (declaration.kind) { case SyntaxKind.ClassExpression: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: if (context && !context.encounteredError && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { context.encounteredError = true; } return declaration.kind === SyntaxKind.ClassExpression ? "(Anonymous class)" : "(Anonymous function)"; } } const name = getNameOfSymbolFromNameType(symbol, context); return name !== undefined ? name : symbolName(symbol); } function isDeclarationVisible(node: Node): boolean { if (node) { const links = getNodeLinks(node); if (links.isVisible === undefined) { links.isVisible = !!determineIfDeclarationIsVisible(); } return links.isVisible; } return false; function determineIfDeclarationIsVisible() { switch (node.kind) { case SyntaxKind.JSDocCallbackTag: case SyntaxKind.JSDocTypedefTag: case SyntaxKind.JSDocEnumTag: // Top-level jsdoc type aliases are considered exported // First parent is comment node, second is hosting declaration or token; we only care about those tokens or declarations whose parent is a source file return !!(node.parent && node.parent.parent && node.parent.parent.parent && isSourceFile(node.parent.parent.parent)); case SyntaxKind.BindingElement: return isDeclarationVisible(node.parent.parent); case SyntaxKind.VariableDeclaration: if (isBindingPattern((node as VariableDeclaration).name) && !((node as VariableDeclaration).name as BindingPattern).elements.length) { // If the binding pattern is empty, this variable declaration is not visible return false; } // falls through case SyntaxKind.ModuleDeclaration: case SyntaxKind.ClassDeclaration: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.TypeAliasDeclaration: case SyntaxKind.FunctionDeclaration: case SyntaxKind.EnumDeclaration: case SyntaxKind.ImportEqualsDeclaration: // external module augmentation is always visible if (isExternalModuleAugmentation(node)) { return true; } const parent = getDeclarationContainer(node); // If the node is not exported or it is not ambient module element (except import declaration) if (!(getCombinedModifierFlags(node as Declaration) & ModifierFlags.Export) && !(node.kind !== SyntaxKind.ImportEqualsDeclaration && parent.kind !== SyntaxKind.SourceFile && parent.flags & NodeFlags.Ambient)) { return isGlobalSourceFile(parent); } // Exported members/ambient module elements (exception import declaration) are visible if parent is visible return isDeclarationVisible(parent); case SyntaxKind.PropertyDeclaration: case SyntaxKind.PropertySignature: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: if (hasEffectiveModifier(node, ModifierFlags.Private | ModifierFlags.Protected)) { // Private/protected properties/methods are not visible return false; } // Public properties/methods are visible if its parents are visible, so: // falls through case SyntaxKind.Constructor: case SyntaxKind.ConstructSignature: case SyntaxKind.CallSignature: case SyntaxKind.IndexSignature: case SyntaxKind.Parameter: case SyntaxKind.ModuleBlock: case SyntaxKind.FunctionType: case SyntaxKind.ConstructorType: case SyntaxKind.TypeLiteral: case SyntaxKind.TypeReference: case SyntaxKind.ArrayType: case SyntaxKind.TupleType: case SyntaxKind.UnionType: case SyntaxKind.IntersectionType: case SyntaxKind.ParenthesizedType: case SyntaxKind.NamedTupleMember: return isDeclarationVisible(node.parent); // Default binding, import specifier and namespace import is visible // only on demand so by default it is not visible case SyntaxKind.ImportClause: case SyntaxKind.NamespaceImport: case SyntaxKind.ImportSpecifier: return false; // Type parameters are always visible case SyntaxKind.TypeParameter: // Source file and namespace export are always visible // falls through case SyntaxKind.SourceFile: case SyntaxKind.NamespaceExportDeclaration: return true; // Export assignments do not create name bindings outside the module case SyntaxKind.ExportAssignment: return false; default: return false; } } } function collectLinkedAliases(node: Identifier, setVisibility?: boolean): Node[] | undefined { let exportSymbol: Symbol | undefined; if (node.parent && node.parent.kind === SyntaxKind.ExportAssignment) { exportSymbol = resolveName(node, node.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, node, /*isUse*/ false); } else if (node.parent.kind === SyntaxKind.ExportSpecifier) { exportSymbol = getTargetOfExportSpecifier(node.parent as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); } let result: Node[] | undefined; let visited: Set | undefined; if (exportSymbol) { visited = new Set(); visited.add(getSymbolId(exportSymbol)); buildVisibleNodeList(exportSymbol.declarations); } return result; function buildVisibleNodeList(declarations: Declaration[] | undefined) { forEach(declarations, declaration => { const resultNode = getAnyImportSyntax(declaration) || declaration; if (setVisibility) { getNodeLinks(declaration).isVisible = true; } else { result = result || []; pushIfUnique(result, resultNode); } if (isInternalModuleImportEqualsDeclaration(declaration)) { // Add the referenced top container visible const internalModuleReference = declaration.moduleReference as Identifier | QualifiedName; const firstIdentifier = getFirstIdentifier(internalModuleReference); const importSymbol = resolveName(declaration, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, undefined, undefined, /*isUse*/ false); if (importSymbol && visited) { if (tryAddToSet(visited, getSymbolId(importSymbol))) { buildVisibleNodeList(importSymbol.declarations); } } } }); } } /** * Push an entry on the type resolution stack. If an entry with the given target and the given property name * is already on the stack, and no entries in between already have a type, then a circularity has occurred. * In this case, the result values of the existing entry and all entries pushed after it are changed to false, * and the value false is returned. Otherwise, the new entry is just pushed onto the stack, and true is returned. * In order to see if the same query has already been done before, the target object and the propertyName both * must match the one passed in. * * @param target The symbol, type, or signature whose type is being queried * @param propertyName The property name that should be used to query the target for its type */ function pushTypeResolution(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { const resolutionCycleStartIndex = findResolutionCycleStartIndex(target, propertyName); if (resolutionCycleStartIndex >= 0) { // A cycle was found const { length } = resolutionTargets; for (let i = resolutionCycleStartIndex; i < length; i++) { resolutionResults[i] = false; } return false; } resolutionTargets.push(target); resolutionResults.push(/*items*/ true); resolutionPropertyNames.push(propertyName); return true; } function findResolutionCycleStartIndex(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): number { for (let i = resolutionTargets.length - 1; i >= 0; i--) { if (resolutionTargetHasProperty(resolutionTargets[i], resolutionPropertyNames[i])) { return -1; } if (resolutionTargets[i] === target && resolutionPropertyNames[i] === propertyName) { return i; } } return -1; } function resolutionTargetHasProperty(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { switch (propertyName) { case TypeSystemPropertyName.Type: return !!getSymbolLinks(target as Symbol).type; case TypeSystemPropertyName.EnumTagType: return !!(getNodeLinks(target as JSDocEnumTag).resolvedEnumType); case TypeSystemPropertyName.DeclaredType: return !!getSymbolLinks(target as Symbol).declaredType; case TypeSystemPropertyName.ResolvedBaseConstructorType: return !!(target as InterfaceType).resolvedBaseConstructorType; case TypeSystemPropertyName.ResolvedReturnType: return !!(target as Signature).resolvedReturnType; case TypeSystemPropertyName.ImmediateBaseConstraint: return !!(target as Type).immediateBaseConstraint; case TypeSystemPropertyName.ResolvedTypeArguments: return !!(target as TypeReference).resolvedTypeArguments; case TypeSystemPropertyName.ResolvedBaseTypes: return !!(target as InterfaceType).baseTypesResolved; case TypeSystemPropertyName.WriteType: return !!getSymbolLinks(target as Symbol).writeType; case TypeSystemPropertyName.ParameterInitializerContainsUndefined: return getNodeLinks(target as ParameterDeclaration).parameterInitializerContainsUndefined !== undefined; } return Debug.assertNever(propertyName); } /** * Pop an entry from the type resolution stack and return its associated result value. The result value will * be true if no circularities were detected, or false if a circularity was found. */ function popTypeResolution(): boolean { resolutionTargets.pop(); resolutionPropertyNames.pop(); return resolutionResults.pop()!; } function getDeclarationContainer(node: Node): Node { return findAncestor(getRootDeclaration(node), node => { switch (node.kind) { case SyntaxKind.VariableDeclaration: case SyntaxKind.VariableDeclarationList: case SyntaxKind.ImportSpecifier: case SyntaxKind.NamedImports: case SyntaxKind.NamespaceImport: case SyntaxKind.ImportClause: return false; default: return true; } })!.parent; } function getTypeOfPrototypeProperty(prototype: Symbol): Type { // TypeScript 1.0 spec (April 2014): 8.4 // Every class automatically contains a static property member named 'prototype', // the type of which is an instantiation of the class type with type Any supplied as a type argument for each type parameter. // It is an error to explicitly declare a static property member with the name 'prototype'. const classType = getDeclaredTypeOfSymbol(getParentOfSymbol(prototype)!) as InterfaceType; return classType.typeParameters ? createTypeReference(classType as GenericType, map(classType.typeParameters, _ => anyType)) : classType; } // Return the type of the given property in the given type, or undefined if no such property exists function getTypeOfPropertyOfType(type: Type, name: __String): Type | undefined { const prop = getPropertyOfType(type, name); return prop ? getTypeOfSymbol(prop) : undefined; } function getTypeOfPropertyOrIndexSignature(type: Type, name: __String): Type { return getTypeOfPropertyOfType(type, name) || getApplicableIndexInfoForName(type, name)?.type || unknownType; } function isTypeAny(type: Type | undefined) { return type && (type.flags & TypeFlags.Any) !== 0; } function isErrorType(type: Type) { // The only 'any' types that have alias symbols are those manufactured by getTypeFromTypeAliasReference for // a reference to an unresolved symbol. We want those to behave like the errorType. return type === errorType || !!(type.flags & TypeFlags.Any && type.aliasSymbol); } // Return the type of a binding element parent. We check SymbolLinks first to see if a type has been // assigned by contextual typing. function getTypeForBindingElementParent(node: BindingElementGrandparent, checkMode: CheckMode) { if (checkMode !== CheckMode.Normal) { return getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); } const symbol = getSymbolOfDeclaration(node); return symbol && getSymbolLinks(symbol).type || getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); } function getRestType(source: Type, properties: PropertyName[], symbol: Symbol | undefined): Type { source = filterType(source, t => !(t.flags & TypeFlags.Nullable)); if (source.flags & TypeFlags.Never) { return emptyObjectType; } if (source.flags & TypeFlags.Union) { return mapType(source, t => getRestType(t, properties, symbol)); } let omitKeyType = getUnionType(map(properties, getLiteralTypeFromPropertyName)); const spreadableProperties: Symbol[] = []; const unspreadableToRestKeys: Type[] = []; for (const prop of getPropertiesOfType(source)) { const literalTypeFromProperty = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); if (!isTypeAssignableTo(literalTypeFromProperty, omitKeyType) && !(getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) && isSpreadableProperty(prop)) { spreadableProperties.push(prop); } else { unspreadableToRestKeys.push(literalTypeFromProperty); } } if (isGenericObjectType(source) || isGenericIndexType(omitKeyType)) { if (unspreadableToRestKeys.length) { // If the type we're spreading from has properties that cannot // be spread into the rest type (e.g. getters, methods), ensure // they are explicitly omitted, as they would in the non-generic case. omitKeyType = getUnionType([omitKeyType, ...unspreadableToRestKeys]); } if (omitKeyType.flags & TypeFlags.Never) { return source; } const omitTypeAlias = getGlobalOmitSymbol(); if (!omitTypeAlias) { return errorType; } return getTypeAliasInstantiation(omitTypeAlias, [source, omitKeyType]); } const members = createSymbolTable(); for (const prop of spreadableProperties) { members.set(prop.escapedName, getSpreadSymbol(prop, /*readonly*/ false)); } const result = createAnonymousType(symbol, members, emptyArray, emptyArray, getIndexInfosOfType(source)); result.objectFlags |= ObjectFlags.ObjectRestType; return result; } function isGenericTypeWithUndefinedConstraint(type: Type) { return !!(type.flags & TypeFlags.Instantiable) && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.Undefined); } function getNonUndefinedType(type: Type) { const typeOrConstraint = someType(type, isGenericTypeWithUndefinedConstraint) ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOrType(t) : t) : type; return getTypeWithFacts(typeOrConstraint, TypeFacts.NEUndefined); } // Determine the control flow type associated with a destructuring declaration or assignment. The following // forms of destructuring are possible: // let { x } = obj; // BindingElement // let [ x ] = obj; // BindingElement // { x } = obj; // ShorthandPropertyAssignment // { x: v } = obj; // PropertyAssignment // [ x ] = obj; // Expression // We construct a synthetic element access expression corresponding to 'obj.x' such that the control // flow analyzer doesn't have to handle all the different syntactic forms. function getFlowTypeOfDestructuring(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression, declaredType: Type) { const reference = getSyntheticElementAccess(node); return reference ? getFlowTypeOfReference(reference, declaredType) : declaredType; } function getSyntheticElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression): ElementAccessExpression | undefined { const parentAccess = getParentElementAccess(node); if (parentAccess && canHaveFlowNode(parentAccess) && parentAccess.flowNode) { const propName = getDestructuringPropertyName(node); if (propName) { const literal = setTextRange(parseNodeFactory.createStringLiteral(propName), node); const lhsExpr = isLeftHandSideExpression(parentAccess) ? parentAccess : parseNodeFactory.createParenthesizedExpression(parentAccess); const result = setTextRange(parseNodeFactory.createElementAccessExpression(lhsExpr, literal), node); setParent(literal, result); setParent(result, node); if (lhsExpr !== parentAccess) { setParent(lhsExpr, result); } result.flowNode = parentAccess.flowNode; return result; } } } function getParentElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { const ancestor = node.parent.parent; switch (ancestor.kind) { case SyntaxKind.BindingElement: case SyntaxKind.PropertyAssignment: return getSyntheticElementAccess(ancestor as BindingElement | PropertyAssignment); case SyntaxKind.ArrayLiteralExpression: return getSyntheticElementAccess(node.parent as Expression); case SyntaxKind.VariableDeclaration: return (ancestor as VariableDeclaration).initializer; case SyntaxKind.BinaryExpression: return (ancestor as BinaryExpression).right; } } function getDestructuringPropertyName(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { const parent = node.parent; if (node.kind === SyntaxKind.BindingElement && parent.kind === SyntaxKind.ObjectBindingPattern) { return getLiteralPropertyNameText((node as BindingElement).propertyName || (node as BindingElement).name as Identifier); } if (node.kind === SyntaxKind.PropertyAssignment || node.kind === SyntaxKind.ShorthandPropertyAssignment) { return getLiteralPropertyNameText((node as PropertyAssignment | ShorthandPropertyAssignment).name); } return "" + ((parent as BindingPattern | ArrayLiteralExpression).elements as NodeArray).indexOf(node); } function getLiteralPropertyNameText(name: PropertyName) { const type = getLiteralTypeFromPropertyName(name); return type.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral) ? "" + (type as StringLiteralType | NumberLiteralType).value : undefined; } /** Return the inferred type for a binding element */ function getTypeForBindingElement(declaration: BindingElement): Type | undefined { const checkMode = declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; const parentType = getTypeForBindingElementParent(declaration.parent.parent, checkMode); return parentType && getBindingElementTypeFromParentType(declaration, parentType); } function getBindingElementTypeFromParentType(declaration: BindingElement, parentType: Type): Type { // If an any type was inferred for parent, infer that for the binding element if (isTypeAny(parentType)) { return parentType; } const pattern = declaration.parent; // Relax null check on ambient destructuring parameters, since the parameters have no implementation and are just documentation if (strictNullChecks && declaration.flags & NodeFlags.Ambient && isParameterDeclaration(declaration)) { parentType = getNonNullableType(parentType); } // Filter `undefined` from the type we check against if the parent has an initializer and that initializer is not possibly `undefined` else if (strictNullChecks && pattern.parent.initializer && !(getTypeFacts(getTypeOfInitializer(pattern.parent.initializer)) & TypeFacts.EQUndefined)) { parentType = getTypeWithFacts(parentType, TypeFacts.NEUndefined); } let type: Type | undefined; if (pattern.kind === SyntaxKind.ObjectBindingPattern) { if (declaration.dotDotDotToken) { parentType = getReducedType(parentType); if (parentType.flags & TypeFlags.Unknown || !isValidSpreadType(parentType)) { error(declaration, Diagnostics.Rest_types_may_only_be_created_from_object_types); return errorType; } const literalMembers: PropertyName[] = []; for (const element of pattern.elements) { if (!element.dotDotDotToken) { literalMembers.push(element.propertyName || element.name as Identifier); } } type = getRestType(parentType, literalMembers, declaration.symbol); } else { // Use explicitly specified property name ({ p: xxx } form), or otherwise the implied name ({ p } form) const name = declaration.propertyName || declaration.name as Identifier; const indexType = getLiteralTypeFromPropertyName(name); const declaredType = getIndexedAccessType(parentType, indexType, AccessFlags.ExpressionPosition, name); type = getFlowTypeOfDestructuring(declaration, declaredType); } } else { // This elementType will be used if the specific property corresponding to this index is not // present (aka the tuple element property). This call also checks that the parentType is in // fact an iterable or array (depending on target language). const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring | (declaration.dotDotDotToken ? 0 : IterationUse.PossiblyOutOfBounds), parentType, undefinedType, pattern); const index = pattern.elements.indexOf(declaration); if (declaration.dotDotDotToken) { // If the parent is a tuple type, the rest element has a tuple type of the // remaining tuple element types. Otherwise, the rest element has an array type with same // element type as the parent type. const baseConstraint = getBaseConstraintOrType(parentType); type = everyType(baseConstraint, isTupleType) ? mapType(baseConstraint, t => sliceTupleType(t as TupleTypeReference, index)) : createArrayType(elementType); } else if (isArrayLikeType(parentType)) { const indexType = getNumberLiteralType(index); const accessFlags = AccessFlags.ExpressionPosition | (hasDefaultValue(declaration) ? AccessFlags.NoTupleBoundsCheck : 0); const declaredType = getIndexedAccessTypeOrUndefined(parentType, indexType, accessFlags, declaration.name) || errorType; type = getFlowTypeOfDestructuring(declaration, declaredType); } else { type = elementType; } } if (!declaration.initializer) { return type; } if (getEffectiveTypeAnnotationNode(walkUpBindingElementsAndPatterns(declaration))) { // In strict null checking mode, if a default value of a non-undefined type is specified, remove // undefined from the final type. return strictNullChecks && !(getTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal)) & TypeFacts.IsUndefined) ? getNonUndefinedType(type) : type; } return widenTypeInferredFromInitializer(declaration, getUnionType([getNonUndefinedType(type), checkDeclarationInitializer(declaration, CheckMode.Normal)], UnionReduction.Subtype)); } function getTypeForDeclarationFromJSDocComment(declaration: Node) { const jsdocType = getJSDocType(declaration); if (jsdocType) { return getTypeFromTypeNode(jsdocType); } return undefined; } function isNullOrUndefined(node: Expression) { const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); return expr.kind === SyntaxKind.NullKeyword || expr.kind === SyntaxKind.Identifier && getResolvedSymbol(expr as Identifier) === undefinedSymbol; } function isEmptyArrayLiteral(node: Expression) { const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); return expr.kind === SyntaxKind.ArrayLiteralExpression && (expr as ArrayLiteralExpression).elements.length === 0; } function addOptionality(type: Type, isProperty = false, isOptional = true): Type { return strictNullChecks && isOptional ? getOptionalType(type, isProperty) : type; } // Return the inferred type for a variable, parameter, or property declaration function getTypeForVariableLikeDeclaration( declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, includeOptionality: boolean, checkMode: CheckMode, ): Type | undefined { // A variable declared in a for..in statement is of type string, or of type keyof T when the // right hand expression is of a type parameter type. if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForInStatement) { const indexType = getIndexType(getNonNullableTypeIfNeeded(checkExpression(declaration.parent.parent.expression, /*checkMode*/ checkMode))); return indexType.flags & (TypeFlags.TypeParameter | TypeFlags.Index) ? getExtractStringType(indexType) : stringType; } if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { // checkRightHandSideOfForOf will return undefined if the for-of expression type was // missing properties/signatures required to get its iteratedType (like // [Symbol.iterator] or next). This may be because we accessed properties from anyType, // or it may have led to an error inside getElementTypeOfIterable. const forOfStatement = declaration.parent.parent; return checkRightHandSideOfForOf(forOfStatement) || anyType; } if (isBindingPattern(declaration.parent)) { return getTypeForBindingElement(declaration as BindingElement); } const isProperty = (isPropertyDeclaration(declaration) && !hasAccessorModifier(declaration)) || isPropertySignature(declaration) || isJSDocPropertyTag(declaration); const isOptional = includeOptionality && isOptionalDeclaration(declaration); // Use type from type annotation if one is present const declaredType = tryGetTypeFromEffectiveTypeNode(declaration); if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) { if (declaredType) { // If the catch clause is explicitly annotated with any or unknown, accept it, otherwise error. return isTypeAny(declaredType) || declaredType === unknownType ? declaredType : errorType; } // If the catch clause is not explicitly annotated, treat it as though it were explicitly // annotated with unknown or any, depending on useUnknownInCatchVariables. return useUnknownInCatchVariables ? unknownType : anyType; } if (declaredType) { return addOptionality(declaredType, isProperty, isOptional); } if ((noImplicitAny || isInJSFile(declaration)) && isVariableDeclaration(declaration) && !isBindingPattern(declaration.name) && !(getCombinedModifierFlags(declaration) & ModifierFlags.Export) && !(declaration.flags & NodeFlags.Ambient)) { // If --noImplicitAny is on or the declaration is in a Javascript file, // use control flow tracked 'any' type for non-ambient, non-exported var or let variables with no // initializer or a 'null' or 'undefined' initializer. if (!(getCombinedNodeFlags(declaration) & NodeFlags.Const) && (!declaration.initializer || isNullOrUndefined(declaration.initializer))) { return autoType; } // Use control flow tracked 'any[]' type for non-ambient, non-exported variables with an empty array // literal initializer. if (declaration.initializer && isEmptyArrayLiteral(declaration.initializer)) { return autoArrayType; } } if (isParameter(declaration)) { const func = declaration.parent as FunctionLikeDeclaration; // For a parameter of a set accessor, use the type of the get accessor if one is present if (func.kind === SyntaxKind.SetAccessor && hasBindableName(func)) { const getter = getDeclarationOfKind(getSymbolOfDeclaration(declaration.parent), SyntaxKind.GetAccessor); if (getter) { const getterSignature = getSignatureFromDeclaration(getter); const thisParameter = getAccessorThisParameter(func as AccessorDeclaration); if (thisParameter && declaration === thisParameter) { // Use the type from the *getter* Debug.assert(!thisParameter.type); return getTypeOfSymbol(getterSignature.thisParameter!); } return getReturnTypeOfSignature(getterSignature); } } const parameterTypeOfTypeTag = getParameterTypeOfTypeTag(func, declaration); if (parameterTypeOfTypeTag) return parameterTypeOfTypeTag; // Use contextual parameter type if one is available const type = declaration.symbol.escapedName === InternalSymbolName.This ? getContextualThisParameterType(func) : getContextuallyTypedParameterType(declaration); if (type) { return addOptionality(type, /*isProperty*/ false, isOptional); } } // Use the type of the initializer expression if one is present and the declaration is // not a parameter of a contextually typed function if (hasOnlyExpressionInitializer(declaration) && !!declaration.initializer) { if (isInJSFile(declaration) && !isParameter(declaration)) { const containerObjectType = getJSContainerObjectType(declaration, getSymbolOfDeclaration(declaration), getDeclaredExpandoInitializer(declaration)); if (containerObjectType) { return containerObjectType; } } const type = widenTypeInferredFromInitializer(declaration, checkDeclarationInitializer(declaration, checkMode)); return addOptionality(type, isProperty, isOptional); } if (isPropertyDeclaration(declaration) && (noImplicitAny || isInJSFile(declaration))) { // We have a property declaration with no type annotation or initializer, in noImplicitAny mode or a .js file. // Use control flow analysis of this.xxx assignments in the constructor or static block to determine the type of the property. if (!hasStaticModifier(declaration)) { const constructor = findConstructorDeclaration(declaration.parent); const type = constructor ? getFlowTypeInConstructor(declaration.symbol, constructor) : getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : undefined; return type && addOptionality(type, /*isProperty*/ true, isOptional); } else { const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); const type = staticBlocks.length ? getFlowTypeInStaticBlocks(declaration.symbol, staticBlocks) : getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : undefined; return type && addOptionality(type, /*isProperty*/ true, isOptional); } } if (isJsxAttribute(declaration)) { // if JSX attribute doesn't have initializer, by default the attribute will have boolean value of true. // I.e is sugar for return trueType; } // If the declaration specifies a binding pattern and is not a parameter of a contextually // typed function, use the type implied by the binding pattern if (isBindingPattern(declaration.name)) { return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ false, /*reportErrors*/ true); } // No type specified and nothing can be inferred return undefined; } function isConstructorDeclaredProperty(symbol: Symbol) { // A property is considered a constructor declared property when all declaration sites are this.xxx assignments, // when no declaration sites have JSDoc type annotations, and when at least one declaration site is in the body of // a class constructor. if (symbol.valueDeclaration && isBinaryExpression(symbol.valueDeclaration)) { const links = getSymbolLinks(symbol); if (links.isConstructorDeclaredProperty === undefined) { links.isConstructorDeclaredProperty = false; links.isConstructorDeclaredProperty = !!getDeclaringConstructor(symbol) && every(symbol.declarations, declaration => isBinaryExpression(declaration) && isPossiblyAliasedThisProperty(declaration) && (declaration.left.kind !== SyntaxKind.ElementAccessExpression || isStringOrNumericLiteralLike((declaration.left as ElementAccessExpression).argumentExpression)) && !getAnnotatedTypeForAssignmentDeclaration(/*declaredType*/ undefined, declaration, symbol, declaration)); } return links.isConstructorDeclaredProperty; } return false; } function isAutoTypedProperty(symbol: Symbol) { // A property is auto-typed when its declaration has no type annotation or initializer and we're in // noImplicitAny mode or a .js file. const declaration = symbol.valueDeclaration; return declaration && isPropertyDeclaration(declaration) && !getEffectiveTypeAnnotationNode(declaration) && !declaration.initializer && (noImplicitAny || isInJSFile(declaration)); } function getDeclaringConstructor(symbol: Symbol) { if (!symbol.declarations) { return; } for (const declaration of symbol.declarations) { const container = getThisContainer(declaration, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); if (container && (container.kind === SyntaxKind.Constructor || isJSConstructor(container))) { return container as ConstructorDeclaration; } } } /** Create a synthetic property access flow node after the last statement of the file */ function getFlowTypeFromCommonJSExport(symbol: Symbol) { const file = getSourceFileOfNode(symbol.declarations![0]); const accessName = unescapeLeadingUnderscores(symbol.escapedName); const areAllModuleExports = symbol.declarations!.every(d => isInJSFile(d) && isAccessExpression(d) && isModuleExportsAccessExpression(d.expression)); const reference = areAllModuleExports ? factory.createPropertyAccessExpression(factory.createPropertyAccessExpression(factory.createIdentifier("module"), factory.createIdentifier("exports")), accessName) : factory.createPropertyAccessExpression(factory.createIdentifier("exports"), accessName); if (areAllModuleExports) { setParent((reference.expression as PropertyAccessExpression).expression, reference.expression); } setParent(reference.expression, reference); setParent(reference, file); reference.flowNode = file.endFlowNode; return getFlowTypeOfReference(reference, autoType, undefinedType); } function getFlowTypeInStaticBlocks(symbol: Symbol, staticBlocks: readonly ClassStaticBlockDeclaration[]) { const accessName = startsWith(symbol.escapedName as string, "__#") ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) : unescapeLeadingUnderscores(symbol.escapedName); for (const staticBlock of staticBlocks) { const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); setParent(reference.expression, reference); setParent(reference, staticBlock); reference.flowNode = staticBlock.returnFlowNode; const flowType = getFlowTypeOfProperty(reference, symbol); if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); } // We don't infer a type if assignments are only null or undefined. if (everyType(flowType, isNullableType)) { continue; } return convertAutoToAny(flowType); } } function getFlowTypeInConstructor(symbol: Symbol, constructor: ConstructorDeclaration) { const accessName = startsWith(symbol.escapedName as string, "__#") ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) : unescapeLeadingUnderscores(symbol.escapedName); const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); setParent(reference.expression, reference); setParent(reference, constructor); reference.flowNode = constructor.returnFlowNode; const flowType = getFlowTypeOfProperty(reference, symbol); if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); } // We don't infer a type if assignments are only null or undefined. return everyType(flowType, isNullableType) ? undefined : convertAutoToAny(flowType); } function getFlowTypeOfProperty(reference: Node, prop: Symbol | undefined) { const initialType = prop?.valueDeclaration && (!isAutoTypedProperty(prop) || getEffectiveModifierFlags(prop.valueDeclaration) & ModifierFlags.Ambient) && getTypeOfPropertyInBaseClass(prop) || undefinedType; return getFlowTypeOfReference(reference, autoType, initialType); } function getWidenedTypeForAssignmentDeclaration(symbol: Symbol, resolvedSymbol?: Symbol) { // function/class/{} initializers are themselves containers, so they won't merge in the same way as other initializers const container = getAssignedExpandoInitializer(symbol.valueDeclaration); if (container) { const tag = isInJSFile(container) ? getJSDocTypeTag(container) : undefined; if (tag && tag.typeExpression) { return getTypeFromTypeNode(tag.typeExpression); } const containerObjectType = symbol.valueDeclaration && getJSContainerObjectType(symbol.valueDeclaration, symbol, container); return containerObjectType || getWidenedLiteralType(checkExpressionCached(container)); } let type; let definedInConstructor = false; let definedInMethod = false; // We use control flow analysis to determine the type of the property if the property qualifies as a constructor // declared property and the resulting control flow type isn't just undefined or null. if (isConstructorDeclaredProperty(symbol)) { type = getFlowTypeInConstructor(symbol, getDeclaringConstructor(symbol)!); } if (!type) { let types: Type[] | undefined; if (symbol.declarations) { let jsdocType: Type | undefined; for (const declaration of symbol.declarations) { const expression = (isBinaryExpression(declaration) || isCallExpression(declaration)) ? declaration : isAccessExpression(declaration) ? isBinaryExpression(declaration.parent) ? declaration.parent : declaration : undefined; if (!expression) { continue; // Non-assignment declaration merged in (eg, an Identifier to mark the thing as a namespace) - skip over it and pull type info from elsewhere } const kind = isAccessExpression(expression) ? getAssignmentDeclarationPropertyAccessKind(expression) : getAssignmentDeclarationKind(expression); if (kind === AssignmentDeclarationKind.ThisProperty || isBinaryExpression(expression) && isPossiblyAliasedThisProperty(expression, kind)) { if (isDeclarationInConstructor(expression)) { definedInConstructor = true; } else { definedInMethod = true; } } if (!isCallExpression(expression)) { jsdocType = getAnnotatedTypeForAssignmentDeclaration(jsdocType, expression, symbol, declaration); } if (!jsdocType) { (types || (types = [])).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType); } } type = jsdocType; } if (!type) { if (!length(types)) { return errorType; // No types from any declarations :( } let constructorTypes = definedInConstructor && symbol.declarations ? getConstructorDefinedThisAssignmentTypes(types!, symbol.declarations) : undefined; // use only the constructor types unless they were only assigned null | undefined (including widening variants) if (definedInMethod) { const propType = getTypeOfPropertyInBaseClass(symbol); if (propType) { (constructorTypes || (constructorTypes = [])).push(propType); definedInConstructor = true; } } const sourceTypes = some(constructorTypes, t => !!(t.flags & ~TypeFlags.Nullable)) ? constructorTypes : types; // TODO: GH#18217 type = getUnionType(sourceTypes!); } } const widened = getWidenedType(addOptionality(type, /*isProperty*/ false, definedInMethod && !definedInConstructor)); if (symbol.valueDeclaration && filterType(widened, t => !!(t.flags & ~TypeFlags.Nullable)) === neverType) { reportImplicitAny(symbol.valueDeclaration, anyType); return anyType; } return widened; } function getJSContainerObjectType(decl: Node, symbol: Symbol, init: Expression | undefined): Type | undefined { if (!isInJSFile(decl) || !init || !isObjectLiteralExpression(init) || init.properties.length) { return undefined; } const exports = createSymbolTable(); while (isBinaryExpression(decl) || isPropertyAccessExpression(decl)) { const s = getSymbolOfNode(decl); if (s?.exports?.size) { mergeSymbolTable(exports, s.exports); } decl = isBinaryExpression(decl) ? decl.parent : decl.parent.parent; } const s = getSymbolOfNode(decl); if (s?.exports?.size) { mergeSymbolTable(exports, s.exports); } const type = createAnonymousType(symbol, exports, emptyArray, emptyArray, emptyArray); type.objectFlags |= ObjectFlags.JSLiteral; return type; } function getAnnotatedTypeForAssignmentDeclaration(declaredType: Type | undefined, expression: Expression, symbol: Symbol, declaration: Declaration) { const typeNode = getEffectiveTypeAnnotationNode(expression.parent); if (typeNode) { const type = getWidenedType(getTypeFromTypeNode(typeNode)); if (!declaredType) { return type; } else if (!isErrorType(declaredType) && !isErrorType(type) && !isTypeIdenticalTo(declaredType, type)) { errorNextVariableOrPropertyDeclarationMustHaveSameType(/*firstDeclaration*/ undefined, declaredType, declaration, type); } } if (symbol.parent?.valueDeclaration) { const typeNode = getEffectiveTypeAnnotationNode(symbol.parent.valueDeclaration); if (typeNode) { const annotationSymbol = getPropertyOfType(getTypeFromTypeNode(typeNode), symbol.escapedName); if (annotationSymbol) { return getNonMissingTypeOfSymbol(annotationSymbol); } } } return declaredType; } /** If we don't have an explicit JSDoc type, get the type from the initializer. */ function getInitializerTypeFromAssignmentDeclaration(symbol: Symbol, resolvedSymbol: Symbol | undefined, expression: BinaryExpression | CallExpression, kind: AssignmentDeclarationKind) { if (isCallExpression(expression)) { if (resolvedSymbol) { return getTypeOfSymbol(resolvedSymbol); // This shouldn't happen except under some hopefully forbidden merges of export assignments and object define assignments } const objectLitType = checkExpressionCached((expression as BindableObjectDefinePropertyCall).arguments[2]); const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); if (valueType) { return valueType; } const getFunc = getTypeOfPropertyOfType(objectLitType, "get" as __String); if (getFunc) { const getSig = getSingleCallSignature(getFunc); if (getSig) { return getReturnTypeOfSignature(getSig); } } const setFunc = getTypeOfPropertyOfType(objectLitType, "set" as __String); if (setFunc) { const setSig = getSingleCallSignature(setFunc); if (setSig) { return getTypeOfFirstParameterOfSignature(setSig); } } return anyType; } if (containsSameNamedThisProperty(expression.left, expression.right)) { return anyType; } const isDirectExport = kind === AssignmentDeclarationKind.ExportsProperty && (isPropertyAccessExpression(expression.left) || isElementAccessExpression(expression.left)) && (isModuleExportsAccessExpression(expression.left.expression) || (isIdentifier(expression.left.expression) && isExportsIdentifier(expression.left.expression))); const type = resolvedSymbol ? getTypeOfSymbol(resolvedSymbol) : isDirectExport ? getRegularTypeOfLiteralType(checkExpressionCached(expression.right)) : getWidenedLiteralType(checkExpressionCached(expression.right)); if (type.flags & TypeFlags.Object && kind === AssignmentDeclarationKind.ModuleExports && symbol.escapedName === InternalSymbolName.ExportEquals) { const exportedType = resolveStructuredTypeMembers(type as ObjectType); const members = createSymbolTable(); copyEntries(exportedType.members, members); const initialSize = members.size; if (resolvedSymbol && !resolvedSymbol.exports) { resolvedSymbol.exports = createSymbolTable(); } (resolvedSymbol || symbol).exports!.forEach((s, name) => { const exportedMember = members.get(name)!; if (exportedMember && exportedMember !== s && !(s.flags & SymbolFlags.Alias)) { if (s.flags & SymbolFlags.Value && exportedMember.flags & SymbolFlags.Value) { // If the member has an additional value-like declaration, union the types from the two declarations, // but issue an error if they occurred in two different files. The purpose is to support a JS file with // a pattern like: // // module.exports = { a: true }; // module.exports.a = 3; // // but we may have a JS file with `module.exports = { a: true }` along with a TypeScript module augmentation // declaring an `export const a: number`. In that case, we issue a duplicate identifier error, because // it's unclear what that's supposed to mean, so it's probably a mistake. if (s.valueDeclaration && exportedMember.valueDeclaration && getSourceFileOfNode(s.valueDeclaration) !== getSourceFileOfNode(exportedMember.valueDeclaration)) { const unescapedName = unescapeLeadingUnderscores(s.escapedName); const exportedMemberName = tryCast(exportedMember.valueDeclaration, isNamedDeclaration)?.name || exportedMember.valueDeclaration; addRelatedInfo( error(s.valueDeclaration, Diagnostics.Duplicate_identifier_0, unescapedName), createDiagnosticForNode(exportedMemberName, Diagnostics._0_was_also_declared_here, unescapedName)); addRelatedInfo( error(exportedMemberName, Diagnostics.Duplicate_identifier_0, unescapedName), createDiagnosticForNode(s.valueDeclaration, Diagnostics._0_was_also_declared_here, unescapedName)); } const union = createSymbol(s.flags | exportedMember.flags, name); union.links.type = getUnionType([getTypeOfSymbol(s), getTypeOfSymbol(exportedMember)]); union.valueDeclaration = exportedMember.valueDeclaration; union.declarations = concatenate(exportedMember.declarations, s.declarations); members.set(name, union); } else { members.set(name, mergeSymbol(s, exportedMember)); } } else { members.set(name, s); } }); const result = createAnonymousType( initialSize !== members.size ? undefined : exportedType.symbol, // Only set the type's symbol if it looks to be the same as the original type members, exportedType.callSignatures, exportedType.constructSignatures, exportedType.indexInfos); if (initialSize === members.size) { if (type.aliasSymbol) { result.aliasSymbol = type.aliasSymbol; result.aliasTypeArguments = type.aliasTypeArguments; } if (getObjectFlags(type) & ObjectFlags.Reference) { result.aliasSymbol = (type as TypeReference).symbol; const args = getTypeArguments(type as TypeReference); result.aliasTypeArguments = length(args) ? args : undefined; } } result.objectFlags |= (getObjectFlags(type) & ObjectFlags.JSLiteral); // Propagate JSLiteral flag if (result.symbol && result.symbol.flags & SymbolFlags.Class && type === getDeclaredTypeOfClassOrInterface(result.symbol)) { result.objectFlags |= ObjectFlags.IsClassInstanceClone; // Propagate the knowledge that this type is equivalent to the symbol's class instance type } return result; } if (isEmptyArrayLiteralType(type)) { reportImplicitAny(expression, anyArrayType); return anyArrayType; } return type; } function containsSameNamedThisProperty(thisProperty: Expression, expression: Expression) { return isPropertyAccessExpression(thisProperty) && thisProperty.expression.kind === SyntaxKind.ThisKeyword && forEachChildRecursively(expression, n => isMatchingReference(thisProperty, n)); } function isDeclarationInConstructor(expression: Expression) { const thisContainer = getThisContainer(expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); // Properties defined in a constructor (or base constructor, or javascript constructor function) don't get undefined added. // Function expressions that are assigned to the prototype count as methods. return thisContainer.kind === SyntaxKind.Constructor || thisContainer.kind === SyntaxKind.FunctionDeclaration || (thisContainer.kind === SyntaxKind.FunctionExpression && !isPrototypePropertyAssignment(thisContainer.parent)); } function getConstructorDefinedThisAssignmentTypes(types: Type[], declarations: Declaration[]): Type[] | undefined { Debug.assert(types.length === declarations.length); return types.filter((_, i) => { const declaration = declarations[i]; const expression = isBinaryExpression(declaration) ? declaration : isBinaryExpression(declaration.parent) ? declaration.parent : undefined; return expression && isDeclarationInConstructor(expression); }); } // Return the type implied by a binding pattern element. This is the type of the initializer of the element if // one is present. Otherwise, if the element is itself a binding pattern, it is the type implied by the binding // pattern. Otherwise, it is the type any. function getTypeFromBindingElement(element: BindingElement, includePatternInType?: boolean, reportErrors?: boolean): Type { if (element.initializer) { // The type implied by a binding pattern is independent of context, so we check the initializer with no // contextual type or, if the element itself is a binding pattern, with the type implied by that binding // pattern. const contextualType = isBindingPattern(element.name) ? getTypeFromBindingPattern(element.name, /*includePatternInType*/ true, /*reportErrors*/ false) : unknownType; return addOptionality(widenTypeInferredFromInitializer(element, checkDeclarationInitializer(element, CheckMode.Normal, contextualType))); } if (isBindingPattern(element.name)) { return getTypeFromBindingPattern(element.name, includePatternInType, reportErrors); } if (reportErrors && !declarationBelongsToPrivateAmbientMember(element)) { reportImplicitAny(element, anyType); } // When we're including the pattern in the type (an indication we're obtaining a contextual type), we // use a non-inferrable any type. Inference will never directly infer this type, but it is possible // to infer a type that contains it, e.g. for a binding pattern like [foo] or { foo }. In such cases, // widening of the binding pattern type substitutes a regular any for the non-inferrable any. return includePatternInType ? nonInferrableAnyType : anyType; } // Return the type implied by an object binding pattern function getTypeFromObjectBindingPattern(pattern: ObjectBindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { const members = createSymbolTable(); let stringIndexInfo: IndexInfo | undefined; let objectFlags = ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; forEach(pattern.elements, e => { const name = e.propertyName || e.name as Identifier; if (e.dotDotDotToken) { stringIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); return; } const exprType = getLiteralTypeFromPropertyName(name); if (!isTypeUsableAsPropertyName(exprType)) { // do not include computed properties in the implied type objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; return; } const text = getPropertyNameFromType(exprType); const flags = SymbolFlags.Property | (e.initializer ? SymbolFlags.Optional : 0); const symbol = createSymbol(flags, text); symbol.links.type = getTypeFromBindingElement(e, includePatternInType, reportErrors); symbol.links.bindingElement = e; members.set(symbol.escapedName, symbol); }); const result = createAnonymousType(undefined, members, emptyArray, emptyArray, stringIndexInfo ? [stringIndexInfo] : emptyArray); result.objectFlags |= objectFlags; if (includePatternInType) { result.pattern = pattern; result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; } return result; } // Return the type implied by an array binding pattern function getTypeFromArrayBindingPattern(pattern: BindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { const elements = pattern.elements; const lastElement = lastOrUndefined(elements); const restElement = lastElement && lastElement.kind === SyntaxKind.BindingElement && lastElement.dotDotDotToken ? lastElement : undefined; if (elements.length === 0 || elements.length === 1 && restElement) { return languageVersion >= ScriptTarget.ES2015 ? createIterableType(anyType) : anyArrayType; } const elementTypes = map(elements, e => isOmittedExpression(e) ? anyType : getTypeFromBindingElement(e, includePatternInType, reportErrors)); const minLength = findLastIndex(elements, e => !(e === restElement || isOmittedExpression(e) || hasDefaultValue(e)), elements.length - 1) + 1; const elementFlags = map(elements, (e, i) => e === restElement ? ElementFlags.Rest : i >= minLength ? ElementFlags.Optional : ElementFlags.Required); let result = createTupleType(elementTypes, elementFlags) as TypeReference; if (includePatternInType) { result = cloneTypeReference(result); result.pattern = pattern; result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; } return result; } // Return the type implied by a binding pattern. This is the type implied purely by the binding pattern itself // and without regard to its context (i.e. without regard any type annotation or initializer associated with the // declaration in which the binding pattern is contained). For example, the implied type of [x, y] is [any, any] // and the implied type of { x, y: z = 1 } is { x: any; y: number; }. The type implied by a binding pattern is // used as the contextual type of an initializer associated with the binding pattern. Also, for a destructuring // parameter with no type annotation or initializer, the type implied by the binding pattern becomes the type of // the parameter. function getTypeFromBindingPattern(pattern: BindingPattern, includePatternInType = false, reportErrors = false): Type { return pattern.kind === SyntaxKind.ObjectBindingPattern ? getTypeFromObjectBindingPattern(pattern, includePatternInType, reportErrors) : getTypeFromArrayBindingPattern(pattern, includePatternInType, reportErrors); } // Return the type associated with a variable, parameter, or property declaration. In the simple case this is the type // specified in a type annotation or inferred from an initializer. However, in the case of a destructuring declaration it // is a bit more involved. For example: // // var [x, s = ""] = [1, "one"]; // // Here, the array literal [1, "one"] is contextually typed by the type [any, string], which is the implied type of the // binding pattern [x, s = ""]. Because the contextual type is a tuple type, the resulting type of [1, "one"] is the // tuple type [number, string]. Thus, the type inferred for 'x' is number and the type inferred for 's' is string. function getWidenedTypeForVariableLikeDeclaration(declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, reportErrors?: boolean): Type { return widenTypeForVariableLikeDeclaration(getTypeForVariableLikeDeclaration(declaration, /*includeOptionality*/ true, CheckMode.Normal), declaration, reportErrors); } function isGlobalSymbolConstructor(node: Node) { const symbol = getSymbolOfNode(node); const globalSymbol = getGlobalESSymbolConstructorTypeSymbol(/*reportErrors*/ false); return globalSymbol && symbol && symbol === globalSymbol; } function widenTypeForVariableLikeDeclaration(type: Type | undefined, declaration: any, reportErrors?: boolean) { if (type) { // TODO: If back compat with pre-3.0/4.0 libs isn't required, remove the following SymbolConstructor special case transforming `symbol` into `unique symbol` if (type.flags & TypeFlags.ESSymbol && isGlobalSymbolConstructor(declaration.parent)) { type = getESSymbolLikeTypeForNode(declaration); } if (reportErrors) { reportErrorsFromWidening(declaration, type); } // always widen a 'unique symbol' type if the type was created for a different declaration. if (type.flags & TypeFlags.UniqueESSymbol && (isBindingElement(declaration) || !declaration.type) && type.symbol !== getSymbolOfDeclaration(declaration)) { type = esSymbolType; } return getWidenedType(type); } // Rest parameters default to type any[], other parameters default to type any type = isParameter(declaration) && declaration.dotDotDotToken ? anyArrayType : anyType; // Report implicit any errors unless this is a private property within an ambient declaration if (reportErrors) { if (!declarationBelongsToPrivateAmbientMember(declaration)) { reportImplicitAny(declaration, type); } } return type; } function declarationBelongsToPrivateAmbientMember(declaration: VariableLikeDeclaration) { const root = getRootDeclaration(declaration); const memberDeclaration = root.kind === SyntaxKind.Parameter ? root.parent : root; return isPrivateWithinAmbient(memberDeclaration); } function tryGetTypeFromEffectiveTypeNode(node: Node) { const typeNode = getEffectiveTypeAnnotationNode(node); if (typeNode) { return getTypeFromTypeNode(typeNode); } } function isParameterOfContextSensitiveSignature(symbol: Symbol) { let decl = symbol.valueDeclaration; if (!decl) { return false; } if (isBindingElement(decl)) { decl = walkUpBindingElementsAndPatterns(decl); } if (isParameter(decl)) { return isContextSensitiveFunctionOrObjectLiteralMethod(decl.parent); } return false; } function getTypeOfVariableOrParameterOrProperty(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.type) { const type = getTypeOfVariableOrParameterOrPropertyWorker(symbol); // For a contextually typed parameter it is possible that a type has already // been assigned (in assignTypeToParameterAndFixTypeParameters), and we want // to preserve this type. In fact, we need to _prefer_ that type, but it won't // be assigned until contextual typing is complete, so we need to defer in // cases where contextual typing may take place. if (!links.type && !isParameterOfContextSensitiveSignature(symbol)) { links.type = type; } return type; } return links.type; } function getTypeOfVariableOrParameterOrPropertyWorker(symbol: Symbol): Type { // Handle prototype property if (symbol.flags & SymbolFlags.Prototype) { return getTypeOfPrototypeProperty(symbol); } // CommonsJS require and module both have type any. if (symbol === requireSymbol) { return anyType; } if (symbol.flags & SymbolFlags.ModuleExports && symbol.valueDeclaration) { const fileSymbol = getSymbolOfDeclaration(getSourceFileOfNode(symbol.valueDeclaration)); const result = createSymbol(fileSymbol.flags, "exports" as __String); result.declarations = fileSymbol.declarations ? fileSymbol.declarations.slice() : []; result.parent = symbol; result.links.target = fileSymbol; if (fileSymbol.valueDeclaration) result.valueDeclaration = fileSymbol.valueDeclaration; if (fileSymbol.members) result.members = new Map(fileSymbol.members); if (fileSymbol.exports) result.exports = new Map(fileSymbol.exports); const members = createSymbolTable(); members.set("exports" as __String, result); return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); } Debug.assertIsDefined(symbol.valueDeclaration); const declaration = symbol.valueDeclaration; // Handle export default expressions if (isSourceFile(declaration) && isJsonSourceFile(declaration)) { if (!declaration.statements.length) { return emptyObjectType; } return getWidenedType(getWidenedLiteralType(checkExpression(declaration.statements[0].expression))); } if (isAccessor(declaration)) { // Binding of certain patterns in JS code will occasionally mark symbols as both properties // and accessors. Here we dispatch to accessor resolution if needed. return getTypeOfAccessors(symbol); } // Handle variable, parameter or property if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { return getTypeOfFuncClassEnumModule(symbol); } return reportCircularityError(symbol); } let type: Type; if (declaration.kind === SyntaxKind.ExportAssignment) { type = widenTypeForVariableLikeDeclaration(tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionCached((declaration as ExportAssignment).expression), declaration); } else if ( isBinaryExpression(declaration) || (isInJSFile(declaration) && (isCallExpression(declaration) || (isPropertyAccessExpression(declaration) || isBindableStaticElementAccessExpression(declaration)) && isBinaryExpression(declaration.parent)))) { type = getWidenedTypeForAssignmentDeclaration(symbol); } else if (isPropertyAccessExpression(declaration) || isElementAccessExpression(declaration) || isIdentifier(declaration) || isStringLiteralLike(declaration) || isNumericLiteral(declaration) || isClassDeclaration(declaration) || isFunctionDeclaration(declaration) || (isMethodDeclaration(declaration) && !isObjectLiteralMethod(declaration)) || isMethodSignature(declaration) || isSourceFile(declaration)) { // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { return getTypeOfFuncClassEnumModule(symbol); } type = isBinaryExpression(declaration.parent) ? getWidenedTypeForAssignmentDeclaration(symbol) : tryGetTypeFromEffectiveTypeNode(declaration) || anyType; } else if (isPropertyAssignment(declaration)) { type = tryGetTypeFromEffectiveTypeNode(declaration) || checkPropertyAssignment(declaration); } else if (isJsxAttribute(declaration)) { type = tryGetTypeFromEffectiveTypeNode(declaration) || checkJsxAttribute(declaration); } else if (isShorthandPropertyAssignment(declaration)) { type = tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionForMutableLocation(declaration.name, CheckMode.Normal); } else if (isObjectLiteralMethod(declaration)) { type = tryGetTypeFromEffectiveTypeNode(declaration) || checkObjectLiteralMethod(declaration, CheckMode.Normal); } else if (isParameter(declaration) || isPropertyDeclaration(declaration) || isPropertySignature(declaration) || isVariableDeclaration(declaration) || isBindingElement(declaration) || isJSDocPropertyLikeTag(declaration)) { type = getWidenedTypeForVariableLikeDeclaration(declaration, /*includeOptionality*/ true); } // getTypeOfSymbol dispatches some JS merges incorrectly because their symbol flags are not mutually exclusive. // Re-dispatch based on valueDeclaration.kind instead. else if (isEnumDeclaration(declaration)) { type = getTypeOfFuncClassEnumModule(symbol); } else if (isEnumMember(declaration)) { type = getTypeOfEnumMember(symbol); } else { return Debug.fail("Unhandled declaration kind! " + Debug.formatSyntaxKind(declaration.kind) + " for " + Debug.formatSymbol(symbol)); } if (!popTypeResolution()) { // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { return getTypeOfFuncClassEnumModule(symbol); } return reportCircularityError(symbol); } return type; } function getAnnotatedAccessorTypeNode(accessor: AccessorDeclaration | PropertyDeclaration | undefined): TypeNode | undefined { if (accessor) { switch (accessor.kind) { case SyntaxKind.GetAccessor: const getterTypeAnnotation = getEffectiveReturnTypeNode(accessor); return getterTypeAnnotation; case SyntaxKind.SetAccessor: const setterTypeAnnotation = getEffectiveSetAccessorTypeAnnotationNode(accessor); return setterTypeAnnotation; case SyntaxKind.PropertyDeclaration: Debug.assert(hasAccessorModifier(accessor)); const accessorTypeAnnotation = getEffectiveTypeAnnotationNode(accessor); return accessorTypeAnnotation; } } return undefined; } function getAnnotatedAccessorType(accessor: AccessorDeclaration | PropertyDeclaration | undefined): Type | undefined { const node = getAnnotatedAccessorTypeNode(accessor); return node && getTypeFromTypeNode(node); } function getAnnotatedAccessorThisParameter(accessor: AccessorDeclaration): Symbol | undefined { const parameter = getAccessorThisParameter(accessor); return parameter && parameter.symbol; } function getThisTypeOfDeclaration(declaration: SignatureDeclaration): Type | undefined { return getThisTypeOfSignature(getSignatureFromDeclaration(declaration)); } function getTypeOfAccessors(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.type) { if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { return errorType; } const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); const accessor = tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); // We try to resolve a getter type annotation, a setter type annotation, or a getter function // body return type inference, in that order. let type = getter && isInJSFile(getter) && getTypeForDeclarationFromJSDocComment(getter) || getAnnotatedAccessorType(getter) || getAnnotatedAccessorType(setter) || getAnnotatedAccessorType(accessor) || getter && getter.body && getReturnTypeFromBody(getter) || accessor && accessor.initializer && getWidenedTypeForVariableLikeDeclaration(accessor, /*includeOptionality*/ true); if (!type) { if (setter && !isPrivateWithinAmbient(setter)) { errorOrSuggestion(noImplicitAny, setter, Diagnostics.Property_0_implicitly_has_type_any_because_its_set_accessor_lacks_a_parameter_type_annotation, symbolToString(symbol)); } else if (getter && !isPrivateWithinAmbient(getter)) { errorOrSuggestion(noImplicitAny, getter, Diagnostics.Property_0_implicitly_has_type_any_because_its_get_accessor_lacks_a_return_type_annotation, symbolToString(symbol)); } else if (accessor && !isPrivateWithinAmbient(accessor)) { errorOrSuggestion(noImplicitAny, accessor, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), "any"); } type = anyType; } if (!popTypeResolution()) { if (getAnnotatedAccessorTypeNode(getter)) { error(getter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); } else if (getAnnotatedAccessorTypeNode(setter)) { error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); } else if (getAnnotatedAccessorTypeNode(accessor)) { error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); } else if (getter && noImplicitAny) { error(getter, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, symbolToString(symbol)); } type = anyType; } links.type = type; } return links.type; } function getWriteTypeOfAccessors(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.writeType) { if (!pushTypeResolution(symbol, TypeSystemPropertyName.WriteType)) { return errorType; } const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor) ?? tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); let writeType = getAnnotatedAccessorType(setter); if (!popTypeResolution()) { if (getAnnotatedAccessorTypeNode(setter)) { error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); } writeType = anyType; } // Absent an explicit setter type annotation we use the read type of the accessor. links.writeType = writeType || getTypeOfAccessors(symbol); } return links.writeType; } function getBaseTypeVariableOfClass(symbol: Symbol) { const baseConstructorType = getBaseConstructorTypeOfClass(getDeclaredTypeOfClassOrInterface(symbol)); return baseConstructorType.flags & TypeFlags.TypeVariable ? baseConstructorType : baseConstructorType.flags & TypeFlags.Intersection ? find((baseConstructorType as IntersectionType).types, t => !!(t.flags & TypeFlags.TypeVariable)) : undefined; } function getTypeOfFuncClassEnumModule(symbol: Symbol): Type { let links = getSymbolLinks(symbol); const originalLinks = links; if (!links.type) { const expando = symbol.valueDeclaration && getSymbolOfExpando(symbol.valueDeclaration, /*allowDeclaration*/ false); if (expando) { const merged = mergeJSSymbols(symbol, expando); if (merged) { // note:we overwrite links because we just cloned the symbol symbol = merged; links = merged.links; } } originalLinks.type = links.type = getTypeOfFuncClassEnumModuleWorker(symbol); } return links.type; } function getTypeOfFuncClassEnumModuleWorker(symbol: Symbol): Type { const declaration = symbol.valueDeclaration; if (symbol.flags & SymbolFlags.Module && isShorthandAmbientModuleSymbol(symbol)) { return anyType; } else if (declaration && (declaration.kind === SyntaxKind.BinaryExpression || isAccessExpression(declaration) && declaration.parent.kind === SyntaxKind.BinaryExpression)) { return getWidenedTypeForAssignmentDeclaration(symbol); } else if (symbol.flags & SymbolFlags.ValueModule && declaration && isSourceFile(declaration) && declaration.commonJsModuleIndicator) { const resolvedModule = resolveExternalModuleSymbol(symbol); if (resolvedModule !== symbol) { if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { return errorType; } const exportEquals = getMergedSymbol(symbol.exports!.get(InternalSymbolName.ExportEquals)!); const type = getWidenedTypeForAssignmentDeclaration(exportEquals, exportEquals === resolvedModule ? undefined : resolvedModule); if (!popTypeResolution()) { return reportCircularityError(symbol); } return type; } } const type = createObjectType(ObjectFlags.Anonymous, symbol); if (symbol.flags & SymbolFlags.Class) { const baseTypeVariable = getBaseTypeVariableOfClass(symbol); return baseTypeVariable ? getIntersectionType([type, baseTypeVariable]) : type; } else { return strictNullChecks && symbol.flags & SymbolFlags.Optional ? getOptionalType(type) : type; } } function getTypeOfEnumMember(symbol: Symbol): Type { const links = getSymbolLinks(symbol); return links.type || (links.type = getDeclaredTypeOfEnumMember(symbol)); } function getTypeOfAlias(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.type) { const targetSymbol = resolveAlias(symbol); const exportSymbol = symbol.declarations && getTargetOfAliasDeclaration(getDeclarationOfAliasSymbol(symbol)!, /*dontResolveAlias*/ true); const declaredType = firstDefined(exportSymbol?.declarations, d => isExportAssignment(d) ? tryGetTypeFromEffectiveTypeNode(d) : undefined); // It only makes sense to get the type of a value symbol. If the result of resolving // the alias is not a value, then it has no type. To get the type associated with a // type symbol, call getDeclaredTypeOfSymbol. // This check is important because without it, a call to getTypeOfSymbol could end // up recursively calling getTypeOfAlias, causing a stack overflow. links.type = exportSymbol?.declarations && isDuplicatedCommonJSExport(exportSymbol.declarations) && symbol.declarations!.length ? getFlowTypeFromCommonJSExport(exportSymbol) : isDuplicatedCommonJSExport(symbol.declarations) ? autoType : declaredType ? declaredType : getAllSymbolFlags(targetSymbol) & SymbolFlags.Value ? getTypeOfSymbol(targetSymbol) : errorType; } return links.type; } function getTypeOfInstantiatedSymbol(symbol: Symbol): Type { const links = getSymbolLinks(symbol); return links.type || (links.type = instantiateType(getTypeOfSymbol(links.target!), links.mapper)); } function getWriteTypeOfInstantiatedSymbol(symbol: Symbol): Type { const links = getSymbolLinks(symbol); return links.writeType || (links.writeType = instantiateType(getWriteTypeOfSymbol(links.target!), links.mapper)); } function reportCircularityError(symbol: Symbol) { const declaration = symbol.valueDeclaration as VariableLikeDeclaration; // Check if variable has type annotation that circularly references the variable itself if (getEffectiveTypeAnnotationNode(declaration)) { error(symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); return errorType; } // Check if variable has initializer that circularly references the variable itself if (noImplicitAny && (declaration.kind !== SyntaxKind.Parameter || (declaration as HasInitializer).initializer)) { error(symbol.valueDeclaration, Diagnostics._0_implicitly_has_type_any_because_it_does_not_have_a_type_annotation_and_is_referenced_directly_or_indirectly_in_its_own_initializer, symbolToString(symbol)); } // Circularities could also result from parameters in function expressions that end up // having themselves as contextual types following type argument inference. In those cases // we have already reported an implicit any error so we don't report anything here. return anyType; } function getTypeOfSymbolWithDeferredType(symbol: Symbol) { const links = getSymbolLinks(symbol); if (!links.type) { Debug.assertIsDefined(links.deferralParent); Debug.assertIsDefined(links.deferralConstituents); links.type = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralConstituents) : getIntersectionType(links.deferralConstituents); } return links.type; } function getWriteTypeOfSymbolWithDeferredType(symbol: Symbol): Type | undefined { const links = getSymbolLinks(symbol); if (!links.writeType && links.deferralWriteConstituents) { Debug.assertIsDefined(links.deferralParent); Debug.assertIsDefined(links.deferralConstituents); links.writeType = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralWriteConstituents) : getIntersectionType(links.deferralWriteConstituents); } return links.writeType; } /** * Distinct write types come only from set accessors, but synthetic union and intersection * properties deriving from set accessors will either pre-compute or defer the union or * intersection of the writeTypes of their constituents. */ function getWriteTypeOfSymbol(symbol: Symbol): Type { const checkFlags = getCheckFlags(symbol); if (symbol.flags & SymbolFlags.Property) { return checkFlags & CheckFlags.SyntheticProperty ? checkFlags & CheckFlags.DeferredType ? getWriteTypeOfSymbolWithDeferredType(symbol) || getTypeOfSymbolWithDeferredType(symbol) : // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty (symbol as TransientSymbol).links.writeType || (symbol as TransientSymbol).links.type! : getTypeOfSymbol(symbol); } if (symbol.flags & SymbolFlags.Accessor) { return checkFlags & CheckFlags.Instantiated ? getWriteTypeOfInstantiatedSymbol(symbol) : getWriteTypeOfAccessors(symbol); } return getTypeOfSymbol(symbol); } function getTypeOfSymbol(symbol: Symbol): Type { const checkFlags = getCheckFlags(symbol); if (checkFlags & CheckFlags.DeferredType) { return getTypeOfSymbolWithDeferredType(symbol); } if (checkFlags & CheckFlags.Instantiated) { return getTypeOfInstantiatedSymbol(symbol); } if (checkFlags & CheckFlags.Mapped) { return getTypeOfMappedSymbol(symbol as MappedSymbol); } if (checkFlags & CheckFlags.ReverseMapped) { return getTypeOfReverseMappedSymbol(symbol as ReverseMappedSymbol); } if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { return getTypeOfVariableOrParameterOrProperty(symbol); } if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { return getTypeOfFuncClassEnumModule(symbol); } if (symbol.flags & SymbolFlags.EnumMember) { return getTypeOfEnumMember(symbol); } if (symbol.flags & SymbolFlags.Accessor) { return getTypeOfAccessors(symbol); } if (symbol.flags & SymbolFlags.Alias) { return getTypeOfAlias(symbol); } return errorType; } function getNonMissingTypeOfSymbol(symbol: Symbol) { return removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); } function isReferenceToType(type: Type, target: Type) { return type !== undefined && target !== undefined && (getObjectFlags(type) & ObjectFlags.Reference) !== 0 && (type as TypeReference).target === target; } function getTargetType(type: Type): Type { return getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target : type; } // TODO: GH#18217 If `checkBase` is undefined, we should not call this because this will always return false. function hasBaseType(type: Type, checkBase: Type | undefined) { return check(type); function check(type: Type): boolean { if (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { const target = getTargetType(type) as InterfaceType; return target === checkBase || some(getBaseTypes(target), check); } else if (type.flags & TypeFlags.Intersection) { return some((type as IntersectionType).types, check); } return false; } } // Appends the type parameters given by a list of declarations to a set of type parameters and returns the resulting set. // The function allocates a new array if the input type parameter set is undefined, but otherwise it modifies the set // in-place and returns the same array. function appendTypeParameters(typeParameters: TypeParameter[] | undefined, declarations: readonly TypeParameterDeclaration[]): TypeParameter[] | undefined { for (const declaration of declarations) { typeParameters = appendIfUnique(typeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(declaration))); } return typeParameters; } // Return the outer type parameters of a node or undefined if the node has no outer type parameters. function getOuterTypeParameters(node: Node, includeThisTypes?: boolean): TypeParameter[] | undefined { while (true) { node = node.parent; // TODO: GH#18217 Use SourceFile kind check instead if (node && isBinaryExpression(node)) { // prototype assignments get the outer type parameters of their constructor function const assignmentKind = getAssignmentDeclarationKind(node); if (assignmentKind === AssignmentDeclarationKind.Prototype || assignmentKind === AssignmentDeclarationKind.PrototypeProperty) { const symbol = getSymbolOfDeclaration(node.left as BindableStaticNameExpression | PropertyAssignment); if (symbol && symbol.parent && !findAncestor(symbol.parent.valueDeclaration, d => node === d)) { node = symbol.parent.valueDeclaration!; } } } if (!node) { return undefined; } switch (node.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.CallSignature: case SyntaxKind.ConstructSignature: case SyntaxKind.MethodSignature: case SyntaxKind.FunctionType: case SyntaxKind.ConstructorType: case SyntaxKind.JSDocFunctionType: case SyntaxKind.FunctionDeclaration: case SyntaxKind.MethodDeclaration: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: case SyntaxKind.TypeAliasDeclaration: case SyntaxKind.JSDocTemplateTag: case SyntaxKind.JSDocTypedefTag: case SyntaxKind.JSDocEnumTag: case SyntaxKind.JSDocCallbackTag: case SyntaxKind.MappedType: case SyntaxKind.ConditionalType: { const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); if (node.kind === SyntaxKind.MappedType) { return append(outerTypeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration((node as MappedTypeNode).typeParameter))); } else if (node.kind === SyntaxKind.ConditionalType) { return concatenate(outerTypeParameters, getInferTypeParameters(node as ConditionalTypeNode)); } const outerAndOwnTypeParameters = appendTypeParameters(outerTypeParameters, getEffectiveTypeParameterDeclarations(node as DeclarationWithTypeParameters)); const thisType = includeThisTypes && (node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression || node.kind === SyntaxKind.InterfaceDeclaration || isJSConstructor(node)) && getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node as ClassLikeDeclaration | InterfaceDeclaration)).thisType; return thisType ? append(outerAndOwnTypeParameters, thisType) : outerAndOwnTypeParameters; } case SyntaxKind.JSDocParameterTag: const paramSymbol = getParameterSymbolFromJSDoc(node as JSDocParameterTag); if (paramSymbol) { node = paramSymbol.valueDeclaration!; } break; case SyntaxKind.JSDoc: { const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); return (node as JSDoc).tags ? appendTypeParameters(outerTypeParameters, flatMap((node as JSDoc).tags, t => isJSDocTemplateTag(t) ? t.typeParameters : undefined)) : outerTypeParameters; } } } } // The outer type parameters are those defined by enclosing generic classes, methods, or functions. function getOuterTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { const declaration = (symbol.flags & SymbolFlags.Class || symbol.flags & SymbolFlags.Function) ? symbol.valueDeclaration : symbol.declarations?.find(decl => { if (decl.kind === SyntaxKind.InterfaceDeclaration) { return true; } if (decl.kind !== SyntaxKind.VariableDeclaration) { return false; } const initializer = (decl as VariableDeclaration).initializer; return !!initializer && (initializer.kind === SyntaxKind.FunctionExpression || initializer.kind === SyntaxKind.ArrowFunction); })!; Debug.assert(!!declaration, "Class was missing valueDeclaration -OR- non-class had no interface declarations"); return getOuterTypeParameters(declaration); } // The local type parameters are the combined set of type parameters from all declarations of the class, // interface, or type alias. function getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol: Symbol): TypeParameter[] | undefined { if (!symbol.declarations) { return; } let result: TypeParameter[] | undefined; for (const node of symbol.declarations) { if (node.kind === SyntaxKind.InterfaceDeclaration || node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression || isJSConstructor(node) || isTypeAlias(node)) { const declaration = node as InterfaceDeclaration | TypeAliasDeclaration | JSDocTypedefTag | JSDocCallbackTag; result = appendTypeParameters(result, getEffectiveTypeParameterDeclarations(declaration)); } } return result; } // The full set of type parameters for a generic class or interface type consists of its outer type parameters plus // its locally declared type parameters. function getTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { return concatenate(getOuterTypeParametersOfClassOrInterface(symbol), getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol)); } // A type is a mixin constructor if it has a single construct signature taking no type parameters and a single // rest parameter of type any[]. function isMixinConstructorType(type: Type) { const signatures = getSignaturesOfType(type, SignatureKind.Construct); if (signatures.length === 1) { const s = signatures[0]; if (!s.typeParameters && s.parameters.length === 1 && signatureHasRestParameter(s)) { const paramType = getTypeOfParameter(s.parameters[0]); return isTypeAny(paramType) || getElementTypeOfArrayType(paramType) === anyType; } } return false; } function isConstructorType(type: Type): boolean { if (getSignaturesOfType(type, SignatureKind.Construct).length > 0) { return true; } if (type.flags & TypeFlags.TypeVariable) { const constraint = getBaseConstraintOfType(type); return !!constraint && isMixinConstructorType(constraint); } return false; } function getBaseTypeNodeOfClass(type: InterfaceType): ExpressionWithTypeArguments | undefined { const decl = getClassLikeDeclarationOfSymbol(type.symbol); return decl && getEffectiveBaseTypeNode(decl); } function getConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { const typeArgCount = length(typeArgumentNodes); const isJavascript = isInJSFile(location); return filter(getSignaturesOfType(type, SignatureKind.Construct), sig => (isJavascript || typeArgCount >= getMinTypeArgumentCount(sig.typeParameters)) && typeArgCount <= length(sig.typeParameters)); } function getInstantiatedConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { const signatures = getConstructorsForTypeArguments(type, typeArgumentNodes, location); const typeArguments = map(typeArgumentNodes, getTypeFromTypeNode); return sameMap(signatures, sig => some(sig.typeParameters) ? getSignatureInstantiation(sig, typeArguments, isInJSFile(location)) : sig); } /** * The base constructor of a class can resolve to * * undefinedType if the class has no extends clause, * * unknownType if an error occurred during resolution of the extends expression, * * nullType if the extends expression is the null value, * * anyType if the extends expression has type any, or * * an object type with at least one construct signature. */ function getBaseConstructorTypeOfClass(type: InterfaceType): Type { if (!type.resolvedBaseConstructorType) { const decl = getClassLikeDeclarationOfSymbol(type.symbol); const extended = decl && getEffectiveBaseTypeNode(decl); const baseTypeNode = getBaseTypeNodeOfClass(type); if (!baseTypeNode) { return type.resolvedBaseConstructorType = undefinedType; } if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseConstructorType)) { return errorType; } const baseConstructorType = checkExpression(baseTypeNode.expression); if (extended && baseTypeNode !== extended) { Debug.assert(!extended.typeArguments); // Because this is in a JS file, and baseTypeNode is in an @extends tag checkExpression(extended.expression); } if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection)) { // Resolving the members of a class requires us to resolve the base class of that class. // We force resolution here such that we catch circularities now. resolveStructuredTypeMembers(baseConstructorType as ObjectType); } if (!popTypeResolution()) { error(type.symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_base_expression, symbolToString(type.symbol)); return type.resolvedBaseConstructorType = errorType; } if (!(baseConstructorType.flags & TypeFlags.Any) && baseConstructorType !== nullWideningType && !isConstructorType(baseConstructorType)) { const err = error(baseTypeNode.expression, Diagnostics.Type_0_is_not_a_constructor_function_type, typeToString(baseConstructorType)); if (baseConstructorType.flags & TypeFlags.TypeParameter) { const constraint = getConstraintFromTypeParameter(baseConstructorType); let ctorReturn: Type = unknownType; if (constraint) { const ctorSig = getSignaturesOfType(constraint, SignatureKind.Construct); if (ctorSig[0]) { ctorReturn = getReturnTypeOfSignature(ctorSig[0]); } } if (baseConstructorType.symbol.declarations) { addRelatedInfo(err, createDiagnosticForNode(baseConstructorType.symbol.declarations[0], Diagnostics.Did_you_mean_for_0_to_be_constrained_to_type_new_args_Colon_any_1, symbolToString(baseConstructorType.symbol), typeToString(ctorReturn))); } } return type.resolvedBaseConstructorType = errorType; } type.resolvedBaseConstructorType = baseConstructorType; } return type.resolvedBaseConstructorType; } function getImplementsTypes(type: InterfaceType): BaseType[] { let resolvedImplementsTypes: BaseType[] = emptyArray; if (type.symbol.declarations) { for (const declaration of type.symbol.declarations) { const implementsTypeNodes = getEffectiveImplementsTypeNodes(declaration as ClassLikeDeclaration); if (!implementsTypeNodes) continue; for (const node of implementsTypeNodes) { const implementsType = getTypeFromTypeNode(node); if (!isErrorType(implementsType)) { if (resolvedImplementsTypes === emptyArray) { resolvedImplementsTypes = [implementsType as ObjectType]; } else { resolvedImplementsTypes.push(implementsType); } } } } } return resolvedImplementsTypes; } function reportCircularBaseType(node: Node, type: Type) { error(node, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); } function getBaseTypes(type: InterfaceType): BaseType[] { if (!type.baseTypesResolved) { if (pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseTypes)) { if (type.objectFlags & ObjectFlags.Tuple) { type.resolvedBaseTypes = [getTupleBaseType(type as TupleType)]; } else if (type.symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { if (type.symbol.flags & SymbolFlags.Class) { resolveBaseTypesOfClass(type); } if (type.symbol.flags & SymbolFlags.Interface) { resolveBaseTypesOfInterface(type); } } else { Debug.fail("type must be class or interface"); } if (!popTypeResolution() && type.symbol.declarations) { for (const declaration of type.symbol.declarations) { if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) { reportCircularBaseType(declaration, type); } } } } type.baseTypesResolved = true; } return type.resolvedBaseTypes; } function getTupleBaseType(type: TupleType) { const elementTypes = sameMap(type.typeParameters, (t, i) => type.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); return createArrayType(getUnionType(elementTypes || emptyArray), type.readonly); } function resolveBaseTypesOfClass(type: InterfaceType) { type.resolvedBaseTypes = resolvingEmptyArray; const baseConstructorType = getApparentType(getBaseConstructorTypeOfClass(type)); if (!(baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Any))) { return type.resolvedBaseTypes = emptyArray; } const baseTypeNode = getBaseTypeNodeOfClass(type)!; let baseType: Type; const originalBaseType = baseConstructorType.symbol ? getDeclaredTypeOfSymbol(baseConstructorType.symbol) : undefined; if (baseConstructorType.symbol && baseConstructorType.symbol.flags & SymbolFlags.Class && areAllOuterTypeParametersApplied(originalBaseType!)) { // When base constructor type is a class with no captured type arguments we know that the constructors all have the same type parameters as the // class and all return the instance type of the class. There is no need for further checks and we can apply the // type arguments in the same manner as a type reference to get the same error reporting experience. baseType = getTypeFromClassOrInterfaceReference(baseTypeNode, baseConstructorType.symbol); } else if (baseConstructorType.flags & TypeFlags.Any) { baseType = baseConstructorType; } else { // The class derives from a "class-like" constructor function, check that we have at least one construct signature // with a matching number of type parameters and use the return type of the first instantiated signature. Elsewhere // we check that all instantiated signatures return the same type. const constructors = getInstantiatedConstructorsForTypeArguments(baseConstructorType, baseTypeNode.typeArguments, baseTypeNode); if (!constructors.length) { error(baseTypeNode.expression, Diagnostics.No_base_constructor_has_the_specified_number_of_type_arguments); return type.resolvedBaseTypes = emptyArray; } baseType = getReturnTypeOfSignature(constructors[0]); } if (isErrorType(baseType)) { return type.resolvedBaseTypes = emptyArray; } const reducedBaseType = getReducedType(baseType); if (!isValidBaseType(reducedBaseType)) { const elaboration = elaborateNeverIntersection(/*errorInfo*/ undefined, baseType); const diagnostic = chainDiagnosticMessages(elaboration, Diagnostics.Base_constructor_return_type_0_is_not_an_object_type_or_intersection_of_object_types_with_statically_known_members, typeToString(reducedBaseType)); diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(baseTypeNode.expression), baseTypeNode.expression, diagnostic)); return type.resolvedBaseTypes = emptyArray; } if (type === reducedBaseType || hasBaseType(reducedBaseType, type)) { error(type.symbol.valueDeclaration, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); return type.resolvedBaseTypes = emptyArray; } if (type.resolvedBaseTypes === resolvingEmptyArray) { // Circular reference, likely through instantiation of default parameters // (otherwise there'd be an error from hasBaseType) - this is fine, but `.members` should be reset // as `getIndexedAccessType` via `instantiateType` via `getTypeFromClassOrInterfaceReference` forces a // partial instantiation of the members without the base types fully resolved type.members = undefined; } return type.resolvedBaseTypes = [reducedBaseType]; } function areAllOuterTypeParametersApplied(type: Type): boolean { // TODO: GH#18217 Shouldn't this take an InterfaceType? // An unapplied type parameter has its symbol still the same as the matching argument symbol. // Since parameters are applied outer-to-inner, only the last outer parameter needs to be checked. const outerTypeParameters = (type as InterfaceType).outerTypeParameters; if (outerTypeParameters) { const last = outerTypeParameters.length - 1; const typeArguments = getTypeArguments(type as TypeReference); return outerTypeParameters[last].symbol !== typeArguments[last].symbol; } return true; } // A valid base type is `any`, an object type or intersection of object types. function isValidBaseType(type: Type): type is BaseType { if (type.flags & TypeFlags.TypeParameter) { const constraint = getBaseConstraintOfType(type); if (constraint) { return isValidBaseType(constraint); } } // TODO: Given that we allow type parmeters here now, is this `!isGenericMappedType(type)` check really needed? // There's no reason a `T` should be allowed while a `Readonly` should not. return !!(type.flags & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.Any) && !isGenericMappedType(type) || type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isValidBaseType)); } function resolveBaseTypesOfInterface(type: InterfaceType): void { type.resolvedBaseTypes = type.resolvedBaseTypes || emptyArray; if (type.symbol.declarations) { for (const declaration of type.symbol.declarations) { if (declaration.kind === SyntaxKind.InterfaceDeclaration && getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)) { for (const node of getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)!) { const baseType = getReducedType(getTypeFromTypeNode(node)); if (!isErrorType(baseType)) { if (isValidBaseType(baseType)) { if (type !== baseType && !hasBaseType(baseType, type)) { if (type.resolvedBaseTypes === emptyArray) { type.resolvedBaseTypes = [baseType as ObjectType]; } else { type.resolvedBaseTypes.push(baseType); } } else { reportCircularBaseType(declaration, type); } } else { error(node, Diagnostics.An_interface_can_only_extend_an_object_type_or_intersection_of_object_types_with_statically_known_members); } } } } } } } /** * Returns true if the interface given by the symbol is free of "this" references. * * Specifically, the result is true if the interface itself contains no references * to "this" in its body, if all base types are interfaces, * and if none of the base interfaces have a "this" type. */ function isThislessInterface(symbol: Symbol): boolean { if (!symbol.declarations) { return true; } for (const declaration of symbol.declarations) { if (declaration.kind === SyntaxKind.InterfaceDeclaration) { if (declaration.flags & NodeFlags.ContainsThis) { return false; } const baseTypeNodes = getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration); if (baseTypeNodes) { for (const node of baseTypeNodes) { if (isEntityNameExpression(node.expression)) { const baseSymbol = resolveEntityName(node.expression, SymbolFlags.Type, /*ignoreErrors*/ true); if (!baseSymbol || !(baseSymbol.flags & SymbolFlags.Interface) || getDeclaredTypeOfClassOrInterface(baseSymbol).thisType) { return false; } } } } } } return true; } function getDeclaredTypeOfClassOrInterface(symbol: Symbol): InterfaceType { let links = getSymbolLinks(symbol); const originalLinks = links; if (!links.declaredType) { const kind = symbol.flags & SymbolFlags.Class ? ObjectFlags.Class : ObjectFlags.Interface; const merged = mergeJSSymbols(symbol, symbol.valueDeclaration && getAssignedClassSymbol(symbol.valueDeclaration)); if (merged) { // note:we overwrite links because we just cloned the symbol symbol = merged; links = merged.links; } const type = originalLinks.declaredType = links.declaredType = createObjectType(kind, symbol) as InterfaceType; const outerTypeParameters = getOuterTypeParametersOfClassOrInterface(symbol); const localTypeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); // A class or interface is generic if it has type parameters or a "this" type. We always give classes a "this" type // because it is not feasible to analyze all members to determine if the "this" type escapes the class (in particular, // property types inferred from initializers and method return types inferred from return statements are very hard // to exhaustively analyze). We give interfaces a "this" type if we can't definitely determine that they are free of // "this" references. if (outerTypeParameters || localTypeParameters || kind === ObjectFlags.Class || !isThislessInterface(symbol)) { type.objectFlags |= ObjectFlags.Reference; type.typeParameters = concatenate(outerTypeParameters, localTypeParameters); type.outerTypeParameters = outerTypeParameters; type.localTypeParameters = localTypeParameters; (type as GenericType).instantiations = new Map(); (type as GenericType).instantiations.set(getTypeListId(type.typeParameters), type as GenericType); (type as GenericType).target = type as GenericType; (type as GenericType).resolvedTypeArguments = type.typeParameters; type.thisType = createTypeParameter(symbol); type.thisType.isThisType = true; type.thisType.constraint = type; } } return links.declaredType as InterfaceType; } function getDeclaredTypeOfTypeAlias(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.declaredType) { // Note that we use the links object as the target here because the symbol object is used as the unique // identity for resolution of the 'type' property in SymbolLinks. if (!pushTypeResolution(symbol, TypeSystemPropertyName.DeclaredType)) { return errorType; } const declaration = Debug.checkDefined(symbol.declarations?.find(isTypeAlias), "Type alias symbol with no valid declaration found"); const typeNode = isJSDocTypeAlias(declaration) ? declaration.typeExpression : declaration.type; // If typeNode is missing, we will error in checkJSDocTypedefTag. let type = typeNode ? getTypeFromTypeNode(typeNode) : errorType; if (popTypeResolution()) { const typeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); if (typeParameters) { // Initialize the instantiation cache for generic type aliases. The declared type corresponds to // an instantiation of the type alias with the type parameters supplied as type arguments. links.typeParameters = typeParameters; links.instantiations = new Map(); links.instantiations.set(getTypeListId(typeParameters), type); } } else { type = errorType; if (declaration.kind === SyntaxKind.JSDocEnumTag) { error(declaration.typeExpression.type, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); } else { error(isNamedDeclaration(declaration) ? declaration.name || declaration : declaration, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); } } links.declaredType = type; } return links.declaredType; } function getBaseTypeOfEnumLikeType(type: Type) { return type.flags & TypeFlags.EnumLike && type.symbol.flags & SymbolFlags.EnumMember ? getDeclaredTypeOfSymbol(getParentOfSymbol(type.symbol)!) : type; } function getDeclaredTypeOfEnum(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.declaredType) { const memberTypeList: Type[] = []; if (symbol.declarations) { for (const declaration of symbol.declarations) { if (declaration.kind === SyntaxKind.EnumDeclaration) { for (const member of (declaration as EnumDeclaration).members) { if (hasBindableName(member)) { const memberSymbol = getSymbolOfDeclaration(member); const value = getEnumMemberValue(member); const memberType = getFreshTypeOfLiteralType(value !== undefined ? getEnumLiteralType(value, getSymbolId(symbol), memberSymbol) : createComputedEnumType(memberSymbol)); getSymbolLinks(memberSymbol).declaredType = memberType; memberTypeList.push(getRegularTypeOfLiteralType(memberType)); } } } } } const enumType = memberTypeList.length ? getUnionType(memberTypeList, UnionReduction.Literal, symbol, /*aliasTypeArguments*/ undefined) : createComputedEnumType(symbol); if (enumType.flags & TypeFlags.Union) { enumType.flags |= TypeFlags.EnumLiteral; enumType.symbol = symbol; } links.declaredType = enumType; } return links.declaredType; } function createComputedEnumType(symbol: Symbol) { const regularType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; const freshType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; regularType.regularType = regularType; regularType.freshType = freshType; freshType.regularType = regularType; freshType.freshType = freshType; return regularType; } function getDeclaredTypeOfEnumMember(symbol: Symbol): Type { const links = getSymbolLinks(symbol); if (!links.declaredType) { const enumType = getDeclaredTypeOfEnum(getParentOfSymbol(symbol)!); if (!links.declaredType) { links.declaredType = enumType; } } return links.declaredType; } function getDeclaredTypeOfTypeParameter(symbol: Symbol): TypeParameter { const links = getSymbolLinks(symbol); return links.declaredType || (links.declaredType = createTypeParameter(symbol)); } function getDeclaredTypeOfAlias(symbol: Symbol): Type { const links = getSymbolLinks(symbol); return links.declaredType || (links.declaredType = getDeclaredTypeOfSymbol(resolveAlias(symbol))); } function getDeclaredTypeOfSymbol(symbol: Symbol): Type { return tryGetDeclaredTypeOfSymbol(symbol) || errorType; } function tryGetDeclaredTypeOfSymbol(symbol: Symbol): Type | undefined { if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { return getDeclaredTypeOfClassOrInterface(symbol); } if (symbol.flags & SymbolFlags.TypeAlias) { return getDeclaredTypeOfTypeAlias(symbol); } if (symbol.flags & SymbolFlags.TypeParameter) { return getDeclaredTypeOfTypeParameter(symbol); } if (symbol.flags & SymbolFlags.Enum) { return getDeclaredTypeOfEnum(symbol); } if (symbol.flags & SymbolFlags.EnumMember) { return getDeclaredTypeOfEnumMember(symbol); } if (symbol.flags & SymbolFlags.Alias) { return getDeclaredTypeOfAlias(symbol); } return undefined; } /** * A type is free of this references if it's the any, string, number, boolean, symbol, or void keyword, a string * literal type, an array with an element type that is free of this references, or a type reference that is * free of this references. */ function isThislessType(node: TypeNode): boolean { switch (node.kind) { case SyntaxKind.AnyKeyword: case SyntaxKind.UnknownKeyword: case SyntaxKind.StringKeyword: case SyntaxKind.NumberKeyword: case SyntaxKind.BigIntKeyword: case SyntaxKind.BooleanKeyword: case SyntaxKind.SymbolKeyword: case SyntaxKind.ObjectKeyword: case SyntaxKind.VoidKeyword: case SyntaxKind.UndefinedKeyword: case SyntaxKind.NeverKeyword: case SyntaxKind.LiteralType: return true; case SyntaxKind.ArrayType: return isThislessType((node as ArrayTypeNode).elementType); case SyntaxKind.TypeReference: return !(node as TypeReferenceNode).typeArguments || (node as TypeReferenceNode).typeArguments!.every(isThislessType); } return false; } /** A type parameter is thisless if its constraint is thisless, or if it has no constraint. */ function isThislessTypeParameter(node: TypeParameterDeclaration) { const constraint = getEffectiveConstraintOfTypeParameter(node); return !constraint || isThislessType(constraint); } /** * A variable-like declaration is free of this references if it has a type annotation * that is thisless, or if it has no type annotation and no initializer (and is thus of type any). */ function isThislessVariableLikeDeclaration(node: VariableLikeDeclaration): boolean { const typeNode = getEffectiveTypeAnnotationNode(node); return typeNode ? isThislessType(typeNode) : !hasInitializer(node); } /** * A function-like declaration is considered free of `this` references if it has a return type * annotation that is free of this references and if each parameter is thisless and if * each type parameter (if present) is thisless. */ function isThislessFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { const returnType = getEffectiveReturnTypeNode(node); const typeParameters = getEffectiveTypeParameterDeclarations(node); return (node.kind === SyntaxKind.Constructor || (!!returnType && isThislessType(returnType))) && node.parameters.every(isThislessVariableLikeDeclaration) && typeParameters.every(isThislessTypeParameter); } /** * Returns true if the class or interface member given by the symbol is free of "this" references. The * function may return false for symbols that are actually free of "this" references because it is not * feasible to perform a complete analysis in all cases. In particular, property members with types * inferred from their initializers and function members with inferred return types are conservatively * assumed not to be free of "this" references. */ function isThisless(symbol: Symbol): boolean { if (symbol.declarations && symbol.declarations.length === 1) { const declaration = symbol.declarations[0]; if (declaration) { switch (declaration.kind) { case SyntaxKind.PropertyDeclaration: case SyntaxKind.PropertySignature: return isThislessVariableLikeDeclaration(declaration as VariableLikeDeclaration); case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: case SyntaxKind.Constructor: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: return isThislessFunctionLikeDeclaration(declaration as FunctionLikeDeclaration | AccessorDeclaration); } } } return false; } // The mappingThisOnly flag indicates that the only type parameter being mapped is "this". When the flag is true, // we check symbols to see if we can quickly conclude they are free of "this" references, thus needing no instantiation. function createInstantiatedSymbolTable(symbols: Symbol[], mapper: TypeMapper, mappingThisOnly: boolean): SymbolTable { const result = createSymbolTable(); for (const symbol of symbols) { result.set(symbol.escapedName, mappingThisOnly && isThisless(symbol) ? symbol : instantiateSymbol(symbol, mapper)); } return result; } function addInheritedMembers(symbols: SymbolTable, baseSymbols: Symbol[]) { for (const s of baseSymbols) { if (!symbols.has(s.escapedName) && !isStaticPrivateIdentifierProperty(s)) { symbols.set(s.escapedName, s); } } } function isStaticPrivateIdentifierProperty(s: Symbol): boolean { return !!s.valueDeclaration && isPrivateIdentifierClassElementDeclaration(s.valueDeclaration) && isStatic(s.valueDeclaration); } function resolveDeclaredMembers(type: InterfaceType): InterfaceTypeWithDeclaredMembers { if (!(type as InterfaceTypeWithDeclaredMembers).declaredProperties) { const symbol = type.symbol; const members = getMembersOfSymbol(symbol); (type as InterfaceTypeWithDeclaredMembers).declaredProperties = getNamedMembers(members); // Start with signatures at empty array in case of recursive types (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = emptyArray; (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = emptyArray; (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = emptyArray; (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = getIndexInfosOfSymbol(symbol); } return type as InterfaceTypeWithDeclaredMembers; } /** * Indicates whether a type can be used as a property name. */ function isTypeUsableAsPropertyName(type: Type): type is StringLiteralType | NumberLiteralType | UniqueESSymbolType { return !!(type.flags & TypeFlags.StringOrNumberLiteralOrUnique); } /** * Indicates whether a declaration name is definitely late-bindable. * A declaration name is only late-bindable if: * - It is a `ComputedPropertyName`. * - Its expression is an `Identifier` or either a `PropertyAccessExpression` an * `ElementAccessExpression` consisting only of these same three types of nodes. * - The type of its expression is a string or numeric literal type, or is a `unique symbol` type. */ function isLateBindableName(node: DeclarationName): node is LateBoundName { if (!isComputedPropertyName(node) && !isElementAccessExpression(node)) { return false; } const expr = isComputedPropertyName(node) ? node.expression : node.argumentExpression; return isEntityNameExpression(expr) && isTypeUsableAsPropertyName(isComputedPropertyName(node) ? checkComputedPropertyName(node) : checkExpressionCached(expr)); } function isLateBoundName(name: __String): boolean { return (name as string).charCodeAt(0) === CharacterCodes._ && (name as string).charCodeAt(1) === CharacterCodes._ && (name as string).charCodeAt(2) === CharacterCodes.at; } /** * Indicates whether a declaration has a late-bindable dynamic name. */ function hasLateBindableName(node: Declaration): node is LateBoundDeclaration | LateBoundBinaryExpressionDeclaration { const name = getNameOfDeclaration(node); return !!name && isLateBindableName(name); } /** * Indicates whether a declaration has an early-bound name or a dynamic name that can be late-bound. */ function hasBindableName(node: Declaration) { return !hasDynamicName(node) || hasLateBindableName(node); } /** * Indicates whether a declaration name is a dynamic name that cannot be late-bound. */ function isNonBindableDynamicName(node: DeclarationName) { return isDynamicName(node) && !isLateBindableName(node); } /** * Gets the symbolic name for a member from its type. */ function getPropertyNameFromType(type: StringLiteralType | NumberLiteralType | UniqueESSymbolType): __String { if (type.flags & TypeFlags.UniqueESSymbol) { return (type as UniqueESSymbolType).escapedName; } if (type.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { return escapeLeadingUnderscores("" + (type as StringLiteralType | NumberLiteralType).value); } return Debug.fail(); } /** * Adds a declaration to a late-bound dynamic member. This performs the same function for * late-bound members that `addDeclarationToSymbol` in binder.ts performs for early-bound * members. */ function addDeclarationToLateBoundSymbol(symbol: Symbol, member: LateBoundDeclaration | BinaryExpression, symbolFlags: SymbolFlags) { Debug.assert(!!(getCheckFlags(symbol) & CheckFlags.Late), "Expected a late-bound symbol."); symbol.flags |= symbolFlags; getSymbolLinks(member.symbol).lateSymbol = symbol; if (!symbol.declarations) { symbol.declarations = [member]; } else if(!member.symbol.isReplaceableByMethod) { symbol.declarations.push(member); } if (symbolFlags & SymbolFlags.Value) { if (!symbol.valueDeclaration || symbol.valueDeclaration.kind !== member.kind) { symbol.valueDeclaration = member; } } } /** * Performs late-binding of a dynamic member. This performs the same function for * late-bound members that `declareSymbol` in binder.ts performs for early-bound * members. * * If a symbol is a dynamic name from a computed property, we perform an additional "late" * binding phase to attempt to resolve the name for the symbol from the type of the computed * property's expression. If the type of the expression is a string-literal, numeric-literal, * or unique symbol type, we can use that type as the name of the symbol. * * For example, given: * * const x = Symbol(); * * interface I { * [x]: number; * } * * The binder gives the property `[x]: number` a special symbol with the name "__computed". * In the late-binding phase we can type-check the expression `x` and see that it has a * unique symbol type which we can then use as the name of the member. This allows users * to define custom symbols that can be used in the members of an object type. * * @param parent The containing symbol for the member. * @param earlySymbols The early-bound symbols of the parent. * @param lateSymbols The late-bound symbols of the parent. * @param decl The member to bind. */ function lateBindMember(parent: Symbol, earlySymbols: SymbolTable | undefined, lateSymbols: UnderscoreEscapedMap, decl: LateBoundDeclaration | LateBoundBinaryExpressionDeclaration) { Debug.assert(!!decl.symbol, "The member is expected to have a symbol."); const links = getNodeLinks(decl); if (!links.resolvedSymbol) { // In the event we attempt to resolve the late-bound name of this member recursively, // fall back to the early-bound name of this member. links.resolvedSymbol = decl.symbol; const declName = isBinaryExpression(decl) ? decl.left : decl.name; const type = isElementAccessExpression(declName) ? checkExpressionCached(declName.argumentExpression) : checkComputedPropertyName(declName); if (isTypeUsableAsPropertyName(type)) { const memberName = getPropertyNameFromType(type); const symbolFlags = decl.symbol.flags; // Get or add a late-bound symbol for the member. This allows us to merge late-bound accessor declarations. let lateSymbol = lateSymbols.get(memberName); if (!lateSymbol) lateSymbols.set(memberName, lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late)); // Report an error if a late-bound member has the same name as an early-bound member, // or if we have another early-bound symbol declaration with the same name and // conflicting flags. const earlySymbol = earlySymbols && earlySymbols.get(memberName); if (lateSymbol.flags & getExcludedSymbolFlags(symbolFlags) || earlySymbol) { // If we have an existing early-bound member, combine its declarations so that we can // report an error at each declaration. const declarations = earlySymbol ? concatenate(earlySymbol.declarations, lateSymbol.declarations) : lateSymbol.declarations; const name = !(type.flags & TypeFlags.UniqueESSymbol) && unescapeLeadingUnderscores(memberName) || declarationNameToString(declName); forEach(declarations, declaration => error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Property_0_was_also_declared_here, name)); error(declName || decl, Diagnostics.Duplicate_property_0, name); lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late); } lateSymbol.links.nameType = type; addDeclarationToLateBoundSymbol(lateSymbol, decl, symbolFlags); if (lateSymbol.parent) { Debug.assert(lateSymbol.parent === parent, "Existing symbol parent should match new one"); } else { lateSymbol.parent = parent; } return links.resolvedSymbol = lateSymbol; } } return links.resolvedSymbol; } function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): UnderscoreEscapedMap { const links = getSymbolLinks(symbol); if (!links[resolutionKind]) { const isStatic = resolutionKind === MembersOrExportsResolutionKind.resolvedExports; const earlySymbols = !isStatic ? symbol.members : symbol.flags & SymbolFlags.Module ? getExportsOfModuleWorker(symbol).exports : symbol.exports; // In the event we recursively resolve the members/exports of the symbol, we // set the initial value of resolvedMembers/resolvedExports to the early-bound // members/exports of the symbol. links[resolutionKind] = earlySymbols || emptySymbols; // fill in any as-yet-unresolved late-bound members. const lateSymbols = createSymbolTable() as UnderscoreEscapedMap; for (const decl of symbol.declarations || emptyArray) { const members = getMembersOfDeclaration(decl); if (members) { for (const member of members) { if (isStatic === hasStaticModifier(member)) { if (hasLateBindableName(member)) { lateBindMember(symbol, earlySymbols, lateSymbols, member); } } } } } const assignments = symbol.assignmentDeclarationMembers; if (assignments) { const decls = arrayFrom(assignments.values()); for (const member of decls) { const assignmentKind = getAssignmentDeclarationKind(member as BinaryExpression | CallExpression); const isInstanceMember = assignmentKind === AssignmentDeclarationKind.PrototypeProperty || isBinaryExpression(member) && isPossiblyAliasedThisProperty(member, assignmentKind) || assignmentKind === AssignmentDeclarationKind.ObjectDefinePrototypeProperty || assignmentKind === AssignmentDeclarationKind.Prototype; // A straight `Prototype` assignment probably can never have a computed name if (isStatic === !isInstanceMember) { if (hasLateBindableName(member)) { lateBindMember(symbol, earlySymbols, lateSymbols, member); } } } } links[resolutionKind] = combineSymbolTables(earlySymbols, lateSymbols) || emptySymbols; } return links[resolutionKind]!; } /** * Gets a SymbolTable containing both the early- and late-bound members of a symbol. * * For a description of late-binding, see `lateBindMember`. */ function getMembersOfSymbol(symbol: Symbol) { return symbol.flags & SymbolFlags.LateBindingContainer ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedMembers) : symbol.members || emptySymbols; } /** * If a symbol is the dynamic name of the member of an object type, get the late-bound * symbol of the member. * * For a description of late-binding, see `lateBindMember`. */ function getLateBoundSymbol(symbol: Symbol): Symbol { if (symbol.flags & SymbolFlags.ClassMember && symbol.escapedName === InternalSymbolName.Computed) { const links = getSymbolLinks(symbol); if (!links.lateSymbol && some(symbol.declarations, hasLateBindableName)) { // force late binding of members/exports. This will set the late-bound symbol const parent = getMergedSymbol(symbol.parent)!; if (some(symbol.declarations, hasStaticModifier)) { getExportsOfSymbol(parent); } else { getMembersOfSymbol(parent); } } return links.lateSymbol || (links.lateSymbol = symbol); } return symbol; } function getTypeWithThisArgument(type: Type, thisArgument?: Type, needApparentType?: boolean): Type { if (getObjectFlags(type) & ObjectFlags.Reference) { const target = (type as TypeReference).target; const typeArguments = getTypeArguments(type as TypeReference); if (length(target.typeParameters) === length(typeArguments)) { const ref = createTypeReference(target, concatenate(typeArguments, [thisArgument || target.thisType!])); return needApparentType ? getApparentType(ref) : ref; } } else if (type.flags & TypeFlags.Intersection) { const types = sameMap((type as IntersectionType).types, t => getTypeWithThisArgument(t, thisArgument, needApparentType)); return types !== (type as IntersectionType).types ? getIntersectionType(types) : type; } return needApparentType ? getApparentType(type) : type; } function resolveObjectTypeMembers(type: ObjectType, source: InterfaceTypeWithDeclaredMembers, typeParameters: readonly TypeParameter[], typeArguments: readonly Type[]) { let mapper: TypeMapper | undefined; let members: SymbolTable; let callSignatures: readonly Signature[]; let constructSignatures: readonly Signature[]; let indexInfos: readonly IndexInfo[]; if (rangeEquals(typeParameters, typeArguments, 0, typeParameters.length)) { members = source.symbol ? getMembersOfSymbol(source.symbol) : createSymbolTable(source.declaredProperties); callSignatures = source.declaredCallSignatures; constructSignatures = source.declaredConstructSignatures; indexInfos = source.declaredIndexInfos; } else { mapper = createTypeMapper(typeParameters, typeArguments); members = createInstantiatedSymbolTable(source.declaredProperties, mapper, /*mappingThisOnly*/ typeParameters.length === 1); callSignatures = instantiateSignatures(source.declaredCallSignatures, mapper); constructSignatures = instantiateSignatures(source.declaredConstructSignatures, mapper); indexInfos = instantiateIndexInfos(source.declaredIndexInfos, mapper); } const baseTypes = getBaseTypes(source); if (baseTypes.length) { if (source.symbol && members === getMembersOfSymbol(source.symbol)) { members = createSymbolTable(source.declaredProperties); } setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); const thisArgument = lastOrUndefined(typeArguments); for (const baseType of baseTypes) { const instantiatedBaseType = thisArgument ? getTypeWithThisArgument(instantiateType(baseType, mapper), thisArgument) : baseType; addInheritedMembers(members, getPropertiesOfType(instantiatedBaseType)); callSignatures = concatenate(callSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Call)); constructSignatures = concatenate(constructSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Construct)); const inheritedIndexInfos = instantiatedBaseType !== anyType ? getIndexInfosOfType(instantiatedBaseType) : [createIndexInfo(stringType, anyType, /*isReadonly*/ false)]; indexInfos = concatenate(indexInfos, filter(inheritedIndexInfos, info => !findIndexInfo(indexInfos, info.keyType))); } } setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); } function resolveClassOrInterfaceMembers(type: InterfaceType): void { resolveObjectTypeMembers(type, resolveDeclaredMembers(type), emptyArray, emptyArray); } function resolveTypeReferenceMembers(type: TypeReference): void { const source = resolveDeclaredMembers(type.target); const typeParameters = concatenate(source.typeParameters!, [source.thisType!]); const typeArguments = getTypeArguments(type); const paddedTypeArguments = typeArguments.length === typeParameters.length ? typeArguments : concatenate(typeArguments, [type]); resolveObjectTypeMembers(type, source, typeParameters, paddedTypeArguments); } function createSignature( declaration: SignatureDeclaration | JSDocSignature | undefined, typeParameters: readonly TypeParameter[] | undefined, thisParameter: Symbol | undefined, parameters: readonly Symbol[], resolvedReturnType: Type | undefined, resolvedTypePredicate: TypePredicate | undefined, minArgumentCount: number, flags: SignatureFlags ): Signature { const sig = new Signature(checker, flags); sig.declaration = declaration; sig.typeParameters = typeParameters; sig.parameters = parameters; sig.thisParameter = thisParameter; sig.resolvedReturnType = resolvedReturnType; sig.resolvedTypePredicate = resolvedTypePredicate; sig.minArgumentCount = minArgumentCount; sig.resolvedMinArgumentCount = undefined; sig.target = undefined; sig.mapper = undefined; sig.compositeSignatures = undefined; sig.compositeKind = undefined; return sig; } function cloneSignature(sig: Signature): Signature { const result = createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags); result.target = sig.target; result.mapper = sig.mapper; result.compositeSignatures = sig.compositeSignatures; result.compositeKind = sig.compositeKind; return result; } function createUnionSignature(signature: Signature, unionSignatures: Signature[]) { const result = cloneSignature(signature); result.compositeSignatures = unionSignatures; result.compositeKind = TypeFlags.Union; result.target = undefined; result.mapper = undefined; return result; } function getOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags): Signature { if ((signature.flags & SignatureFlags.CallChainFlags) === callChainFlags) { return signature; } if (!signature.optionalCallSignatureCache) { signature.optionalCallSignatureCache = {}; } const key = callChainFlags === SignatureFlags.IsInnerCallChain ? "inner" : "outer"; return signature.optionalCallSignatureCache[key] || (signature.optionalCallSignatureCache[key] = createOptionalCallSignature(signature, callChainFlags)); } function createOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags) { Debug.assert(callChainFlags === SignatureFlags.IsInnerCallChain || callChainFlags === SignatureFlags.IsOuterCallChain, "An optional call signature can either be for an inner call chain or an outer call chain, but not both."); const result = cloneSignature(signature); result.flags |= callChainFlags; return result; } function getExpandedParameters(sig: Signature, skipUnionExpanding?: boolean): readonly (readonly Symbol[])[] { if (signatureHasRestParameter(sig)) { const restIndex = sig.parameters.length - 1; const restType = getTypeOfSymbol(sig.parameters[restIndex]); if (isTupleType(restType)) { return [expandSignatureParametersWithTupleMembers(restType, restIndex)]; } else if (!skipUnionExpanding && restType.flags & TypeFlags.Union && every((restType as UnionType).types, isTupleType)) { return map((restType as UnionType).types, t => expandSignatureParametersWithTupleMembers(t as TupleTypeReference, restIndex)); } } return [sig.parameters]; function expandSignatureParametersWithTupleMembers(restType: TupleTypeReference, restIndex: number) { const elementTypes = getTypeArguments(restType); const associatedNames = restType.target.labeledElementDeclarations; const restParams = map(elementTypes, (t, i) => { // Lookup the label from the individual tuple passed in before falling back to the signature `rest` parameter name const tupleLabelName = !!associatedNames && getTupleElementLabel(associatedNames[i]); const name = tupleLabelName || getParameterNameAtPosition(sig, restIndex + i, restType); const flags = restType.target.elementFlags[i]; const checkFlags = flags & ElementFlags.Variable ? CheckFlags.RestParameter : flags & ElementFlags.Optional ? CheckFlags.OptionalParameter : 0; const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name, checkFlags); symbol.links.type = flags & ElementFlags.Rest ? createArrayType(t) : t; return symbol; }); return concatenate(sig.parameters.slice(0, restIndex), restParams); } } function getDefaultConstructSignatures(classType: InterfaceType): Signature[] { const baseConstructorType = getBaseConstructorTypeOfClass(classType); const baseSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); const declaration = getClassLikeDeclarationOfSymbol(classType.symbol); const isAbstract = !!declaration && hasSyntacticModifier(declaration, ModifierFlags.Abstract); if (baseSignatures.length === 0) { return [createSignature(undefined, classType.localTypeParameters, undefined, emptyArray, classType, /*resolvedTypePredicate*/ undefined, 0, isAbstract ? SignatureFlags.Abstract : SignatureFlags.None)]; } const baseTypeNode = getBaseTypeNodeOfClass(classType)!; const isJavaScript = isInJSFile(baseTypeNode); const typeArguments = typeArgumentsFromTypeReferenceNode(baseTypeNode); const typeArgCount = length(typeArguments); const result: Signature[] = []; for (const baseSig of baseSignatures) { const minTypeArgumentCount = getMinTypeArgumentCount(baseSig.typeParameters); const typeParamCount = length(baseSig.typeParameters); if (isJavaScript || typeArgCount >= minTypeArgumentCount && typeArgCount <= typeParamCount) { const sig = typeParamCount ? createSignatureInstantiation(baseSig, fillMissingTypeArguments(typeArguments, baseSig.typeParameters, minTypeArgumentCount, isJavaScript)) : cloneSignature(baseSig); sig.typeParameters = classType.localTypeParameters; sig.resolvedReturnType = classType; sig.flags = isAbstract ? sig.flags | SignatureFlags.Abstract : sig.flags & ~SignatureFlags.Abstract; result.push(sig); } } return result; } function findMatchingSignature(signatureList: readonly Signature[], signature: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean): Signature | undefined { for (const s of signatureList) { if (compareSignaturesIdentical(s, signature, partialMatch, ignoreThisTypes, ignoreReturnTypes, partialMatch ? compareTypesSubtypeOf : compareTypesIdentical)) { return s; } } } function findMatchingSignatures(signatureLists: readonly (readonly Signature[])[], signature: Signature, listIndex: number): Signature[] | undefined { if (signature.typeParameters) { // We require an exact match for generic signatures, so we only return signatures from the first // signature list and only if they have exact matches in the other signature lists. if (listIndex > 0) { return undefined; } for (let i = 1; i < signatureLists.length; i++) { if (!findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false)) { return undefined; } } return [signature]; } let result: Signature[] | undefined; for (let i = 0; i < signatureLists.length; i++) { // Allow matching non-generic signatures to have excess parameters and different return types. // Prefer matching this types if possible. const match = i === listIndex ? signature : findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ true, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true); if (!match) { return undefined; } result = appendIfUnique(result, match); } return result; } // The signatures of a union type are those signatures that are present in each of the constituent types. // Generic signatures must match exactly, but non-generic signatures are allowed to have extra optional // parameters and may differ in return types. When signatures differ in return types, the resulting return // type is the union of the constituent return types. function getUnionSignatures(signatureLists: readonly (readonly Signature[])[]): Signature[] { let result: Signature[] | undefined; let indexWithLengthOverOne: number | undefined; for (let i = 0; i < signatureLists.length; i++) { if (signatureLists[i].length === 0) return emptyArray; if (signatureLists[i].length > 1) { indexWithLengthOverOne = indexWithLengthOverOne === undefined ? i : -1; // -1 is a signal there are multiple overload sets } for (const signature of signatureLists[i]) { // Only process signatures with parameter lists that aren't already in the result list if (!result || !findMatchingSignature(result, signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true)) { const unionSignatures = findMatchingSignatures(signatureLists, signature, i); if (unionSignatures) { let s = signature; // Union the result types when more than one signature matches if (unionSignatures.length > 1) { let thisParameter = signature.thisParameter; const firstThisParameterOfUnionSignatures = forEach(unionSignatures, sig => sig.thisParameter); if (firstThisParameterOfUnionSignatures) { const thisType = getIntersectionType(mapDefined(unionSignatures, sig => sig.thisParameter && getTypeOfSymbol(sig.thisParameter))); thisParameter = createSymbolWithType(firstThisParameterOfUnionSignatures, thisType); } s = createUnionSignature(signature, unionSignatures); s.thisParameter = thisParameter; } (result || (result = [])).push(s); } } } } if (!length(result) && indexWithLengthOverOne !== -1) { // No sufficiently similar signature existed to subsume all the other signatures in the union - time to see if we can make a single // signature that handles all over them. We only do this when there are overloads in only one constituent. // (Overloads are conditional in nature and having overloads in multiple constituents would necessitate making a power set of // signatures from the type, whose ordering would be non-obvious) const masterList = signatureLists[indexWithLengthOverOne !== undefined ? indexWithLengthOverOne : 0]; let results: Signature[] | undefined = masterList.slice(); for (const signatures of signatureLists) { if (signatures !== masterList) { const signature = signatures[0]; Debug.assert(!!signature, "getUnionSignatures bails early on empty signature lists and should not have empty lists on second pass"); results = !!signature.typeParameters && some(results, s => !!s.typeParameters && !compareTypeParametersIdentical(signature.typeParameters, s.typeParameters)) ? undefined : map(results, sig => combineSignaturesOfUnionMembers(sig, signature)); if (!results) { break; } } } result = results; } return result || emptyArray; } function compareTypeParametersIdentical(sourceParams: readonly TypeParameter[] | undefined, targetParams: readonly TypeParameter[] | undefined): boolean { if (length(sourceParams) !== length(targetParams)) { return false; } if (!sourceParams || !targetParams) { return true; } const mapper = createTypeMapper(targetParams, sourceParams); for (let i = 0; i < sourceParams.length; i++) { const source = sourceParams[i]; const target = targetParams[i]; if (source === target) continue; // We instantiate the target type parameter constraints into the source types so we can recognize `` as the same as `` if (!isTypeIdenticalTo(getConstraintFromTypeParameter(source) || unknownType, instantiateType(getConstraintFromTypeParameter(target) || unknownType, mapper))) return false; // We don't compare defaults - we just use the type parameter defaults from the first signature that seems to match. // It might make sense to combine these defaults in the future, but doing so intelligently requires knowing // if the parameter is used covariantly or contravariantly (so we intersect if it's used like a parameter or union if used like a return type) // and, since it's just an inference _default_, just picking one arbitrarily works OK. } return true; } function combineUnionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { if (!left || !right) { return left || right; } // A signature `this` type might be a read or a write position... It's very possible that it should be invariant // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be // permissive when calling, for now, we'll intersect the `this` types just like we do for param types in union signatures. const thisType = getIntersectionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); return createSymbolWithType(left, thisType); } function combineUnionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { const leftCount = getParameterCount(left); const rightCount = getParameterCount(right); const longest = leftCount >= rightCount ? left : right; const shorter = longest === left ? right : left; const longestCount = longest === left ? leftCount : rightCount; const eitherHasEffectiveRest = (hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right)); const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); for (let i = 0; i < longestCount; i++) { let longestParamType = tryGetTypeAtPosition(longest, i)!; if (longest === right) { longestParamType = instantiateType(longestParamType, mapper); } let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; if (shorter === right) { shorterParamType = instantiateType(shorterParamType, mapper); } const unionParamType = getIntersectionType([longestParamType, shorterParamType]); const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); const paramName = leftName === rightName ? leftName : !leftName ? rightName : !rightName ? leftName : undefined; const paramSymbol = createSymbol( SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), paramName || `arg${i}` as __String ); paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; params[i] = paramSymbol; } if (needsExtraRestElement) { const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String); restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); if (shorter === right) { restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); } params[longestCount] = restParamSymbol; } return params; } function combineSignaturesOfUnionMembers(left: Signature, right: Signature): Signature { const typeParams = left.typeParameters || right.typeParameters; let paramMapper: TypeMapper | undefined; if (left.typeParameters && right.typeParameters) { paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); // We just use the type parameter defaults from the first signature } const declaration = left.declaration; const params = combineUnionParameters(left, right, paramMapper); const thisParam = combineUnionThisParam(left.thisParameter, right.thisParameter, paramMapper); const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); const result = createSignature( declaration, typeParams, thisParam, params, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, minArgCount, (left.flags | right.flags) & SignatureFlags.PropagatingFlags ); result.compositeKind = TypeFlags.Union; result.compositeSignatures = concatenate(left.compositeKind !== TypeFlags.Intersection && left.compositeSignatures || [left], [right]); if (paramMapper) { result.mapper = left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; } return result; } function getUnionIndexInfos(types: readonly Type[]): IndexInfo[] { const sourceInfos = getIndexInfosOfType(types[0]); if (sourceInfos) { const result = []; for (const info of sourceInfos) { const indexType = info.keyType; if (every(types, t => !!getIndexInfoOfType(t, indexType))) { result.push(createIndexInfo(indexType, getUnionType(map(types, t => getIndexTypeOfType(t, indexType)!)), some(types, t => getIndexInfoOfType(t, indexType)!.isReadonly))); } } return result; } return emptyArray; } function resolveUnionTypeMembers(type: UnionType) { // The members and properties collections are empty for union types. To get all properties of a union // type use getPropertiesOfType (only the language service uses this). const callSignatures = getUnionSignatures(map(type.types, t => t === globalFunctionType ? [unknownSignature] : getSignaturesOfType(t, SignatureKind.Call))); const constructSignatures = getUnionSignatures(map(type.types, t => getSignaturesOfType(t, SignatureKind.Construct))); const indexInfos = getUnionIndexInfos(type.types); setStructuredTypeMembers(type, emptySymbols, callSignatures, constructSignatures, indexInfos); } function intersectTypes(type1: Type, type2: Type): Type; function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined; function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined { return !type1 ? type2 : !type2 ? type1 : getIntersectionType([type1, type2]); } function findMixins(types: readonly Type[]): readonly boolean[] { const constructorTypeCount = countWhere(types, (t) => getSignaturesOfType(t, SignatureKind.Construct).length > 0); const mixinFlags = map(types, isMixinConstructorType); if (constructorTypeCount > 0 && constructorTypeCount === countWhere(mixinFlags, (b) => b)) { const firstMixinIndex = mixinFlags.indexOf(/*searchElement*/ true); mixinFlags[firstMixinIndex] = false; } return mixinFlags; } function includeMixinType(type: Type, types: readonly Type[], mixinFlags: readonly boolean[], index: number): Type { const mixedTypes: Type[] = []; for (let i = 0; i < types.length; i++) { if (i === index) { mixedTypes.push(type); } else if (mixinFlags[i]) { mixedTypes.push(getReturnTypeOfSignature(getSignaturesOfType(types[i], SignatureKind.Construct)[0])); } } return getIntersectionType(mixedTypes); } function resolveIntersectionTypeMembers(type: IntersectionType) { // The members and properties collections are empty for intersection types. To get all properties of an // intersection type use getPropertiesOfType (only the language service uses this). let callSignatures: Signature[] | undefined; let constructSignatures: Signature[] | undefined; let indexInfos: IndexInfo[] | undefined; const types = type.types; const mixinFlags = findMixins(types); const mixinCount = countWhere(mixinFlags, (b) => b); for (let i = 0; i < types.length; i++) { const t = type.types[i]; // When an intersection type contains mixin constructor types, the construct signatures from // those types are discarded and their return types are mixed into the return types of all // other construct signatures in the intersection type. For example, the intersection type // '{ new(...args: any[]) => A } & { new(s: string) => B }' has a single construct signature // 'new(s: string) => A & B'. if (!mixinFlags[i]) { let signatures = getSignaturesOfType(t, SignatureKind.Construct); if (signatures.length && mixinCount > 0) { signatures = map(signatures, s => { const clone = cloneSignature(s); clone.resolvedReturnType = includeMixinType(getReturnTypeOfSignature(s), types, mixinFlags, i); return clone; }); } constructSignatures = appendSignatures(constructSignatures, signatures); } callSignatures = appendSignatures(callSignatures, getSignaturesOfType(t, SignatureKind.Call)); indexInfos = reduceLeft(getIndexInfosOfType(t), (infos, newInfo) => appendIndexInfo(infos, newInfo, /*union*/ false), indexInfos); } setStructuredTypeMembers(type, emptySymbols, callSignatures || emptyArray, constructSignatures || emptyArray, indexInfos || emptyArray); } function appendSignatures(signatures: Signature[] | undefined, newSignatures: readonly Signature[]) { for (const sig of newSignatures) { if (!signatures || every(signatures, s => !compareSignaturesIdentical(s, sig, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, compareTypesIdentical))) { signatures = append(signatures, sig); } } return signatures; } function appendIndexInfo(indexInfos: IndexInfo[] | undefined, newInfo: IndexInfo, union: boolean) { if (indexInfos) { for (let i = 0; i < indexInfos.length; i++) { const info = indexInfos[i]; if (info.keyType === newInfo.keyType) { indexInfos[i] = createIndexInfo(info.keyType, union ? getUnionType([info.type, newInfo.type]) : getIntersectionType([info.type, newInfo.type]), union ? info.isReadonly || newInfo.isReadonly : info.isReadonly && newInfo.isReadonly); return indexInfos; } } } return append(indexInfos, newInfo); } /** * Converts an AnonymousType to a ResolvedType. */ function resolveAnonymousTypeMembers(type: AnonymousType) { if (type.target) { setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); const members = createInstantiatedSymbolTable(getPropertiesOfObjectType(type.target), type.mapper!, /*mappingThisOnly*/ false); const callSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Call), type.mapper!); const constructSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Construct), type.mapper!); const indexInfos = instantiateIndexInfos(getIndexInfosOfType(type.target), type.mapper!); setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); return; } const symbol = getMergedSymbol(type.symbol); if (symbol.flags & SymbolFlags.TypeLiteral) { setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); const members = getMembersOfSymbol(symbol); const callSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); const constructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); const indexInfos = getIndexInfosOfSymbol(symbol); setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); return; } // Combinations of function, class, enum and module let members = emptySymbols; let indexInfos: IndexInfo[] | undefined; if (symbol.exports) { members = getExportsOfSymbol(symbol); if (symbol === globalThisSymbol) { const varsOnly = new Map() as SymbolTable; members.forEach(p => { if (!(p.flags & SymbolFlags.BlockScoped) && !(p.flags & SymbolFlags.ValueModule && p.declarations?.length && every(p.declarations, isAmbientModule))) { varsOnly.set(p.escapedName, p); } }); members = varsOnly; } } let baseConstructorIndexInfo: IndexInfo | undefined; setStructuredTypeMembers(type, members, emptyArray, emptyArray, emptyArray); if (symbol.flags & SymbolFlags.Class) { const classType = getDeclaredTypeOfClassOrInterface(symbol); const baseConstructorType = getBaseConstructorTypeOfClass(classType); if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.TypeVariable)) { members = createSymbolTable(getNamedOrIndexSignatureMembers(members)); addInheritedMembers(members, getPropertiesOfType(baseConstructorType)); } else if (baseConstructorType === anyType) { baseConstructorIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); } } const indexSymbol = getIndexSymbolFromSymbolTable(members); if (indexSymbol) { indexInfos = getIndexInfosOfIndexSymbol(indexSymbol); } else { if (baseConstructorIndexInfo) { indexInfos = append(indexInfos, baseConstructorIndexInfo); } if (symbol.flags & SymbolFlags.Enum && (getDeclaredTypeOfSymbol(symbol).flags & TypeFlags.Enum || some(type.properties, prop => !!(getTypeOfSymbol(prop).flags & TypeFlags.NumberLike)))) { indexInfos = append(indexInfos, enumNumberIndexInfo); } } setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); // We resolve the members before computing the signatures because a signature may use // typeof with a qualified name expression that circularly references the type we are // in the process of resolving (see issue #6072). The temporarily empty signature list // will never be observed because a qualified name can't reference signatures. if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { type.callSignatures = getSignaturesOfSymbol(symbol); } // And likewise for construct signatures for classes if (symbol.flags & SymbolFlags.Class) { const classType = getDeclaredTypeOfClassOrInterface(symbol); let constructSignatures = symbol.members ? getSignaturesOfSymbol(symbol.members.get(InternalSymbolName.Constructor)) : emptyArray; if (symbol.flags & SymbolFlags.Function) { constructSignatures = addRange(constructSignatures.slice(), mapDefined( type.callSignatures, sig => isJSConstructor(sig.declaration) ? createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, classType, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags) : undefined)); } if (!constructSignatures.length) { constructSignatures = getDefaultConstructSignatures(classType); } type.constructSignatures = constructSignatures; } } type ReplaceableIndexedAccessType = IndexedAccessType & { objectType: TypeParameter, indexType: TypeParameter }; function replaceIndexedAccess(instantiable: Type, type: ReplaceableIndexedAccessType, replacement: Type) { // map type.indexType to 0 // map type.objectType to `[TReplacement]` // thus making the indexed access `[TReplacement][0]` or `TReplacement` return instantiateType(instantiable, createTypeMapper([type.indexType, type.objectType], [getNumberLiteralType(0), createTupleType([replacement])])); } function resolveReverseMappedTypeMembers(type: ReverseMappedType) { const indexInfo = getIndexInfoOfType(type.source, stringType); const modifiers = getMappedTypeModifiers(type.mappedType); const readonlyMask = modifiers & MappedTypeModifiers.IncludeReadonly ? false : true; const optionalMask = modifiers & MappedTypeModifiers.IncludeOptional ? 0 : SymbolFlags.Optional; const indexInfos = indexInfo ? [createIndexInfo(stringType, inferReverseMappedType(indexInfo.type, type.mappedType, type.constraintType), readonlyMask && indexInfo.isReadonly)] : emptyArray; const members = createSymbolTable(); for (const prop of getPropertiesOfType(type.source)) { const checkFlags = CheckFlags.ReverseMapped | (readonlyMask && isReadonlySymbol(prop) ? CheckFlags.Readonly : 0); const inferredProp = createSymbol(SymbolFlags.Property | prop.flags & optionalMask, prop.escapedName, checkFlags) as ReverseMappedSymbol; inferredProp.declarations = prop.declarations; inferredProp.links.nameType = getSymbolLinks(prop).nameType; inferredProp.links.propertyType = getTypeOfSymbol(prop); if (type.constraintType.type.flags & TypeFlags.IndexedAccess && (type.constraintType.type as IndexedAccessType).objectType.flags & TypeFlags.TypeParameter && (type.constraintType.type as IndexedAccessType).indexType.flags & TypeFlags.TypeParameter) { // A reverse mapping of `{[K in keyof T[K_1]]: T[K_1]}` is the same as that of `{[K in keyof T]: T}`, since all we care about is // inferring to the "type parameter" (or indexed access) shared by the constraint and template. So, to reduce the number of // type identities produced, we simplify such indexed access occurences const newTypeParam = (type.constraintType.type as IndexedAccessType).objectType; const newMappedType = replaceIndexedAccess(type.mappedType, type.constraintType.type as ReplaceableIndexedAccessType, newTypeParam); inferredProp.links.mappedType = newMappedType as MappedType; inferredProp.links.constraintType = getIndexType(newTypeParam) as IndexType; } else { inferredProp.links.mappedType = type.mappedType; inferredProp.links.constraintType = type.constraintType; } members.set(prop.escapedName, inferredProp); } setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos); } // Return the lower bound of the key type in a mapped type. Intuitively, the lower // bound includes those keys that are known to always be present, for example because // because of constraints on type parameters (e.g. 'keyof T' for a constrained T). function getLowerBoundOfKeyType(type: Type): Type { if (type.flags & TypeFlags.Index) { const t = getApparentType((type as IndexType).type); return isGenericTupleType(t) ? getKnownKeysOfTupleType(t) : getIndexType(t); } if (type.flags & TypeFlags.Conditional) { if ((type as ConditionalType).root.isDistributive) { const checkType = (type as ConditionalType).checkType; const constraint = getLowerBoundOfKeyType(checkType); if (constraint !== checkType) { return getConditionalTypeInstantiation(type as ConditionalType, prependTypeMapping((type as ConditionalType).root.checkType, constraint, (type as ConditionalType).mapper)); } } return type; } if (type.flags & TypeFlags.Union) { return mapType(type as UnionType, getLowerBoundOfKeyType, /*noReductions*/ true); } if (type.flags & TypeFlags.Intersection) { // Similarly to getTypeFromIntersectionTypeNode, we preserve the special string & {}, number & {}, // and bigint & {} intersections that are used to prevent subtype reduction in union types. const types = (type as IntersectionType).types; if (types.length === 2 && !!(types[0].flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) && types[1] === emptyTypeLiteralType) { return type; } return getIntersectionType(sameMap((type as UnionType).types, getLowerBoundOfKeyType)); } return type; } function getIsLateCheckFlag(s: Symbol): CheckFlags { return getCheckFlags(s) & CheckFlags.Late; } function forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(type: Type, include: TypeFlags, stringsOnly: boolean, cb: (keyType: Type) => void) { for (const prop of getPropertiesOfType(type)) { cb(getLiteralTypeFromProperty(prop, include)); } if (type.flags & TypeFlags.Any) { cb(stringType); } else { for (const info of getIndexInfosOfType(type)) { if (!stringsOnly || info.keyType.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { cb(info.keyType); } } } } /** Resolve the members of a mapped type { [P in K]: T } */ function resolveMappedTypeMembers(type: MappedType) { const members: SymbolTable = createSymbolTable(); let indexInfos: IndexInfo[] | undefined; // Resolve upfront such that recursive references see an empty object type. setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); // In { [P in K]: T }, we refer to P as the type parameter type, K as the constraint type, // and T as the template type. const typeParameter = getTypeParameterFromMappedType(type); const constraintType = getConstraintTypeFromMappedType(type); const mappedType = (type.target as MappedType) || type; const nameType = getNameTypeFromMappedType(mappedType); const shouldLinkPropDeclarations = !nameType || isFilteringMappedType(mappedType); const templateType = getTemplateTypeFromMappedType(mappedType); const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' const templateModifiers = getMappedTypeModifiers(type); const include = keyofStringsOnly ? TypeFlags.StringLiteral : TypeFlags.StringOrNumberLiteralOrUnique; if (isMappedTypeWithKeyofConstraintDeclaration(type)) { // We have a { [P in keyof T]: X } forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, include, keyofStringsOnly, addMemberForKeyType); } else { forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); } setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); function addMemberForKeyType(keyType: Type) { const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; forEachType(propNameType, t => addMemberForKeyTypeWorker(keyType, t)); } function addMemberForKeyTypeWorker(keyType: Type, propNameType: Type) { // If the current iteration type constituent is a string literal type, create a property. // Otherwise, for type string create a string index signature. if (isTypeUsableAsPropertyName(propNameType)) { const propName = getPropertyNameFromType(propNameType); // String enum members from separate enums with identical values // are distinct types with the same property name. Make the resulting // property symbol's name type be the union of those enum member types. const existingProp = members.get(propName) as MappedSymbol | undefined; if (existingProp) { existingProp.links.nameType = getUnionType([existingProp.links.nameType!, propNameType]); existingProp.links.keyType = getUnionType([existingProp.links.keyType, keyType]); } else { const modifiersProp = isTypeUsableAsPropertyName(keyType) ? getPropertyOfType(modifiersType, getPropertyNameFromType(keyType)) : undefined; const isOptional = !!(templateModifiers & MappedTypeModifiers.IncludeOptional || !(templateModifiers & MappedTypeModifiers.ExcludeOptional) && modifiersProp && modifiersProp.flags & SymbolFlags.Optional); const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersProp && isReadonlySymbol(modifiersProp)); const stripOptional = strictNullChecks && !isOptional && modifiersProp && modifiersProp.flags & SymbolFlags.Optional; const lateFlag: CheckFlags = modifiersProp ? getIsLateCheckFlag(modifiersProp) : 0; const prop = createSymbol(SymbolFlags.Property | (isOptional ? SymbolFlags.Optional : 0), propName, lateFlag | CheckFlags.Mapped | (isReadonly ? CheckFlags.Readonly : 0) | (stripOptional ? CheckFlags.StripOptional : 0)) as MappedSymbol; prop.links.mappedType = type; prop.links.nameType = propNameType; prop.links.keyType = keyType; if (modifiersProp) { prop.links.syntheticOrigin = modifiersProp; prop.declarations = shouldLinkPropDeclarations ? modifiersProp.declarations : undefined; } members.set(propName, prop); } } else if (isValidIndexKeyType(propNameType) || propNameType.flags & (TypeFlags.Any | TypeFlags.Enum)) { const indexKeyType = propNameType.flags & (TypeFlags.Any | TypeFlags.String) ? stringType : propNameType.flags & (TypeFlags.Number | TypeFlags.Enum) ? numberType : propNameType; const propType = instantiateType(templateType, appendTypeMapping(type.mapper, typeParameter, keyType)); const indexInfo = createIndexInfo(indexKeyType, propType, !!(templateModifiers & MappedTypeModifiers.IncludeReadonly)); indexInfos = appendIndexInfo(indexInfos, indexInfo, /*union*/ true); } } } function getTypeOfMappedSymbol(symbol: MappedSymbol) { if (!symbol.links.type) { const mappedType = symbol.links.mappedType; if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { mappedType.containsError = true; return errorType; } const templateType = getTemplateTypeFromMappedType(mappedType.target as MappedType || mappedType); const mapper = appendTypeMapping(mappedType.mapper, getTypeParameterFromMappedType(mappedType), symbol.links.keyType); const propType = instantiateType(templateType, mapper); // When creating an optional property in strictNullChecks mode, if 'undefined' isn't assignable to the // type, we include 'undefined' in the type. Similarly, when creating a non-optional property in strictNullChecks // mode, if the underlying property is optional we remove 'undefined' from the type. let type = strictNullChecks && symbol.flags & SymbolFlags.Optional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : symbol.links.checkFlags & CheckFlags.StripOptional ? removeMissingOrUndefinedType(propType) : propType; if (!popTypeResolution()) { error(currentNode, Diagnostics.Type_of_property_0_circularly_references_itself_in_mapped_type_1, symbolToString(symbol), typeToString(mappedType)); type = errorType; } symbol.links.type = type; } return symbol.links.type; } function getTypeParameterFromMappedType(type: MappedType) { return type.typeParameter || (type.typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(type.declaration.typeParameter))); } function getConstraintTypeFromMappedType(type: MappedType) { return type.constraintType || (type.constraintType = getConstraintOfTypeParameter(getTypeParameterFromMappedType(type)) || errorType); } function getNameTypeFromMappedType(type: MappedType) { return type.declaration.nameType ? type.nameType || (type.nameType = instantiateType(getTypeFromTypeNode(type.declaration.nameType), type.mapper)) : undefined; } function getTemplateTypeFromMappedType(type: MappedType) { return type.templateType || (type.templateType = type.declaration.type ? instantiateType(addOptionality(getTypeFromTypeNode(type.declaration.type), /*isProperty*/ true, !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), type.mapper) : errorType); } function getConstraintDeclarationForMappedType(type: MappedType) { return getEffectiveConstraintOfTypeParameter(type.declaration.typeParameter); } function isMappedTypeWithKeyofConstraintDeclaration(type: MappedType) { const constraintDeclaration = getConstraintDeclarationForMappedType(type)!; // TODO: GH#18217 return constraintDeclaration.kind === SyntaxKind.TypeOperator && (constraintDeclaration as TypeOperatorNode).operator === SyntaxKind.KeyOfKeyword; } function getModifiersTypeFromMappedType(type: MappedType) { if (!type.modifiersType) { if (isMappedTypeWithKeyofConstraintDeclaration(type)) { // If the constraint declaration is a 'keyof T' node, the modifiers type is T. We check // AST nodes here because, when T is a non-generic type, the logic below eagerly resolves // 'keyof T' to a literal union type and we can't recover T from that type. type.modifiersType = instantiateType(getTypeFromTypeNode((getConstraintDeclarationForMappedType(type) as TypeOperatorNode).type), type.mapper); } else { // Otherwise, get the declared constraint type, and if the constraint type is a type parameter, // get the constraint of that type parameter. If the resulting type is an indexed type 'keyof T', // the modifiers type is T. Otherwise, the modifiers type is unknown. const declaredType = getTypeFromMappedTypeNode(type.declaration) as MappedType; const constraint = getConstraintTypeFromMappedType(declaredType); const extendedConstraint = constraint && constraint.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(constraint as TypeParameter) : constraint; type.modifiersType = extendedConstraint && extendedConstraint.flags & TypeFlags.Index ? instantiateType((extendedConstraint as IndexType).type, type.mapper) : unknownType; } } return type.modifiersType; } function getMappedTypeModifiers(type: MappedType): MappedTypeModifiers { const declaration = type.declaration; return (declaration.readonlyToken ? declaration.readonlyToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeReadonly : MappedTypeModifiers.IncludeReadonly : 0) | (declaration.questionToken ? declaration.questionToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeOptional : MappedTypeModifiers.IncludeOptional : 0); } function getMappedTypeOptionality(type: MappedType): number { const modifiers = getMappedTypeModifiers(type); return modifiers & MappedTypeModifiers.ExcludeOptional ? -1 : modifiers & MappedTypeModifiers.IncludeOptional ? 1 : 0; } function getCombinedMappedTypeOptionality(type: MappedType): number { const optionality = getMappedTypeOptionality(type); const modifiersType = getModifiersTypeFromMappedType(type); return optionality || (isGenericMappedType(modifiersType) ? getMappedTypeOptionality(modifiersType) : 0); } function isPartialMappedType(type: Type) { return !!(getObjectFlags(type) & ObjectFlags.Mapped && getMappedTypeModifiers(type as MappedType) & MappedTypeModifiers.IncludeOptional); } function isGenericMappedType(type: Type): type is MappedType { if (getObjectFlags(type) & ObjectFlags.Mapped) { const constraint = getConstraintTypeFromMappedType(type as MappedType); if (isGenericIndexType(constraint)) { return true; } // A mapped type is generic if the 'as' clause references generic types other than the iteration type. // To determine this, we substitute the constraint type (that we now know isn't generic) for the iteration // type and check whether the resulting type is generic. const nameType = getNameTypeFromMappedType(type as MappedType); if (nameType && isGenericIndexType(instantiateType(nameType, makeUnaryTypeMapper(getTypeParameterFromMappedType(type as MappedType), constraint)))) { return true; } } return false; } function isFilteringMappedType(type: MappedType): boolean { const nameType = getNameTypeFromMappedType(type); return !!nameType && isTypeAssignableTo(nameType, getTypeParameterFromMappedType(type)); } function resolveStructuredTypeMembers(type: StructuredType): ResolvedType { if (!(type as ResolvedType).members) { if (type.flags & TypeFlags.Object) { if ((type as ObjectType).objectFlags & ObjectFlags.Reference) { resolveTypeReferenceMembers(type as TypeReference); } else if ((type as ObjectType).objectFlags & ObjectFlags.ClassOrInterface) { resolveClassOrInterfaceMembers(type as InterfaceType); } else if ((type as ReverseMappedType).objectFlags & ObjectFlags.ReverseMapped) { resolveReverseMappedTypeMembers(type as ReverseMappedType); } else if ((type as ObjectType).objectFlags & ObjectFlags.Anonymous) { resolveAnonymousTypeMembers(type as AnonymousType); } else if ((type as MappedType).objectFlags & ObjectFlags.Mapped) { resolveMappedTypeMembers(type as MappedType); } else { Debug.fail("Unhandled object type " + Debug.formatObjectFlags(type.objectFlags)); } } else if (type.flags & TypeFlags.Union) { resolveUnionTypeMembers(type as UnionType); } else if (type.flags & TypeFlags.Intersection) { resolveIntersectionTypeMembers(type as IntersectionType); } else { Debug.fail("Unhandled type " + Debug.formatTypeFlags(type.flags)); } } return type as ResolvedType; } /** Return properties of an object type or an empty array for other types */ function getPropertiesOfObjectType(type: Type): Symbol[] { if (type.flags & TypeFlags.Object) { return resolveStructuredTypeMembers(type as ObjectType).properties; } return emptyArray; } /** If the given type is an object type and that type has a property by the given name, * return the symbol for that property. Otherwise return undefined. */ function getPropertyOfObjectType(type: Type, name: __String): Symbol | undefined { if (type.flags & TypeFlags.Object) { const resolved = resolveStructuredTypeMembers(type as ObjectType); const symbol = resolved.members.get(name); if (symbol && symbolIsValue(symbol)) { return symbol; } } } function getPropertiesOfUnionOrIntersectionType(type: UnionOrIntersectionType): Symbol[] { if (!type.resolvedProperties) { const members = createSymbolTable(); for (const current of type.types) { for (const prop of getPropertiesOfType(current)) { if (!members.has(prop.escapedName)) { const combinedProp = getPropertyOfUnionOrIntersectionType(type, prop.escapedName); if (combinedProp) { members.set(prop.escapedName, combinedProp); } } } // The properties of a union type are those that are present in all constituent types, so // we only need to check the properties of the first type without index signature if (type.flags & TypeFlags.Union && getIndexInfosOfType(current).length === 0) { break; } } type.resolvedProperties = getNamedMembers(members); } return type.resolvedProperties; } function getPropertiesOfType(type: Type): Symbol[] { type = getReducedApparentType(type); return type.flags & TypeFlags.UnionOrIntersection ? getPropertiesOfUnionOrIntersectionType(type as UnionType) : getPropertiesOfObjectType(type); } function forEachPropertyOfType(type: Type, action: (symbol: Symbol, escapedName: __String) => void): void { type = getReducedApparentType(type); if (type.flags & TypeFlags.StructuredType) { resolveStructuredTypeMembers(type as StructuredType).members.forEach((symbol, escapedName) => { if (isNamedMember(symbol, escapedName)) { action(symbol, escapedName); } }); } } function isTypeInvalidDueToUnionDiscriminant(contextualType: Type, obj: ObjectLiteralExpression | JsxAttributes): boolean { const list = obj.properties as NodeArray; return list.some(property => { const nameType = property.name && getLiteralTypeFromPropertyName(property.name); const name = nameType && isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; const expected = name === undefined ? undefined : getTypeOfPropertyOfType(contextualType, name); return !!expected && isLiteralType(expected) && !isTypeAssignableTo(getTypeOfNode(property), expected); }); } function getAllPossiblePropertiesOfTypes(types: readonly Type[]): Symbol[] { const unionType = getUnionType(types); if (!(unionType.flags & TypeFlags.Union)) { return getAugmentedPropertiesOfType(unionType); } const props = createSymbolTable(); for (const memberType of types) { for (const { escapedName } of getAugmentedPropertiesOfType(memberType)) { if (!props.has(escapedName)) { const prop = createUnionOrIntersectionProperty(unionType as UnionType, escapedName); // May be undefined if the property is private if (prop) props.set(escapedName, prop); } } } return arrayFrom(props.values()); } function getConstraintOfType(type: InstantiableType | UnionOrIntersectionType): Type | undefined { return type.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(type as TypeParameter) : type.flags & TypeFlags.IndexedAccess ? getConstraintOfIndexedAccess(type as IndexedAccessType) : type.flags & TypeFlags.Conditional ? getConstraintOfConditionalType(type as ConditionalType) : getBaseConstraintOfType(type); } function getConstraintOfTypeParameter(typeParameter: TypeParameter): Type | undefined { return hasNonCircularBaseConstraint(typeParameter) ? getConstraintFromTypeParameter(typeParameter) : undefined; } function isConstTypeVariable(type: Type): boolean { return !!(type.flags & TypeFlags.TypeParameter && some((type as TypeParameter).symbol?.declarations, d => hasSyntacticModifier(d, ModifierFlags.Const)) || isGenericTupleType(type) && findIndex(getTypeArguments(type), (t, i) => !!(type.target.elementFlags[i] & ElementFlags.Variadic) && isConstTypeVariable(t)) >= 0 || type.flags & TypeFlags.IndexedAccess && isConstTypeVariable((type as IndexedAccessType).objectType)); } function getConstraintOfIndexedAccess(type: IndexedAccessType) { return hasNonCircularBaseConstraint(type) ? getConstraintFromIndexedAccess(type) : undefined; } function getSimplifiedTypeOrConstraint(type: Type) { const simplified = getSimplifiedType(type, /*writing*/ false); return simplified !== type ? simplified : getConstraintOfType(type); } function getConstraintFromIndexedAccess(type: IndexedAccessType) { if (isMappedTypeGenericIndexedAccess(type)) { // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, // we substitute an instantiation of E where P is replaced with X. return substituteIndexedMappedType(type.objectType as MappedType, type.indexType); } const indexConstraint = getSimplifiedTypeOrConstraint(type.indexType); if (indexConstraint && indexConstraint !== type.indexType) { const indexedAccess = getIndexedAccessTypeOrUndefined(type.objectType, indexConstraint, type.accessFlags); if (indexedAccess) { return indexedAccess; } } const objectConstraint = getSimplifiedTypeOrConstraint(type.objectType); if (objectConstraint && objectConstraint !== type.objectType) { return getIndexedAccessTypeOrUndefined(objectConstraint, type.indexType, type.accessFlags); } return undefined; } function getDefaultConstraintOfConditionalType(type: ConditionalType) { if (!type.resolvedDefaultConstraint) { // An `any` branch of a conditional type would normally be viral - specifically, without special handling here, // a conditional type with a single branch of type `any` would be assignable to anything, since it's constraint would simplify to // just `any`. This result is _usually_ unwanted - so instead here we elide an `any` branch from the constraint type, // in effect treating `any` like `never` rather than `unknown` in this location. const trueConstraint = getInferredTrueTypeFromConditionalType(type); const falseConstraint = getFalseTypeFromConditionalType(type); type.resolvedDefaultConstraint = isTypeAny(trueConstraint) ? falseConstraint : isTypeAny(falseConstraint) ? trueConstraint : getUnionType([trueConstraint, falseConstraint]); } return type.resolvedDefaultConstraint; } function getConstraintOfDistributiveConditionalType(type: ConditionalType): Type | undefined { // Check if we have a conditional type of the form 'T extends U ? X : Y', where T is a constrained // type parameter. If so, create an instantiation of the conditional type where T is replaced // with its constraint. We do this because if the constraint is a union type it will be distributed // over the conditional type and possibly reduced. For example, 'T extends undefined ? never : T' // removes 'undefined' from T. // We skip returning a distributive constraint for a restrictive instantiation of a conditional type // as the constraint for all type params (check type included) have been replace with `unknown`, which // is going to produce even more false positive/negative results than the distribute constraint already does. // Please note: the distributive constraint is a kludge for emulating what a negated type could to do filter // a union - once negated types exist and are applied to the conditional false branch, this "constraint" // likely doesn't need to exist. if (type.root.isDistributive && type.restrictiveInstantiation !== type) { const simplified = getSimplifiedType(type.checkType, /*writing*/ false); const constraint = simplified === type.checkType ? getConstraintOfType(simplified) : simplified; if (constraint && constraint !== type.checkType) { const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper)); if (!(instantiated.flags & TypeFlags.Never)) { return instantiated; } } } return undefined; } function getConstraintFromConditionalType(type: ConditionalType) { return getConstraintOfDistributiveConditionalType(type) || getDefaultConstraintOfConditionalType(type); } function getConstraintOfConditionalType(type: ConditionalType) { return hasNonCircularBaseConstraint(type) ? getConstraintFromConditionalType(type) : undefined; } function getEffectiveConstraintOfIntersection(types: readonly Type[], targetIsUnion: boolean) { let constraints: Type[] | undefined; let hasDisjointDomainType = false; for (const t of types) { if (t.flags & TypeFlags.Instantiable) { // We keep following constraints as long as we have an instantiable type that is known // not to be circular or infinite (hence we stop on index access types). let constraint = getConstraintOfType(t); while (constraint && constraint.flags & (TypeFlags.TypeParameter | TypeFlags.Index | TypeFlags.Conditional)) { constraint = getConstraintOfType(constraint); } if (constraint) { constraints = append(constraints, constraint); if (targetIsUnion) { constraints = append(constraints, t); } } } else if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { hasDisjointDomainType = true; } } // If the target is a union type or if we are intersecting with types belonging to one of the // disjoint domains, we may end up producing a constraint that hasn't been examined before. if (constraints && (targetIsUnion || hasDisjointDomainType)) { if (hasDisjointDomainType) { // We add any types belong to one of the disjoint domains because they might cause the final // intersection operation to reduce the union constraints. for (const t of types) { if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { constraints = append(constraints, t); } } } // The source types were normalized; ensure the result is normalized too. return getNormalizedType(getIntersectionType(constraints), /*writing*/ false); } return undefined; } function getBaseConstraintOfType(type: Type): Type | undefined { if (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) { const constraint = getResolvedBaseConstraint(type as InstantiableType | UnionOrIntersectionType); return constraint !== noConstraintType && constraint !== circularConstraintType ? constraint : undefined; } return type.flags & TypeFlags.Index ? keyofConstraintType : undefined; } /** * This is similar to `getBaseConstraintOfType` except it returns the input type if there's no base constraint, instead of `undefined` * It also doesn't map indexes to `string`, as where this is used this would be unneeded (and likely undesirable) */ function getBaseConstraintOrType(type: Type) { return getBaseConstraintOfType(type) || type; } function hasNonCircularBaseConstraint(type: InstantiableType): boolean { return getResolvedBaseConstraint(type) !== circularConstraintType; } /** * Return the resolved base constraint of a type variable. The noConstraintType singleton is returned if the * type variable has no constraint, and the circularConstraintType singleton is returned if the constraint * circularly references the type variable. */ function getResolvedBaseConstraint(type: InstantiableType | UnionOrIntersectionType): Type { if (type.resolvedBaseConstraint) { return type.resolvedBaseConstraint; } const stack: object[] = []; return type.resolvedBaseConstraint = getTypeWithThisArgument(getImmediateBaseConstraint(type), type); function getImmediateBaseConstraint(t: Type): Type { if (!t.immediateBaseConstraint) { if (!pushTypeResolution(t, TypeSystemPropertyName.ImmediateBaseConstraint)) { return circularConstraintType; } let result; // We always explore at least 10 levels of nested constraints. Thereafter, we continue to explore // up to 50 levels of nested constraints provided there are no "deeply nested" types on the stack // (i.e. no types for which five instantiations have been recorded on the stack). If we reach 50 // levels of nesting, we are presumably exploring a repeating pattern with a long cycle that hasn't // yet triggered the deeply nested limiter. We have no test cases that actually get to 50 levels of // nesting, so it is effectively just a safety stop. const identity = getRecursionIdentity(t); if (stack.length < 10 || stack.length < 50 && !contains(stack, identity)) { stack.push(identity); result = computeBaseConstraint(getSimplifiedType(t, /*writing*/ false)); stack.pop(); } if (!popTypeResolution()) { if (t.flags & TypeFlags.TypeParameter) { const errorNode = getConstraintDeclaration(t as TypeParameter); if (errorNode) { const diagnostic = error(errorNode, Diagnostics.Type_parameter_0_has_a_circular_constraint, typeToString(t)); if (currentNode && !isNodeDescendantOf(errorNode, currentNode) && !isNodeDescendantOf(currentNode, errorNode)) { addRelatedInfo(diagnostic, createDiagnosticForNode(currentNode, Diagnostics.Circularity_originates_in_type_at_this_location)); } } } result = circularConstraintType; } t.immediateBaseConstraint = result || noConstraintType; } return t.immediateBaseConstraint; } function getBaseConstraint(t: Type): Type | undefined { const c = getImmediateBaseConstraint(t); return c !== noConstraintType && c !== circularConstraintType ? c : undefined; } function computeBaseConstraint(t: Type): Type | undefined { if (t.flags & TypeFlags.TypeParameter) { const constraint = getConstraintFromTypeParameter(t as TypeParameter); return (t as TypeParameter).isThisType || !constraint ? constraint : getBaseConstraint(constraint); } if (t.flags & TypeFlags.UnionOrIntersection) { const types = (t as UnionOrIntersectionType).types; const baseTypes: Type[] = []; let different = false; for (const type of types) { const baseType = getBaseConstraint(type); if (baseType) { if (baseType !== type) { different = true; } baseTypes.push(baseType); } else { different = true; } } if (!different) { return t; } return t.flags & TypeFlags.Union && baseTypes.length === types.length ? getUnionType(baseTypes) : t.flags & TypeFlags.Intersection && baseTypes.length ? getIntersectionType(baseTypes) : undefined; } if (t.flags & TypeFlags.Index) { return keyofConstraintType; } if (t.flags & TypeFlags.TemplateLiteral) { const types = (t as TemplateLiteralType).types; const constraints = mapDefined(types, getBaseConstraint); return constraints.length === types.length ? getTemplateLiteralType((t as TemplateLiteralType).texts, constraints) : stringType; } if (t.flags & TypeFlags.StringMapping) { const constraint = getBaseConstraint((t as StringMappingType).type); return constraint && constraint !== (t as StringMappingType).type ? getStringMappingType((t as StringMappingType).symbol, constraint) : stringType; } if (t.flags & TypeFlags.IndexedAccess) { if (isMappedTypeGenericIndexedAccess(t)) { // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, // we substitute an instantiation of E where P is replaced with X. return getBaseConstraint(substituteIndexedMappedType((t as IndexedAccessType).objectType as MappedType, (t as IndexedAccessType).indexType)); } const baseObjectType = getBaseConstraint((t as IndexedAccessType).objectType); const baseIndexType = getBaseConstraint((t as IndexedAccessType).indexType); const baseIndexedAccess = baseObjectType && baseIndexType && getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, (t as IndexedAccessType).accessFlags); return baseIndexedAccess && getBaseConstraint(baseIndexedAccess); } if (t.flags & TypeFlags.Conditional) { const constraint = getConstraintFromConditionalType(t as ConditionalType); return constraint && getBaseConstraint(constraint); } if (t.flags & TypeFlags.Substitution) { return getBaseConstraint(getSubstitutionIntersection(t as SubstitutionType)); } return t; } } function getApparentTypeOfIntersectionType(type: IntersectionType) { return type.resolvedApparentType || (type.resolvedApparentType = getTypeWithThisArgument(type, type, /*apparentType*/ true)); } function getResolvedTypeParameterDefault(typeParameter: TypeParameter): Type | undefined { if (!typeParameter.default) { if (typeParameter.target) { const targetDefault = getResolvedTypeParameterDefault(typeParameter.target); typeParameter.default = targetDefault ? instantiateType(targetDefault, typeParameter.mapper) : noConstraintType; } else { // To block recursion, set the initial value to the resolvingDefaultType. typeParameter.default = resolvingDefaultType; const defaultDeclaration = typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default); const defaultType = defaultDeclaration ? getTypeFromTypeNode(defaultDeclaration) : noConstraintType; if (typeParameter.default === resolvingDefaultType) { // If we have not been called recursively, set the correct default type. typeParameter.default = defaultType; } } } else if (typeParameter.default === resolvingDefaultType) { // If we are called recursively for this type parameter, mark the default as circular. typeParameter.default = circularConstraintType; } return typeParameter.default; } /** * Gets the default type for a type parameter. * * If the type parameter is the result of an instantiation, this gets the instantiated * default type of its target. If the type parameter has no default type or the default is * circular, `undefined` is returned. */ function getDefaultFromTypeParameter(typeParameter: TypeParameter): Type | undefined { const defaultType = getResolvedTypeParameterDefault(typeParameter); return defaultType !== noConstraintType && defaultType !== circularConstraintType ? defaultType : undefined; } function hasNonCircularTypeParameterDefault(typeParameter: TypeParameter) { return getResolvedTypeParameterDefault(typeParameter) !== circularConstraintType; } /** * Indicates whether the declaration of a typeParameter has a default type. */ function hasTypeParameterDefault(typeParameter: TypeParameter): boolean { return !!(typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default)); } function getApparentTypeOfMappedType(type: MappedType) { return type.resolvedApparentType || (type.resolvedApparentType = getResolvedApparentTypeOfMappedType(type)); } function getResolvedApparentTypeOfMappedType(type: MappedType) { const typeVariable = getHomomorphicTypeVariable(type); if (typeVariable && !type.declaration.nameType) { const constraint = getConstraintOfTypeParameter(typeVariable); if (constraint && isArrayOrTupleType(constraint)) { return instantiateType(type, prependTypeMapping(typeVariable, constraint, type.mapper)); } } return type; } function isMappedTypeGenericIndexedAccess(type: Type) { let objectType; return !!(type.flags & TypeFlags.IndexedAccess && getObjectFlags(objectType = (type as IndexedAccessType).objectType) & ObjectFlags.Mapped && !isGenericMappedType(objectType) && isGenericIndexType((type as IndexedAccessType).indexType) && !(getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.ExcludeOptional) && !(objectType as MappedType).declaration.nameType); } /** * For a type parameter, return the base constraint of the type parameter. For the string, number, * boolean, and symbol primitive types, return the corresponding object types. Otherwise return the * type itself. */ function getApparentType(type: Type): Type { const t = !(type.flags & TypeFlags.Instantiable) ? type : getBaseConstraintOfType(type) || unknownType; return getObjectFlags(t) & ObjectFlags.Mapped ? getApparentTypeOfMappedType(t as MappedType) : t.flags & TypeFlags.Intersection ? getApparentTypeOfIntersectionType(t as IntersectionType) : t.flags & TypeFlags.StringLike ? globalStringType : t.flags & TypeFlags.NumberLike ? globalNumberType : t.flags & TypeFlags.BigIntLike ? getGlobalBigIntType() : t.flags & TypeFlags.BooleanLike ? globalBooleanType : t.flags & TypeFlags.ESSymbolLike ? getGlobalESSymbolType() : t.flags & TypeFlags.NonPrimitive ? emptyObjectType : t.flags & TypeFlags.Index ? keyofConstraintType : t.flags & TypeFlags.Unknown && !strictNullChecks ? emptyObjectType : t; } function getReducedApparentType(type: Type): Type { // Since getApparentType may return a non-reduced union or intersection type, we need to perform // type reduction both before and after obtaining the apparent type. For example, given a type parameter // 'T extends A | B', the type 'T & X' becomes 'A & X | B & X' after obtaining the apparent type, and // that type may need further reduction to remove empty intersections. return getReducedType(getApparentType(getReducedType(type))); } function createUnionOrIntersectionProperty(containingType: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { let singleProp: Symbol | undefined; let propSet: Map | undefined; let indexTypes: Type[] | undefined; const isUnion = containingType.flags & TypeFlags.Union; // Flags we want to propagate to the result if they exist in all source symbols let optionalFlag: SymbolFlags | undefined; let syntheticFlag = CheckFlags.SyntheticMethod; let checkFlags = isUnion ? 0 : CheckFlags.Readonly; let mergedInstantiations = false; for (const current of containingType.types) { const type = getApparentType(current); if (!(isErrorType(type) || type.flags & TypeFlags.Never)) { const prop = getPropertyOfType(type, name, skipObjectFunctionPropertyAugment); const modifiers = prop ? getDeclarationModifierFlagsFromSymbol(prop) : 0; if (prop) { if (prop.flags & SymbolFlags.ClassMember) { optionalFlag ??= isUnion ? SymbolFlags.None : SymbolFlags.Optional; if (isUnion) { optionalFlag |= (prop.flags & SymbolFlags.Optional); } else { optionalFlag &= prop.flags; } } if (!singleProp) { singleProp = prop; } else if (prop !== singleProp) { const isInstantiation = (getTargetSymbol(prop) || prop) === (getTargetSymbol(singleProp) || singleProp); // If the symbols are instances of one another with identical types - consider the symbols // equivalent and just use the first one, which thus allows us to avoid eliding private // members when intersecting a (this-)instantiations of a class with its raw base or another instance if (isInstantiation && compareProperties(singleProp, prop, (a, b) => a === b ? Ternary.True : Ternary.False) === Ternary.True) { // If we merged instantiations of a generic type, we replicate the symbol parent resetting behavior we used // to do when we recorded multiple distinct symbols so that we still get, eg, `Array.length` printed // back and not `Array.length` when we're looking at a `.length` access on a `string[] | number[]` mergedInstantiations = !!singleProp.parent && !!length(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(singleProp.parent)); } else { if (!propSet) { propSet = new Map(); propSet.set(getSymbolId(singleProp), singleProp); } const id = getSymbolId(prop); if (!propSet.has(id)) { propSet.set(id, prop); } } } if (isUnion && isReadonlySymbol(prop)) { checkFlags |= CheckFlags.Readonly; } else if (!isUnion && !isReadonlySymbol(prop)) { checkFlags &= ~CheckFlags.Readonly; } checkFlags |= (!(modifiers & ModifierFlags.NonPublicAccessibilityModifier) ? CheckFlags.ContainsPublic : 0) | (modifiers & ModifierFlags.Protected ? CheckFlags.ContainsProtected : 0) | (modifiers & ModifierFlags.Private ? CheckFlags.ContainsPrivate : 0) | (modifiers & ModifierFlags.Static ? CheckFlags.ContainsStatic : 0); if (!isPrototypeProperty(prop)) { syntheticFlag = CheckFlags.SyntheticProperty; } } else if (isUnion) { const indexInfo = !isLateBoundName(name) && getApplicableIndexInfoForName(type, name); if (indexInfo) { checkFlags |= CheckFlags.WritePartial | (indexInfo.isReadonly ? CheckFlags.Readonly : 0); indexTypes = append(indexTypes, isTupleType(type) ? getRestTypeOfTupleType(type) || undefinedType : indexInfo.type); } else if (isObjectLiteralType(type) && !(getObjectFlags(type) & ObjectFlags.ContainsSpread)) { checkFlags |= CheckFlags.WritePartial; indexTypes = append(indexTypes, undefinedType); } else { checkFlags |= CheckFlags.ReadPartial; } } } } if (!singleProp || isUnion && (propSet || checkFlags & CheckFlags.Partial) && checkFlags & (CheckFlags.ContainsPrivate | CheckFlags.ContainsProtected) && !(propSet && getCommonDeclarationsOfSymbols(propSet.values())) ) { // No property was found, or, in a union, a property has a private or protected declaration in one // constituent, but is missing or has a different declaration in another constituent. return undefined; } if (!propSet && !(checkFlags & CheckFlags.ReadPartial) && !indexTypes) { if (mergedInstantiations) { // No symbol from a union/intersection should have a `.parent` set (since unions/intersections don't act as symbol parents) // Unless that parent is "reconstituted" from the "first value declaration" on the symbol (which is likely different than its instantiated parent!) // They also have a `.containingType` set, which affects some services endpoints behavior, like `getRootSymbol` const links = tryCast(singleProp, isTransientSymbol)?.links; const clone = createSymbolWithType(singleProp, links?.type); clone.parent = singleProp.valueDeclaration?.symbol?.parent; clone.links.containingType = containingType; clone.links.mapper = links?.mapper; return clone; } else { return singleProp; } } const props = propSet ? arrayFrom(propSet.values()) : [singleProp]; let declarations: Declaration[] | undefined; let firstType: Type | undefined; let nameType: Type | undefined; const propTypes: Type[] = []; let writeTypes: Type[] | undefined; let firstValueDeclaration: Declaration | undefined; let hasNonUniformValueDeclaration = false; for (const prop of props) { if (!firstValueDeclaration) { firstValueDeclaration = prop.valueDeclaration; } else if (prop.valueDeclaration && prop.valueDeclaration !== firstValueDeclaration) { hasNonUniformValueDeclaration = true; } declarations = addRange(declarations, prop.declarations); const type = getTypeOfSymbol(prop); if (!firstType) { firstType = type; nameType = getSymbolLinks(prop).nameType; } const writeType = getWriteTypeOfSymbol(prop); if (writeTypes || writeType !== type) { writeTypes = append(!writeTypes ? propTypes.slice() : writeTypes, writeType); } else if (type !== firstType) { checkFlags |= CheckFlags.HasNonUniformType; } if (isLiteralType(type) || isPatternLiteralType(type) || type === uniqueLiteralType) { checkFlags |= CheckFlags.HasLiteralType; } if (type.flags & TypeFlags.Never && type !== uniqueLiteralType) { checkFlags |= CheckFlags.HasNeverType; } propTypes.push(type); } addRange(propTypes, indexTypes); const result = createSymbol(SymbolFlags.Property | (optionalFlag ?? 0), name, syntheticFlag | checkFlags); result.links.containingType = containingType; if (!hasNonUniformValueDeclaration && firstValueDeclaration) { result.valueDeclaration = firstValueDeclaration; // Inherit information about parent type. if (firstValueDeclaration.symbol.parent) { result.parent = firstValueDeclaration.symbol.parent; } } result.declarations = declarations; result.links.nameType = nameType; if (propTypes.length > 2) { // When `propTypes` has the potential to explode in size when normalized, defer normalization until absolutely needed result.links.checkFlags |= CheckFlags.DeferredType; result.links.deferralParent = containingType; result.links.deferralConstituents = propTypes; result.links.deferralWriteConstituents = writeTypes; } else { result.links.type = isUnion ? getUnionType(propTypes) : getIntersectionType(propTypes); if (writeTypes) { result.links.writeType = isUnion ? getUnionType(writeTypes) : getIntersectionType(writeTypes); } } return result; } // Return the symbol for a given property in a union or intersection type, or undefined if the property // does not exist in any constituent type. Note that the returned property may only be present in some // constituents, in which case the isPartial flag is set when the containing type is union type. We need // these partial properties when identifying discriminant properties, but otherwise they are filtered out // and do not appear to be present in the union type. function getUnionOrIntersectionProperty(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { let property = type.propertyCacheWithoutObjectFunctionPropertyAugment?.get(name) || !skipObjectFunctionPropertyAugment ? type.propertyCache?.get(name) : undefined; if (!property) { property = createUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); if (property) { const properties = skipObjectFunctionPropertyAugment ? type.propertyCacheWithoutObjectFunctionPropertyAugment ||= createSymbolTable() : type.propertyCache ||= createSymbolTable(); properties.set(name, property); } } return property; } function getCommonDeclarationsOfSymbols(symbols: Iterable) { let commonDeclarations: Set | undefined; for (const symbol of symbols) { if (!symbol.declarations) { return undefined; } if (!commonDeclarations) { commonDeclarations = new Set(symbol.declarations); continue; } commonDeclarations.forEach(declaration => { if (!contains(symbol.declarations, declaration)) { commonDeclarations!.delete(declaration); } }); if (commonDeclarations.size === 0) { return undefined; } } return commonDeclarations; } function getPropertyOfUnionOrIntersectionType(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { const property = getUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); // We need to filter out partial properties in union types return property && !(getCheckFlags(property) & CheckFlags.ReadPartial) ? property : undefined; } /** * Return the reduced form of the given type. For a union type, it is a union of the normalized constituent types. * For an intersection of types containing one or more mututally exclusive discriminant properties, it is 'never'. * For all other types, it is simply the type itself. Discriminant properties are considered mutually exclusive when * no constituent property has type 'never', but the intersection of the constituent property types is 'never'. */ function getReducedType(type: Type): Type { if (type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections) { return (type as UnionType).resolvedReducedType || ((type as UnionType).resolvedReducedType = getReducedUnionType(type as UnionType)); } else if (type.flags & TypeFlags.Intersection) { if (!((type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersectionComputed)) { (type as IntersectionType).objectFlags |= ObjectFlags.IsNeverIntersectionComputed | (some(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isNeverReducedProperty) ? ObjectFlags.IsNeverIntersection : 0); } return (type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersection ? neverType : type; } return type; } function getReducedUnionType(unionType: UnionType) { const reducedTypes = sameMap(unionType.types, getReducedType); if (reducedTypes === unionType.types) { return unionType; } const reduced = getUnionType(reducedTypes); if (reduced.flags & TypeFlags.Union) { (reduced as UnionType).resolvedReducedType = reduced; } return reduced; } function isNeverReducedProperty(prop: Symbol) { return isDiscriminantWithNeverType(prop) || isConflictingPrivateProperty(prop); } function isDiscriminantWithNeverType(prop: Symbol) { // Return true for a synthetic non-optional property with non-uniform types, where at least one is // a literal type and none is never, that reduces to never. return !(prop.flags & SymbolFlags.Optional) && (getCheckFlags(prop) & (CheckFlags.Discriminant | CheckFlags.HasNeverType)) === CheckFlags.Discriminant && !!(getTypeOfSymbol(prop).flags & TypeFlags.Never); } function isConflictingPrivateProperty(prop: Symbol) { // Return true for a synthetic property with multiple declarations, at least one of which is private. return !prop.valueDeclaration && !!(getCheckFlags(prop) & CheckFlags.ContainsPrivate); } function elaborateNeverIntersection(errorInfo: DiagnosticMessageChain | undefined, type: Type) { if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsNeverIntersection) { const neverProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isDiscriminantWithNeverType); if (neverProp) { return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_has_conflicting_types_in_some_constituents, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(neverProp)); } const privateProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isConflictingPrivateProperty); if (privateProp) { return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_exists_in_multiple_constituents_and_is_private_in_some, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(privateProp)); } } return errorInfo; } /** * Return the symbol for the property with the given name in the given type. Creates synthetic union properties when * necessary, maps primitive types and type parameters are to their apparent types, and augments with properties from * Object and Function as appropriate. * * @param type a type to look up property from * @param name a name of property to look up in a given type */ function getPropertyOfType(type: Type, name: __String, skipObjectFunctionPropertyAugment?: boolean, includeTypeOnlyMembers?: boolean): Symbol | undefined { type = getReducedApparentType(type); if (type.flags & TypeFlags.Object) { const resolved = resolveStructuredTypeMembers(type as ObjectType); const symbol = resolved.members.get(name); if (symbol && symbolIsValue(symbol, includeTypeOnlyMembers)) { return symbol; } if (skipObjectFunctionPropertyAugment) return undefined; const functionType = resolved === anyFunctionType ? globalFunctionType : resolved.callSignatures.length ? globalCallableFunctionType : resolved.constructSignatures.length ? globalNewableFunctionType : undefined; if (functionType) { const symbol = getPropertyOfObjectType(functionType, name); if (symbol) { return symbol; } } return getPropertyOfObjectType(globalObjectType, name); } if (type.flags & TypeFlags.UnionOrIntersection) { return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); } return undefined; } function getSignaturesOfStructuredType(type: Type, kind: SignatureKind): readonly Signature[] { if (type.flags & TypeFlags.StructuredType) { const resolved = resolveStructuredTypeMembers(type as ObjectType); return kind === SignatureKind.Call ? resolved.callSignatures : resolved.constructSignatures; } return emptyArray; } /** * Return the signatures of the given kind in the given type. Creates synthetic union signatures when necessary and * maps primitive types and type parameters are to their apparent types. */ function getSignaturesOfType(type: Type, kind: SignatureKind): readonly Signature[] { return getSignaturesOfStructuredType(getReducedApparentType(type), kind); } function findIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { return find(indexInfos, info => info.keyType === keyType); } function findApplicableIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { // Index signatures for type 'string' are considered only when no other index signatures apply. let stringIndexInfo: IndexInfo | undefined; let applicableInfo: IndexInfo | undefined; let applicableInfos: IndexInfo[] | undefined; for (const info of indexInfos) { if (info.keyType === stringType) { stringIndexInfo = info; } else if (isApplicableIndexType(keyType, info.keyType)) { if (!applicableInfo) { applicableInfo = info; } else { (applicableInfos || (applicableInfos = [applicableInfo])).push(info); } } } // When more than one index signature is applicable we create a synthetic IndexInfo. Instead of computing // the intersected key type, we just use unknownType for the key type as nothing actually depends on the // keyType property of the returned IndexInfo. return applicableInfos ? createIndexInfo(unknownType, getIntersectionType(map(applicableInfos, info => info.type)), reduceLeft(applicableInfos, (isReadonly, info) => isReadonly && info.isReadonly, /*initial*/ true)) : applicableInfo ? applicableInfo : stringIndexInfo && isApplicableIndexType(keyType, stringType) ? stringIndexInfo : undefined; } function isApplicableIndexType(source: Type, target: Type): boolean { // A 'string' index signature applies to types assignable to 'string' or 'number', and a 'number' index // signature applies to types assignable to 'number', `${number}` and numeric string literal types. return isTypeAssignableTo(source, target) || target === stringType && isTypeAssignableTo(source, numberType) || target === numberType && (source === numericStringType || !!(source.flags & TypeFlags.StringLiteral) && isNumericLiteralName((source as StringLiteralType).value)); } function getIndexInfosOfStructuredType(type: Type): readonly IndexInfo[] { if (type.flags & TypeFlags.StructuredType) { const resolved = resolveStructuredTypeMembers(type as ObjectType); return resolved.indexInfos; } return emptyArray; } function getIndexInfosOfType(type: Type): readonly IndexInfo[] { return getIndexInfosOfStructuredType(getReducedApparentType(type)); } // Return the indexing info of the given kind in the given type. Creates synthetic union index types when necessary and // maps primitive types and type parameters are to their apparent types. function getIndexInfoOfType(type: Type, keyType: Type): IndexInfo | undefined { return findIndexInfo(getIndexInfosOfType(type), keyType); } // Return the index type of the given kind in the given type. Creates synthetic union index types when necessary and // maps primitive types and type parameters are to their apparent types. function getIndexTypeOfType(type: Type, keyType: Type): Type | undefined { return getIndexInfoOfType(type, keyType)?.type; } function getApplicableIndexInfos(type: Type, keyType: Type): IndexInfo[] { return getIndexInfosOfType(type).filter(info => isApplicableIndexType(keyType, info.keyType)); } function getApplicableIndexInfo(type: Type, keyType: Type): IndexInfo | undefined { return findApplicableIndexInfo(getIndexInfosOfType(type), keyType); } function getApplicableIndexInfoForName(type: Type, name: __String): IndexInfo | undefined { return getApplicableIndexInfo(type, isLateBoundName(name) ? esSymbolType : getStringLiteralType(unescapeLeadingUnderscores(name))); } // Return list of type parameters with duplicates removed (duplicate identifier errors are generated in the actual // type checking functions). function getTypeParametersFromDeclaration(declaration: DeclarationWithTypeParameters): readonly TypeParameter[] | undefined { let result: TypeParameter[] | undefined; for (const node of getEffectiveTypeParameterDeclarations(declaration)) { result = appendIfUnique(result, getDeclaredTypeOfTypeParameter(node.symbol)); } return result?.length ? result : isFunctionDeclaration(declaration) ? getSignatureOfTypeTag(declaration)?.typeParameters : undefined; } function symbolsToArray(symbols: SymbolTable): Symbol[] { const result: Symbol[] = []; symbols.forEach((symbol, id) => { if (!isReservedMemberName(id)) { result.push(symbol); } }); return result; } function tryFindAmbientModule(moduleName: string, withAugmentations: boolean) { if (isExternalModuleNameRelative(moduleName)) { return undefined; } const symbol = getSymbol(globals, '"' + moduleName + '"' as __String, SymbolFlags.ValueModule); // merged symbol is module declaration symbol combined with all augmentations return symbol && withAugmentations ? getMergedSymbol(symbol) : symbol; } function isOptionalParameter(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { if (hasQuestionToken(node) || isOptionalJSDocPropertyLikeTag(node) || isJSDocOptionalParameter(node)) { return true; } if (node.initializer) { const signature = getSignatureFromDeclaration(node.parent); const parameterIndex = node.parent.parameters.indexOf(node); Debug.assert(parameterIndex >= 0); // Only consider syntactic or instantiated parameters as optional, not `void` parameters as this function is used // in grammar checks and checking for `void` too early results in parameter types widening too early // and causes some noImplicitAny errors to be lost. return parameterIndex >= getMinArgumentCount(signature, MinArgumentCountFlags.StrongArityForUntypedJS | MinArgumentCountFlags.VoidIsNonOptional); } const iife = getImmediatelyInvokedFunctionExpression(node.parent); if (iife) { return !node.type && !node.dotDotDotToken && node.parent.parameters.indexOf(node) >= iife.arguments.length; } return false; } function isOptionalPropertyDeclaration(node: Declaration) { return isPropertyDeclaration(node) && !hasAccessorModifier(node) && node.questionToken; } function createTypePredicate(kind: TypePredicateKind, parameterName: string | undefined, parameterIndex: number | undefined, type: Type | undefined): TypePredicate { return { kind, parameterName, parameterIndex, type } as TypePredicate; } /** * Gets the minimum number of type arguments needed to satisfy all non-optional type * parameters. */ function getMinTypeArgumentCount(typeParameters: readonly TypeParameter[] | undefined): number { let minTypeArgumentCount = 0; if (typeParameters) { for (let i = 0; i < typeParameters.length; i++) { if (!hasTypeParameterDefault(typeParameters[i])) { minTypeArgumentCount = i + 1; } } } return minTypeArgumentCount; } /** * Fill in default types for unsupplied type arguments. If `typeArguments` is undefined * when a default type is supplied, a new array will be created and returned. * * @param typeArguments The supplied type arguments. * @param typeParameters The requested type parameters. * @param minTypeArgumentCount The minimum number of required type arguments. */ function fillMissingTypeArguments(typeArguments: readonly Type[], typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[]; function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[] | undefined; function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean) { const numTypeParameters = length(typeParameters); if (!numTypeParameters) { return []; } const numTypeArguments = length(typeArguments); if (isJavaScriptImplicitAny || (numTypeArguments >= minTypeArgumentCount && numTypeArguments <= numTypeParameters)) { const result = typeArguments ? typeArguments.slice() : []; // Map invalid forward references in default types to the error type for (let i = numTypeArguments; i < numTypeParameters; i++) { result[i] = errorType; } const baseDefaultType = getDefaultTypeArgumentType(isJavaScriptImplicitAny); for (let i = numTypeArguments; i < numTypeParameters; i++) { let defaultType = getDefaultFromTypeParameter(typeParameters![i]); if (isJavaScriptImplicitAny && defaultType && (isTypeIdenticalTo(defaultType, unknownType) || isTypeIdenticalTo(defaultType, emptyObjectType))) { defaultType = anyType; } result[i] = defaultType ? instantiateType(defaultType, createTypeMapper(typeParameters!, result)) : baseDefaultType; } result.length = typeParameters!.length; return result; } return typeArguments && typeArguments.slice(); } function getSignatureFromDeclaration(declaration: SignatureDeclaration | JSDocSignature): Signature { const links = getNodeLinks(declaration); if (!links.resolvedSignature) { const parameters: Symbol[] = []; let flags = SignatureFlags.None; let minArgumentCount = 0; let thisParameter: Symbol | undefined; let hasThisParameter = false; const iife = getImmediatelyInvokedFunctionExpression(declaration); const isJSConstructSignature = isJSDocConstructSignature(declaration); const isUntypedSignatureInJSFile = !iife && isInJSFile(declaration) && isValueSignatureDeclaration(declaration) && !hasJSDocParameterTags(declaration) && !getJSDocType(declaration); if (isUntypedSignatureInJSFile) { flags |= SignatureFlags.IsUntypedSignatureInJSFile; } // If this is a JSDoc construct signature, then skip the first parameter in the // parameter list. The first parameter represents the return type of the construct // signature. for (let i = isJSConstructSignature ? 1 : 0; i < declaration.parameters.length; i++) { const param = declaration.parameters[i]; let paramSymbol = param.symbol; const type = isJSDocParameterTag(param) ? (param.typeExpression && param.typeExpression.type) : param.type; // Include parameter symbol instead of property symbol in the signature if (paramSymbol && !!(paramSymbol.flags & SymbolFlags.Property) && !isBindingPattern(param.name)) { const resolvedSymbol = resolveName(param, paramSymbol.escapedName, SymbolFlags.Value, undefined, undefined, /*isUse*/ false); paramSymbol = resolvedSymbol!; } if (i === 0 && paramSymbol.escapedName === InternalSymbolName.This) { hasThisParameter = true; thisParameter = param.symbol; } else { parameters.push(paramSymbol); } if (type && type.kind === SyntaxKind.LiteralType) { flags |= SignatureFlags.HasLiteralTypes; } // Record a new minimum argument count if this is not an optional parameter const isOptionalParameter = isOptionalJSDocPropertyLikeTag(param) || param.initializer || param.questionToken || isRestParameter(param) || iife && parameters.length > iife.arguments.length && !type || isJSDocOptionalParameter(param); if (!isOptionalParameter) { minArgumentCount = parameters.length; } } // If only one accessor includes a this-type annotation, the other behaves as if it had the same type annotation if ((declaration.kind === SyntaxKind.GetAccessor || declaration.kind === SyntaxKind.SetAccessor) && hasBindableName(declaration) && (!hasThisParameter || !thisParameter)) { const otherKind = declaration.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; const other = getDeclarationOfKind(getSymbolOfDeclaration(declaration), otherKind); if (other) { thisParameter = getAnnotatedAccessorThisParameter(other); } } if (isInJSFile(declaration)) { const thisTag = getJSDocThisTag(declaration); if (thisTag && thisTag.typeExpression) { thisParameter = createSymbolWithType(createSymbol(SymbolFlags.FunctionScopedVariable, InternalSymbolName.This), getTypeFromTypeNode(thisTag.typeExpression)); } } const classType = declaration.kind === SyntaxKind.Constructor ? getDeclaredTypeOfClassOrInterface(getMergedSymbol((declaration.parent as ClassDeclaration).symbol)) : undefined; const typeParameters = classType ? classType.localTypeParameters : getTypeParametersFromDeclaration(declaration); if (hasRestParameter(declaration) || isInJSFile(declaration) && maybeAddJsSyntheticRestParameter(declaration, parameters)) { flags |= SignatureFlags.HasRestParameter; } if (isConstructorTypeNode(declaration) && hasSyntacticModifier(declaration, ModifierFlags.Abstract) || isConstructorDeclaration(declaration) && hasSyntacticModifier(declaration.parent, ModifierFlags.Abstract)) { flags |= SignatureFlags.Abstract; } links.resolvedSignature = createSignature(declaration, typeParameters, thisParameter, parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, minArgumentCount, flags); } return links.resolvedSignature; } /** * A JS function gets a synthetic rest parameter if it references `arguments` AND: * 1. It has no parameters but at least one `@param` with a type that starts with `...` * OR * 2. It has at least one parameter, and the last parameter has a matching `@param` with a type that starts with `...` */ function maybeAddJsSyntheticRestParameter(declaration: SignatureDeclaration | JSDocSignature, parameters: Symbol[]): boolean { if (isJSDocSignature(declaration) || !containsArgumentsReference(declaration)) { return false; } const lastParam = lastOrUndefined(declaration.parameters); const lastParamTags = lastParam ? getJSDocParameterTags(lastParam) : getJSDocTags(declaration).filter(isJSDocParameterTag); const lastParamVariadicType = firstDefined(lastParamTags, p => p.typeExpression && isJSDocVariadicType(p.typeExpression.type) ? p.typeExpression.type : undefined); const syntheticArgsSymbol = createSymbol(SymbolFlags.Variable, "args" as __String, CheckFlags.RestParameter); if (lastParamVariadicType) { // Parameter has effective annotation, lock in type syntheticArgsSymbol.links.type = createArrayType(getTypeFromTypeNode(lastParamVariadicType.type)); } else { // Parameter has no annotation // By using a `DeferredType` symbol, we allow the type of this rest arg to be overriden by contextual type assignment so long as its type hasn't been // cached by `getTypeOfSymbol` yet. syntheticArgsSymbol.links.checkFlags |= CheckFlags.DeferredType; syntheticArgsSymbol.links.deferralParent = neverType; syntheticArgsSymbol.links.deferralConstituents = [anyArrayType]; syntheticArgsSymbol.links.deferralWriteConstituents = [anyArrayType]; } if (lastParamVariadicType) { // Replace the last parameter with a rest parameter. parameters.pop(); } parameters.push(syntheticArgsSymbol); return true; } function getSignatureOfTypeTag(node: SignatureDeclaration | JSDocSignature) { // should be attached to a function declaration or expression if (!(isInJSFile(node) && isFunctionLikeDeclaration(node))) return undefined; const typeTag = getJSDocTypeTag(node); return typeTag?.typeExpression && getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); } function getParameterTypeOfTypeTag(func: FunctionLikeDeclaration, parameter: ParameterDeclaration) { const signature = getSignatureOfTypeTag(func); if (!signature) return undefined; const pos = func.parameters.indexOf(parameter); return parameter.dotDotDotToken ? getRestTypeAtPosition(signature, pos) : getTypeAtPosition(signature, pos); } function getReturnTypeOfTypeTag(node: SignatureDeclaration | JSDocSignature) { const signature = getSignatureOfTypeTag(node); return signature && getReturnTypeOfSignature(signature); } function containsArgumentsReference(declaration: SignatureDeclaration): boolean { const links = getNodeLinks(declaration); if (links.containsArgumentsReference === undefined) { if (links.flags & NodeCheckFlags.CaptureArguments) { links.containsArgumentsReference = true; } else { links.containsArgumentsReference = traverse((declaration as FunctionLikeDeclaration).body!); } } return links.containsArgumentsReference; function traverse(node: Node): boolean { if (!node) return false; switch (node.kind) { case SyntaxKind.Identifier: return (node as Identifier).escapedText === argumentsSymbol.escapedName && getReferencedValueSymbol(node as Identifier) === argumentsSymbol; case SyntaxKind.PropertyDeclaration: case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: return (node as NamedDeclaration).name!.kind === SyntaxKind.ComputedPropertyName && traverse((node as NamedDeclaration).name!); case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: return traverse((node as PropertyAccessExpression | ElementAccessExpression).expression); case SyntaxKind.PropertyAssignment: return traverse((node as PropertyAssignment).initializer); default: return !nodeStartsNewLexicalEnvironment(node) && !isPartOfTypeNode(node) && !!forEachChild(node, traverse); } } } function getSignaturesOfSymbol(symbol: Symbol | undefined): Signature[] { if (!symbol || !symbol.declarations) return emptyArray; const result: Signature[] = []; for (let i = 0; i < symbol.declarations.length; i++) { const decl = symbol.declarations[i]; if (!isFunctionLike(decl)) continue; // Don't include signature if node is the implementation of an overloaded function. A node is considered // an implementation node if it has a body and the previous node is of the same kind and immediately // precedes the implementation node (i.e. has the same parent and ends where the implementation starts). if (i > 0 && (decl as FunctionLikeDeclaration).body) { const previous = symbol.declarations[i - 1]; if (decl.parent === previous.parent && decl.kind === previous.kind && decl.pos === previous.end) { continue; } } if (isInJSFile(decl) && decl.jsDoc) { let hasJSDocOverloads = false; for (const node of decl.jsDoc) { if (node.tags) { for (const tag of node.tags) { if (isJSDocOverloadTag(tag)) { const jsDocSignature = tag.typeExpression; if (jsDocSignature.type === undefined && !isConstructorDeclaration(decl)) { reportImplicitAny(jsDocSignature, anyType); } result.push(getSignatureFromDeclaration(jsDocSignature)); hasJSDocOverloads = true; } } } } if (hasJSDocOverloads) { continue; } } // If this is a function or method declaration, get the signature from the @type tag for the sake of optional parameters. // Exclude contextually-typed kinds because we already apply the @type tag to the context, plus applying it here to the initializer would supress checks that the two are compatible. result.push( (!isFunctionExpressionOrArrowFunction(decl) && !isObjectLiteralMethod(decl) && getSignatureOfTypeTag(decl)) || getSignatureFromDeclaration(decl) ); } return result; } function resolveExternalModuleTypeByLiteral(name: StringLiteral) { const moduleSym = resolveExternalModuleName(name, name); if (moduleSym) { const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); if (resolvedModuleSymbol) { return getTypeOfSymbol(resolvedModuleSymbol); } } return anyType; } function getThisTypeOfSignature(signature: Signature): Type | undefined { if (signature.thisParameter) { return getTypeOfSymbol(signature.thisParameter); } } function getTypePredicateOfSignature(signature: Signature): TypePredicate | undefined { if (!signature.resolvedTypePredicate) { if (signature.target) { const targetTypePredicate = getTypePredicateOfSignature(signature.target); signature.resolvedTypePredicate = targetTypePredicate ? instantiateTypePredicate(targetTypePredicate, signature.mapper!) : noTypePredicate; } else if (signature.compositeSignatures) { signature.resolvedTypePredicate = getUnionOrIntersectionTypePredicate(signature.compositeSignatures, signature.compositeKind) || noTypePredicate; } else { const type = signature.declaration && getEffectiveReturnTypeNode(signature.declaration); let jsdocPredicate: TypePredicate | undefined; if (!type) { const jsdocSignature = getSignatureOfTypeTag(signature.declaration!); if (jsdocSignature && signature !== jsdocSignature) { jsdocPredicate = getTypePredicateOfSignature(jsdocSignature); } } signature.resolvedTypePredicate = type && isTypePredicateNode(type) ? createTypePredicateFromTypePredicateNode(type, signature) : jsdocPredicate || noTypePredicate; } Debug.assert(!!signature.resolvedTypePredicate); } return signature.resolvedTypePredicate === noTypePredicate ? undefined : signature.resolvedTypePredicate; } function createTypePredicateFromTypePredicateNode(node: TypePredicateNode, signature: Signature): TypePredicate { const parameterName = node.parameterName; const type = node.type && getTypeFromTypeNode(node.type); return parameterName.kind === SyntaxKind.ThisType ? createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsThis : TypePredicateKind.This, /*parameterName*/ undefined, /*parameterIndex*/ undefined, type) : createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsIdentifier : TypePredicateKind.Identifier, parameterName.escapedText as string, findIndex(signature.parameters, p => p.escapedName === parameterName.escapedText), type); } function getUnionOrIntersectionType(types: Type[], kind: TypeFlags | undefined, unionReduction?: UnionReduction) { return kind !== TypeFlags.Intersection ? getUnionType(types, unionReduction) : getIntersectionType(types); } function getReturnTypeOfSignature(signature: Signature): Type { if (!signature.resolvedReturnType) { if (!pushTypeResolution(signature, TypeSystemPropertyName.ResolvedReturnType)) { return errorType; } let type = signature.target ? instantiateType(getReturnTypeOfSignature(signature.target), signature.mapper) : signature.compositeSignatures ? instantiateType(getUnionOrIntersectionType(map(signature.compositeSignatures, getReturnTypeOfSignature), signature.compositeKind, UnionReduction.Subtype), signature.mapper) : getReturnTypeFromAnnotation(signature.declaration!) || (nodeIsMissing((signature.declaration as FunctionLikeDeclaration).body) ? anyType : getReturnTypeFromBody(signature.declaration as FunctionLikeDeclaration)); if (signature.flags & SignatureFlags.IsInnerCallChain) { type = addOptionalTypeMarker(type); } else if (signature.flags & SignatureFlags.IsOuterCallChain) { type = getOptionalType(type); } if (!popTypeResolution()) { if (signature.declaration) { const typeNode = getEffectiveReturnTypeNode(signature.declaration); if (typeNode) { error(typeNode, Diagnostics.Return_type_annotation_circularly_references_itself); } else if (noImplicitAny) { const declaration = signature.declaration as Declaration; const name = getNameOfDeclaration(declaration); if (name) { error(name, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, declarationNameToString(name)); } else { error(declaration, Diagnostics.Function_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions); } } } type = anyType; } signature.resolvedReturnType = type; } return signature.resolvedReturnType; } function getReturnTypeFromAnnotation(declaration: SignatureDeclaration | JSDocSignature) { if (declaration.kind === SyntaxKind.Constructor) { return getDeclaredTypeOfClassOrInterface(getMergedSymbol((declaration.parent as ClassDeclaration).symbol)); } if (isJSDocSignature(declaration)) { const root = getJSDocRoot(declaration); if (root && isConstructorDeclaration(root.parent)) { return getDeclaredTypeOfClassOrInterface(getMergedSymbol((root.parent.parent as ClassDeclaration).symbol)); } } if (isJSDocConstructSignature(declaration)) { return getTypeFromTypeNode((declaration.parameters[0] as ParameterDeclaration).type!); // TODO: GH#18217 } const typeNode = getEffectiveReturnTypeNode(declaration); if (typeNode) { return getTypeFromTypeNode(typeNode); } if (declaration.kind === SyntaxKind.GetAccessor && hasBindableName(declaration)) { const jsDocType = isInJSFile(declaration) && getTypeForDeclarationFromJSDocComment(declaration); if (jsDocType) { return jsDocType; } const setter = getDeclarationOfKind(getSymbolOfDeclaration(declaration), SyntaxKind.SetAccessor); const setterType = getAnnotatedAccessorType(setter); if (setterType) { return setterType; } } return getReturnTypeOfTypeTag(declaration); } function isResolvingReturnTypeOfSignature(signature: Signature) { return !signature.resolvedReturnType && findResolutionCycleStartIndex(signature, TypeSystemPropertyName.ResolvedReturnType) >= 0; } function getRestTypeOfSignature(signature: Signature): Type { return tryGetRestTypeOfSignature(signature) || anyType; } function tryGetRestTypeOfSignature(signature: Signature): Type | undefined { if (signatureHasRestParameter(signature)) { const sigRestType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); const restType = isTupleType(sigRestType) ? getRestTypeOfTupleType(sigRestType) : sigRestType; return restType && getIndexTypeOfType(restType, numberType); } return undefined; } function getSignatureInstantiation(signature: Signature, typeArguments: Type[] | undefined, isJavascript: boolean, inferredTypeParameters?: readonly TypeParameter[]): Signature { const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, fillMissingTypeArguments(typeArguments, signature.typeParameters, getMinTypeArgumentCount(signature.typeParameters), isJavascript)); if (inferredTypeParameters) { const returnSignature = getSingleCallOrConstructSignature(getReturnTypeOfSignature(instantiatedSignature)); if (returnSignature) { const newReturnSignature = cloneSignature(returnSignature); newReturnSignature.typeParameters = inferredTypeParameters; const newInstantiatedSignature = cloneSignature(instantiatedSignature); newInstantiatedSignature.resolvedReturnType = getOrCreateTypeFromSignature(newReturnSignature); return newInstantiatedSignature; } } return instantiatedSignature; } function getSignatureInstantiationWithoutFillingInTypeArguments(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { const instantiations = signature.instantiations || (signature.instantiations = new Map()); const id = getTypeListId(typeArguments); let instantiation = instantiations.get(id); if (!instantiation) { instantiations.set(id, instantiation = createSignatureInstantiation(signature, typeArguments)); } return instantiation; } function createSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { return instantiateSignature(signature, createSignatureTypeMapper(signature, typeArguments), /*eraseTypeParameters*/ true); } function createSignatureTypeMapper(signature: Signature, typeArguments: readonly Type[] | undefined): TypeMapper { return createTypeMapper(signature.typeParameters!, typeArguments); } function getErasedSignature(signature: Signature): Signature { return signature.typeParameters ? signature.erasedSignatureCache || (signature.erasedSignatureCache = createErasedSignature(signature)) : signature; } function createErasedSignature(signature: Signature) { // Create an instantiation of the signature where all type arguments are the any type. return instantiateSignature(signature, createTypeEraser(signature.typeParameters!), /*eraseTypeParameters*/ true); } function getCanonicalSignature(signature: Signature): Signature { return signature.typeParameters ? signature.canonicalSignatureCache || (signature.canonicalSignatureCache = createCanonicalSignature(signature)) : signature; } function createCanonicalSignature(signature: Signature) { // Create an instantiation of the signature where each unconstrained type parameter is replaced with // its original. When a generic class or interface is instantiated, each generic method in the class or // interface is instantiated with a fresh set of cloned type parameters (which we need to handle scenarios // where different generations of the same type parameter are in scope). This leads to a lot of new type // identities, and potentially a lot of work comparing those identities, so here we create an instantiation // that uses the original type identities for all unconstrained type parameters. return getSignatureInstantiation( signature, map(signature.typeParameters, tp => tp.target && !getConstraintOfTypeParameter(tp.target) ? tp.target : tp), isInJSFile(signature.declaration)); } function getBaseSignature(signature: Signature) { const typeParameters = signature.typeParameters; if (typeParameters) { if (signature.baseSignatureCache) { return signature.baseSignatureCache; } const typeEraser = createTypeEraser(typeParameters); const baseConstraintMapper = createTypeMapper(typeParameters, map(typeParameters, tp => getConstraintOfTypeParameter(tp) || unknownType)); let baseConstraints: readonly Type[] = map(typeParameters, tp => instantiateType(tp, baseConstraintMapper) || unknownType); // Run N type params thru the immediate constraint mapper up to N times // This way any noncircular interdependent type parameters are definitely resolved to their external dependencies for (let i = 0; i < typeParameters.length - 1; i++) { baseConstraints = instantiateTypes(baseConstraints, baseConstraintMapper); } // and then apply a type eraser to remove any remaining circularly dependent type parameters baseConstraints = instantiateTypes(baseConstraints, typeEraser); return signature.baseSignatureCache = instantiateSignature(signature, createTypeMapper(typeParameters, baseConstraints), /*eraseTypeParameters*/ true); } return signature; } function getOrCreateTypeFromSignature(signature: Signature): ObjectType { // There are two ways to declare a construct signature, one is by declaring a class constructor // using the constructor keyword, and the other is declaring a bare construct signature in an // object type literal or interface (using the new keyword). Each way of declaring a constructor // will result in a different declaration kind. if (!signature.isolatedSignatureType) { const kind = signature.declaration?.kind; // If declaration is undefined, it is likely to be the signature of the default constructor. const isConstructor = kind === undefined || kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType; const type = createObjectType(ObjectFlags.Anonymous); type.members = emptySymbols; type.properties = emptyArray; type.callSignatures = !isConstructor ? [signature] : emptyArray; type.constructSignatures = isConstructor ? [signature] : emptyArray; type.indexInfos = emptyArray; signature.isolatedSignatureType = type; } return signature.isolatedSignatureType; } function getIndexSymbol(symbol: Symbol): Symbol | undefined { return symbol.members ? getIndexSymbolFromSymbolTable(symbol.members) : undefined; } function getIndexSymbolFromSymbolTable(symbolTable: SymbolTable): Symbol | undefined { return symbolTable.get(InternalSymbolName.Index); } function createIndexInfo(keyType: Type, type: Type, isReadonly: boolean, declaration?: IndexSignatureDeclaration): IndexInfo { return { keyType, type, isReadonly, declaration }; } function getIndexInfosOfSymbol(symbol: Symbol): IndexInfo[] { const indexSymbol = getIndexSymbol(symbol); return indexSymbol ? getIndexInfosOfIndexSymbol(indexSymbol) : emptyArray; } function getIndexInfosOfIndexSymbol(indexSymbol: Symbol): IndexInfo[] { if (indexSymbol.declarations) { const indexInfos: IndexInfo[] = []; for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { if (declaration.parameters.length === 1) { const parameter = declaration.parameters[0]; if (parameter.type) { forEachType(getTypeFromTypeNode(parameter.type), keyType => { if (isValidIndexKeyType(keyType) && !findIndexInfo(indexInfos, keyType)) { indexInfos.push(createIndexInfo(keyType, declaration.type ? getTypeFromTypeNode(declaration.type) : anyType, hasEffectiveModifier(declaration, ModifierFlags.Readonly), declaration)); } }); } } } return indexInfos; } return emptyArray; } function isValidIndexKeyType(type: Type): boolean { return !!(type.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.ESSymbol)) || isPatternLiteralType(type) || !!(type.flags & TypeFlags.Intersection) && !isGenericType(type) && some((type as IntersectionType).types, isValidIndexKeyType); } function getConstraintDeclaration(type: TypeParameter): TypeNode | undefined { return mapDefined(filter(type.symbol && type.symbol.declarations, isTypeParameterDeclaration), getEffectiveConstraintOfTypeParameter)[0]; } function getInferredTypeParameterConstraint(typeParameter: TypeParameter, omitTypeReferences?: boolean) { let inferences: Type[] | undefined; if (typeParameter.symbol?.declarations) { for (const declaration of typeParameter.symbol.declarations) { if (declaration.parent.kind === SyntaxKind.InferType) { // When an 'infer T' declaration is immediately contained in a type reference node // (such as 'Foo'), T's constraint is inferred from the constraint of the // corresponding type parameter in 'Foo'. When multiple 'infer T' declarations are // present, we form an intersection of the inferred constraint types. const [childTypeParameter = declaration.parent, grandParent] = walkUpParenthesizedTypesAndGetParentAndChild(declaration.parent.parent); if (grandParent.kind === SyntaxKind.TypeReference && !omitTypeReferences) { const typeReference = grandParent as TypeReferenceNode; const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReference); if (typeParameters) { const index = typeReference.typeArguments!.indexOf(childTypeParameter as TypeNode); if (index < typeParameters.length) { const declaredConstraint = getConstraintOfTypeParameter(typeParameters[index]); if (declaredConstraint) { // Type parameter constraints can reference other type parameters so // constraints need to be instantiated. If instantiation produces the // type parameter itself, we discard that inference. For example, in // type Foo = [T, U]; // type Bar = T extends Foo ? Foo : T; // the instantiated constraint for U is X, so we discard that inference. const mapper = makeDeferredTypeMapper(typeParameters, typeParameters.map((_, index) => () => { return getEffectiveTypeArgumentAtIndex(typeReference, typeParameters, index); })); const constraint = instantiateType(declaredConstraint, mapper); if (constraint !== typeParameter) { inferences = append(inferences, constraint); } } } } } // When an 'infer T' declaration is immediately contained in a rest parameter declaration, a rest type // or a named rest tuple element, we infer an 'unknown[]' constraint. else if (grandParent.kind === SyntaxKind.Parameter && (grandParent as ParameterDeclaration).dotDotDotToken || grandParent.kind === SyntaxKind.RestType || grandParent.kind === SyntaxKind.NamedTupleMember && (grandParent as NamedTupleMember).dotDotDotToken) { inferences = append(inferences, createArrayType(unknownType)); } // When an 'infer T' declaration is immediately contained in a string template type, we infer a 'string' // constraint. else if (grandParent.kind === SyntaxKind.TemplateLiteralTypeSpan) { inferences = append(inferences, stringType); } // When an 'infer T' declaration is in the constraint position of a mapped type, we infer a 'keyof any' // constraint. else if (grandParent.kind === SyntaxKind.TypeParameter && grandParent.parent.kind === SyntaxKind.MappedType) { inferences = append(inferences, keyofConstraintType); } // When an 'infer T' declaration is the template of a mapped type, and that mapped type is the extends // clause of a conditional whose check type is also a mapped type, give it a constraint equal to the template // of the check type's mapped type else if (grandParent.kind === SyntaxKind.MappedType && (grandParent as MappedTypeNode).type && skipParentheses((grandParent as MappedTypeNode).type!) === declaration.parent && grandParent.parent.kind === SyntaxKind.ConditionalType && (grandParent.parent as ConditionalTypeNode).extendsType === grandParent && (grandParent.parent as ConditionalTypeNode).checkType.kind === SyntaxKind.MappedType && ((grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode).type) { const checkMappedType = (grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode; const nodeType = getTypeFromTypeNode(checkMappedType.type!); inferences = append(inferences, instantiateType(nodeType, makeUnaryTypeMapper(getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(checkMappedType.typeParameter)), checkMappedType.typeParameter.constraint ? getTypeFromTypeNode(checkMappedType.typeParameter.constraint) : keyofConstraintType) )); } } } } return inferences && getIntersectionType(inferences); } /** This is a worker function. Use getConstraintOfTypeParameter which guards against circular constraints. */ function getConstraintFromTypeParameter(typeParameter: TypeParameter): Type | undefined { if (!typeParameter.constraint) { if (typeParameter.target) { const targetConstraint = getConstraintOfTypeParameter(typeParameter.target); typeParameter.constraint = targetConstraint ? instantiateType(targetConstraint, typeParameter.mapper) : noConstraintType; } else { const constraintDeclaration = getConstraintDeclaration(typeParameter); if (!constraintDeclaration) { typeParameter.constraint = getInferredTypeParameterConstraint(typeParameter) || noConstraintType; } else { let type = getTypeFromTypeNode(constraintDeclaration); if (type.flags & TypeFlags.Any && !isErrorType(type)) { // Allow errorType to propegate to keep downstream errors suppressed // use keyofConstraintType as the base constraint for mapped type key constraints (unknown isn;t assignable to that, but `any` was), // use unknown otherwise type = constraintDeclaration.parent.parent.kind === SyntaxKind.MappedType ? keyofConstraintType : unknownType; } typeParameter.constraint = type; } } } return typeParameter.constraint === noConstraintType ? undefined : typeParameter.constraint; } function getParentSymbolOfTypeParameter(typeParameter: TypeParameter): Symbol | undefined { const tp = getDeclarationOfKind(typeParameter.symbol, SyntaxKind.TypeParameter)!; const host = isJSDocTemplateTag(tp.parent) ? getEffectiveContainerForJSDocTemplateTag(tp.parent) : tp.parent; return host && getSymbolOfNode(host); } function getTypeListId(types: readonly Type[] | undefined) { let result = ""; if (types) { const length = types.length; let i = 0; while (i < length) { const startId = types[i].id; let count = 1; while (i + count < length && types[i + count].id === startId + count) { count++; } if (result.length) { result += ","; } result += startId; if (count > 1) { result += ":" + count; } i += count; } } return result; } function getAliasId(aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { return aliasSymbol ? `@${getSymbolId(aliasSymbol)}` + (aliasTypeArguments ? `:${getTypeListId(aliasTypeArguments)}` : "") : ""; } // This function is used to propagate certain flags when creating new object type references and union types. // It is only necessary to do so if a constituent type might be the undefined type, the null type, the type // of an object literal or a non-inferrable type. This is because there are operations in the type checker // that care about the presence of such types at arbitrary depth in a containing type. function getPropagatingFlagsOfTypes(types: readonly Type[], excludeKinds?: TypeFlags): ObjectFlags { let result: ObjectFlags = 0; for (const type of types) { if (excludeKinds === undefined || !(type.flags & excludeKinds)) { result |= getObjectFlags(type); } } return result & ObjectFlags.PropagatingFlags; } function tryCreateTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): Type { if (some(typeArguments) && target === emptyGenericType) { return unknownType; } return createTypeReference(target, typeArguments); } function createTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): TypeReference { const id = getTypeListId(typeArguments); let type = target.instantiations.get(id); if (!type) { type = createObjectType(ObjectFlags.Reference, target.symbol) as TypeReference; target.instantiations.set(id, type); type.objectFlags |= typeArguments ? getPropagatingFlagsOfTypes(typeArguments) : 0; type.target = target; type.resolvedTypeArguments = typeArguments; } return type; } function cloneTypeReference(source: TypeReference): TypeReference { const type = createTypeWithSymbol(source.flags, source.symbol) as TypeReference; type.objectFlags = source.objectFlags; type.target = source.target; type.resolvedTypeArguments = source.resolvedTypeArguments; return type; } function createDeferredTypeReference(target: GenericType, node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, mapper?: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): DeferredTypeReference { if (!aliasSymbol) { aliasSymbol = getAliasSymbolForTypeNode(node); const localAliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); aliasTypeArguments = mapper ? instantiateTypes(localAliasTypeArguments, mapper) : localAliasTypeArguments; } const type = createObjectType(ObjectFlags.Reference, target.symbol) as DeferredTypeReference; type.target = target; type.node = node; type.mapper = mapper; type.aliasSymbol = aliasSymbol; type.aliasTypeArguments = aliasTypeArguments; return type; } function getTypeArguments(type: TypeReference): readonly Type[] { if (!type.resolvedTypeArguments) { if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedTypeArguments)) { return type.target.localTypeParameters?.map(() => errorType) || emptyArray; } const node = type.node; const typeArguments = !node ? emptyArray : node.kind === SyntaxKind.TypeReference ? concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters!)) : node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : map(node.elements, getTypeFromTypeNode); if (popTypeResolution()) { type.resolvedTypeArguments = type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments; } else { type.resolvedTypeArguments = type.target.localTypeParameters?.map(() => errorType) || emptyArray; error( type.node || currentNode, type.target.symbol ? Diagnostics.Type_arguments_for_0_circularly_reference_themselves : Diagnostics.Tuple_type_arguments_circularly_reference_themselves, type.target.symbol && symbolToString(type.target.symbol) ); } } return type.resolvedTypeArguments; } function getTypeReferenceArity(type: TypeReference): number { return length(type.target.typeParameters); } /** * Get type from type-reference that reference to class or interface */ function getTypeFromClassOrInterfaceReference(node: NodeWithTypeArguments, symbol: Symbol): Type { const type = getDeclaredTypeOfSymbol(getMergedSymbol(symbol)) as InterfaceType; const typeParameters = type.localTypeParameters; if (typeParameters) { const numTypeArguments = length(node.typeArguments); const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); const isJs = isInJSFile(node); const isJsImplicitAny = !noImplicitAny && isJs; if (!isJsImplicitAny && (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length)) { const missingAugmentsTag = isJs && isExpressionWithTypeArguments(node) && !isJSDocAugmentsTag(node.parent); const diag = minTypeArgumentCount === typeParameters.length ? missingAugmentsTag ? Diagnostics.Expected_0_type_arguments_provide_these_with_an_extends_tag : Diagnostics.Generic_type_0_requires_1_type_argument_s : missingAugmentsTag ? Diagnostics.Expected_0_1_type_arguments_provide_these_with_an_extends_tag : Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments; const typeStr = typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType); error(node, diag, typeStr, minTypeArgumentCount, typeParameters.length); if (!isJs) { // TODO: Adopt same permissive behavior in TS as in JS to reduce follow-on editing experience failures (requires editing fillMissingTypeArguments) return errorType; } } if (node.kind === SyntaxKind.TypeReference && isDeferredTypeReferenceNode(node as TypeReferenceNode, length(node.typeArguments) !== typeParameters.length)) { return createDeferredTypeReference(type as GenericType, node as TypeReferenceNode, /*mapper*/ undefined); } // In a type reference, the outer type parameters of the referenced class or interface are automatically // supplied as type arguments and the type reference only specifies arguments for the local type parameters // of the class or interface. const typeArguments = concatenate(type.outerTypeParameters, fillMissingTypeArguments(typeArgumentsFromTypeReferenceNode(node), typeParameters, minTypeArgumentCount, isJs)); return createTypeReference(type as GenericType, typeArguments); } return checkNoTypeArguments(node, symbol) ? type : errorType; } function getTypeAliasInstantiation(symbol: Symbol, typeArguments: readonly Type[] | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { const type = getDeclaredTypeOfSymbol(symbol); if (type === intrinsicMarkerType && intrinsicTypeKinds.has(symbol.escapedName as string) && typeArguments && typeArguments.length === 1) { return getStringMappingType(symbol, typeArguments[0]); } const links = getSymbolLinks(symbol); const typeParameters = links.typeParameters!; const id = getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); let instantiation = links.instantiations!.get(id); if (!instantiation) { links.instantiations!.set(id, instantiation = instantiateTypeWithAlias(type, createTypeMapper(typeParameters, fillMissingTypeArguments(typeArguments, typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(symbol.valueDeclaration))), aliasSymbol, aliasTypeArguments)); } return instantiation; } /** * Get type from reference to type alias. When a type alias is generic, the declared type of the type alias may include * references to the type parameters of the alias. We replace those with the actual type arguments by instantiating the * declared type. Instantiations are cached using the type identities of the type arguments as the key. */ function getTypeFromTypeAliasReference(node: NodeWithTypeArguments, symbol: Symbol): Type { if (getCheckFlags(symbol) & CheckFlags.Unresolved) { const typeArguments = typeArgumentsFromTypeReferenceNode(node); const id = getAliasId(symbol, typeArguments); let errorType = errorTypes.get(id); if (!errorType) { errorType = createIntrinsicType(TypeFlags.Any, "error"); errorType.aliasSymbol = symbol; errorType.aliasTypeArguments = typeArguments; errorTypes.set(id, errorType); } return errorType; } const type = getDeclaredTypeOfSymbol(symbol); const typeParameters = getSymbolLinks(symbol).typeParameters; if (typeParameters) { const numTypeArguments = length(node.typeArguments); const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); if (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length) { error(node, minTypeArgumentCount === typeParameters.length ? Diagnostics.Generic_type_0_requires_1_type_argument_s : Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments, symbolToString(symbol), minTypeArgumentCount, typeParameters.length); return errorType; } // We refrain from associating a local type alias with an instantiation of a top-level type alias // because the local alias may end up being referenced in an inferred return type where it is not // accessible--which in turn may lead to a large structural expansion of the type when generating // a .d.ts file. See #43622 for an example. const aliasSymbol = getAliasSymbolForTypeNode(node); let newAliasSymbol = aliasSymbol && (isLocalTypeAlias(symbol) || !isLocalTypeAlias(aliasSymbol)) ? aliasSymbol : undefined; let aliasTypeArguments: Type[] | undefined; if (newAliasSymbol) { aliasTypeArguments = getTypeArgumentsForAliasSymbol(newAliasSymbol); } else if (isTypeReferenceType(node)) { const aliasSymbol = resolveTypeReferenceName(node, SymbolFlags.Alias, /*ignoreErrors*/ true); // refers to an alias import/export/reexport - by making sure we use the target as an aliasSymbol, // we ensure the exported symbol is used to refer to the type when it's reserialized later if (aliasSymbol && aliasSymbol !== unknownSymbol) { const resolved = resolveAlias(aliasSymbol); if (resolved && resolved.flags & SymbolFlags.TypeAlias) { newAliasSymbol = resolved; aliasTypeArguments = typeArgumentsFromTypeReferenceNode(node) || (typeParameters ? [] : undefined); } } } return getTypeAliasInstantiation(symbol, typeArgumentsFromTypeReferenceNode(node), newAliasSymbol, aliasTypeArguments); } return checkNoTypeArguments(node, symbol) ? type : errorType; } function isLocalTypeAlias(symbol: Symbol) { const declaration = symbol.declarations?.find(isTypeAlias); return !!(declaration && getContainingFunction(declaration)); } function getTypeReferenceName(node: TypeReferenceType): EntityNameOrEntityNameExpression | undefined { switch (node.kind) { case SyntaxKind.TypeReference: return node.typeName; case SyntaxKind.ExpressionWithTypeArguments: // We only support expressions that are simple qualified names. For other // expressions this produces undefined. const expr = node.expression; if (isEntityNameExpression(expr)) { return expr; } // fall through; } return undefined; } function getSymbolPath(symbol: Symbol): string { return symbol.parent ? `${getSymbolPath(symbol.parent)}.${symbol.escapedName}` : symbol.escapedName as string; } function getUnresolvedSymbolForEntityName(name: EntityNameOrEntityNameExpression) { const identifier = name.kind === SyntaxKind.QualifiedName ? name.right : name.kind === SyntaxKind.PropertyAccessExpression ? name.name : name; const text = identifier.escapedText; if (text) { const parentSymbol = name.kind === SyntaxKind.QualifiedName ? getUnresolvedSymbolForEntityName(name.left) : name.kind === SyntaxKind.PropertyAccessExpression ? getUnresolvedSymbolForEntityName(name.expression) : undefined; const path = parentSymbol ? `${getSymbolPath(parentSymbol)}.${text}` : text as string; let result = unresolvedSymbols.get(path); if (!result) { unresolvedSymbols.set(path, result = createSymbol(SymbolFlags.TypeAlias, text, CheckFlags.Unresolved)); result.parent = parentSymbol; result.links.declaredType = unresolvedType; } return result; } return unknownSymbol; } function resolveTypeReferenceName(typeReference: TypeReferenceType, meaning: SymbolFlags, ignoreErrors?: boolean) { const name = getTypeReferenceName(typeReference); if (!name) { return unknownSymbol; } const symbol = resolveEntityName(name, meaning, ignoreErrors); return symbol && symbol !== unknownSymbol ? symbol : ignoreErrors ? unknownSymbol : getUnresolvedSymbolForEntityName(name); } function getTypeReferenceType(node: NodeWithTypeArguments, symbol: Symbol): Type { if (symbol === unknownSymbol) { return errorType; } symbol = getExpandoSymbol(symbol) || symbol; if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { return getTypeFromClassOrInterfaceReference(node, symbol); } if (symbol.flags & SymbolFlags.TypeAlias) { return getTypeFromTypeAliasReference(node, symbol); } // Get type from reference to named type that cannot be generic (enum or type parameter) const res = tryGetDeclaredTypeOfSymbol(symbol); if (res) { return checkNoTypeArguments(node, symbol) ? getRegularTypeOfLiteralType(res) : errorType; } if (symbol.flags & SymbolFlags.Value && isJSDocTypeReference(node)) { const jsdocType = getTypeFromJSDocValueReference(node, symbol); if (jsdocType) { return jsdocType; } else { // Resolve the type reference as a Type for the purpose of reporting errors. resolveTypeReferenceName(node, SymbolFlags.Type); return getTypeOfSymbol(symbol); } } return errorType; } /** * A JSdoc TypeReference may be to a value, but resolve it as a type anyway. * Example: import('./b').ConstructorFunction */ function getTypeFromJSDocValueReference(node: NodeWithTypeArguments, symbol: Symbol): Type | undefined { const links = getNodeLinks(node); if (!links.resolvedJSDocType) { const valueType = getTypeOfSymbol(symbol); let typeType = valueType; if (symbol.valueDeclaration) { const isImportTypeWithQualifier = node.kind === SyntaxKind.ImportType && (node as ImportTypeNode).qualifier; // valueType might not have a symbol, eg, {import('./b').STRING_LITERAL} if (valueType.symbol && valueType.symbol !== symbol && isImportTypeWithQualifier) { typeType = getTypeReferenceType(node, valueType.symbol); } } links.resolvedJSDocType = typeType; } return links.resolvedJSDocType; } function getSubstitutionType(baseType: Type, constraint: Type) { if (constraint.flags & TypeFlags.AnyOrUnknown || constraint === baseType || baseType.flags & TypeFlags.Any) { return baseType; } const id = `${getTypeId(baseType)}>${getTypeId(constraint)}`; const cached = substitutionTypes.get(id); if (cached) { return cached; } const result = createType(TypeFlags.Substitution) as SubstitutionType; result.baseType = baseType; result.constraint = constraint; substitutionTypes.set(id, result); return result; } function getSubstitutionIntersection(substitutionType: SubstitutionType) { return getIntersectionType([substitutionType.constraint, substitutionType.baseType]); } function isUnaryTupleTypeNode(node: TypeNode) { return node.kind === SyntaxKind.TupleType && (node as TupleTypeNode).elements.length === 1; } function getImpliedConstraint(type: Type, checkNode: TypeNode, extendsNode: TypeNode): Type | undefined { return isUnaryTupleTypeNode(checkNode) && isUnaryTupleTypeNode(extendsNode) ? getImpliedConstraint(type, (checkNode as TupleTypeNode).elements[0], (extendsNode as TupleTypeNode).elements[0]) : getActualTypeVariable(getTypeFromTypeNode(checkNode)) === getActualTypeVariable(type) ? getTypeFromTypeNode(extendsNode) : undefined; } function getConditionalFlowTypeOfType(type: Type, node: Node) { let constraints: Type[] | undefined; let covariant = true; while (node && !isStatement(node) && node.kind !== SyntaxKind.JSDoc) { const parent = node.parent; // only consider variance flipped by parameter locations - `keyof` types would usually be considered variance inverting, but // often get used in indexed accesses where they behave sortof invariantly, but our checking is lax if (parent.kind === SyntaxKind.Parameter) { covariant = !covariant; } // Always substitute on type parameters, regardless of variance, since even // in contravariant positions, they may rely on substituted constraints to be valid if ((covariant || type.flags & TypeFlags.TypeVariable) && parent.kind === SyntaxKind.ConditionalType && node === (parent as ConditionalTypeNode).trueType) { const constraint = getImpliedConstraint(type, (parent as ConditionalTypeNode).checkType, (parent as ConditionalTypeNode).extendsType); if (constraint) { constraints = append(constraints, constraint); } } // Given a homomorphic mapped type { [K in keyof T]: XXX }, where T is constrained to an array or tuple type, in the // template type XXX, K has an added constraint of number | `${number}`. else if (type.flags & TypeFlags.TypeParameter && parent.kind === SyntaxKind.MappedType && node === (parent as MappedTypeNode).type) { const mappedType = getTypeFromTypeNode(parent as TypeNode) as MappedType; if (getTypeParameterFromMappedType(mappedType) === getActualTypeVariable(type)) { const typeParameter = getHomomorphicTypeVariable(mappedType); if (typeParameter) { const constraint = getConstraintOfTypeParameter(typeParameter); if (constraint && everyType(constraint, isArrayOrTupleType)) { constraints = append(constraints, getUnionType([numberType, numericStringType])); } } } } node = parent; } return constraints ? getSubstitutionType(type, getIntersectionType(constraints)) : type; } function isJSDocTypeReference(node: Node): node is TypeReferenceNode { return !!(node.flags & NodeFlags.JSDoc) && (node.kind === SyntaxKind.TypeReference || node.kind === SyntaxKind.ImportType); } function checkNoTypeArguments(node: NodeWithTypeArguments, symbol?: Symbol) { if (node.typeArguments) { error(node, Diagnostics.Type_0_is_not_generic, symbol ? symbolToString(symbol) : (node as TypeReferenceNode).typeName ? declarationNameToString((node as TypeReferenceNode).typeName) : anon); return false; } return true; } function getIntendedTypeFromJSDocTypeReference(node: TypeReferenceNode): Type | undefined { if (isIdentifier(node.typeName)) { const typeArgs = node.typeArguments; switch (node.typeName.escapedText) { case "String": checkNoTypeArguments(node); return stringType; case "Number": checkNoTypeArguments(node); return numberType; case "Boolean": checkNoTypeArguments(node); return booleanType; case "Void": checkNoTypeArguments(node); return voidType; case "Undefined": checkNoTypeArguments(node); return undefinedType; case "Null": checkNoTypeArguments(node); return nullType; case "Function": case "function": checkNoTypeArguments(node); return globalFunctionType; case "array": return (!typeArgs || !typeArgs.length) && !noImplicitAny ? anyArrayType : undefined; case "promise": return (!typeArgs || !typeArgs.length) && !noImplicitAny ? createPromiseType(anyType) : undefined; case "Object": if (typeArgs && typeArgs.length === 2) { if (isJSDocIndexSignature(node)) { const indexed = getTypeFromTypeNode(typeArgs[0]); const target = getTypeFromTypeNode(typeArgs[1]); const indexInfo = indexed === stringType || indexed === numberType ? [createIndexInfo(indexed, target, /*isReadonly*/ false)] : emptyArray; return createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, indexInfo); } return anyType; } checkNoTypeArguments(node); return !noImplicitAny ? anyType : undefined; } } } function getTypeFromJSDocNullableTypeNode(node: JSDocNullableType) { const type = getTypeFromTypeNode(node.type); return strictNullChecks ? getNullableType(type, TypeFlags.Null) : type; } function getTypeFromTypeReference(node: TypeReferenceType): Type { const links = getNodeLinks(node); if (!links.resolvedType) { // handle LS queries on the `const` in `x as const` by resolving to the type of `x` if (isConstTypeReference(node) && isAssertionExpression(node.parent)) { links.resolvedSymbol = unknownSymbol; return links.resolvedType = checkExpressionCached(node.parent.expression); } let symbol: Symbol | undefined; let type: Type | undefined; const meaning = SymbolFlags.Type; if (isJSDocTypeReference(node)) { type = getIntendedTypeFromJSDocTypeReference(node); if (!type) { symbol = resolveTypeReferenceName(node, meaning, /*ignoreErrors*/ true); if (symbol === unknownSymbol) { symbol = resolveTypeReferenceName(node, meaning | SymbolFlags.Value); } else { resolveTypeReferenceName(node, meaning); // Resolve again to mark errors, if any } type = getTypeReferenceType(node, symbol); } } if (!type) { symbol = resolveTypeReferenceName(node, meaning); type = getTypeReferenceType(node, symbol); } // Cache both the resolved symbol and the resolved type. The resolved symbol is needed when we check the // type reference in checkTypeReferenceNode. links.resolvedSymbol = symbol; links.resolvedType = type; } return links.resolvedType; } function typeArgumentsFromTypeReferenceNode(node: NodeWithTypeArguments): Type[] | undefined { return map(node.typeArguments, getTypeFromTypeNode); } function getTypeFromTypeQueryNode(node: TypeQueryNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { // TypeScript 1.0 spec (April 2014): 3.6.3 // The expression is processed as an identifier expression (section 4.3) // or property access expression(section 4.10), // the widened type(section 3.9) of which becomes the result. const type = checkExpressionWithTypeArguments(node); links.resolvedType = getRegularTypeOfLiteralType(getWidenedType(type)); } return links.resolvedType; } function getTypeOfGlobalSymbol(symbol: Symbol | undefined, arity: number): ObjectType { function getTypeDeclaration(symbol: Symbol): Declaration | undefined { const declarations = symbol.declarations; if (declarations) { for (const declaration of declarations) { switch (declaration.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.EnumDeclaration: return declaration; } } } } if (!symbol) { return arity ? emptyGenericType : emptyObjectType; } const type = getDeclaredTypeOfSymbol(symbol); if (!(type.flags & TypeFlags.Object)) { error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_be_a_class_or_interface_type, symbolName(symbol)); return arity ? emptyGenericType : emptyObjectType; } if (length((type as InterfaceType).typeParameters) !== arity) { error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); return arity ? emptyGenericType : emptyObjectType; } return type as ObjectType; } function getGlobalValueSymbol(name: __String, reportErrors: boolean): Symbol | undefined { return getGlobalSymbol(name, SymbolFlags.Value, reportErrors ? Diagnostics.Cannot_find_global_value_0 : undefined); } function getGlobalTypeSymbol(name: __String, reportErrors: boolean): Symbol | undefined { return getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); } function getGlobalTypeAliasSymbol(name: __String, arity: number, reportErrors: boolean): Symbol | undefined { const symbol = getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); if (symbol) { // Resolve the declared type of the symbol. This resolves type parameters for the type // alias so that we can check arity. getDeclaredTypeOfSymbol(symbol); if (length(getSymbolLinks(symbol).typeParameters) !== arity) { const decl = symbol.declarations && find(symbol.declarations, isTypeAliasDeclaration); error(decl, Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); return undefined; } } return symbol; } function getGlobalSymbol(name: __String, meaning: SymbolFlags, diagnostic: DiagnosticMessage | undefined): Symbol | undefined { // Don't track references for global symbols anyway, so value if `isReference` is arbitrary return resolveName(undefined, name, meaning, diagnostic, name, /*isUse*/ false, /*excludeGlobals*/ false, /*getSpellingSuggestions*/ false); } function getGlobalType(name: __String, arity: 0, reportErrors: true): ObjectType; function getGlobalType(name: __String, arity: 0, reportErrors: boolean): ObjectType | undefined; function getGlobalType(name: __String, arity: number, reportErrors: true): GenericType; function getGlobalType(name: __String, arity: number, reportErrors: boolean): GenericType | undefined; function getGlobalType(name: __String, arity: number, reportErrors: boolean): ObjectType | undefined { const symbol = getGlobalTypeSymbol(name, reportErrors); return symbol || reportErrors ? getTypeOfGlobalSymbol(symbol, arity) : undefined; } function getGlobalTypedPropertyDescriptorType() { // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times return deferredGlobalTypedPropertyDescriptorType ||= getGlobalType("TypedPropertyDescriptor" as __String, /*arity*/ 1, /*reportErrors*/ true) || emptyGenericType; } function getGlobalTemplateStringsArrayType() { // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times return deferredGlobalTemplateStringsArrayType ||= getGlobalType("TemplateStringsArray" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; } function getGlobalImportMetaType() { // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times return deferredGlobalImportMetaType ||= getGlobalType("ImportMeta" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; } function getGlobalImportMetaExpressionType() { if (!deferredGlobalImportMetaExpressionType) { // Create a synthetic type `ImportMetaExpression { meta: MetaProperty }` const symbol = createSymbol(SymbolFlags.None, "ImportMetaExpression" as __String); const importMetaType = getGlobalImportMetaType(); const metaPropertySymbol = createSymbol(SymbolFlags.Property, "meta" as __String, CheckFlags.Readonly); metaPropertySymbol.parent = symbol; metaPropertySymbol.links.type = importMetaType; const members = createSymbolTable([metaPropertySymbol]); symbol.members = members; deferredGlobalImportMetaExpressionType = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); } return deferredGlobalImportMetaExpressionType; } function getGlobalImportCallOptionsType(reportErrors: boolean) { return (deferredGlobalImportCallOptionsType ||= getGlobalType("ImportCallOptions" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; } function getGlobalESSymbolConstructorSymbol(reportErrors: boolean): Symbol | undefined { return deferredGlobalESSymbolConstructorSymbol ||= getGlobalValueSymbol("Symbol" as __String, reportErrors); } function getGlobalESSymbolConstructorTypeSymbol(reportErrors: boolean): Symbol | undefined { return deferredGlobalESSymbolConstructorTypeSymbol ||= getGlobalTypeSymbol("SymbolConstructor" as __String, reportErrors); } function getGlobalESSymbolType() { return (deferredGlobalESSymbolType ||= getGlobalType("Symbol" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; } function getGlobalPromiseType(reportErrors: boolean) { return (deferredGlobalPromiseType ||= getGlobalType("Promise" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalPromiseLikeType(reportErrors: boolean) { return (deferredGlobalPromiseLikeType ||= getGlobalType("PromiseLike" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalPromiseConstructorSymbol(reportErrors: boolean): Symbol | undefined { return deferredGlobalPromiseConstructorSymbol ||= getGlobalValueSymbol("Promise" as __String, reportErrors); } function getGlobalPromiseConstructorLikeType(reportErrors: boolean) { return (deferredGlobalPromiseConstructorLikeType ||= getGlobalType("PromiseConstructorLike" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; } function getGlobalAsyncIterableType(reportErrors: boolean) { return (deferredGlobalAsyncIterableType ||= getGlobalType("AsyncIterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalAsyncIteratorType(reportErrors: boolean) { return (deferredGlobalAsyncIteratorType ||= getGlobalType("AsyncIterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; } function getGlobalAsyncIterableIteratorType(reportErrors: boolean) { return (deferredGlobalAsyncIterableIteratorType ||= getGlobalType("AsyncIterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalAsyncGeneratorType(reportErrors: boolean) { return (deferredGlobalAsyncGeneratorType ||= getGlobalType("AsyncGenerator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; } function getGlobalIterableType(reportErrors: boolean) { return (deferredGlobalIterableType ||= getGlobalType("Iterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalIteratorType(reportErrors: boolean) { return (deferredGlobalIteratorType ||= getGlobalType("Iterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; } function getGlobalIterableIteratorType(reportErrors: boolean) { return (deferredGlobalIterableIteratorType ||= getGlobalType("IterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalGeneratorType(reportErrors: boolean) { return (deferredGlobalGeneratorType ||= getGlobalType("Generator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; } function getGlobalIteratorYieldResultType(reportErrors: boolean) { return (deferredGlobalIteratorYieldResultType ||= getGlobalType("IteratorYieldResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalIteratorReturnResultType(reportErrors: boolean) { return (deferredGlobalIteratorReturnResultType ||= getGlobalType("IteratorReturnResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; } function getGlobalTypeOrUndefined(name: __String, arity = 0): ObjectType | undefined { const symbol = getGlobalSymbol(name, SymbolFlags.Type, /*diagnostic*/ undefined); return symbol && getTypeOfGlobalSymbol(symbol, arity) as GenericType; } function getGlobalExtractSymbol(): Symbol | undefined { // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times deferredGlobalExtractSymbol ||= getGlobalTypeAliasSymbol("Extract" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; return deferredGlobalExtractSymbol === unknownSymbol ? undefined : deferredGlobalExtractSymbol; } function getGlobalOmitSymbol(): Symbol | undefined { // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times deferredGlobalOmitSymbol ||= getGlobalTypeAliasSymbol("Omit" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; return deferredGlobalOmitSymbol === unknownSymbol ? undefined : deferredGlobalOmitSymbol; } function getGlobalAwaitedSymbol(reportErrors: boolean): Symbol | undefined { // Only cache `unknownSymbol` if we are reporting errors so that we don't report the error more than once. deferredGlobalAwaitedSymbol ||= getGlobalTypeAliasSymbol("Awaited" as __String, /*arity*/ 1, reportErrors) || (reportErrors ? unknownSymbol : undefined); return deferredGlobalAwaitedSymbol === unknownSymbol ? undefined : deferredGlobalAwaitedSymbol; } function getGlobalBigIntType() { return (deferredGlobalBigIntType ||= getGlobalType("BigInt" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; } function getGlobalClassDecoratorContextType(reportErrors: boolean) { return (deferredGlobalClassDecoratorContextType ??= getGlobalType("ClassDecoratorContext" as __String, /*arity*/ 1, reportErrors)) ?? emptyGenericType; } function getGlobalClassMethodDecoratorContextType(reportErrors: boolean) { return (deferredGlobalClassMethodDecoratorContextType ??= getGlobalType("ClassMethodDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalClassGetterDecoratorContextType(reportErrors: boolean) { return (deferredGlobalClassGetterDecoratorContextType ??= getGlobalType("ClassGetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalClassSetterDecoratorContextType(reportErrors: boolean) { return (deferredGlobalClassSetterDecoratorContextType ??= getGlobalType("ClassSetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalClassAccessorDecoratorContextType(reportErrors: boolean) { return (deferredGlobalClassAccessorDecoratorContextType ??= getGlobalType("ClassAccessorDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalClassAccessorDecoratorTargetType(reportErrors: boolean) { return (deferredGlobalClassAccessorDecoratorTargetType ??= getGlobalType("ClassAccessorDecoratorTarget" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalClassAccessorDecoratorResultType(reportErrors: boolean) { return (deferredGlobalClassAccessorDecoratorResultType ??= getGlobalType("ClassAccessorDecoratorResult" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalClassFieldDecoratorContextType(reportErrors: boolean) { return (deferredGlobalClassFieldDecoratorContextType ??= getGlobalType("ClassFieldDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; } function getGlobalNaNSymbol(): Symbol | undefined { return (deferredGlobalNaNSymbol ||= getGlobalValueSymbol("NaN" as __String, /*reportErrors*/ false)); } function getGlobalRecordSymbol(): Symbol | undefined { deferredGlobalRecordSymbol ||= getGlobalTypeAliasSymbol("Record" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; return deferredGlobalRecordSymbol === unknownSymbol ? undefined : deferredGlobalRecordSymbol; } /** * Instantiates a global type that is generic with some element type, and returns that instantiation. */ function createTypeFromGenericGlobalType(genericGlobalType: GenericType, typeArguments: readonly Type[]): ObjectType { return genericGlobalType !== emptyGenericType ? createTypeReference(genericGlobalType, typeArguments) : emptyObjectType; } function createTypedPropertyDescriptorType(propertyType: Type): Type { return createTypeFromGenericGlobalType(getGlobalTypedPropertyDescriptorType(), [propertyType]); } function createIterableType(iteratedType: Type): Type { return createTypeFromGenericGlobalType(getGlobalIterableType(/*reportErrors*/ true), [iteratedType]); } function createArrayType(elementType: Type, readonly?: boolean): ObjectType { return createTypeFromGenericGlobalType(readonly ? globalReadonlyArrayType : globalArrayType, [elementType]); } function getTupleElementFlags(node: TypeNode) { switch (node.kind) { case SyntaxKind.OptionalType: return ElementFlags.Optional; case SyntaxKind.RestType: return getRestTypeElementFlags(node as RestTypeNode); case SyntaxKind.NamedTupleMember: return (node as NamedTupleMember).questionToken ? ElementFlags.Optional : (node as NamedTupleMember).dotDotDotToken ? getRestTypeElementFlags(node as NamedTupleMember) : ElementFlags.Required; default: return ElementFlags.Required; } } function getRestTypeElementFlags(node: RestTypeNode | NamedTupleMember) { return getArrayElementTypeNode(node.type) ? ElementFlags.Rest : ElementFlags.Variadic; } function getArrayOrTupleTargetType(node: ArrayTypeNode | TupleTypeNode): GenericType { const readonly = isReadonlyTypeOperator(node.parent); const elementType = getArrayElementTypeNode(node); if (elementType) { return readonly ? globalReadonlyArrayType : globalArrayType; } const elementFlags = map((node as TupleTypeNode).elements, getTupleElementFlags); const missingName = some((node as TupleTypeNode).elements, e => e.kind !== SyntaxKind.NamedTupleMember); return getTupleTargetType(elementFlags, readonly, /*associatedNames*/ missingName ? undefined : (node as TupleTypeNode).elements as readonly NamedTupleMember[]); } // Return true if the given type reference node is directly aliased or if it needs to be deferred // because it is possibly contained in a circular chain of eagerly resolved types. function isDeferredTypeReferenceNode(node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, hasDefaultTypeArguments?: boolean) { return !!getAliasSymbolForTypeNode(node) || isResolvedByTypeAlias(node) && ( node.kind === SyntaxKind.ArrayType ? mayResolveTypeAlias(node.elementType) : node.kind === SyntaxKind.TupleType ? some(node.elements, mayResolveTypeAlias) : hasDefaultTypeArguments || some(node.typeArguments, mayResolveTypeAlias)); } // Return true when the given node is transitively contained in type constructs that eagerly // resolve their constituent types. We include SyntaxKind.TypeReference because type arguments // of type aliases are eagerly resolved. function isResolvedByTypeAlias(node: Node): boolean { const parent = node.parent; switch (parent.kind) { case SyntaxKind.ParenthesizedType: case SyntaxKind.NamedTupleMember: case SyntaxKind.TypeReference: case SyntaxKind.UnionType: case SyntaxKind.IntersectionType: case SyntaxKind.IndexedAccessType: case SyntaxKind.ConditionalType: case SyntaxKind.TypeOperator: case SyntaxKind.ArrayType: case SyntaxKind.TupleType: return isResolvedByTypeAlias(parent); case SyntaxKind.TypeAliasDeclaration: return true; } return false; } // Return true if resolving the given node (i.e. getTypeFromTypeNode) possibly causes resolution // of a type alias. function mayResolveTypeAlias(node: Node): boolean { switch (node.kind) { case SyntaxKind.TypeReference: return isJSDocTypeReference(node) || !!(resolveTypeReferenceName(node as TypeReferenceNode, SymbolFlags.Type).flags & SymbolFlags.TypeAlias); case SyntaxKind.TypeQuery: return true; case SyntaxKind.TypeOperator: return (node as TypeOperatorNode).operator !== SyntaxKind.UniqueKeyword && mayResolveTypeAlias((node as TypeOperatorNode).type); case SyntaxKind.ParenthesizedType: case SyntaxKind.OptionalType: case SyntaxKind.NamedTupleMember: case SyntaxKind.JSDocOptionalType: case SyntaxKind.JSDocNullableType: case SyntaxKind.JSDocNonNullableType: case SyntaxKind.JSDocTypeExpression: return mayResolveTypeAlias((node as ParenthesizedTypeNode | OptionalTypeNode | JSDocTypeReferencingNode | NamedTupleMember).type); case SyntaxKind.RestType: return (node as RestTypeNode).type.kind !== SyntaxKind.ArrayType || mayResolveTypeAlias(((node as RestTypeNode).type as ArrayTypeNode).elementType); case SyntaxKind.UnionType: case SyntaxKind.IntersectionType: return some((node as UnionOrIntersectionTypeNode).types, mayResolveTypeAlias); case SyntaxKind.IndexedAccessType: return mayResolveTypeAlias((node as IndexedAccessTypeNode).objectType) || mayResolveTypeAlias((node as IndexedAccessTypeNode).indexType); case SyntaxKind.ConditionalType: return mayResolveTypeAlias((node as ConditionalTypeNode).checkType) || mayResolveTypeAlias((node as ConditionalTypeNode).extendsType) || mayResolveTypeAlias((node as ConditionalTypeNode).trueType) || mayResolveTypeAlias((node as ConditionalTypeNode).falseType); } return false; } function getTypeFromArrayOrTupleTypeNode(node: ArrayTypeNode | TupleTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { const target = getArrayOrTupleTargetType(node); if (target === emptyGenericType) { links.resolvedType = emptyObjectType; } else if (!(node.kind === SyntaxKind.TupleType && some(node.elements, e => !!(getTupleElementFlags(e) & ElementFlags.Variadic))) && isDeferredTypeReferenceNode(node)) { links.resolvedType = node.kind === SyntaxKind.TupleType && node.elements.length === 0 ? target : createDeferredTypeReference(target, node, /*mapper*/ undefined); } else { const elementTypes = node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : map(node.elements, getTypeFromTypeNode); links.resolvedType = createNormalizedTypeReference(target, elementTypes); } } return links.resolvedType; } function isReadonlyTypeOperator(node: Node) { return isTypeOperatorNode(node) && node.operator === SyntaxKind.ReadonlyKeyword; } function createTupleType(elementTypes: readonly Type[], elementFlags?: readonly ElementFlags[], readonly = false, namedMemberDeclarations?: readonly (NamedTupleMember | ParameterDeclaration)[]) { const tupleTarget = getTupleTargetType(elementFlags || map(elementTypes, _ => ElementFlags.Required), readonly, namedMemberDeclarations); return tupleTarget === emptyGenericType ? emptyObjectType : elementTypes.length ? createNormalizedTypeReference(tupleTarget, elementTypes) : tupleTarget; } function getTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations?: readonly (NamedTupleMember | ParameterDeclaration)[]): GenericType { if (elementFlags.length === 1 && elementFlags[0] & ElementFlags.Rest) { // [...X[]] is equivalent to just X[] return readonly ? globalReadonlyArrayType : globalArrayType; } const key = map(elementFlags, f => f & ElementFlags.Required ? "#" : f & ElementFlags.Optional ? "?" : f & ElementFlags.Rest ? "." : "*").join() + (readonly ? "R" : "") + (namedMemberDeclarations && namedMemberDeclarations.length ? "," + map(namedMemberDeclarations, getNodeId).join(",") : ""); let type = tupleTypes.get(key); if (!type) { tupleTypes.set(key, type = createTupleTargetType(elementFlags, readonly, namedMemberDeclarations)); } return type; } // We represent tuple types as type references to synthesized generic interface types created by // this function. The types are of the form: // // interface Tuple extends Array { 0: T0, 1: T1, 2: T2, ... } // // Note that the generic type created by this function has no symbol associated with it. The same // is true for each of the synthesized type parameters. function createTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration)[] | undefined): TupleType { const arity = elementFlags.length; const minLength = countWhere(elementFlags, f => !!(f & (ElementFlags.Required | ElementFlags.Variadic))); let typeParameters: TypeParameter[] | undefined; const properties: Symbol[] = []; let combinedFlags = 0 as ElementFlags; if (arity) { typeParameters = new Array(arity); for (let i = 0; i < arity; i++) { const typeParameter = typeParameters[i] = createTypeParameter(); const flags = elementFlags[i]; combinedFlags |= flags; if (!(combinedFlags & ElementFlags.Variable)) { const property = createSymbol(SymbolFlags.Property | (flags & ElementFlags.Optional ? SymbolFlags.Optional : 0), "" + i as __String, readonly ? CheckFlags.Readonly : 0); property.links.tupleLabelDeclaration = namedMemberDeclarations?.[i]; property.links.type = typeParameter; properties.push(property); } } } const fixedLength = properties.length; const lengthSymbol = createSymbol(SymbolFlags.Property, "length" as __String, readonly ? CheckFlags.Readonly : 0); if (combinedFlags & ElementFlags.Variable) { lengthSymbol.links.type = numberType; } else { const literalTypes = []; for (let i = minLength; i <= arity; i++) literalTypes.push(getNumberLiteralType(i)); lengthSymbol.links.type = getUnionType(literalTypes); } properties.push(lengthSymbol); const type = createObjectType(ObjectFlags.Tuple | ObjectFlags.Reference) as TupleType & InterfaceTypeWithDeclaredMembers; type.typeParameters = typeParameters; type.outerTypeParameters = undefined; type.localTypeParameters = typeParameters; type.instantiations = new Map(); type.instantiations.set(getTypeListId(type.typeParameters), type as GenericType); type.target = type as GenericType; type.resolvedTypeArguments = type.typeParameters; type.thisType = createTypeParameter(); type.thisType.isThisType = true; type.thisType.constraint = type; type.declaredProperties = properties; type.declaredCallSignatures = emptyArray; type.declaredConstructSignatures = emptyArray; type.declaredIndexInfos = emptyArray; type.elementFlags = elementFlags; type.minLength = minLength; type.fixedLength = fixedLength; type.hasRestElement = !!(combinedFlags & ElementFlags.Variable); type.combinedFlags = combinedFlags; type.readonly = readonly; type.labeledElementDeclarations = namedMemberDeclarations; return type; } function createNormalizedTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined) { return target.objectFlags & ObjectFlags.Tuple ? createNormalizedTupleType(target as TupleType, typeArguments!) : createTypeReference(target, typeArguments); } function createNormalizedTupleType(target: TupleType, elementTypes: readonly Type[]): Type { if (!(target.combinedFlags & ElementFlags.NonRequired)) { // No need to normalize when we only have regular required elements return createTypeReference(target, elementTypes); } if (target.combinedFlags & ElementFlags.Variadic) { // Transform [A, ...(X | Y | Z)] into [A, ...X] | [A, ...Y] | [A, ...Z] const unionIndex = findIndex(elementTypes, (t, i) => !!(target.elementFlags[i] & ElementFlags.Variadic && t.flags & (TypeFlags.Never | TypeFlags.Union))); if (unionIndex >= 0) { return checkCrossProductUnion(map(elementTypes, (t, i) => target.elementFlags[i] & ElementFlags.Variadic ? t : unknownType)) ? mapType(elementTypes[unionIndex], t => createNormalizedTupleType(target, replaceElement(elementTypes, unionIndex, t))) : errorType; } } // We have optional, rest, or variadic elements that may need normalizing. Normalization ensures that all variadic // elements are generic and that the tuple type has one of the following layouts, disregarding variadic elements: // (1) Zero or more required elements, followed by zero or more optional elements, followed by zero or one rest element. // (2) Zero or more required elements, followed by a rest element, followed by zero or more required elements. // In either layout, zero or more generic variadic elements may be present at any location. const expandedTypes: Type[] = []; const expandedFlags: ElementFlags[] = []; let expandedDeclarations: (NamedTupleMember | ParameterDeclaration)[] | undefined = []; let lastRequiredIndex = -1; let firstRestIndex = -1; let lastOptionalOrRestIndex = -1; for (let i = 0; i < elementTypes.length; i++) { const type = elementTypes[i]; const flags = target.elementFlags[i]; if (flags & ElementFlags.Variadic) { if (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type)) { // Generic variadic elements stay as they are. addElement(type, ElementFlags.Variadic, target.labeledElementDeclarations?.[i]); } else if (isTupleType(type)) { const elements = getTypeArguments(type); if (elements.length + expandedTypes.length >= 10_000) { error(currentNode, isPartOfTypeNode(currentNode!) ? Diagnostics.Type_produces_a_tuple_type_that_is_too_large_to_represent : Diagnostics.Expression_produces_a_tuple_type_that_is_too_large_to_represent); return errorType; } // Spread variadic elements with tuple types into the resulting tuple. forEach(elements, (t, n) => addElement(t, type.target.elementFlags[n], type.target.labeledElementDeclarations?.[n])); } else { // Treat everything else as an array type and create a rest element. addElement(isArrayLikeType(type) && getIndexTypeOfType(type, numberType) || errorType, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); } } else { // Copy other element kinds with no change. addElement(type, flags, target.labeledElementDeclarations?.[i]); } } // Turn optional elements preceding the last required element into required elements for (let i = 0; i < lastRequiredIndex; i++) { if (expandedFlags[i] & ElementFlags.Optional) expandedFlags[i] = ElementFlags.Required; } if (firstRestIndex >= 0 && firstRestIndex < lastOptionalOrRestIndex) { // Turn elements between first rest and last optional/rest into a single rest element expandedTypes[firstRestIndex] = getUnionType(sameMap(expandedTypes.slice(firstRestIndex, lastOptionalOrRestIndex + 1), (t, i) => expandedFlags[firstRestIndex + i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t)); expandedTypes.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); expandedFlags.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); expandedDeclarations?.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); } const tupleTarget = getTupleTargetType(expandedFlags, target.readonly, expandedDeclarations); return tupleTarget === emptyGenericType ? emptyObjectType : expandedFlags.length ? createTypeReference(tupleTarget, expandedTypes) : tupleTarget; function addElement(type: Type, flags: ElementFlags, declaration: NamedTupleMember | ParameterDeclaration | undefined) { if (flags & ElementFlags.Required) { lastRequiredIndex = expandedFlags.length; } if (flags & ElementFlags.Rest && firstRestIndex < 0) { firstRestIndex = expandedFlags.length; } if (flags & (ElementFlags.Optional | ElementFlags.Rest)) { lastOptionalOrRestIndex = expandedFlags.length; } expandedTypes.push(flags & ElementFlags.Optional ? addOptionality(type, /*isProperty*/ true) : type); expandedFlags.push(flags); if (expandedDeclarations && declaration) { expandedDeclarations.push(declaration); } else { expandedDeclarations = undefined; } } } function sliceTupleType(type: TupleTypeReference, index: number, endSkipCount = 0) { const target = type.target; const endIndex = getTypeReferenceArity(type) - endSkipCount; return index > target.fixedLength ? getRestArrayTypeOfTupleType(type) || createTupleType(emptyArray) : createTupleType(getTypeArguments(type).slice(index, endIndex), target.elementFlags.slice(index, endIndex), /*readonly*/ false, target.labeledElementDeclarations && target.labeledElementDeclarations.slice(index, endIndex)); } function getKnownKeysOfTupleType(type: TupleTypeReference) { return getUnionType(append(arrayOf(type.target.fixedLength, i => getStringLiteralType("" + i)), getIndexType(type.target.readonly ? globalReadonlyArrayType : globalArrayType))); } // Return count of starting consecutive tuple elements of the given kind(s) function getStartElementCount(type: TupleType, flags: ElementFlags) { const index = findIndex(type.elementFlags, f => !(f & flags)); return index >= 0 ? index : type.elementFlags.length; } // Return count of ending consecutive tuple elements of the given kind(s) function getEndElementCount(type: TupleType, flags: ElementFlags) { return type.elementFlags.length - findLastIndex(type.elementFlags, f => !(f & flags)) - 1; } function getTypeFromOptionalTypeNode(node: OptionalTypeNode): Type { return addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true); } function getTypeId(type: Type): TypeId { return type.id; } function containsType(types: readonly Type[], type: Type): boolean { return binarySearch(types, type, getTypeId, compareValues) >= 0; } function insertType(types: Type[], type: Type): boolean { const index = binarySearch(types, type, getTypeId, compareValues); if (index < 0) { types.splice(~index, 0, type); return true; } return false; } function addTypeToUnion(typeSet: Type[], includes: TypeFlags, type: Type) { const flags = type.flags; if (flags & TypeFlags.Union) { return addTypesToUnion(typeSet, includes | (isNamedUnionType(type) ? TypeFlags.Union : 0), (type as UnionType).types); } // We ignore 'never' types in unions if (!(flags & TypeFlags.Never)) { includes |= flags & TypeFlags.IncludesMask; if (flags & TypeFlags.Instantiable) includes |= TypeFlags.IncludesInstantiable; if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; if (!strictNullChecks && flags & TypeFlags.Nullable) { if (!(getObjectFlags(type) & ObjectFlags.ContainsWideningType)) includes |= TypeFlags.IncludesNonWideningType; } else { const len = typeSet.length; const index = len && type.id > typeSet[len - 1].id ? ~len : binarySearch(typeSet, type, getTypeId, compareValues); if (index < 0) { typeSet.splice(~index, 0, type); } } } return includes; } // Add the given types to the given type set. Order is preserved, duplicates are removed, // and nested types of the given kind are flattened into the set. function addTypesToUnion(typeSet: Type[], includes: TypeFlags, types: readonly Type[]): TypeFlags { for (const type of types) { includes = addTypeToUnion(typeSet, includes, type); } return includes; } function removeSubtypes(types: Type[], hasObjectTypes: boolean): Type[] | undefined { // [] and [T] immediately reduce to [] and [T] respectively if (types.length < 2) { return types; } const id = getTypeListId(types); const match = subtypeReductionCache.get(id); if (match) { return match; } // We assume that redundant primitive types have already been removed from the types array and that there // are no any and unknown types in the array. Thus, the only possible supertypes for primitive types are empty // object types, and if none of those are present we can exclude primitive types from the subtype check. const hasEmptyObject = hasObjectTypes && some(types, t => !!(t.flags & TypeFlags.Object) && !isGenericMappedType(t) && isEmptyResolvedType(resolveStructuredTypeMembers(t as ObjectType))); const len = types.length; let i = len; let count = 0; while (i > 0) { i--; const source = types[i]; if (hasEmptyObject || source.flags & TypeFlags.StructuredOrInstantiable) { // A type parameter with a union constraint may be a subtype of some union, but not a subtype of the // individual constituents of that union. For example, `T extends A | B` is a subtype of `A | B`, but not // a subtype of just `A` or just `B`. When we encounter such a type parameter, we therefore check if the // type parameter is a subtype of a union of all the other types. if (source.flags & TypeFlags.TypeParameter && getBaseConstraintOrType(source).flags & TypeFlags.Union) { if (isTypeRelatedTo(source, getUnionType(map(types, t => t === source ? neverType : t)), strictSubtypeRelation)) { orderedRemoveItemAt(types, i); } continue; } // Find the first property with a unit type, if any. When constituents have a property by the same name // but of a different unit type, we can quickly disqualify them from subtype checks. This helps subtype // reduction of large discriminated union types. const keyProperty = source.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive) ? find(getPropertiesOfType(source), p => isUnitType(getTypeOfSymbol(p))) : undefined; const keyPropertyType = keyProperty && getRegularTypeOfLiteralType(getTypeOfSymbol(keyProperty)); for (const target of types) { if (source !== target) { if (count === 100000) { // After 100000 subtype checks we estimate the remaining amount of work by assuming the // same ratio of checks per element. If the estimated number of remaining type checks is // greater than 1M we deem the union type too complex to represent. This for example // caps union types at 1000 unique object types. const estimatedCount = (count / (len - i)) * len; if (estimatedCount > 1000000) { tracing?.instant(tracing.Phase.CheckTypes, "removeSubtypes_DepthLimit", { typeIds: types.map(t => t.id) }); error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); return undefined; } } count++; if (keyProperty && target.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { const t = getTypeOfPropertyOfType(target, keyProperty.escapedName); if (t && isUnitType(t) && getRegularTypeOfLiteralType(t) !== keyPropertyType) { continue; } } if (isTypeRelatedTo(source, target, strictSubtypeRelation) && ( !(getObjectFlags(getTargetType(source)) & ObjectFlags.Class) || !(getObjectFlags(getTargetType(target)) & ObjectFlags.Class) || isTypeDerivedFrom(source, target))) { orderedRemoveItemAt(types, i); break; } } } } } subtypeReductionCache.set(id, types); return types; } function removeRedundantLiteralTypes(types: Type[], includes: TypeFlags, reduceVoidUndefined: boolean) { let i = types.length; while (i > 0) { i--; const t = types[i]; const flags = t.flags; const remove = flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.String || flags & TypeFlags.NumberLiteral && includes & TypeFlags.Number || flags & TypeFlags.BigIntLiteral && includes & TypeFlags.BigInt || flags & TypeFlags.UniqueESSymbol && includes & TypeFlags.ESSymbol || reduceVoidUndefined && flags & TypeFlags.Undefined && includes & TypeFlags.Void || isFreshLiteralType(t) && containsType(types, (t as LiteralType).regularType); if (remove) { orderedRemoveItemAt(types, i); } } } function removeStringLiteralsMatchedByTemplateLiterals(types: Type[]) { const templates = filter(types, t => !!(t.flags & TypeFlags.TemplateLiteral) && isPatternLiteralType(t)) as TemplateLiteralType[]; if (templates.length) { let i = types.length; while (i > 0) { i--; const t = types[i]; if (t.flags & TypeFlags.StringLiteral && some(templates, template => isTypeMatchedByTemplateLiteralType(t, template))) { orderedRemoveItemAt(types, i); } } } } function isNamedUnionType(type: Type) { return !!(type.flags & TypeFlags.Union && (type.aliasSymbol || (type as UnionType).origin)); } function addNamedUnions(namedUnions: Type[], types: readonly Type[]) { for (const t of types) { if (t.flags & TypeFlags.Union) { const origin = (t as UnionType).origin; if (t.aliasSymbol || origin && !(origin.flags & TypeFlags.Union)) { pushIfUnique(namedUnions, t); } else if (origin && origin.flags & TypeFlags.Union) { addNamedUnions(namedUnions, (origin as UnionType).types); } } } } function createOriginUnionOrIntersectionType(flags: TypeFlags, types: Type[]) { const result = createOriginType(flags) as UnionOrIntersectionType; result.types = types; return result; } // We sort and deduplicate the constituent types based on object identity. If the subtypeReduction // flag is specified we also reduce the constituent type set to only include types that aren't subtypes // of other types. Subtype reduction is expensive for large union types and is possible only when union // types are known not to circularly reference themselves (as is the case with union types created by // expression constructs such as array literals and the || and ?: operators). Named types can // circularly reference themselves and therefore cannot be subtype reduced during their declaration. // For example, "type Item = string | (() => Item" is a named type that circularly references itself. function getUnionType(types: readonly Type[], unionReduction: UnionReduction = UnionReduction.Literal, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { if (types.length === 0) { return neverType; } if (types.length === 1) { return types[0]; } let typeSet: Type[] | undefined = []; const includes = addTypesToUnion(typeSet, 0 as TypeFlags, types); if (unionReduction !== UnionReduction.None) { if (includes & TypeFlags.AnyOrUnknown) { return includes & TypeFlags.Any ? includes & TypeFlags.IncludesWildcard ? wildcardType : anyType : includes & TypeFlags.Null || containsType(typeSet, unknownType) ? unknownType : nonNullUnknownType; } if (includes & TypeFlags.Undefined) { // If type set contains both undefinedType and missingType, remove missingType if (typeSet.length >= 2 && typeSet[0] === undefinedType && typeSet[1] === missingType) { orderedRemoveItemAt(typeSet, 1); } } if (includes & (TypeFlags.Enum | TypeFlags.Literal | TypeFlags.UniqueESSymbol | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || includes & TypeFlags.Void && includes & TypeFlags.Undefined) { removeRedundantLiteralTypes(typeSet, includes, !!(unionReduction & UnionReduction.Subtype)); } if (includes & TypeFlags.StringLiteral && includes & TypeFlags.TemplateLiteral) { removeStringLiteralsMatchedByTemplateLiterals(typeSet); } if (unionReduction === UnionReduction.Subtype) { typeSet = removeSubtypes(typeSet, !!(includes & TypeFlags.Object)); if (!typeSet) { return errorType; } } if (typeSet.length === 0) { return includes & TypeFlags.Null ? includes & TypeFlags.IncludesNonWideningType ? nullType : nullWideningType : includes & TypeFlags.Undefined ? includes & TypeFlags.IncludesNonWideningType ? undefinedType : undefinedWideningType : neverType; } } if (!origin && includes & TypeFlags.Union) { const namedUnions: Type[] = []; addNamedUnions(namedUnions, types); const reducedTypes: Type[] = []; for (const t of typeSet) { if (!some(namedUnions, union => containsType((union as UnionType).types, t))) { reducedTypes.push(t); } } if (!aliasSymbol && namedUnions.length === 1 && reducedTypes.length === 0) { return namedUnions[0]; } // We create a denormalized origin type only when the union was created from one or more named unions // (unions with alias symbols or origins) and when there is no overlap between those named unions. const namedTypesCount = reduceLeft(namedUnions, (sum, union) => sum + (union as UnionType).types.length, 0); if (namedTypesCount + reducedTypes.length === typeSet.length) { for (const t of namedUnions) { insertType(reducedTypes, t); } origin = createOriginUnionOrIntersectionType(TypeFlags.Union, reducedTypes); } } const objectFlags = (includes & TypeFlags.NotPrimitiveUnion ? 0 : ObjectFlags.PrimitiveUnion) | (includes & TypeFlags.Intersection ? ObjectFlags.ContainsIntersections : 0); return getUnionTypeFromSortedList(typeSet, objectFlags, aliasSymbol, aliasTypeArguments, origin); } function getUnionOrIntersectionTypePredicate(signatures: readonly Signature[], kind: TypeFlags | undefined): TypePredicate | undefined { let first: TypePredicate | undefined; const types: Type[] = []; for (const sig of signatures) { const pred = getTypePredicateOfSignature(sig); if (!pred || pred.kind === TypePredicateKind.AssertsThis || pred.kind === TypePredicateKind.AssertsIdentifier) { if (kind !== TypeFlags.Intersection) { continue; } else { return; // intersections demand all members be type predicates for the result to have a predicate } } if (first) { if (!typePredicateKindsMatch(first, pred)) { // No common type predicate. return undefined; } } else { first = pred; } types.push(pred.type); } if (!first) { // No signatures had a type predicate. return undefined; } const compositeType = getUnionOrIntersectionType(types, kind); return createTypePredicate(first.kind, first.parameterName, first.parameterIndex, compositeType); } function typePredicateKindsMatch(a: TypePredicate, b: TypePredicate): boolean { return a.kind === b.kind && a.parameterIndex === b.parameterIndex; } // This function assumes the constituent type list is sorted and deduplicated. function getUnionTypeFromSortedList(types: Type[], precomputedObjectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { if (types.length === 0) { return neverType; } if (types.length === 1) { return types[0]; } const typeKey = !origin ? getTypeListId(types) : origin.flags & TypeFlags.Union ? `|${getTypeListId((origin as UnionType).types)}` : origin.flags & TypeFlags.Intersection ? `&${getTypeListId((origin as IntersectionType).types)}` : `#${(origin as IndexType).type.id}|${getTypeListId(types)}`; // origin type id alone is insufficient, as `keyof x` may resolve to multiple WIP values while `x` is still resolving const id = typeKey + getAliasId(aliasSymbol, aliasTypeArguments); let type = unionTypes.get(id); if (!type) { type = createType(TypeFlags.Union) as UnionType; type.objectFlags = precomputedObjectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); type.types = types; type.origin = origin; type.aliasSymbol = aliasSymbol; type.aliasTypeArguments = aliasTypeArguments; if (types.length === 2 && types[0].flags & TypeFlags.BooleanLiteral && types[1].flags & TypeFlags.BooleanLiteral) { type.flags |= TypeFlags.Boolean; (type as UnionType & IntrinsicType).intrinsicName = "boolean"; } unionTypes.set(id, type); } return type; } function getTypeFromUnionTypeNode(node: UnionTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { const aliasSymbol = getAliasSymbolForTypeNode(node); links.resolvedType = getUnionType(map(node.types, getTypeFromTypeNode), UnionReduction.Literal, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); } return links.resolvedType; } function addTypeToIntersection(typeSet: Map, includes: TypeFlags, type: Type) { const flags = type.flags; if (flags & TypeFlags.Intersection) { return addTypesToIntersection(typeSet, includes, (type as IntersectionType).types); } if (isEmptyAnonymousObjectType(type)) { if (!(includes & TypeFlags.IncludesEmptyObject)) { includes |= TypeFlags.IncludesEmptyObject; typeSet.set(type.id.toString(), type); } } else { if (flags & TypeFlags.AnyOrUnknown) { if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; } else if (strictNullChecks || !(flags & TypeFlags.Nullable)) { if (type === missingType) { includes |= TypeFlags.IncludesMissingType; type = undefinedType; } if (!typeSet.has(type.id.toString())) { if (type.flags & TypeFlags.Unit && includes & TypeFlags.Unit) { // We have seen two distinct unit types which means we should reduce to an // empty intersection. Adding TypeFlags.NonPrimitive causes that to happen. includes |= TypeFlags.NonPrimitive; } typeSet.set(type.id.toString(), type); } } includes |= flags & TypeFlags.IncludesMask; } return includes; } // Add the given types to the given type set. Order is preserved, freshness is removed from literal // types, duplicates are removed, and nested types of the given kind are flattened into the set. function addTypesToIntersection(typeSet: Map, includes: TypeFlags, types: readonly Type[]) { for (const type of types) { includes = addTypeToIntersection(typeSet, includes, getRegularTypeOfLiteralType(type)); } return includes; } function removeRedundantSupertypes(types: Type[], includes: TypeFlags) { let i = types.length; while (i > 0) { i--; const t = types[i]; const remove = t.flags & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || t.flags & TypeFlags.Number && includes & TypeFlags.NumberLiteral || t.flags & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || t.flags & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || t.flags & TypeFlags.Void && includes & TypeFlags.Undefined || isEmptyAnonymousObjectType(t) && includes & TypeFlags.DefinitelyNonNullable; if (remove) { orderedRemoveItemAt(types, i); } } } // Check that the given type has a match in every union. A given type is matched by // an identical type, and a literal type is additionally matched by its corresponding // primitive type. function eachUnionContains(unionTypes: UnionType[], type: Type) { for (const u of unionTypes) { if (!containsType(u.types, type)) { const primitive = type.flags & TypeFlags.StringLiteral ? stringType : type.flags & TypeFlags.NumberLiteral ? numberType : type.flags & TypeFlags.BigIntLiteral ? bigintType : type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : undefined; if (!primitive || !containsType(u.types, primitive)) { return false; } } } return true; } /** * Returns `true` if the intersection of the template literals and string literals is the empty set, eg `get${string}` & "setX", and should reduce to `never` */ function extractRedundantTemplateLiterals(types: Type[]): boolean { let i = types.length; const literals = filter(types, t => !!(t.flags & TypeFlags.StringLiteral)); while (i > 0) { i--; const t = types[i]; if (!(t.flags & TypeFlags.TemplateLiteral)) continue; for (const t2 of literals) { if (isTypeSubtypeOf(t2, t)) { // eg, ``get${T}` & "getX"` is just `"getX"` orderedRemoveItemAt(types, i); break; } else if (isPatternLiteralType(t)) { return true; } } } return false; } function eachIsUnionContaining(types: Type[], flag: TypeFlags) { return every(types, t => !!(t.flags & TypeFlags.Union) && some((t as UnionType).types, tt => !!(tt.flags & flag))); } function removeFromEach(types: Type[], flag: TypeFlags) { for (let i = 0; i < types.length; i++) { types[i] = filterType(types[i], t => !(t.flags & flag)); } } // If the given list of types contains more than one union of primitive types, replace the // first with a union containing an intersection of those primitive types, then remove the // other unions and return true. Otherwise, do nothing and return false. function intersectUnionsOfPrimitiveTypes(types: Type[]) { let unionTypes: UnionType[] | undefined; const index = findIndex(types, t => !!(getObjectFlags(t) & ObjectFlags.PrimitiveUnion)); if (index < 0) { return false; } let i = index + 1; // Remove all but the first union of primitive types and collect them in // the unionTypes array. while (i < types.length) { const t = types[i]; if (getObjectFlags(t) & ObjectFlags.PrimitiveUnion) { (unionTypes || (unionTypes = [types[index] as UnionType])).push(t as UnionType); orderedRemoveItemAt(types, i); } else { i++; } } // Return false if there was only one union of primitive types if (!unionTypes) { return false; } // We have more than one union of primitive types, now intersect them. For each // type in each union we check if the type is matched in every union and if so // we include it in the result. const checked: Type[] = []; const result: Type[] = []; for (const u of unionTypes) { for (const t of u.types) { if (insertType(checked, t)) { if (eachUnionContains(unionTypes, t)) { insertType(result, t); } } } } // Finally replace the first union with the result types[index] = getUnionTypeFromSortedList(result, ObjectFlags.PrimitiveUnion); return true; } function createIntersectionType(types: Type[], aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { const result = createType(TypeFlags.Intersection) as IntersectionType; result.objectFlags = getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); result.types = types; result.aliasSymbol = aliasSymbol; result.aliasTypeArguments = aliasTypeArguments; return result; } // We normalize combinations of intersection and union types based on the distributive property of the '&' // operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection // types with union type constituents into equivalent union types with intersection type constituents and // effectively ensure that union types are always at the top level in type representations. // // We do not perform structural deduplication on intersection types. Intersection types are created only by the & // type operator and we can't reduce those because we want to support recursive intersection types. For example, // a type alias of the form "type List = T & { next: List }" cannot be reduced during its declaration. // Also, unlike union types, the order of the constituent types is preserved in order that overload resolution // for intersections of types with signatures can be deterministic. function getIntersectionType(types: readonly Type[], aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], noSupertypeReduction?: boolean): Type { const typeMembershipMap: Map = new Map(); const includes = addTypesToIntersection(typeMembershipMap, 0 as TypeFlags, types); const typeSet: Type[] = arrayFrom(typeMembershipMap.values()); // An intersection type is considered empty if it contains // the type never, or // more than one unit type or, // an object type and a nullable type (null or undefined), or // a string-like type and a type known to be non-string-like, or // a number-like type and a type known to be non-number-like, or // a symbol-like type and a type known to be non-symbol-like, or // a void-like type and a type known to be non-void-like, or // a non-primitive type and a type known to be primitive. if (includes & TypeFlags.Never) { return contains(typeSet, silentNeverType) ? silentNeverType : neverType; } if (strictNullChecks && includes & TypeFlags.Nullable && includes & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.IncludesEmptyObject) || includes & TypeFlags.NonPrimitive && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NonPrimitive) || includes & TypeFlags.StringLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.StringLike) || includes & TypeFlags.NumberLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NumberLike) || includes & TypeFlags.BigIntLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.BigIntLike) || includes & TypeFlags.ESSymbolLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.ESSymbolLike) || includes & TypeFlags.VoidLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.VoidLike)) { return neverType; } if (includes & TypeFlags.TemplateLiteral && includes & TypeFlags.StringLiteral && extractRedundantTemplateLiterals(typeSet)) { return neverType; } if (includes & TypeFlags.Any) { return includes & TypeFlags.IncludesWildcard ? wildcardType : anyType; } if (!strictNullChecks && includes & TypeFlags.Nullable) { return includes & TypeFlags.IncludesEmptyObject ? neverType : includes & TypeFlags.Undefined ? undefinedType : nullType; } if (includes & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || includes & TypeFlags.Number && includes & TypeFlags.NumberLiteral || includes & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || includes & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || includes & TypeFlags.Void && includes & TypeFlags.Undefined || includes & TypeFlags.IncludesEmptyObject && includes & TypeFlags.DefinitelyNonNullable) { if (!noSupertypeReduction) removeRedundantSupertypes(typeSet, includes); } if (includes & TypeFlags.IncludesMissingType) { typeSet[typeSet.indexOf(undefinedType)] = missingType; } if (typeSet.length === 0) { return unknownType; } if (typeSet.length === 1) { return typeSet[0]; } const id = getTypeListId(typeSet) + getAliasId(aliasSymbol, aliasTypeArguments); let result = intersectionTypes.get(id); if (!result) { if (includes & TypeFlags.Union) { if (intersectUnionsOfPrimitiveTypes(typeSet)) { // When the intersection creates a reduced set (which might mean that *all* union types have // disappeared), we restart the operation to get a new set of combined flags. Once we have // reduced we'll never reduce again, so this occurs at most once. result = getIntersectionType(typeSet, aliasSymbol, aliasTypeArguments); } else if (eachIsUnionContaining(typeSet, TypeFlags.Undefined)) { const containedUndefinedType = some(typeSet, containsMissingType) ? missingType : undefinedType; removeFromEach(typeSet, TypeFlags.Undefined); result = getUnionType([getIntersectionType(typeSet), containedUndefinedType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); } else if (eachIsUnionContaining(typeSet, TypeFlags.Null)) { removeFromEach(typeSet, TypeFlags.Null); result = getUnionType([getIntersectionType(typeSet), nullType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); } else { // We are attempting to construct a type of the form X & (A | B) & (C | D). Transform this into a type of // the form X & A & C | X & A & D | X & B & C | X & B & D. If the estimated size of the resulting union type // exceeds 100000 constituents, report an error. if (!checkCrossProductUnion(typeSet)) { return errorType; } const constituents = getCrossProductIntersections(typeSet); // We attach a denormalized origin type when at least one constituent of the cross-product union is an // intersection (i.e. when the intersection didn't just reduce one or more unions to smaller unions) and // the denormalized origin has fewer constituents than the union itself. const origin = some(constituents, t => !!(t.flags & TypeFlags.Intersection)) && getConstituentCountOfTypes(constituents) > getConstituentCountOfTypes(typeSet) ? createOriginUnionOrIntersectionType(TypeFlags.Intersection, typeSet) : undefined; result = getUnionType(constituents, UnionReduction.Literal, aliasSymbol, aliasTypeArguments, origin); } } else { result = createIntersectionType(typeSet, aliasSymbol, aliasTypeArguments); } intersectionTypes.set(id, result); } return result; } function getCrossProductUnionSize(types: readonly Type[]) { return reduceLeft(types, (n, t) => t.flags & TypeFlags.Union ? n * (t as UnionType).types.length : t.flags & TypeFlags.Never ? 0 : n, 1); } function checkCrossProductUnion(types: readonly Type[]) { const size = getCrossProductUnionSize(types); if (size >= 100000) { tracing?.instant(tracing.Phase.CheckTypes, "checkCrossProductUnion_DepthLimit", { typeIds: types.map(t => t.id), size }); error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); return false; } return true; } function getCrossProductIntersections(types: readonly Type[]) { const count = getCrossProductUnionSize(types); const intersections: Type[] = []; for (let i = 0; i < count; i++) { const constituents = types.slice(); let n = i; for (let j = types.length - 1; j >= 0; j--) { if (types[j].flags & TypeFlags.Union) { const sourceTypes = (types[j] as UnionType).types; const length = sourceTypes.length; constituents[j] = sourceTypes[n % length]; n = Math.floor(n / length); } } const t = getIntersectionType(constituents); if (!(t.flags & TypeFlags.Never)) intersections.push(t); } return intersections; } function getConstituentCount(type: Type): number { return !(type.flags & TypeFlags.UnionOrIntersection) || type.aliasSymbol ? 1 : type.flags & TypeFlags.Union && (type as UnionType).origin ? getConstituentCount((type as UnionType).origin!) : getConstituentCountOfTypes((type as UnionOrIntersectionType).types); } function getConstituentCountOfTypes(types: Type[]): number { return reduceLeft(types, (n, t) => n + getConstituentCount(t), 0); } function getTypeFromIntersectionTypeNode(node: IntersectionTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { const aliasSymbol = getAliasSymbolForTypeNode(node); const types = map(node.types, getTypeFromTypeNode); const noSupertypeReduction = types.length === 2 && !!(types[0].flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) && types[1] === emptyTypeLiteralType; links.resolvedType = getIntersectionType(types, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol), noSupertypeReduction); } return links.resolvedType; } function createIndexType(type: InstantiableType | UnionOrIntersectionType, stringsOnly: boolean) { const result = createType(TypeFlags.Index) as IndexType; result.type = type; result.stringsOnly = stringsOnly; return result; } function createOriginIndexType(type: InstantiableType | UnionOrIntersectionType) { const result = createOriginType(TypeFlags.Index) as IndexType; result.type = type; return result; } function getIndexTypeForGenericType(type: InstantiableType | UnionOrIntersectionType, stringsOnly: boolean) { return stringsOnly ? type.resolvedStringIndexType || (type.resolvedStringIndexType = createIndexType(type, /*stringsOnly*/ true)) : type.resolvedIndexType || (type.resolvedIndexType = createIndexType(type, /*stringsOnly*/ false)); } /** * This roughly mirrors `resolveMappedTypeMembers` in the nongeneric case, except only reports a union of the keys calculated, * rather than manufacturing the properties. We can't just fetch the `constraintType` since that would ignore mappings * and mapping the `constraintType` directly ignores how mapped types map _properties_ and not keys (thus ignoring subtype * reduction in the constraintType) when possible. * @param noIndexSignatures Indicates if _string_ index signatures should be elided. (other index signatures are always reported) */ function getIndexTypeForMappedType(type: MappedType, stringsOnly: boolean, noIndexSignatures: boolean | undefined) { const typeParameter = getTypeParameterFromMappedType(type); const constraintType = getConstraintTypeFromMappedType(type); const nameType = getNameTypeFromMappedType(type.target as MappedType || type); if (!nameType && !noIndexSignatures) { // no mapping and no filtering required, just quickly bail to returning the constraint in the common case return constraintType; } const keyTypes: Type[] = []; if (isMappedTypeWithKeyofConstraintDeclaration(type)) { // We have a { [P in keyof T]: X } // `getApparentType` on the T in a generic mapped type can trigger a circularity // (conditionals and `infer` types create a circular dependency in the constraint resolution) // so we only eagerly manifest the keys if the constraint is nongeneric if (!isGenericIndexType(constraintType)) { const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, TypeFlags.StringOrNumberLiteralOrUnique, stringsOnly, addMemberForKeyType); } else { // we have a generic index and a homomorphic mapping (but a distributive key remapping) - we need to defer the whole `keyof whatever` for later // since it's not safe to resolve the shape of modifier type return getIndexTypeForGenericType(type, stringsOnly); } } else { forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); } if (isGenericIndexType(constraintType)) { // include the generic component in the resulting type forEachType(constraintType, addMemberForKeyType); } // we had to pick apart the constraintType to potentially map/filter it - compare the final resulting list with the original constraintType, // so we can return the union that preserves aliases/origin data if possible const result = noIndexSignatures ? filterType(getUnionType(keyTypes), t => !(t.flags & (TypeFlags.Any | TypeFlags.String))) : getUnionType(keyTypes); if (result.flags & TypeFlags.Union && constraintType.flags & TypeFlags.Union && getTypeListId((result as UnionType).types) === getTypeListId((constraintType as UnionType).types)){ return constraintType; } return result; function addMemberForKeyType(keyType: Type) { const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; // `keyof` currently always returns `string | number` for concrete `string` index signatures - the below ternary keeps that behavior for mapped types // See `getLiteralTypeFromProperties` where there's a similar ternary to cause the same behavior. keyTypes.push(propNameType === stringType ? stringOrNumberType : propNameType); } } // Ordinarily we reduce a keyof M, where M is a mapped type { [P in K as N

]: X }, to simply N. This however presumes // that N distributes over union types, i.e. that N is equivalent to N | N | N. Specifically, we only // want to perform the reduction when the name type of a mapped type is distributive with respect to the type variable // introduced by the 'in' clause of the mapped type. Note that non-generic types are considered to be distributive because // they're the same type regardless of what's being distributed over. function hasDistributiveNameType(mappedType: MappedType) { const typeVariable = getTypeParameterFromMappedType(mappedType); return isDistributive(getNameTypeFromMappedType(mappedType) || typeVariable); function isDistributive(type: Type): boolean { return type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Primitive | TypeFlags.Never | TypeFlags.TypeParameter | TypeFlags.Object | TypeFlags.NonPrimitive) ? true : type.flags & TypeFlags.Conditional ? (type as ConditionalType).root.isDistributive && (type as ConditionalType).checkType === typeVariable : type.flags & (TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral) ? every((type as UnionOrIntersectionType | TemplateLiteralType).types, isDistributive) : type.flags & TypeFlags.IndexedAccess ? isDistributive((type as IndexedAccessType).objectType) && isDistributive((type as IndexedAccessType).indexType) : type.flags & TypeFlags.Substitution ? isDistributive((type as SubstitutionType).baseType) && isDistributive((type as SubstitutionType).constraint): type.flags & TypeFlags.StringMapping ? isDistributive((type as StringMappingType).type) : false; } } function getLiteralTypeFromPropertyName(name: PropertyName) { if (isPrivateIdentifier(name)) { return neverType; } return isIdentifier(name) ? getStringLiteralType(unescapeLeadingUnderscores(name.escapedText)) : getRegularTypeOfLiteralType(isComputedPropertyName(name) ? checkComputedPropertyName(name) : checkExpression(name)); } function getLiteralTypeFromProperty(prop: Symbol, include: TypeFlags, includeNonPublic?: boolean) { if (includeNonPublic || !(getDeclarationModifierFlagsFromSymbol(prop) & ModifierFlags.NonPublicAccessibilityModifier)) { let type = getSymbolLinks(getLateBoundSymbol(prop)).nameType; if (!type) { const name = getNameOfDeclaration(prop.valueDeclaration) as PropertyName; type = prop.escapedName === InternalSymbolName.Default ? getStringLiteralType("default") : name && getLiteralTypeFromPropertyName(name) || (!isKnownSymbol(prop) ? getStringLiteralType(symbolName(prop)) : undefined); } if (type && type.flags & include) { return type; } } return neverType; } function isKeyTypeIncluded(keyType: Type, include: TypeFlags): boolean { return !!(keyType.flags & include || keyType.flags & TypeFlags.Intersection && some((keyType as IntersectionType).types, t => isKeyTypeIncluded(t, include))); } function getLiteralTypeFromProperties(type: Type, include: TypeFlags, includeOrigin: boolean) { const origin = includeOrigin && (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference) || type.aliasSymbol) ? createOriginIndexType(type) : undefined; const propertyTypes = map(getPropertiesOfType(type), prop => getLiteralTypeFromProperty(prop, include)); const indexKeyTypes = map(getIndexInfosOfType(type), info => info !== enumNumberIndexInfo && isKeyTypeIncluded(info.keyType, include) ? info.keyType === stringType && include & TypeFlags.Number ? stringOrNumberType : info.keyType : neverType); return getUnionType(concatenate(propertyTypes, indexKeyTypes), UnionReduction.Literal, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, origin); } /** * A union type which is reducible upon instantiation (meaning some members are removed under certain instantiations) * must be kept generic, as that instantiation information needs to flow through the type system. By replacing all * type parameters in the union with a special never type that is treated as a literal in `getReducedType`, we can cause the `getReducedType` logic * to reduce the resulting type if possible (since only intersections with conflicting literal-typed properties are reducible). */ function isPossiblyReducibleByInstantiation(type: Type): boolean { const uniqueFilled = getUniqueLiteralFilledInstantiation(type); return getReducedType(uniqueFilled) !== uniqueFilled; } function shouldDeferIndexType(type: Type) { return !!(type.flags & TypeFlags.InstantiableNonPrimitive || isGenericTupleType(type) || isGenericMappedType(type) && !hasDistributiveNameType(type) || type.flags & TypeFlags.Union && some((type as UnionType).types, isPossiblyReducibleByInstantiation) || type.flags & TypeFlags.Intersection && maybeTypeOfKind(type, TypeFlags.Instantiable) && some((type as IntersectionType).types, isEmptyAnonymousObjectType)); } function getIndexType(type: Type, stringsOnly = keyofStringsOnly, noIndexSignatures?: boolean): Type { type = getReducedType(type); return shouldDeferIndexType(type) ? getIndexTypeForGenericType(type as InstantiableType | UnionOrIntersectionType, stringsOnly) : type.flags & TypeFlags.Union ? getIntersectionType(map((type as UnionType).types, t => getIndexType(t, stringsOnly, noIndexSignatures))) : type.flags & TypeFlags.Intersection ? getUnionType(map((type as IntersectionType).types, t => getIndexType(t, stringsOnly, noIndexSignatures))) : getObjectFlags(type) & ObjectFlags.Mapped ? getIndexTypeForMappedType(type as MappedType, stringsOnly, noIndexSignatures) : type === wildcardType ? wildcardType : type.flags & TypeFlags.Unknown ? neverType : type.flags & (TypeFlags.Any | TypeFlags.Never) ? keyofConstraintType : getLiteralTypeFromProperties(type, (noIndexSignatures ? TypeFlags.StringLiteral : TypeFlags.StringLike) | (stringsOnly ? 0 : TypeFlags.NumberLike | TypeFlags.ESSymbolLike), stringsOnly === keyofStringsOnly && !noIndexSignatures); } function getExtractStringType(type: Type) { if (keyofStringsOnly) { return type; } const extractTypeAlias = getGlobalExtractSymbol(); return extractTypeAlias ? getTypeAliasInstantiation(extractTypeAlias, [type, stringType]) : stringType; } function getIndexTypeOrString(type: Type): Type { const indexType = getExtractStringType(getIndexType(type)); return indexType.flags & TypeFlags.Never ? stringType : indexType; } function getTypeFromTypeOperatorNode(node: TypeOperatorNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { switch (node.operator) { case SyntaxKind.KeyOfKeyword: links.resolvedType = getIndexType(getTypeFromTypeNode(node.type)); break; case SyntaxKind.UniqueKeyword: links.resolvedType = node.type.kind === SyntaxKind.SymbolKeyword ? getESSymbolLikeTypeForNode(walkUpParenthesizedTypes(node.parent)) : errorType; break; case SyntaxKind.ReadonlyKeyword: links.resolvedType = getTypeFromTypeNode(node.type); break; default: throw Debug.assertNever(node.operator); } } return links.resolvedType; } function getTypeFromTemplateTypeNode(node: TemplateLiteralTypeNode) { const links = getNodeLinks(node); if (!links.resolvedType) { links.resolvedType = getTemplateLiteralType( [node.head.text, ...map(node.templateSpans, span => span.literal.text)], map(node.templateSpans, span => getTypeFromTypeNode(span.type))); } return links.resolvedType; } function getTemplateLiteralType(texts: readonly string[], types: readonly Type[]): Type { const unionIndex = findIndex(types, t => !!(t.flags & (TypeFlags.Never | TypeFlags.Union))); if (unionIndex >= 0) { return checkCrossProductUnion(types) ? mapType(types[unionIndex], t => getTemplateLiteralType(texts, replaceElement(types, unionIndex, t))) : errorType; } if (contains(types, wildcardType)) { return wildcardType; } const newTypes: Type[] = []; const newTexts: string[] = []; let text = texts[0]; if (!addSpans(texts, types)) { return stringType; } if (newTypes.length === 0) { return getStringLiteralType(text); } newTexts.push(text); if (every(newTexts, t => t === "")) { if (every(newTypes, t => !!(t.flags & TypeFlags.String))) { return stringType; } // Normalize `${Mapping}` into Mapping if (newTypes.length === 1 && isPatternLiteralType(newTypes[0])) { return newTypes[0]; } } const id = `${getTypeListId(newTypes)}|${map(newTexts, t => t.length).join(",")}|${newTexts.join("")}`; let type = templateLiteralTypes.get(id); if (!type) { templateLiteralTypes.set(id, type = createTemplateLiteralType(newTexts, newTypes)); } return type; function addSpans(texts: readonly string[] | string, types: readonly Type[]): boolean { const isTextsArray = isArray(texts); for (let i = 0; i < types.length; i++) { const t = types[i]; const addText = isTextsArray ? texts[i + 1] : texts; if (t.flags & (TypeFlags.Literal | TypeFlags.Null | TypeFlags.Undefined)) { text += getTemplateStringForType(t) || ""; text += addText; if (!isTextsArray) return true; } else if (t.flags & TypeFlags.TemplateLiteral) { text += (t as TemplateLiteralType).texts[0]; if (!addSpans((t as TemplateLiteralType).texts, (t as TemplateLiteralType).types)) return false; text += addText; if (!isTextsArray) return true; } else if (isGenericIndexType(t) || isPatternLiteralPlaceholderType(t)) { newTypes.push(t); newTexts.push(text); text = addText; } else if (t.flags & TypeFlags.Intersection) { const added = addSpans(texts[i + 1], (t as IntersectionType).types); if (!added) return false; } else if (isTextsArray) { return false; } } return true; } } function getTemplateStringForType(type: Type) { return type.flags & TypeFlags.StringLiteral ? (type as StringLiteralType).value : type.flags & TypeFlags.NumberLiteral ? "" + (type as NumberLiteralType).value : type.flags & TypeFlags.BigIntLiteral ? pseudoBigIntToString((type as BigIntLiteralType).value) : type.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) ? (type as IntrinsicType).intrinsicName : undefined; } function createTemplateLiteralType(texts: readonly string[], types: readonly Type[]) { const type = createType(TypeFlags.TemplateLiteral) as TemplateLiteralType; type.texts = texts; type.types = types; return type; } function getStringMappingType(symbol: Symbol, type: Type): Type { return type.flags & (TypeFlags.Union | TypeFlags.Never) ? mapType(type, t => getStringMappingType(symbol, t)) : type.flags & TypeFlags.StringLiteral ? getStringLiteralType(applyStringMapping(symbol, (type as StringLiteralType).value)) : type.flags & TypeFlags.TemplateLiteral ? getTemplateLiteralType(...applyTemplateStringMapping(symbol, (type as TemplateLiteralType).texts, (type as TemplateLiteralType).types)) : // Mapping> === Mapping type.flags & TypeFlags.StringMapping && symbol === type.symbol ? type : type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.StringMapping) || isGenericIndexType(type) ? getStringMappingTypeForGenericType(symbol, type) : // This handles Mapping<`${number}`> and Mapping<`${bigint}`> isPatternLiteralPlaceholderType(type) ? getStringMappingTypeForGenericType(symbol, getTemplateLiteralType(["", ""], [type])) : type; } function applyStringMapping(symbol: Symbol, str: string) { switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { case IntrinsicTypeKind.Uppercase: return str.toUpperCase(); case IntrinsicTypeKind.Lowercase: return str.toLowerCase(); case IntrinsicTypeKind.Capitalize: return str.charAt(0).toUpperCase() + str.slice(1); case IntrinsicTypeKind.Uncapitalize: return str.charAt(0).toLowerCase() + str.slice(1); } return str; } function applyTemplateStringMapping(symbol: Symbol, texts: readonly string[], types: readonly Type[]): [texts: readonly string[], types: readonly Type[]] { switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { case IntrinsicTypeKind.Uppercase: return [texts.map(t => t.toUpperCase()), types.map(t => getStringMappingType(symbol, t))]; case IntrinsicTypeKind.Lowercase: return [texts.map(t => t.toLowerCase()), types.map(t => getStringMappingType(symbol, t))]; case IntrinsicTypeKind.Capitalize: return [texts[0] === "" ? texts : [texts[0].charAt(0).toUpperCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; case IntrinsicTypeKind.Uncapitalize: return [texts[0] === "" ? texts : [texts[0].charAt(0).toLowerCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; } return [texts, types]; } function getStringMappingTypeForGenericType(symbol: Symbol, type: Type): Type { const id = `${getSymbolId(symbol)},${getTypeId(type)}`; let result = stringMappingTypes.get(id); if (!result) { stringMappingTypes.set(id, result = createStringMappingType(symbol, type)); } return result; } function createStringMappingType(symbol: Symbol, type: Type) { const result = createTypeWithSymbol(TypeFlags.StringMapping, symbol) as StringMappingType; result.type = type; return result; } function createIndexedAccessType(objectType: Type, indexType: Type, accessFlags: AccessFlags, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { const type = createType(TypeFlags.IndexedAccess) as IndexedAccessType; type.objectType = objectType; type.indexType = indexType; type.accessFlags = accessFlags; type.aliasSymbol = aliasSymbol; type.aliasTypeArguments = aliasTypeArguments; return type; } /** * Returns if a type is or consists of a JSLiteral object type * In addition to objects which are directly literals, * * unions where every element is a jsliteral * * intersections where at least one element is a jsliteral * * and instantiable types constrained to a jsliteral * Should all count as literals and not print errors on access or assignment of possibly existing properties. * This mirrors the behavior of the index signature propagation, to which this behaves similarly (but doesn't affect assignability or inference). */ function isJSLiteralType(type: Type): boolean { if (noImplicitAny) { return false; // Flag is meaningless under `noImplicitAny` mode } if (getObjectFlags(type) & ObjectFlags.JSLiteral) { return true; } if (type.flags & TypeFlags.Union) { return every((type as UnionType).types, isJSLiteralType); } if (type.flags & TypeFlags.Intersection) { return some((type as IntersectionType).types, isJSLiteralType); } if (type.flags & TypeFlags.Instantiable) { const constraint = getResolvedBaseConstraint(type); return constraint !== type && isJSLiteralType(constraint); } return false; } function getPropertyNameFromIndex(indexType: Type, accessNode: StringLiteral | Identifier | PrivateIdentifier | ObjectBindingPattern | ArrayBindingPattern | ComputedPropertyName | NumericLiteral | IndexedAccessTypeNode | ElementAccessExpression | SyntheticExpression | undefined) { return isTypeUsableAsPropertyName(indexType) ? getPropertyNameFromType(indexType) : accessNode && isPropertyName(accessNode) ? // late bound names are handled in the first branch, so here we only need to handle normal names getPropertyNameForPropertyNameNode(accessNode) : undefined; } function isUncalledFunctionReference(node: Node, symbol: Symbol) { if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { const parent = findAncestor(node.parent, n => !isAccessExpression(n)) || node.parent; if (isCallLikeExpression(parent)) { return isCallOrNewExpression(parent) && isIdentifier(node) && hasMatchingArgument(parent, node); } return every(symbol.declarations, d => !isFunctionLike(d) || !!(getCombinedNodeFlags(d) & NodeFlags.Deprecated)); } return true; } function getPropertyTypeForIndexType(originalObjectType: Type, objectType: Type, indexType: Type, fullIndexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression | undefined, accessFlags: AccessFlags) { const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode : undefined; const propName = accessNode && isPrivateIdentifier(accessNode) ? undefined : getPropertyNameFromIndex(indexType, accessNode); if (propName !== undefined) { if (accessFlags & AccessFlags.Contextual) { return getTypeOfPropertyOfContextualType(objectType, propName) || anyType; } const prop = getPropertyOfType(objectType, propName); if (prop) { if (accessFlags & AccessFlags.ReportDeprecated && accessNode && prop.declarations && isDeprecatedSymbol(prop) && isUncalledFunctionReference(accessNode, prop)) { const deprecatedNode = accessExpression?.argumentExpression ?? (isIndexedAccessTypeNode(accessNode) ? accessNode.indexType : accessNode); addDeprecatedSuggestion(deprecatedNode, prop.declarations, propName as string); } if (accessExpression) { markPropertyAsReferenced(prop, accessExpression, isSelfTypeAccess(accessExpression.expression, objectType.symbol)); if (isAssignmentToReadonlyEntity(accessExpression, prop, getAssignmentTargetKind(accessExpression))) { error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(prop)); return undefined; } if (accessFlags & AccessFlags.CacheSymbol) { getNodeLinks(accessNode!).resolvedSymbol = prop; } if (isThisPropertyAccessInConstructor(accessExpression, prop)) { return autoType; } } const propType = getTypeOfSymbol(prop); return accessExpression && getAssignmentTargetKind(accessExpression) !== AssignmentKind.Definite ? getFlowTypeOfReference(accessExpression, propType) : accessNode && isIndexedAccessTypeNode(accessNode) && containsMissingType(propType) ? getUnionType([propType, undefinedType]) : propType; } if (everyType(objectType, isTupleType) && isNumericLiteralName(propName)) { const index = +propName; if (accessNode && everyType(objectType, t => !(t as TupleTypeReference).target.hasRestElement) && !(accessFlags & AccessFlags.NoTupleBoundsCheck)) { const indexNode = getIndexNodeForAccessExpression(accessNode); if (isTupleType(objectType)) { if (index < 0) { error(indexNode, Diagnostics.A_tuple_type_cannot_be_indexed_with_a_negative_value); return undefinedType; } error(indexNode, Diagnostics.Tuple_type_0_of_length_1_has_no_element_at_index_2, typeToString(objectType), getTypeReferenceArity(objectType), unescapeLeadingUnderscores(propName)); } else { error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); } } if (index >= 0) { errorIfWritingToReadonlyIndex(getIndexInfoOfType(objectType, numberType)); return mapType(objectType, t => { const restType = getRestTypeOfTupleType(t as TupleTypeReference) || undefinedType; return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([restType, missingType]) : restType; }); } } } if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike)) { if (objectType.flags & (TypeFlags.Any | TypeFlags.Never)) { return objectType; } // If no index signature is applicable, we default to the string index signature. In effect, this means the string // index signature applies even when accessing with a symbol-like type. const indexInfo = getApplicableIndexInfo(objectType, indexType) || getIndexInfoOfType(objectType, stringType); if (indexInfo) { if (accessFlags & AccessFlags.NoIndexSignatures && indexInfo.keyType !== numberType) { if (accessExpression) { error(accessExpression, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(originalObjectType)); } return undefined; } if (accessNode && indexInfo.keyType === stringType && !isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { const indexNode = getIndexNodeForAccessExpression(accessNode); error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, missingType]) : indexInfo.type; } errorIfWritingToReadonlyIndex(indexInfo); // When accessing an enum object with its own type, // e.g. E[E.A] for enum E { A }, undefined shouldn't // be included in the result type if ((accessFlags & AccessFlags.IncludeUndefined) && !(objectType.symbol && objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum) && (indexType.symbol && indexType.flags & TypeFlags.EnumLiteral && getParentOfSymbol(indexType.symbol) === objectType.symbol))) { return getUnionType([indexInfo.type, missingType]); } return indexInfo.type; } if (indexType.flags & TypeFlags.Never) { return neverType; } if (isJSLiteralType(objectType)) { return anyType; } if (accessExpression && !isConstEnumObjectType(objectType)) { if (isObjectLiteralType(objectType)) { if (noImplicitAny && indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { diagnostics.add(createDiagnosticForNode(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType))); return undefinedType; } else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { const types = map((objectType as ResolvedType).properties, property => { return getTypeOfSymbol(property); }); return getUnionType(append(types, undefinedType)); } } if (objectType.symbol === globalThisSymbol && propName !== undefined && globalThisSymbol.exports!.has(propName) && (globalThisSymbol.exports!.get(propName)!.flags & SymbolFlags.BlockScoped)) { error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); } else if (noImplicitAny && !compilerOptions.suppressImplicitAnyIndexErrors && !(accessFlags & AccessFlags.SuppressNoImplicitAnyError)) { if (propName !== undefined && typeHasStaticProperty(propName, objectType)) { const typeName = typeToString(objectType); error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName as string, typeName, typeName + "[" + getTextOfNode(accessExpression.argumentExpression) + "]"); } else if (getIndexTypeOfType(objectType, numberType)) { error(accessExpression.argumentExpression, Diagnostics.Element_implicitly_has_an_any_type_because_index_expression_is_not_of_type_number); } else { let suggestion: string | undefined; if (propName !== undefined && (suggestion = getSuggestionForNonexistentProperty(propName as string, objectType))) { if (suggestion !== undefined) { error(accessExpression.argumentExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName as string, typeToString(objectType), suggestion); } } else { const suggestion = getSuggestionForNonexistentIndexSignature(objectType, accessExpression, indexType); if (suggestion !== undefined) { error(accessExpression, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature_Did_you_mean_to_call_1, typeToString(objectType), suggestion); } else { let errorInfo: DiagnosticMessageChain | undefined; if (indexType.flags & TypeFlags.EnumLiteral) { errorInfo = chainDiagnosticMessages(/* details */ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + typeToString(indexType) + "]", typeToString(objectType)); } else if (indexType.flags & TypeFlags.UniqueESSymbol) { const symbolName = getFullyQualifiedName((indexType as UniqueESSymbolType).symbol, accessExpression); errorInfo = chainDiagnosticMessages(/* details */ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + symbolName + "]", typeToString(objectType)); } else if (indexType.flags & TypeFlags.StringLiteral) { errorInfo = chainDiagnosticMessages(/* details */ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType)); } else if (indexType.flags & TypeFlags.NumberLiteral) { errorInfo = chainDiagnosticMessages(/* details */ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as NumberLiteralType).value, typeToString(objectType)); } else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { errorInfo = chainDiagnosticMessages(/* details */ undefined, Diagnostics.No_index_signature_with_a_parameter_of_type_0_was_found_on_type_1, typeToString(indexType), typeToString(objectType)); } errorInfo = chainDiagnosticMessages( errorInfo, Diagnostics.Element_implicitly_has_an_any_type_because_expression_of_type_0_can_t_be_used_to_index_type_1, typeToString(fullIndexType), typeToString(objectType) ); diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(accessExpression), accessExpression, errorInfo)); } } } } return undefined; } } if (isJSLiteralType(objectType)) { return anyType; } if (accessNode) { const indexNode = getIndexNodeForAccessExpression(accessNode); if (indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, "" + (indexType as StringLiteralType | NumberLiteralType).value, typeToString(objectType)); } else if (indexType.flags & (TypeFlags.String | TypeFlags.Number)) { error(indexNode, Diagnostics.Type_0_has_no_matching_index_signature_for_type_1, typeToString(objectType), typeToString(indexType)); } else { error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); } } if (isTypeAny(indexType)) { return indexType; } return undefined; function errorIfWritingToReadonlyIndex(indexInfo: IndexInfo | undefined): void { if (indexInfo && indexInfo.isReadonly && accessExpression && (isAssignmentTarget(accessExpression) || isDeleteTarget(accessExpression))) { error(accessExpression, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); } } } function getIndexNodeForAccessExpression(accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression) { return accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : accessNode.kind === SyntaxKind.IndexedAccessType ? accessNode.indexType : accessNode.kind === SyntaxKind.ComputedPropertyName ? accessNode.expression : accessNode; } function isPatternLiteralPlaceholderType(type: Type): boolean { return !!(type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) || isPatternLiteralType(type); } function isPatternLiteralType(type: Type) { return !!(type.flags & TypeFlags.TemplateLiteral) && every((type as TemplateLiteralType).types, isPatternLiteralPlaceholderType) || !!(type.flags & TypeFlags.StringMapping) && isPatternLiteralPlaceholderType((type as StringMappingType).type); } function isGenericType(type: Type): boolean { return !!getGenericObjectFlags(type); } function isGenericObjectType(type: Type): boolean { return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericObjectType); } function isGenericIndexType(type: Type): boolean { return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericIndexType); } function getGenericObjectFlags(type: Type): ObjectFlags { if (type.flags & TypeFlags.UnionOrIntersection) { if (!((type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { (type as UnionOrIntersectionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | reduceLeft((type as UnionOrIntersectionType).types, (flags, t) => flags | getGenericObjectFlags(t), 0); } return (type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericType; } if (type.flags & TypeFlags.Substitution) { if (!((type as SubstitutionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { (type as SubstitutionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | getGenericObjectFlags((type as SubstitutionType).baseType) | getGenericObjectFlags((type as SubstitutionType).constraint); } return (type as SubstitutionType).objectFlags & ObjectFlags.IsGenericType; } return (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type) || isGenericTupleType(type) ? ObjectFlags.IsGenericObjectType : 0) | (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && !isPatternLiteralType(type) ? ObjectFlags.IsGenericIndexType : 0); } function getSimplifiedType(type: Type, writing: boolean): Type { return type.flags & TypeFlags.IndexedAccess ? getSimplifiedIndexedAccessType(type as IndexedAccessType, writing) : type.flags & TypeFlags.Conditional ? getSimplifiedConditionalType(type as ConditionalType, writing) : type; } function distributeIndexOverObjectType(objectType: Type, indexType: Type, writing: boolean) { // (T | U)[K] -> T[K] | U[K] (reading) // (T | U)[K] -> T[K] & U[K] (writing) // (T & U)[K] -> T[K] & U[K] if (objectType.flags & TypeFlags.Union || objectType.flags & TypeFlags.Intersection && !shouldDeferIndexType(objectType)) { const types = map((objectType as UnionOrIntersectionType).types, t => getSimplifiedType(getIndexedAccessType(t, indexType), writing)); return objectType.flags & TypeFlags.Intersection || writing ? getIntersectionType(types) : getUnionType(types); } } function distributeObjectOverIndexType(objectType: Type, indexType: Type, writing: boolean) { // T[A | B] -> T[A] | T[B] (reading) // T[A | B] -> T[A] & T[B] (writing) if (indexType.flags & TypeFlags.Union) { const types = map((indexType as UnionType).types, t => getSimplifiedType(getIndexedAccessType(objectType, t), writing)); return writing ? getIntersectionType(types) : getUnionType(types); } } // Transform an indexed access to a simpler form, if possible. Return the simpler form, or return // the type itself if no transformation is possible. The writing flag indicates that the type is // the target of an assignment. function getSimplifiedIndexedAccessType(type: IndexedAccessType, writing: boolean): Type { const cache = writing ? "simplifiedForWriting" : "simplifiedForReading"; if (type[cache]) { return type[cache] === circularConstraintType ? type : type[cache]!; } type[cache] = circularConstraintType; // We recursively simplify the object type as it may in turn be an indexed access type. For example, with // '{ [P in T]: { [Q in U]: number } }[T][U]' we want to first simplify the inner indexed access type. const objectType = getSimplifiedType(type.objectType, writing); const indexType = getSimplifiedType(type.indexType, writing); // T[A | B] -> T[A] | T[B] (reading) // T[A | B] -> T[A] & T[B] (writing) const distributedOverIndex = distributeObjectOverIndexType(objectType, indexType, writing); if (distributedOverIndex) { return type[cache] = distributedOverIndex; } // Only do the inner distributions if the index can no longer be instantiated to cause index distribution again if (!(indexType.flags & TypeFlags.Instantiable)) { // (T | U)[K] -> T[K] | U[K] (reading) // (T | U)[K] -> T[K] & U[K] (writing) // (T & U)[K] -> T[K] & U[K] const distributedOverObject = distributeIndexOverObjectType(objectType, indexType, writing); if (distributedOverObject) { return type[cache] = distributedOverObject; } } // So ultimately (reading): // ((A & B) | C)[K1 | K2] -> ((A & B) | C)[K1] | ((A & B) | C)[K2] -> (A & B)[K1] | C[K1] | (A & B)[K2] | C[K2] -> (A[K1] & B[K1]) | C[K1] | (A[K2] & B[K2]) | C[K2] // A generic tuple type indexed by a number exists only when the index type doesn't select a // fixed element. We simplify to either the combined type of all elements (when the index type // the actual number type) or to the combined type of all non-fixed elements. if (isGenericTupleType(objectType) && indexType.flags & TypeFlags.NumberLike) { const elementType = getElementTypeOfSliceOfTupleType(objectType, indexType.flags & TypeFlags.Number ? 0 : objectType.target.fixedLength, /*endSkipCount*/ 0, writing); if (elementType) { return type[cache] = elementType; } } // If the object type is a mapped type { [P in K]: E }, where K is generic, or { [P in K as N]: E }, where // K is generic and N is assignable to P, instantiate E using a mapper that substitutes the index type for P. // For example, for an index access { [P in K]: Box }[X], we construct the type Box. if (isGenericMappedType(objectType)) { if (!getNameTypeFromMappedType(objectType) || isFilteringMappedType(objectType)) { return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing)); } } return type[cache] = type; } function getSimplifiedConditionalType(type: ConditionalType, writing: boolean) { const checkType = type.checkType; const extendsType = type.extendsType; const trueType = getTrueTypeFromConditionalType(type); const falseType = getFalseTypeFromConditionalType(type); // Simplifications for types of the form `T extends U ? T : never` and `T extends U ? never : T`. if (falseType.flags & TypeFlags.Never && getActualTypeVariable(trueType) === getActualTypeVariable(checkType)) { if (checkType.flags & TypeFlags.Any || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true return getSimplifiedType(trueType, writing); } else if (isIntersectionEmpty(checkType, extendsType)) { // Always false return neverType; } } else if (trueType.flags & TypeFlags.Never && getActualTypeVariable(falseType) === getActualTypeVariable(checkType)) { if (!(checkType.flags & TypeFlags.Any) && isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true return neverType; } else if (checkType.flags & TypeFlags.Any || isIntersectionEmpty(checkType, extendsType)) { // Always false return getSimplifiedType(falseType, writing); } } return type; } /** * Invokes union simplification logic to determine if an intersection is considered empty as a union constituent */ function isIntersectionEmpty(type1: Type, type2: Type) { return !!(getUnionType([intersectTypes(type1, type2), neverType]).flags & TypeFlags.Never); } function substituteIndexedMappedType(objectType: MappedType, index: Type) { const mapper = createTypeMapper([getTypeParameterFromMappedType(objectType)], [index]); const templateMapper = combineTypeMappers(objectType.mapper, mapper); return instantiateType(getTemplateTypeFromMappedType(objectType.target as MappedType || objectType), templateMapper); } function getIndexedAccessType(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { return getIndexedAccessTypeOrUndefined(objectType, indexType, accessFlags, accessNode, aliasSymbol, aliasTypeArguments) || (accessNode ? errorType : unknownType); } function indexTypeLessThan(indexType: Type, limit: number) { return everyType(indexType, t => { if (t.flags & TypeFlags.StringOrNumberLiteral) { const propName = getPropertyNameFromType(t as StringLiteralType | NumberLiteralType); if (isNumericLiteralName(propName)) { const index = +propName; return index >= 0 && index < limit; } } return false; }); } function getIndexedAccessTypeOrUndefined(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type | undefined { if (objectType === wildcardType || indexType === wildcardType) { return wildcardType; } // If the object type has a string index signature and no other members we know that the result will // always be the type of that index signature and we can simplify accordingly. if (isStringIndexSignatureOnlyType(objectType) && !(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { indexType = stringType; } // In noUncheckedIndexedAccess mode, indexed access operations that occur in an expression in a read position and resolve to // an index signature have 'undefined' included in their type. if (compilerOptions.noUncheckedIndexedAccess && accessFlags & AccessFlags.ExpressionPosition) accessFlags |= AccessFlags.IncludeUndefined; // If the index type is generic, or if the object type is generic and doesn't originate in an expression and // the operation isn't exclusively indexing the fixed (non-variadic) portion of a tuple type, we are performing // a higher-order index access where we cannot meaningfully access the properties of the object type. Note that // for a generic T and a non-generic K, we eagerly resolve T[K] if it originates in an expression. This is to // preserve backwards compatibility. For example, an element access 'this["foo"]' has always been resolved // eagerly using the constraint type of 'this' at the given location. if (isGenericIndexType(indexType) || (accessNode && accessNode.kind !== SyntaxKind.IndexedAccessType ? isGenericTupleType(objectType) && !indexTypeLessThan(indexType, objectType.target.fixedLength) : isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, objectType.target.fixedLength)))) { if (objectType.flags & TypeFlags.AnyOrUnknown) { return objectType; } // Defer the operation by creating an indexed access type. const persistentAccessFlags = accessFlags & AccessFlags.Persistent; const id = objectType.id + "," + indexType.id + "," + persistentAccessFlags + getAliasId(aliasSymbol, aliasTypeArguments); let type = indexedAccessTypes.get(id); if (!type) { indexedAccessTypes.set(id, type = createIndexedAccessType(objectType, indexType, persistentAccessFlags, aliasSymbol, aliasTypeArguments)); } return type; } // In the following we resolve T[K] to the type of the property in T selected by K. // We treat boolean as different from other unions to improve errors; // skipping straight to getPropertyTypeForIndexType gives errors with 'boolean' instead of 'true'. const apparentObjectType = getReducedApparentType(objectType); if (indexType.flags & TypeFlags.Union && !(indexType.flags & TypeFlags.Boolean)) { const propTypes: Type[] = []; let wasMissingProp = false; for (const t of (indexType as UnionType).types) { const propType = getPropertyTypeForIndexType(objectType, apparentObjectType, t, indexType, accessNode, accessFlags | (wasMissingProp ? AccessFlags.SuppressNoImplicitAnyError : 0)); if (propType) { propTypes.push(propType); } else if (!accessNode) { // If there's no error node, we can immeditely stop, since error reporting is off return undefined; } else { // Otherwise we set a flag and return at the end of the loop so we still mark all errors wasMissingProp = true; } } if (wasMissingProp) { return undefined; } return accessFlags & AccessFlags.Writing ? getIntersectionType(propTypes, aliasSymbol, aliasTypeArguments) : getUnionType(propTypes, UnionReduction.Literal, aliasSymbol, aliasTypeArguments); } return getPropertyTypeForIndexType(objectType, apparentObjectType, indexType, indexType, accessNode, accessFlags | AccessFlags.CacheSymbol | AccessFlags.ReportDeprecated); } function getTypeFromIndexedAccessTypeNode(node: IndexedAccessTypeNode) { const links = getNodeLinks(node); if (!links.resolvedType) { const objectType = getTypeFromTypeNode(node.objectType); const indexType = getTypeFromTypeNode(node.indexType); const potentialAlias = getAliasSymbolForTypeNode(node); links.resolvedType = getIndexedAccessType(objectType, indexType, AccessFlags.None, node, potentialAlias, getTypeArgumentsForAliasSymbol(potentialAlias)); } return links.resolvedType; } function getTypeFromMappedTypeNode(node: MappedTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { const type = createObjectType(ObjectFlags.Mapped, node.symbol) as MappedType; type.declaration = node; type.aliasSymbol = getAliasSymbolForTypeNode(node); type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(type.aliasSymbol); links.resolvedType = type; // Eagerly resolve the constraint type which forces an error if the constraint type circularly // references itself through one or more type aliases. getConstraintTypeFromMappedType(type); } return links.resolvedType; } function getActualTypeVariable(type: Type): Type { if (type.flags & TypeFlags.Substitution) { return getActualTypeVariable((type as SubstitutionType).baseType); } if (type.flags & TypeFlags.IndexedAccess && ( (type as IndexedAccessType).objectType.flags & TypeFlags.Substitution || (type as IndexedAccessType).indexType.flags & TypeFlags.Substitution)) { return getIndexedAccessType(getActualTypeVariable((type as IndexedAccessType).objectType), getActualTypeVariable((type as IndexedAccessType).indexType)); } return type; } function maybeCloneTypeParameter(p: TypeParameter) { const constraint = getConstraintOfTypeParameter(p); return constraint && (isGenericObjectType(constraint) || isGenericIndexType(constraint)) ? cloneTypeParameter(p) : p; } function isSimpleTupleType(node: TypeNode) { return isTupleTypeNode(node) && length(node.elements) > 0 && !some(node.elements, e => isOptionalTypeNode(e) || isRestTypeNode(e) || isNamedTupleMember(e) && !!(e.questionToken || e.dotDotDotToken)); } function isDeferredType(type: Type, checkTuples: boolean) { return isGenericType(type) || checkTuples && isTupleType(type) && some(getTypeArguments(type), isGenericType); } function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { let result; let extraTypes: Type[] | undefined; let tailCount = 0; // We loop here for an immediately nested conditional type in the false position, effectively treating // types of the form 'A extends B ? X : C extends D ? Y : E extends F ? Z : ...' as a single construct for // purposes of resolution. We also loop here when resolution of a conditional type ends in resolution of // another (or, through recursion, possibly the same) conditional type. In the potentially tail-recursive // cases we increment the tail recursion counter and stop after 1000 iterations. while (true) { if (tailCount === 1000) { error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); result = errorType; break; } // When the check and extends types are simple tuple types of the same arity, we defer resolution of the // conditional type when any tuple elements are generic. This is such that non-distributable conditional // types can be written `[X] extends [Y] ? ...` and be deferred similarly to `X extends Y ? ...`. const checkTuples = isSimpleTupleType(root.node.checkType) && isSimpleTupleType(root.node.extendsType) && length((root.node.checkType as TupleTypeNode).elements) === length((root.node.extendsType as TupleTypeNode).elements); const checkType = instantiateType(getActualTypeVariable(root.checkType), mapper); const checkTypeDeferred = isDeferredType(checkType, checkTuples); const extendsType = instantiateType(root.extendsType, mapper); if (checkType === wildcardType || extendsType === wildcardType) { return wildcardType; } let combinedMapper: TypeMapper | undefined; if (root.inferTypeParameters) { // When we're looking at making an inference for an infer type, when we get its constraint, it'll automagically be // instantiated with the context, so it doesn't need the mapper for the inference contex - however the constraint // may refer to another _root_, _uncloned_ `infer` type parameter [1], or to something mapped by `mapper` [2]. // [1] Eg, if we have `Foo` and `Foo` - `B` is constrained to `T`, which, in turn, has been instantiated // as `number` // Conversely, if we have `Foo`, `B` is still constrained to `T` and `T` is instantiated as `A` // [2] Eg, if we have `Foo` and `Foo` where `Q` is mapped by `mapper` into `number` - `B` is constrained to `T` // which is in turn instantiated as `Q`, which is in turn instantiated as `number`. // So we need to: // * Clone the type parameters so their constraints can be instantiated in the context of `mapper` (otherwise theyd only get inference context information) // * Set the clones to both map the conditional's enclosing `mapper` and the original params // * instantiate the extends type with the clones // * incorporate all of the component mappers into the combined mapper for the true and false members // This means we have three mappers that need applying: // * The original `mapper` used to create this conditional // * The mapper that maps the old root type parameter to the clone (`freshMapper`) // * The mapper that maps the clone to its inference result (`context.mapper`) const freshParams = sameMap(root.inferTypeParameters, maybeCloneTypeParameter); const freshMapper = freshParams !== root.inferTypeParameters ? createTypeMapper(root.inferTypeParameters, freshParams) : undefined; const context = createInferenceContext(freshParams, /*signature*/ undefined, InferenceFlags.None); if (freshMapper) { const freshCombinedMapper = combineTypeMappers(mapper, freshMapper); for (const p of freshParams) { if (root.inferTypeParameters.indexOf(p) === -1) { p.mapper = freshCombinedMapper; } } } if (!checkTypeDeferred) { // We don't want inferences from constraints as they may cause us to eagerly resolve the // conditional type instead of deferring resolution. Also, we always want strict function // types rules (i.e. proper contravariance) for inferences. inferTypes(context.inferences, checkType, instantiateType(extendsType, freshMapper), InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); } const innerMapper = combineTypeMappers(freshMapper, context.mapper); // It's possible for 'infer T' type paramteters to be given uninstantiated constraints when the // those type parameters are used in type references (see getInferredTypeParameterConstraint). For // that reason we need context.mapper to be first in the combined mapper. See #42636 for examples. combinedMapper = mapper ? combineTypeMappers(innerMapper, mapper) : innerMapper; } // Instantiate the extends type including inferences for 'infer T' type parameters const inferredExtendsType = combinedMapper ? instantiateType(root.extendsType, combinedMapper) : extendsType; // We attempt to resolve the conditional type only when the check and extends types are non-generic if (!checkTypeDeferred && !isDeferredType(inferredExtendsType, checkTuples)) { // Return falseType for a definitely false extends check. We check an instantiations of the two // types with type parameters mapped to the wildcard type, the most permissive instantiations // possible (the wildcard type is assignable to and from all types). If those are not related, // then no instantiations will be and we can just return the false branch type. if (!(inferredExtendsType.flags & TypeFlags.AnyOrUnknown) && (checkType.flags & TypeFlags.Any || !isTypeAssignableTo(getPermissiveInstantiation(checkType), getPermissiveInstantiation(inferredExtendsType)))) { // Return union of trueType and falseType for 'any' since it matches anything if (checkType.flags & TypeFlags.Any) { (extraTypes || (extraTypes = [])).push(instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper)); } // If falseType is an immediately nested conditional type that isn't distributive or has an // identical checkType, switch to that type and loop. const falseType = getTypeFromTypeNode(root.node.falseType); if (falseType.flags & TypeFlags.Conditional) { const newRoot = (falseType as ConditionalType).root; if (newRoot.node.parent === root.node && (!newRoot.isDistributive || newRoot.checkType === root.checkType)) { root = newRoot; continue; } if (canTailRecurse(falseType, mapper)) { continue; } } result = instantiateType(falseType, mapper); break; } // Return trueType for a definitely true extends check. We check instantiations of the two // types with type parameters mapped to their restrictive form, i.e. a form of the type parameter // that has no constraint. This ensures that, for example, the type // type Foo = T extends { x: string } ? string : number // doesn't immediately resolve to 'string' instead of being deferred. if (inferredExtendsType.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(inferredExtendsType))) { const trueType = getTypeFromTypeNode(root.node.trueType); const trueMapper = combinedMapper || mapper; if (canTailRecurse(trueType, trueMapper)) { continue; } result = instantiateType(trueType, trueMapper); break; } } // Return a deferred type for a check that is neither definitely true nor definitely false result = createType(TypeFlags.Conditional) as ConditionalType; result.root = root; result.checkType = instantiateType(root.checkType, mapper); result.extendsType = instantiateType(root.extendsType, mapper); result.mapper = mapper; result.combinedMapper = combinedMapper; result.aliasSymbol = aliasSymbol || root.aliasSymbol; result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(root.aliasTypeArguments, mapper!); // TODO: GH#18217 break; } return extraTypes ? getUnionType(append(extraTypes, result)) : result; // We tail-recurse for generic conditional types that (a) have not already been evaluated and cached, and // (b) are non distributive, have a check type that is unaffected by instantiation, or have a non-union check // type. Note that recursion is possible only through aliased conditional types, so we only increment the tail // recursion counter for those. function canTailRecurse(newType: Type, newMapper: TypeMapper | undefined) { if (newType.flags & TypeFlags.Conditional && newMapper) { const newRoot = (newType as ConditionalType).root; if (newRoot.outerTypeParameters) { const typeParamMapper = combineTypeMappers((newType as ConditionalType).mapper, newMapper); const typeArguments = map(newRoot.outerTypeParameters, t => getMappedType(t, typeParamMapper)); const newRootMapper = createTypeMapper(newRoot.outerTypeParameters, typeArguments); const newCheckType = newRoot.isDistributive ? getMappedType(newRoot.checkType, newRootMapper) : undefined; if (!newCheckType || newCheckType === newRoot.checkType || !(newCheckType.flags & (TypeFlags.Union | TypeFlags.Never))) { root = newRoot; mapper = newRootMapper; aliasSymbol = undefined; aliasTypeArguments = undefined; if (newRoot.aliasSymbol) { tailCount++; } return true; } } } return false; } } function getTrueTypeFromConditionalType(type: ConditionalType) { return type.resolvedTrueType || (type.resolvedTrueType = instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.mapper)); } function getFalseTypeFromConditionalType(type: ConditionalType) { return type.resolvedFalseType || (type.resolvedFalseType = instantiateType(getTypeFromTypeNode(type.root.node.falseType), type.mapper)); } function getInferredTrueTypeFromConditionalType(type: ConditionalType) { return type.resolvedInferredTrueType || (type.resolvedInferredTrueType = type.combinedMapper ? instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.combinedMapper) : getTrueTypeFromConditionalType(type)); } function getInferTypeParameters(node: ConditionalTypeNode): TypeParameter[] | undefined { let result: TypeParameter[] | undefined; if (node.locals) { node.locals.forEach(symbol => { if (symbol.flags & SymbolFlags.TypeParameter) { result = append(result, getDeclaredTypeOfSymbol(symbol)); } }); } return result; } function isDistributionDependent(root: ConditionalRoot) { return root.isDistributive && ( isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.trueType) || isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.falseType)); } function getTypeFromConditionalTypeNode(node: ConditionalTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { const checkType = getTypeFromTypeNode(node.checkType); const aliasSymbol = getAliasSymbolForTypeNode(node); const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); const allOuterTypeParameters = getOuterTypeParameters(node, /*includeThisTypes*/ true); const outerTypeParameters = aliasTypeArguments ? allOuterTypeParameters : filter(allOuterTypeParameters, tp => isTypeParameterPossiblyReferenced(tp, node)); const root: ConditionalRoot = { node, checkType, extendsType: getTypeFromTypeNode(node.extendsType), isDistributive: !!(checkType.flags & TypeFlags.TypeParameter), inferTypeParameters: getInferTypeParameters(node), outerTypeParameters, instantiations: undefined, aliasSymbol, aliasTypeArguments }; links.resolvedType = getConditionalType(root, /*mapper*/ undefined); if (outerTypeParameters) { root.instantiations = new Map(); root.instantiations.set(getTypeListId(outerTypeParameters), links.resolvedType); } } return links.resolvedType; } function getTypeFromInferTypeNode(node: InferTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { links.resolvedType = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter)); } return links.resolvedType; } function getIdentifierChain(node: EntityName): Identifier[] { if (isIdentifier(node)) { return [node]; } else { return append(getIdentifierChain(node.left), node.right); } } function getTypeFromImportTypeNode(node: ImportTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { if (!isLiteralImportTypeNode(node)) { error(node.argument, Diagnostics.String_literal_expected); links.resolvedSymbol = unknownSymbol; return links.resolvedType = errorType; } const targetMeaning = node.isTypeOf ? SymbolFlags.Value : node.flags & NodeFlags.JSDoc ? SymbolFlags.Value | SymbolFlags.Type : SymbolFlags.Type; // TODO: Future work: support unions/generics/whatever via a deferred import-type const innerModuleSymbol = resolveExternalModuleName(node, node.argument.literal); if (!innerModuleSymbol) { links.resolvedSymbol = unknownSymbol; return links.resolvedType = errorType; } const isExportEquals = !!innerModuleSymbol.exports?.get(InternalSymbolName.ExportEquals); const moduleSymbol = resolveExternalModuleSymbol(innerModuleSymbol, /*dontResolveAlias*/ false); if (!nodeIsMissing(node.qualifier)) { const nameStack: Identifier[] = getIdentifierChain(node.qualifier!); let currentNamespace = moduleSymbol; let current: Identifier | undefined; while (current = nameStack.shift()) { const meaning = nameStack.length ? SymbolFlags.Namespace : targetMeaning; // typeof a.b.c is normally resolved using `checkExpression` which in turn defers to `checkQualifiedName` // That, in turn, ultimately uses `getPropertyOfType` on the type of the symbol, which differs slightly from // the `exports` lookup process that only looks up namespace members which is used for most type references const mergedResolvedSymbol = getMergedSymbol(resolveSymbol(currentNamespace)); const symbolFromVariable = node.isTypeOf || isInJSFile(node) && isExportEquals ? getPropertyOfType(getTypeOfSymbol(mergedResolvedSymbol), current.escapedText, /*skipObjectFunctionPropertyAugment*/ false, /*includeTypeOnlyMembers*/ true) : undefined; const symbolFromModule = node.isTypeOf ? undefined : getSymbol(getExportsOfSymbol(mergedResolvedSymbol), current.escapedText, meaning); const next = symbolFromModule ?? symbolFromVariable; if (!next) { error(current, Diagnostics.Namespace_0_has_no_exported_member_1, getFullyQualifiedName(currentNamespace), declarationNameToString(current)); return links.resolvedType = errorType; } getNodeLinks(current).resolvedSymbol = next; getNodeLinks(current.parent).resolvedSymbol = next; currentNamespace = next; } links.resolvedType = resolveImportSymbolType(node, links, currentNamespace, targetMeaning); } else { if (moduleSymbol.flags & targetMeaning) { links.resolvedType = resolveImportSymbolType(node, links, moduleSymbol, targetMeaning); } else { const errorMessage = targetMeaning === SymbolFlags.Value ? Diagnostics.Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here : Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0; error(node, errorMessage, node.argument.literal.text); links.resolvedSymbol = unknownSymbol; links.resolvedType = errorType; } } } return links.resolvedType; } function resolveImportSymbolType(node: ImportTypeNode, links: NodeLinks, symbol: Symbol, meaning: SymbolFlags) { const resolvedSymbol = resolveSymbol(symbol); links.resolvedSymbol = resolvedSymbol; if (meaning === SymbolFlags.Value) { return getInstantiationExpressionType(getTypeOfSymbol(symbol), node); // intentionally doesn't use resolved symbol so type is cached as expected on the alias } else { return getTypeReferenceType(node, resolvedSymbol); // getTypeReferenceType doesn't handle aliases - it must get the resolved symbol } } function getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node: TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature): Type { const links = getNodeLinks(node); if (!links.resolvedType) { // Deferred resolution of members is handled by resolveObjectTypeMembers const aliasSymbol = getAliasSymbolForTypeNode(node); if (getMembersOfSymbol(node.symbol).size === 0 && !aliasSymbol) { links.resolvedType = emptyTypeLiteralType; } else { let type = createObjectType(ObjectFlags.Anonymous, node.symbol); type.aliasSymbol = aliasSymbol; type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); if (isJSDocTypeLiteral(node) && node.isArrayType) { type = createArrayType(type); } links.resolvedType = type; } } return links.resolvedType; } function getAliasSymbolForTypeNode(node: Node) { let host = node.parent; while (isParenthesizedTypeNode(host) || isJSDocTypeExpression(host) || isTypeOperatorNode(host) && host.operator === SyntaxKind.ReadonlyKeyword) { host = host.parent; } return isTypeAlias(host) ? getSymbolOfDeclaration(host) : undefined; } function getTypeArgumentsForAliasSymbol(symbol: Symbol | undefined) { return symbol ? getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol) : undefined; } function isNonGenericObjectType(type: Type) { return !!(type.flags & TypeFlags.Object) && !isGenericMappedType(type); } function isEmptyObjectTypeOrSpreadsIntoEmptyObject(type: Type) { return isEmptyObjectType(type) || !!(type.flags & (TypeFlags.Null | TypeFlags.Undefined | TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)); } function tryMergeUnionOfObjectTypeAndEmptyObject(type: Type, readonly: boolean): Type { if (!(type.flags & TypeFlags.Union)) { return type; } if (every((type as UnionType).types, isEmptyObjectTypeOrSpreadsIntoEmptyObject)) { return find((type as UnionType).types, isEmptyObjectType) || emptyObjectType; } const firstType = find((type as UnionType).types, t => !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); if (!firstType) { return type; } const secondType = find((type as UnionType).types, t => t !== firstType && !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); if (secondType) { return type; } return getAnonymousPartialType(firstType); function getAnonymousPartialType(type: Type) { // gets the type as if it had been spread, but where everything in the spread is made optional const members = createSymbolTable(); for (const prop of getPropertiesOfType(type)) { if (getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) { // do nothing, skip privates } else if (isSpreadableProperty(prop)) { const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); const flags = SymbolFlags.Property | SymbolFlags.Optional; const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); result.links.type = isSetonlyAccessor ? undefinedType : addOptionality(getTypeOfSymbol(prop), /*isProperty*/ true); result.declarations = prop.declarations; result.links.nameType = getSymbolLinks(prop).nameType; result.links.syntheticOrigin = prop; members.set(prop.escapedName, result); } } const spread = createAnonymousType(type.symbol, members, emptyArray, emptyArray, getIndexInfosOfType(type)); spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; return spread; } } /** * Since the source of spread types are object literals, which are not binary, * this function should be called in a left folding style, with left = previous result of getSpreadType * and right = the new element to be spread. */ function getSpreadType(left: Type, right: Type, symbol: Symbol | undefined, objectFlags: ObjectFlags, readonly: boolean): Type { if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) { return anyType; } if (left.flags & TypeFlags.Unknown || right.flags & TypeFlags.Unknown) { return unknownType; } if (left.flags & TypeFlags.Never) { return right; } if (right.flags & TypeFlags.Never) { return left; } left = tryMergeUnionOfObjectTypeAndEmptyObject(left, readonly); if (left.flags & TypeFlags.Union) { return checkCrossProductUnion([left, right]) ? mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly)) : errorType; } right = tryMergeUnionOfObjectTypeAndEmptyObject(right, readonly); if (right.flags & TypeFlags.Union) { return checkCrossProductUnion([left, right]) ? mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly)) : errorType; } if (right.flags & (TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)) { return left; } if (isGenericObjectType(left) || isGenericObjectType(right)) { if (isEmptyObjectType(left)) { return right; } // When the left type is an intersection, we may need to merge the last constituent of the // intersection with the right type. For example when the left type is 'T & { a: string }' // and the right type is '{ b: string }' we produce 'T & { a: string, b: string }'. if (left.flags & TypeFlags.Intersection) { const types = (left as IntersectionType).types; const lastLeft = types[types.length - 1]; if (isNonGenericObjectType(lastLeft) && isNonGenericObjectType(right)) { return getIntersectionType(concatenate(types.slice(0, types.length - 1), [getSpreadType(lastLeft, right, symbol, objectFlags, readonly)])); } } return getIntersectionType([left, right]); } const members = createSymbolTable(); const skippedPrivateMembers = new Set<__String>(); const indexInfos = left === emptyObjectType ? getIndexInfosOfType(right) : getUnionIndexInfos([left, right]); for (const rightProp of getPropertiesOfType(right)) { if (getDeclarationModifierFlagsFromSymbol(rightProp) & (ModifierFlags.Private | ModifierFlags.Protected)) { skippedPrivateMembers.add(rightProp.escapedName); } else if (isSpreadableProperty(rightProp)) { members.set(rightProp.escapedName, getSpreadSymbol(rightProp, readonly)); } } for (const leftProp of getPropertiesOfType(left)) { if (skippedPrivateMembers.has(leftProp.escapedName) || !isSpreadableProperty(leftProp)) { continue; } if (members.has(leftProp.escapedName)) { const rightProp = members.get(leftProp.escapedName)!; const rightType = getTypeOfSymbol(rightProp); if (rightProp.flags & SymbolFlags.Optional) { const declarations = concatenate(leftProp.declarations, rightProp.declarations); const flags = SymbolFlags.Property | (leftProp.flags & SymbolFlags.Optional); const result = createSymbol(flags, leftProp.escapedName); result.links.type = getUnionType([getTypeOfSymbol(leftProp), removeMissingOrUndefinedType(rightType)], UnionReduction.Subtype); result.links.leftSpread = leftProp; result.links.rightSpread = rightProp; result.declarations = declarations; result.links.nameType = getSymbolLinks(leftProp).nameType; members.set(leftProp.escapedName, result); } } else { members.set(leftProp.escapedName, getSpreadSymbol(leftProp, readonly)); } } const spread = createAnonymousType(symbol, members, emptyArray, emptyArray, sameMap(indexInfos, info => getIndexInfoWithReadonly(info, readonly))); spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral | ObjectFlags.ContainsSpread | objectFlags; return spread; } /** We approximate own properties as non-methods plus methods that are inside the object literal */ function isSpreadableProperty(prop: Symbol): boolean { return !some(prop.declarations, isPrivateIdentifierClassElementDeclaration) && (!(prop.flags & (SymbolFlags.Method | SymbolFlags.GetAccessor | SymbolFlags.SetAccessor)) || !prop.declarations?.some(decl => isClassLike(decl.parent))); } function getSpreadSymbol(prop: Symbol, readonly: boolean) { const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); if (!isSetonlyAccessor && readonly === isReadonlySymbol(prop)) { return prop; } const flags = SymbolFlags.Property | (prop.flags & SymbolFlags.Optional); const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); result.links.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop); result.declarations = prop.declarations; result.links.nameType = getSymbolLinks(prop).nameType; result.links.syntheticOrigin = prop; return result; } function getIndexInfoWithReadonly(info: IndexInfo, readonly: boolean) { return info.isReadonly !== readonly ? createIndexInfo(info.keyType, info.type, readonly, info.declaration) : info; } function createLiteralType(flags: TypeFlags, value: string | number | PseudoBigInt, symbol?: Symbol, regularType?: LiteralType) { const type = createTypeWithSymbol(flags, symbol!) as LiteralType; type.value = value; type.regularType = regularType || type; return type; } function getFreshTypeOfLiteralType(type: Type): Type { if (type.flags & TypeFlags.Freshable) { if (!(type as FreshableType).freshType) { const freshType = createLiteralType(type.flags, (type as LiteralType).value, (type as LiteralType).symbol, type as LiteralType); freshType.freshType = freshType; (type as FreshableType).freshType = freshType; } return (type as FreshableType).freshType; } return type; } function getRegularTypeOfLiteralType(type: Type): Type { return type.flags & TypeFlags.Freshable ? (type as FreshableType).regularType : type.flags & TypeFlags.Union ? ((type as UnionType).regularType || ((type as UnionType).regularType = mapType(type, getRegularTypeOfLiteralType) as UnionType)) : type; } function isFreshLiteralType(type: Type) { return !!(type.flags & TypeFlags.Freshable) && (type as LiteralType).freshType === type; } function getStringLiteralType(value: string): StringLiteralType { let type; return stringLiteralTypes.get(value) || (stringLiteralTypes.set(value, type = createLiteralType(TypeFlags.StringLiteral, value) as StringLiteralType), type); } function getNumberLiteralType(value: number): NumberLiteralType { let type; return numberLiteralTypes.get(value) || (numberLiteralTypes.set(value, type = createLiteralType(TypeFlags.NumberLiteral, value) as NumberLiteralType), type); } function getBigIntLiteralType(value: PseudoBigInt): BigIntLiteralType { let type; const key = pseudoBigIntToString(value); return bigIntLiteralTypes.get(key) || (bigIntLiteralTypes.set(key, type = createLiteralType(TypeFlags.BigIntLiteral, value) as BigIntLiteralType), type); } function getEnumLiteralType(value: string | number, enumId: number, symbol: Symbol): LiteralType { let type; const key = `${enumId}${typeof value === "string" ? "@" : "#"}${value}`; const flags = TypeFlags.EnumLiteral | (typeof value === "string" ? TypeFlags.StringLiteral : TypeFlags.NumberLiteral); return enumLiteralTypes.get(key) || (enumLiteralTypes.set(key, type = createLiteralType(flags, value, symbol)), type); } function getTypeFromLiteralTypeNode(node: LiteralTypeNode): Type { if (node.literal.kind === SyntaxKind.NullKeyword) { return nullType; } const links = getNodeLinks(node); if (!links.resolvedType) { links.resolvedType = getRegularTypeOfLiteralType(checkExpression(node.literal)); } return links.resolvedType; } function createUniqueESSymbolType(symbol: Symbol) { const type = createTypeWithSymbol(TypeFlags.UniqueESSymbol, symbol) as UniqueESSymbolType; type.escapedName = `__@${type.symbol.escapedName}@${getSymbolId(type.symbol)}` as __String; return type; } function getESSymbolLikeTypeForNode(node: Node) { if (isValidESSymbolDeclaration(node)) { const symbol = isCommonJsExportPropertyAssignment(node) ? getSymbolOfNode((node as BinaryExpression).left) : getSymbolOfNode(node); if (symbol) { const links = getSymbolLinks(symbol); return links.uniqueESSymbolType || (links.uniqueESSymbolType = createUniqueESSymbolType(symbol)); } } return esSymbolType; } function getThisType(node: Node): Type { const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); const parent = container && container.parent; if (parent && (isClassLike(parent) || parent.kind === SyntaxKind.InterfaceDeclaration)) { if (!isStatic(container) && (!isConstructorDeclaration(container) || isNodeDescendantOf(node, container.body))) { return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(parent as ClassLikeDeclaration | InterfaceDeclaration)).thisType!; } } // inside x.prototype = { ... } if (parent && isObjectLiteralExpression(parent) && isBinaryExpression(parent.parent) && getAssignmentDeclarationKind(parent.parent) === AssignmentDeclarationKind.Prototype) { return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(parent.parent.left)!.parent!).thisType!; } // /** @return {this} */ // x.prototype.m = function() { ... } const host = node.flags & NodeFlags.JSDoc ? getHostSignatureFromJSDoc(node) : undefined; if (host && isFunctionExpression(host) && isBinaryExpression(host.parent) && getAssignmentDeclarationKind(host.parent) === AssignmentDeclarationKind.PrototypeProperty) { return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(host.parent.left)!.parent!).thisType!; } // inside constructor function C() { ... } if (isJSConstructor(container) && isNodeDescendantOf(node, container.body)) { return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(container)).thisType!; } error(node, Diagnostics.A_this_type_is_available_only_in_a_non_static_member_of_a_class_or_interface); return errorType; } function getTypeFromThisTypeNode(node: ThisExpression | ThisTypeNode): Type { const links = getNodeLinks(node); if (!links.resolvedType) { links.resolvedType = getThisType(node); } return links.resolvedType; } function getTypeFromRestTypeNode(node: RestTypeNode | NamedTupleMember) { return getTypeFromTypeNode(getArrayElementTypeNode(node.type) || node.type); } function getArrayElementTypeNode(node: TypeNode): TypeNode | undefined { switch (node.kind) { case SyntaxKind.ParenthesizedType: return getArrayElementTypeNode((node as ParenthesizedTypeNode).type); case SyntaxKind.TupleType: if ((node as TupleTypeNode).elements.length === 1) { node = (node as TupleTypeNode).elements[0]; if (node.kind === SyntaxKind.RestType || node.kind === SyntaxKind.NamedTupleMember && (node as NamedTupleMember).dotDotDotToken) { return getArrayElementTypeNode((node as RestTypeNode | NamedTupleMember).type); } } break; case SyntaxKind.ArrayType: return (node as ArrayTypeNode).elementType; } return undefined; } function getTypeFromNamedTupleTypeNode(node: NamedTupleMember): Type { const links = getNodeLinks(node); return links.resolvedType || (links.resolvedType = node.dotDotDotToken ? getTypeFromRestTypeNode(node) : addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true, !!node.questionToken)); } function getTypeFromTypeNode(node: TypeNode): Type { return getConditionalFlowTypeOfType(getTypeFromTypeNodeWorker(node), node); } function getTypeFromTypeNodeWorker(node: TypeNode): Type { switch (node.kind) { case SyntaxKind.AnyKeyword: case SyntaxKind.JSDocAllType: case SyntaxKind.JSDocUnknownType: return anyType; case SyntaxKind.UnknownKeyword: return unknownType; case SyntaxKind.StringKeyword: return stringType; case SyntaxKind.NumberKeyword: return numberType; case SyntaxKind.BigIntKeyword: return bigintType; case SyntaxKind.BooleanKeyword: return booleanType; case SyntaxKind.SymbolKeyword: return esSymbolType; case SyntaxKind.VoidKeyword: return voidType; case SyntaxKind.UndefinedKeyword: return undefinedType; case SyntaxKind.NullKeyword as TypeNodeSyntaxKind: // TODO(rbuckton): `NullKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service. return nullType; case SyntaxKind.NeverKeyword: return neverType; case SyntaxKind.ObjectKeyword: return node.flags & NodeFlags.JavaScriptFile && !noImplicitAny ? anyType : nonPrimitiveType; case SyntaxKind.IntrinsicKeyword: return intrinsicMarkerType; case SyntaxKind.ThisType: case SyntaxKind.ThisKeyword as TypeNodeSyntaxKind: // TODO(rbuckton): `ThisKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service and because of `isPartOfTypeNode`. return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode); case SyntaxKind.LiteralType: return getTypeFromLiteralTypeNode(node as LiteralTypeNode); case SyntaxKind.TypeReference: return getTypeFromTypeReference(node as TypeReferenceNode); case SyntaxKind.TypePredicate: return (node as TypePredicateNode).assertsModifier ? voidType : booleanType; case SyntaxKind.ExpressionWithTypeArguments: return getTypeFromTypeReference(node as ExpressionWithTypeArguments); case SyntaxKind.TypeQuery: return getTypeFromTypeQueryNode(node as TypeQueryNode); case SyntaxKind.ArrayType: case SyntaxKind.TupleType: return getTypeFromArrayOrTupleTypeNode(node as ArrayTypeNode | TupleTypeNode); case SyntaxKind.OptionalType: return getTypeFromOptionalTypeNode(node as OptionalTypeNode); case SyntaxKind.UnionType: return getTypeFromUnionTypeNode(node as UnionTypeNode); case SyntaxKind.IntersectionType: return getTypeFromIntersectionTypeNode(node as IntersectionTypeNode); case SyntaxKind.JSDocNullableType: return getTypeFromJSDocNullableTypeNode(node as JSDocNullableType); case SyntaxKind.JSDocOptionalType: return addOptionality(getTypeFromTypeNode((node as JSDocOptionalType).type)); case SyntaxKind.NamedTupleMember: return getTypeFromNamedTupleTypeNode(node as NamedTupleMember); case SyntaxKind.ParenthesizedType: case SyntaxKind.JSDocNonNullableType: case SyntaxKind.JSDocTypeExpression: return getTypeFromTypeNode((node as ParenthesizedTypeNode | JSDocTypeReferencingNode | JSDocTypeExpression | NamedTupleMember).type); case SyntaxKind.RestType: return getTypeFromRestTypeNode(node as RestTypeNode); case SyntaxKind.JSDocVariadicType: return getTypeFromJSDocVariadicType(node as JSDocVariadicType); case SyntaxKind.FunctionType: case SyntaxKind.ConstructorType: case SyntaxKind.TypeLiteral: case SyntaxKind.JSDocTypeLiteral: case SyntaxKind.JSDocFunctionType: case SyntaxKind.JSDocSignature: return getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node as TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature); case SyntaxKind.TypeOperator: return getTypeFromTypeOperatorNode(node as TypeOperatorNode); case SyntaxKind.IndexedAccessType: return getTypeFromIndexedAccessTypeNode(node as IndexedAccessTypeNode); case SyntaxKind.MappedType: return getTypeFromMappedTypeNode(node as MappedTypeNode); case SyntaxKind.ConditionalType: return getTypeFromConditionalTypeNode(node as ConditionalTypeNode); case SyntaxKind.InferType: return getTypeFromInferTypeNode(node as InferTypeNode); case SyntaxKind.TemplateLiteralType: return getTypeFromTemplateTypeNode(node as TemplateLiteralTypeNode); case SyntaxKind.ImportType: return getTypeFromImportTypeNode(node as ImportTypeNode); // This function assumes that an identifier, qualified name, or property access expression is a type expression // Callers should first ensure this by calling `isPartOfTypeNode` // TODO(rbuckton): These aren't valid TypeNodes, but we treat them as such because of `isPartOfTypeNode`, which returns `true` for things that aren't `TypeNode`s. case SyntaxKind.Identifier as TypeNodeSyntaxKind: case SyntaxKind.QualifiedName as TypeNodeSyntaxKind: case SyntaxKind.PropertyAccessExpression as TypeNodeSyntaxKind: const symbol = getSymbolAtLocation(node); return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; default: return errorType; } } function instantiateList(items: readonly T[], mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[]; function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined; function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined { if (items && items.length) { for (let i = 0; i < items.length; i++) { const item = items[i]; const mapped = instantiator(item, mapper); if (item !== mapped) { const result = i === 0 ? [] : items.slice(0, i); result.push(mapped); for (i++; i < items.length; i++) { result.push(instantiator(items[i], mapper)); } return result; } } } return items; } function instantiateTypes(types: readonly Type[], mapper: TypeMapper): readonly Type[]; function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined; function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined { return instantiateList(types, mapper, instantiateType); } function instantiateSignatures(signatures: readonly Signature[], mapper: TypeMapper): readonly Signature[] { return instantiateList(signatures, mapper, instantiateSignature); } function instantiateIndexInfos(indexInfos: readonly IndexInfo[], mapper: TypeMapper): readonly IndexInfo[] { return instantiateList(indexInfos, mapper, instantiateIndexInfo); } function createTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { return sources.length === 1 ? makeUnaryTypeMapper(sources[0], targets ? targets[0] : anyType) : makeArrayTypeMapper(sources, targets); } function getMappedType(type: Type, mapper: TypeMapper): Type { switch (mapper.kind) { case TypeMapKind.Simple: return type === mapper.source ? mapper.target : type; case TypeMapKind.Array: { const sources = mapper.sources; const targets = mapper.targets; for (let i = 0; i < sources.length; i++) { if (type === sources[i]) { return targets ? targets[i] : anyType; } } return type; } case TypeMapKind.Deferred: { const sources = mapper.sources; const targets = mapper.targets; for (let i = 0; i < sources.length; i++) { if (type === sources[i]) { return targets[i](); } } return type; } case TypeMapKind.Function: return mapper.func(type); case TypeMapKind.Composite: case TypeMapKind.Merged: const t1 = getMappedType(type, mapper.mapper1); return t1 !== type && mapper.kind === TypeMapKind.Composite ? instantiateType(t1, mapper.mapper2) : getMappedType(t1, mapper.mapper2); } } function makeUnaryTypeMapper(source: Type, target: Type): TypeMapper { return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Simple, source, target }); } function makeArrayTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Array, sources, targets }); } function makeFunctionTypeMapper(func: (t: Type) => Type, debugInfo: () => string): TypeMapper { return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Function, func, debugInfo: Debug.isDebugging ? debugInfo : undefined }); } function makeDeferredTypeMapper(sources: readonly TypeParameter[], targets: (() => Type)[]) { return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Deferred, sources, targets }); } function makeCompositeTypeMapper(kind: TypeMapKind.Composite | TypeMapKind.Merged, mapper1: TypeMapper, mapper2: TypeMapper): TypeMapper { return Debug.attachDebugPrototypeIfDebug({ kind, mapper1, mapper2 }); } function createTypeEraser(sources: readonly TypeParameter[]): TypeMapper { return createTypeMapper(sources, /*targets*/ undefined); } /** * Maps forward-references to later types parameters to the empty object type. * This is used during inference when instantiating type parameter defaults. */ function createBackreferenceMapper(context: InferenceContext, index: number): TypeMapper { const forwardInferences = context.inferences.slice(index); return createTypeMapper(map(forwardInferences, i => i.typeParameter), map(forwardInferences, () => unknownType)); } function combineTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Composite, mapper1, mapper2) : mapper2; } function mergeTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Merged, mapper1, mapper2) : mapper2; } function prependTypeMapping(source: Type, target: Type, mapper: TypeMapper | undefined) { return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, makeUnaryTypeMapper(source, target), mapper); } function appendTypeMapping(mapper: TypeMapper | undefined, source: Type, target: Type) { return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, mapper, makeUnaryTypeMapper(source, target)); } function getRestrictiveTypeParameter(tp: TypeParameter) { return !tp.constraint && !getConstraintDeclaration(tp) || tp.constraint === noConstraintType ? tp : tp.restrictiveInstantiation || ( tp.restrictiveInstantiation = createTypeParameter(tp.symbol), (tp.restrictiveInstantiation as TypeParameter).constraint = noConstraintType, tp.restrictiveInstantiation ); } function cloneTypeParameter(typeParameter: TypeParameter): TypeParameter { const result = createTypeParameter(typeParameter.symbol); result.target = typeParameter; return result; } function instantiateTypePredicate(predicate: TypePredicate, mapper: TypeMapper): TypePredicate { return createTypePredicate(predicate.kind, predicate.parameterName, predicate.parameterIndex, instantiateType(predicate.type, mapper)); } function instantiateSignature(signature: Signature, mapper: TypeMapper, eraseTypeParameters?: boolean): Signature { let freshTypeParameters: TypeParameter[] | undefined; if (signature.typeParameters && !eraseTypeParameters) { // First create a fresh set of type parameters, then include a mapping from the old to the // new type parameters in the mapper function. Finally store this mapper in the new type // parameters such that we can use it when instantiating constraints. freshTypeParameters = map(signature.typeParameters, cloneTypeParameter); mapper = combineTypeMappers(createTypeMapper(signature.typeParameters, freshTypeParameters), mapper); for (const tp of freshTypeParameters) { tp.mapper = mapper; } } // Don't compute resolvedReturnType and resolvedTypePredicate now, // because using `mapper` now could trigger inferences to become fixed. (See `createInferenceContext`.) // See GH#17600. const result = createSignature(signature.declaration, freshTypeParameters, signature.thisParameter && instantiateSymbol(signature.thisParameter, mapper), instantiateList(signature.parameters, mapper, instantiateSymbol), /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, signature.minArgumentCount, signature.flags & SignatureFlags.PropagatingFlags); result.target = signature; result.mapper = mapper; return result; } function instantiateSymbol(symbol: Symbol, mapper: TypeMapper): Symbol { const links = getSymbolLinks(symbol); if (links.type && !couldContainTypeVariables(links.type)) { // If the type of the symbol is already resolved, and if that type could not possibly // be affected by instantiation, simply return the symbol itself. return symbol; } if (getCheckFlags(symbol) & CheckFlags.Instantiated) { // If symbol being instantiated is itself a instantiation, fetch the original target and combine the // type mappers. This ensures that original type identities are properly preserved and that aliases // always reference a non-aliases. symbol = links.target!; mapper = combineTypeMappers(links.mapper, mapper); } // Keep the flags from the symbol we're instantiating. Mark that is instantiated, and // also transient so that we can just store data on it directly. const result = createSymbol(symbol.flags, symbol.escapedName, CheckFlags.Instantiated | getCheckFlags(symbol) & (CheckFlags.Readonly | CheckFlags.Late | CheckFlags.OptionalParameter | CheckFlags.RestParameter)); result.declarations = symbol.declarations; result.parent = symbol.parent; result.links.target = symbol; result.links.mapper = mapper; if (symbol.valueDeclaration) { result.valueDeclaration = symbol.valueDeclaration; } if (links.nameType) { result.links.nameType = links.nameType; } return result; } function getObjectTypeInstantiation(type: AnonymousType | DeferredTypeReference, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { const declaration = type.objectFlags & ObjectFlags.Reference ? (type as TypeReference).node! : type.objectFlags & ObjectFlags.InstantiationExpressionType ? (type as InstantiationExpressionType).node : type.symbol.declarations![0]; const links = getNodeLinks(declaration); const target = type.objectFlags & ObjectFlags.Reference ? links.resolvedType! as DeferredTypeReference : type.objectFlags & ObjectFlags.Instantiated ? type.target! : type; let typeParameters = links.outerTypeParameters; if (!typeParameters) { // The first time an anonymous type is instantiated we compute and store a list of the type // parameters that are in scope (and therefore potentially referenced). For type literals that // aren't the right hand side of a generic type alias declaration we optimize by reducing the // set of type parameters to those that are possibly referenced in the literal. let outerTypeParameters = getOuterTypeParameters(declaration, /*includeThisTypes*/ true); if (isJSConstructor(declaration)) { const templateTagParameters = getTypeParametersFromDeclaration(declaration as DeclarationWithTypeParameters); outerTypeParameters = addRange(outerTypeParameters, templateTagParameters); } typeParameters = outerTypeParameters || emptyArray; const allDeclarations = type.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) ? [declaration] : type.symbol.declarations!; typeParameters = (target.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) || target.symbol.flags & SymbolFlags.Method || target.symbol.flags & SymbolFlags.TypeLiteral) && !target.aliasTypeArguments ? filter(typeParameters, tp => some(allDeclarations, d => isTypeParameterPossiblyReferenced(tp, d))) : typeParameters; links.outerTypeParameters = typeParameters; } if (typeParameters.length) { // We are instantiating an anonymous type that has one or more type parameters in scope. Apply the // mapper to the type parameters to produce the effective list of type arguments, and compute the // instantiation cache key from the type IDs of the type arguments. const combinedMapper = combineTypeMappers(type.mapper, mapper); const typeArguments = map(typeParameters, t => getMappedType(t, combinedMapper)); const newAliasSymbol = aliasSymbol || type.aliasSymbol; const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); const id = getTypeListId(typeArguments) + getAliasId(newAliasSymbol, newAliasTypeArguments); if (!target.instantiations) { target.instantiations = new Map(); target.instantiations.set(getTypeListId(typeParameters) + getAliasId(target.aliasSymbol, target.aliasTypeArguments), target); } let result = target.instantiations.get(id); if (!result) { const newMapper = createTypeMapper(typeParameters, typeArguments); result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((type as DeferredTypeReference).target, (type as DeferredTypeReference).node, newMapper, newAliasSymbol, newAliasTypeArguments) : target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(target as MappedType, newMapper, newAliasSymbol, newAliasTypeArguments) : instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments); target.instantiations.set(id, result); } return result; } return type; } function maybeTypeParameterReference(node: Node) { return !(node.parent.kind === SyntaxKind.TypeReference && (node.parent as TypeReferenceNode).typeArguments && node === (node.parent as TypeReferenceNode).typeName || node.parent.kind === SyntaxKind.ImportType && (node.parent as ImportTypeNode).typeArguments && node === (node.parent as ImportTypeNode).qualifier); } function isTypeParameterPossiblyReferenced(tp: TypeParameter, node: Node) { // If the type parameter doesn't have exactly one declaration, if there are intervening statement blocks // between the node and the type parameter declaration, if the node contains actual references to the // type parameter, or if the node contains type queries that we can't prove couldn't contain references to the type parameter, // we consider the type parameter possibly referenced. if (tp.symbol && tp.symbol.declarations && tp.symbol.declarations.length === 1) { const container = tp.symbol.declarations[0].parent; for (let n = node; n !== container; n = n.parent) { if (!n || n.kind === SyntaxKind.Block || n.kind === SyntaxKind.ConditionalType && forEachChild((n as ConditionalTypeNode).extendsType, containsReference)) { return true; } } return containsReference(node); } return true; function containsReference(node: Node): boolean { switch (node.kind) { case SyntaxKind.ThisType: return !!tp.isThisType; case SyntaxKind.Identifier: return !tp.isThisType && isPartOfTypeNode(node) && maybeTypeParameterReference(node) && getTypeFromTypeNodeWorker(node as TypeNode) === tp; // use worker because we're looking for === equality case SyntaxKind.TypeQuery: const entityName = (node as TypeQueryNode).exprName; const firstIdentifier = getFirstIdentifier(entityName); const firstIdentifierSymbol = getResolvedSymbol(firstIdentifier); const tpDeclaration = tp.symbol.declarations![0]; // There is exactly one declaration, otherwise `containsReference` is not called let tpScope: Node; if (tpDeclaration.kind === SyntaxKind.TypeParameter) { // Type parameter is a regular type parameter, e.g. foo tpScope = tpDeclaration.parent; } else if (tp.isThisType) { // Type parameter is the this type, and its declaration is the class declaration. tpScope = tpDeclaration; } else { // Type parameter's declaration was unrecognized. // This could happen if the type parameter comes from e.g. a JSDoc annotation, so we default to returning true. return true; } if (firstIdentifierSymbol.declarations) { return some(firstIdentifierSymbol.declarations, idDecl => isNodeDescendantOf(idDecl, tpScope)) || some((node as TypeQueryNode).typeArguments, containsReference); } return true; case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: return !(node as FunctionLikeDeclaration).type && !!(node as FunctionLikeDeclaration).body || some((node as FunctionLikeDeclaration).typeParameters, containsReference) || some((node as FunctionLikeDeclaration).parameters, containsReference) || !!(node as FunctionLikeDeclaration).type && containsReference((node as FunctionLikeDeclaration).type!); } return !!forEachChild(node, containsReference); } } function getHomomorphicTypeVariable(type: MappedType) { const constraintType = getConstraintTypeFromMappedType(type); if (constraintType.flags & TypeFlags.Index) { const typeVariable = getActualTypeVariable((constraintType as IndexType).type); if (typeVariable.flags & TypeFlags.TypeParameter) { return typeVariable as TypeParameter; } } return undefined; } function instantiateMappedType(type: MappedType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { // For a homomorphic mapped type { [P in keyof T]: X }, where T is some type variable, the mapping // operation depends on T as follows: // * If T is a primitive type no mapping is performed and the result is simply T. // * If T is a union type we distribute the mapped type over the union. // * If T is an array we map to an array where the element type has been transformed. // * If T is a tuple we map to a tuple where the element types have been transformed. // * Otherwise we map to an object type where the type of each property has been transformed. // For example, when T is instantiated to a union type A | B, we produce { [P in keyof A]: X } | // { [P in keyof B]: X }, and when when T is instantiated to a union type A | undefined, we produce // { [P in keyof A]: X } | undefined. const typeVariable = getHomomorphicTypeVariable(type); if (typeVariable) { const mappedTypeVariable = instantiateType(typeVariable, mapper); if (typeVariable !== mappedTypeVariable) { return mapTypeWithAlias(getReducedType(mappedTypeVariable), t => { if (t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.InstantiableNonPrimitive | TypeFlags.Object | TypeFlags.Intersection) && t !== wildcardType && !isErrorType(t)) { if (!type.declaration.nameType) { let constraint; if (isArrayType(t) || t.flags & TypeFlags.Any && findResolutionCycleStartIndex(typeVariable, TypeSystemPropertyName.ImmediateBaseConstraint) < 0 && (constraint = getConstraintOfTypeParameter(typeVariable)) && everyType(constraint, isArrayOrTupleType)) { return instantiateMappedArrayType(t, type, prependTypeMapping(typeVariable, t, mapper)); } if (isGenericTupleType(t)) { return instantiateMappedGenericTupleType(t, type, typeVariable, mapper); } if (isTupleType(t)) { return instantiateMappedTupleType(t, type, prependTypeMapping(typeVariable, t, mapper)); } } return instantiateAnonymousType(type, prependTypeMapping(typeVariable, t, mapper)); } return t; }, aliasSymbol, aliasTypeArguments); } } // If the constraint type of the instantiation is the wildcard type, return the wildcard type. return instantiateType(getConstraintTypeFromMappedType(type), mapper) === wildcardType ? wildcardType : instantiateAnonymousType(type, mapper, aliasSymbol, aliasTypeArguments); } function getModifiedReadonlyState(state: boolean, modifiers: MappedTypeModifiers) { return modifiers & MappedTypeModifiers.IncludeReadonly ? true : modifiers & MappedTypeModifiers.ExcludeReadonly ? false : state; } function instantiateMappedGenericTupleType(tupleType: TupleTypeReference, mappedType: MappedType, typeVariable: TypeVariable, mapper: TypeMapper) { // When a tuple type is generic (i.e. when it contains variadic elements), we want to eagerly map the // non-generic elements and defer mapping the generic elements. In order to facilitate this, we transform // M<[A, B?, ...T, ...C[]] into [...M<[A]>, ...M<[B?]>, ...M, ...M] and then rely on tuple type // normalization to resolve the non-generic parts of the resulting tuple. const elementFlags = tupleType.target.elementFlags; const elementTypes = map(getTypeArguments(tupleType), (t, i) => { const singleton = elementFlags[i] & ElementFlags.Variadic ? t : elementFlags[i] & ElementFlags.Rest ? createArrayType(t) : createTupleType([t], [elementFlags[i]]); // The singleton is never a generic tuple type, so it is safe to recurse here. return instantiateMappedType(mappedType, prependTypeMapping(typeVariable, singleton, mapper)); }); const newReadonly = getModifiedReadonlyState(tupleType.target.readonly, getMappedTypeModifiers(mappedType)); return createTupleType(elementTypes, map(elementTypes, _ => ElementFlags.Variadic), newReadonly); } function instantiateMappedArrayType(arrayType: Type, mappedType: MappedType, mapper: TypeMapper) { const elementType = instantiateMappedTypeTemplate(mappedType, numberType, /*isOptional*/ true, mapper); return isErrorType(elementType) ? errorType : createArrayType(elementType, getModifiedReadonlyState(isReadonlyArrayType(arrayType), getMappedTypeModifiers(mappedType))); } function instantiateMappedTupleType(tupleType: TupleTypeReference, mappedType: MappedType, mapper: TypeMapper) { const elementFlags = tupleType.target.elementFlags; const elementTypes = map(getTypeArguments(tupleType), (_, i) => instantiateMappedTypeTemplate(mappedType, getStringLiteralType("" + i), !!(elementFlags[i] & ElementFlags.Optional), mapper)); const modifiers = getMappedTypeModifiers(mappedType); const newTupleModifiers = modifiers & MappedTypeModifiers.IncludeOptional ? map(elementFlags, f => f & ElementFlags.Required ? ElementFlags.Optional : f) : modifiers & MappedTypeModifiers.ExcludeOptional ? map(elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : elementFlags; const newReadonly = getModifiedReadonlyState(tupleType.target.readonly, modifiers); return contains(elementTypes, errorType) ? errorType : createTupleType(elementTypes, newTupleModifiers, newReadonly, tupleType.target.labeledElementDeclarations); } function instantiateMappedTypeTemplate(type: MappedType, key: Type, isOptional: boolean, mapper: TypeMapper) { const templateMapper = appendTypeMapping(mapper, getTypeParameterFromMappedType(type), key); const propType = instantiateType(getTemplateTypeFromMappedType(type.target as MappedType || type), templateMapper); const modifiers = getMappedTypeModifiers(type); return strictNullChecks && modifiers & MappedTypeModifiers.IncludeOptional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : strictNullChecks && modifiers & MappedTypeModifiers.ExcludeOptional && isOptional ? getTypeWithFacts(propType, TypeFacts.NEUndefined) : propType; } function instantiateAnonymousType(type: AnonymousType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): AnonymousType { const result = createObjectType(type.objectFlags | ObjectFlags.Instantiated, type.symbol) as AnonymousType; if (type.objectFlags & ObjectFlags.Mapped) { (result as MappedType).declaration = (type as MappedType).declaration; // C.f. instantiateSignature const origTypeParameter = getTypeParameterFromMappedType(type as MappedType); const freshTypeParameter = cloneTypeParameter(origTypeParameter); (result as MappedType).typeParameter = freshTypeParameter; mapper = combineTypeMappers(makeUnaryTypeMapper(origTypeParameter, freshTypeParameter), mapper); freshTypeParameter.mapper = mapper; } if (type.objectFlags & ObjectFlags.InstantiationExpressionType) { (result as InstantiationExpressionType).node = (type as InstantiationExpressionType).node; } result.target = type; result.mapper = mapper; result.aliasSymbol = aliasSymbol || type.aliasSymbol; result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); result.objectFlags |= result.aliasTypeArguments ? getPropagatingFlagsOfTypes(result.aliasTypeArguments) : 0; return result; } function getConditionalTypeInstantiation(type: ConditionalType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { const root = type.root; if (root.outerTypeParameters) { // We are instantiating a conditional type that has one or more type parameters in scope. Apply the // mapper to the type parameters to produce the effective list of type arguments, and compute the // instantiation cache key from the type IDs of the type arguments. const typeArguments = map(root.outerTypeParameters, t => getMappedType(t, mapper)); const id = getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); let result = root.instantiations!.get(id); if (!result) { const newMapper = createTypeMapper(root.outerTypeParameters, typeArguments); const checkType = root.checkType; const distributionType = root.isDistributive ? getMappedType(checkType, newMapper) : undefined; // Distributive conditional types are distributed over union types. For example, when the // distributive conditional type T extends U ? X : Y is instantiated with A | B for T, the // result is (A extends U ? X : Y) | (B extends U ? X : Y). result = distributionType && checkType !== distributionType && distributionType.flags & (TypeFlags.Union | TypeFlags.Never) ? mapTypeWithAlias(getReducedType(distributionType), t => getConditionalType(root, prependTypeMapping(checkType, t, newMapper)), aliasSymbol, aliasTypeArguments) : getConditionalType(root, newMapper, aliasSymbol, aliasTypeArguments); root.instantiations!.set(id, result); } return result; } return type; } function instantiateType(type: Type, mapper: TypeMapper | undefined): Type; function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined; function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined { return type && mapper ? instantiateTypeWithAlias(type, mapper, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined) : type; } function instantiateTypeWithAlias(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { if (!couldContainTypeVariables(type)) { return type; } if (instantiationDepth === 100 || instantiationCount >= 5000000) { // We have reached 100 recursive type instantiations, or 5M type instantiations caused by the same statement // or expression. There is a very high likelyhood we're dealing with a combination of infinite generic types // that perpetually generate new type identities, so we stop the recursion here by yielding the error type. tracing?.instant(tracing.Phase.CheckTypes, "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth, instantiationCount }); error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); return errorType; } totalInstantiationCount++; instantiationCount++; instantiationDepth++; const result = instantiateTypeWorker(type, mapper, aliasSymbol, aliasTypeArguments); instantiationDepth--; return result; } function instantiateTypeWorker(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { const flags = type.flags; if (flags & TypeFlags.TypeParameter) { return getMappedType(type, mapper); } if (flags & TypeFlags.Object) { const objectFlags = (type as ObjectType).objectFlags; if (objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped)) { if (objectFlags & ObjectFlags.Reference && !(type as TypeReference).node) { const resolvedTypeArguments = (type as TypeReference).resolvedTypeArguments; const newTypeArguments = instantiateTypes(resolvedTypeArguments, mapper); return newTypeArguments !== resolvedTypeArguments ? createNormalizedTypeReference((type as TypeReference).target, newTypeArguments) : type; } if (objectFlags & ObjectFlags.ReverseMapped) { return instantiateReverseMappedType(type as ReverseMappedType, mapper); } return getObjectTypeInstantiation(type as TypeReference | AnonymousType | MappedType, mapper, aliasSymbol, aliasTypeArguments); } return type; } if (flags & TypeFlags.UnionOrIntersection) { const origin = type.flags & TypeFlags.Union ? (type as UnionType).origin : undefined; const types = origin && origin.flags & TypeFlags.UnionOrIntersection ? (origin as UnionOrIntersectionType).types : (type as UnionOrIntersectionType).types; const newTypes = instantiateTypes(types, mapper); if (newTypes === types && aliasSymbol === type.aliasSymbol) { return type; } const newAliasSymbol = aliasSymbol || type.aliasSymbol; const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); return flags & TypeFlags.Intersection || origin && origin.flags & TypeFlags.Intersection ? getIntersectionType(newTypes, newAliasSymbol, newAliasTypeArguments) : getUnionType(newTypes, UnionReduction.Literal, newAliasSymbol, newAliasTypeArguments); } if (flags & TypeFlags.Index) { return getIndexType(instantiateType((type as IndexType).type, mapper)); } if (flags & TypeFlags.TemplateLiteral) { return getTemplateLiteralType((type as TemplateLiteralType).texts, instantiateTypes((type as TemplateLiteralType).types, mapper)); } if (flags & TypeFlags.StringMapping) { return getStringMappingType((type as StringMappingType).symbol, instantiateType((type as StringMappingType).type, mapper)); } if (flags & TypeFlags.IndexedAccess) { const newAliasSymbol = aliasSymbol || type.aliasSymbol; const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); return getIndexedAccessType(instantiateType((type as IndexedAccessType).objectType, mapper), instantiateType((type as IndexedAccessType).indexType, mapper), (type as IndexedAccessType).accessFlags, /*accessNode*/ undefined, newAliasSymbol, newAliasTypeArguments); } if (flags & TypeFlags.Conditional) { return getConditionalTypeInstantiation(type as ConditionalType, combineTypeMappers((type as ConditionalType).mapper, mapper), aliasSymbol, aliasTypeArguments); } if (flags & TypeFlags.Substitution) { const newBaseType = instantiateType((type as SubstitutionType).baseType, mapper); const newConstraint = instantiateType((type as SubstitutionType).constraint, mapper); // A substitution type originates in the true branch of a conditional type and can be resolved // to just the base type in the same cases as the conditional type resolves to its true branch // (because the base type is then known to satisfy the constraint). if (newBaseType.flags & TypeFlags.TypeVariable && isGenericType(newConstraint)) { return getSubstitutionType(newBaseType, newConstraint); } if (newConstraint.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(newBaseType), getRestrictiveInstantiation(newConstraint))) { return newBaseType; } return newBaseType.flags & TypeFlags.TypeVariable ? getSubstitutionType(newBaseType, newConstraint) : getIntersectionType([newConstraint, newBaseType]); } return type; } function instantiateReverseMappedType(type: ReverseMappedType, mapper: TypeMapper) { const innerMappedType = instantiateType(type.mappedType, mapper); if (!(getObjectFlags(innerMappedType) & ObjectFlags.Mapped)) { return type; } const innerIndexType = instantiateType(type.constraintType, mapper); if (!(innerIndexType.flags & TypeFlags.Index)) { return type; } const instantiated = inferTypeForHomomorphicMappedType( instantiateType(type.source, mapper), innerMappedType as MappedType, innerIndexType as IndexType ); if (instantiated) { return instantiated; } return type; // Nested invocation of `inferTypeForHomomorphicMappedType` or the `source` instantiated into something unmappable } function getUniqueLiteralFilledInstantiation(type: Type) { return type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never) ? type : type.uniqueLiteralFilledInstantiation || (type.uniqueLiteralFilledInstantiation = instantiateType(type, uniqueLiteralMapper)); } function getPermissiveInstantiation(type: Type) { return type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never) ? type : type.permissiveInstantiation || (type.permissiveInstantiation = instantiateType(type, permissiveMapper)); } function getRestrictiveInstantiation(type: Type) { if (type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never)) { return type; } if (type.restrictiveInstantiation) { return type.restrictiveInstantiation; } type.restrictiveInstantiation = instantiateType(type, restrictiveMapper); // We set the following so we don't attempt to set the restrictive instance of a restrictive instance // which is redundant - we'll produce new type identities, but all type params have already been mapped. // This also gives us a way to detect restrictive instances upon comparisons and _disable_ the "distributeive constraint" // assignability check for them, which is distinctly unsafe, as once you have a restrctive instance, all the type parameters // are constrained to `unknown` and produce tons of false positives/negatives! type.restrictiveInstantiation.restrictiveInstantiation = type.restrictiveInstantiation; return type.restrictiveInstantiation; } function instantiateIndexInfo(info: IndexInfo, mapper: TypeMapper) { return createIndexInfo(info.keyType, instantiateType(info.type, mapper), info.isReadonly, info.declaration); } // Returns true if the given expression contains (at any level of nesting) a function or arrow expression // that is subject to contextual typing. function isContextSensitive(node: Expression | MethodDeclaration | ObjectLiteralElementLike | JsxAttributeLike | JsxChild): boolean { Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); switch (node.kind) { case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: case SyntaxKind.MethodDeclaration: case SyntaxKind.FunctionDeclaration: // Function declarations can have context when annotated with a jsdoc @type return isContextSensitiveFunctionLikeDeclaration(node as FunctionExpression | ArrowFunction | MethodDeclaration); case SyntaxKind.ObjectLiteralExpression: return some((node as ObjectLiteralExpression).properties, isContextSensitive); case SyntaxKind.ArrayLiteralExpression: return some((node as ArrayLiteralExpression).elements, isContextSensitive); case SyntaxKind.ConditionalExpression: return isContextSensitive((node as ConditionalExpression).whenTrue) || isContextSensitive((node as ConditionalExpression).whenFalse); case SyntaxKind.BinaryExpression: return ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken || (node as BinaryExpression).operatorToken.kind === SyntaxKind.QuestionQuestionToken) && (isContextSensitive((node as BinaryExpression).left) || isContextSensitive((node as BinaryExpression).right)); case SyntaxKind.PropertyAssignment: return isContextSensitive((node as PropertyAssignment).initializer); case SyntaxKind.ParenthesizedExpression: return isContextSensitive((node as ParenthesizedExpression).expression); case SyntaxKind.JsxAttributes: return some((node as JsxAttributes).properties, isContextSensitive) || isJsxOpeningElement(node.parent) && some(node.parent.parent.children, isContextSensitive); case SyntaxKind.JsxAttribute: { // If there is no initializer, JSX attribute has a boolean value of true which is not context sensitive. const { initializer } = node as JsxAttribute; return !!initializer && isContextSensitive(initializer); } case SyntaxKind.JsxExpression: { // It is possible to that node.expression is undefined (e.g

) const { expression } = node as JsxExpression; return !!expression && isContextSensitive(expression); } } return false; } function isContextSensitiveFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { return hasContextSensitiveParameters(node) || hasContextSensitiveReturnExpression(node); } function hasContextSensitiveReturnExpression(node: FunctionLikeDeclaration) { // TODO(anhans): A block should be context-sensitive if it has a context-sensitive return value. return !node.typeParameters && !getEffectiveReturnTypeNode(node) && !!node.body && node.body.kind !== SyntaxKind.Block && isContextSensitive(node.body); } function isContextSensitiveFunctionOrObjectLiteralMethod(func: Node): func is FunctionExpression | ArrowFunction | MethodDeclaration { return (isFunctionExpressionOrArrowFunction(func) || isObjectLiteralMethod(func)) && isContextSensitiveFunctionLikeDeclaration(func); } function getTypeWithoutSignatures(type: Type): Type { if (type.flags & TypeFlags.Object) { const resolved = resolveStructuredTypeMembers(type as ObjectType); if (resolved.constructSignatures.length || resolved.callSignatures.length) { const result = createObjectType(ObjectFlags.Anonymous, type.symbol); result.members = resolved.members; result.properties = resolved.properties; result.callSignatures = emptyArray; result.constructSignatures = emptyArray; result.indexInfos = emptyArray; return result; } } else if (type.flags & TypeFlags.Intersection) { return getIntersectionType(map((type as IntersectionType).types, getTypeWithoutSignatures)); } return type; } // TYPE CHECKING function isTypeIdenticalTo(source: Type, target: Type): boolean { return isTypeRelatedTo(source, target, identityRelation); } function compareTypesIdentical(source: Type, target: Type): Ternary { return isTypeRelatedTo(source, target, identityRelation) ? Ternary.True : Ternary.False; } function compareTypesAssignable(source: Type, target: Type): Ternary { return isTypeRelatedTo(source, target, assignableRelation) ? Ternary.True : Ternary.False; } function compareTypesSubtypeOf(source: Type, target: Type): Ternary { return isTypeRelatedTo(source, target, subtypeRelation) ? Ternary.True : Ternary.False; } function isTypeSubtypeOf(source: Type, target: Type): boolean { return isTypeRelatedTo(source, target, subtypeRelation); } function isTypeStrictSubtypeOf(source: Type, target: Type): boolean { return isTypeRelatedTo(source, target, strictSubtypeRelation); } function isTypeAssignableTo(source: Type, target: Type): boolean { return isTypeRelatedTo(source, target, assignableRelation); } // An object type S is considered to be derived from an object type T if // S is a union type and every constituent of S is derived from T, // T is a union type and S is derived from at least one constituent of T, or // S is an intersection type and some constituent of S is derived from T, or // S is a type variable with a base constraint that is derived from T, or // T is {} and S is an object-like type (ensuring {} is less derived than Object), or // T is one of the global types Object and Function and S is a subtype of T, or // T occurs directly or indirectly in an 'extends' clause of S. // Note that this check ignores type parameters and only considers the // inheritance hierarchy. function isTypeDerivedFrom(source: Type, target: Type): boolean { return source.flags & TypeFlags.Union ? every((source as UnionType).types, t => isTypeDerivedFrom(t, target)) : target.flags & TypeFlags.Union ? some((target as UnionType).types, t => isTypeDerivedFrom(source, t)) : source.flags & TypeFlags.Intersection ? some((source as IntersectionType).types, t => isTypeDerivedFrom(t, target)) : source.flags & TypeFlags.InstantiableNonPrimitive ? isTypeDerivedFrom(getBaseConstraintOfType(source) || unknownType, target) : isEmptyAnonymousObjectType(target) ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) : target === globalObjectType ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) && !isEmptyAnonymousObjectType(source) : target === globalFunctionType ? !!(source.flags & TypeFlags.Object) && isFunctionObjectType(source as ObjectType) : hasBaseType(source, getTargetType(target)) || (isArrayType(target) && !isReadonlyArrayType(target) && isTypeDerivedFrom(source, globalReadonlyArrayType)); } /** * This is *not* a bi-directional relationship. * If one needs to check both directions for comparability, use a second call to this function or 'checkTypeComparableTo'. * * A type S is comparable to a type T if some (but not necessarily all) of the possible values of S are also possible values of T. * It is used to check following cases: * - the types of the left and right sides of equality/inequality operators (`===`, `!==`, `==`, `!=`). * - the types of `case` clause expressions and their respective `switch` expressions. * - the type of an expression in a type assertion with the type being asserted. */ function isTypeComparableTo(source: Type, target: Type): boolean { return isTypeRelatedTo(source, target, comparableRelation); } function areTypesComparable(type1: Type, type2: Type): boolean { return isTypeComparableTo(type1, type2) || isTypeComparableTo(type2, type1); } function checkTypeAssignableTo(source: Type, target: Type, errorNode: Node | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined, errorOutputObject?: { errors?: Diagnostic[] }): boolean { return checkTypeRelatedTo(source, target, assignableRelation, errorNode, headMessage, containingMessageChain, errorOutputObject); } /** * Like `checkTypeAssignableTo`, but if it would issue an error, instead performs structural comparisons of the types using the given expression node to * attempt to issue more specific errors on, for example, specific object literal properties or tuple members. */ function checkTypeAssignableToAndOptionallyElaborate(source: Type, target: Type, errorNode: Node | undefined, expr: Expression | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { return checkTypeRelatedToAndOptionallyElaborate(source, target, assignableRelation, errorNode, expr, headMessage, containingMessageChain, /*errorOutputContainer*/ undefined); } function checkTypeRelatedToAndOptionallyElaborate( source: Type, target: Type, relation: Map, errorNode: Node | undefined, expr: Expression | undefined, headMessage: DiagnosticMessage | undefined, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ): boolean { if (isTypeRelatedTo(source, target, relation)) return true; if (!errorNode || !elaborateError(expr, source, target, relation, headMessage, containingMessageChain, errorOutputContainer)) { return checkTypeRelatedTo(source, target, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer); } return false; } function isOrHasGenericConditional(type: Type): boolean { return !!(type.flags & TypeFlags.Conditional || (type.flags & TypeFlags.Intersection && some((type as IntersectionType).types, isOrHasGenericConditional))); } function elaborateError( node: Expression | undefined, source: Type, target: Type, relation: Map, headMessage: DiagnosticMessage | undefined, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ): boolean { if (!node || isOrHasGenericConditional(target)) return false; if (!checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined) && elaborateDidYouMeanToCallOrConstruct(node, source, target, relation, headMessage, containingMessageChain, errorOutputContainer)) { return true; } switch (node.kind) { case SyntaxKind.JsxExpression: case SyntaxKind.ParenthesizedExpression: return elaborateError((node as ParenthesizedExpression | JsxExpression).expression, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); case SyntaxKind.BinaryExpression: switch ((node as BinaryExpression).operatorToken.kind) { case SyntaxKind.EqualsToken: case SyntaxKind.CommaToken: return elaborateError((node as BinaryExpression).right, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); } break; case SyntaxKind.ObjectLiteralExpression: return elaborateObjectLiteral(node as ObjectLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); case SyntaxKind.ArrayLiteralExpression: return elaborateArrayLiteral(node as ArrayLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); case SyntaxKind.JsxAttributes: return elaborateJsxComponents(node as JsxAttributes, source, target, relation, containingMessageChain, errorOutputContainer); case SyntaxKind.ArrowFunction: return elaborateArrowFunction(node as ArrowFunction, source, target, relation, containingMessageChain, errorOutputContainer); } return false; } function elaborateDidYouMeanToCallOrConstruct( node: Expression, source: Type, target: Type, relation: Map, headMessage: DiagnosticMessage | undefined, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ): boolean { const callSignatures = getSignaturesOfType(source, SignatureKind.Call); const constructSignatures = getSignaturesOfType(source, SignatureKind.Construct); for (const signatures of [constructSignatures, callSignatures]) { if (some(signatures, s => { const returnType = getReturnTypeOfSignature(s); return !(returnType.flags & (TypeFlags.Any | TypeFlags.Never)) && checkTypeRelatedTo(returnType, target, relation, /*errorNode*/ undefined); })) { const resultObj: { errors?: Diagnostic[] } = errorOutputContainer || {}; checkTypeAssignableTo(source, target, node, headMessage, containingMessageChain, resultObj); const diagnostic = resultObj.errors![resultObj.errors!.length - 1]; addRelatedInfo(diagnostic, createDiagnosticForNode( node, signatures === constructSignatures ? Diagnostics.Did_you_mean_to_use_new_with_this_expression : Diagnostics.Did_you_mean_to_call_this_expression )); return true; } } return false; } function elaborateArrowFunction( node: ArrowFunction, source: Type, target: Type, relation: Map, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ): boolean { // Don't elaborate blocks if (isBlock(node.body)) { return false; } // Or functions with annotated parameter types if (some(node.parameters, hasType)) { return false; } const sourceSig = getSingleCallSignature(source); if (!sourceSig) { return false; } const targetSignatures = getSignaturesOfType(target, SignatureKind.Call); if (!length(targetSignatures)) { return false; } const returnExpression = node.body; const sourceReturn = getReturnTypeOfSignature(sourceSig); const targetReturn = getUnionType(map(targetSignatures, getReturnTypeOfSignature)); if (!checkTypeRelatedTo(sourceReturn, targetReturn, relation, /*errorNode*/ undefined)) { const elaborated = returnExpression && elaborateError(returnExpression, sourceReturn, targetReturn, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); if (elaborated) { return elaborated; } const resultObj: { errors?: Diagnostic[] } = errorOutputContainer || {}; checkTypeRelatedTo(sourceReturn, targetReturn, relation, returnExpression, /*message*/ undefined, containingMessageChain, resultObj); if (resultObj.errors) { if (target.symbol && length(target.symbol.declarations)) { addRelatedInfo(resultObj.errors[resultObj.errors.length - 1], createDiagnosticForNode( target.symbol.declarations![0], Diagnostics.The_expected_type_comes_from_the_return_type_of_this_signature, )); } if ((getFunctionFlags(node) & FunctionFlags.Async) === 0 // exclude cases where source itself is promisy - this way we don't make a suggestion when relating // an IPromise and a Promise that are slightly different && !getTypeOfPropertyOfType(sourceReturn, "then" as __String) && checkTypeRelatedTo(createPromiseType(sourceReturn), targetReturn, relation, /*errorNode*/ undefined) ) { addRelatedInfo(resultObj.errors[resultObj.errors.length - 1], createDiagnosticForNode( node, Diagnostics.Did_you_mean_to_mark_this_function_as_async )); } return true; } } return false; } function getBestMatchIndexedAccessTypeOrUndefined(source: Type, target: Type, nameType: Type) { const idx = getIndexedAccessTypeOrUndefined(target, nameType); if (idx) { return idx; } if (target.flags & TypeFlags.Union) { const best = getBestMatchingType(source, target as UnionType); if (best) { return getIndexedAccessTypeOrUndefined(best, nameType); } } } function checkExpressionForMutableLocationWithContextualType(next: Expression, sourcePropType: Type) { pushContextualType(next, sourcePropType, /*isCache*/ false); const result = checkExpressionForMutableLocation(next, CheckMode.Contextual); popContextualType(); return result; } type ElaborationIterator = IterableIterator<{ errorNode: Node, innerExpression: Expression | undefined, nameType: Type, errorMessage?: DiagnosticMessage | undefined }>; /** * For every element returned from the iterator, checks that element to issue an error on a property of that element's type * If that element would issue an error, we first attempt to dive into that element's inner expression and issue a more specific error by recuring into `elaborateError` * Otherwise, we issue an error on _every_ element which fail the assignability check */ function elaborateElementwise( iterator: ElaborationIterator, source: Type, target: Type, relation: Map, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ) { // Assignability failure - check each prop individually, and if that fails, fall back on the bad error span let reportedError = false; for (const value of iterator) { const { errorNode: prop, innerExpression: next, nameType, errorMessage } = value; let targetPropType = getBestMatchIndexedAccessTypeOrUndefined(source, target, nameType); if (!targetPropType || targetPropType.flags & TypeFlags.IndexedAccess) continue; // Don't elaborate on indexes on generic variables let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); if (!sourcePropType) continue; const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); reportedError = true; if (!elaborated) { // Issue error on the prop itself, since the prop couldn't elaborate the error const resultObj: { errors?: Diagnostic[] } = errorOutputContainer || {}; // Use the expression type, if available const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); diagnostics.add(diag); resultObj.errors = [diag]; } else { const targetIsOptional = !!(propName && (getPropertyOfType(target, propName) || unknownSymbol).flags & SymbolFlags.Optional); const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); targetPropType = removeMissingType(targetPropType, targetIsOptional); sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); if (result && specificSource !== sourcePropType) { // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); } } if (resultObj.errors) { const reportedDiag = resultObj.errors[resultObj.errors.length - 1]; const propertyName = isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; const targetProp = propertyName !== undefined ? getPropertyOfType(target, propertyName) : undefined; let issuedElaboration = false; if (!targetProp) { const indexInfo = getApplicableIndexInfo(target, nameType); if (indexInfo && indexInfo.declaration && !getSourceFileOfNode(indexInfo.declaration).hasNoDefaultLib) { issuedElaboration = true; addRelatedInfo(reportedDiag, createDiagnosticForNode(indexInfo.declaration, Diagnostics.The_expected_type_comes_from_this_index_signature)); } } if (!issuedElaboration && (targetProp && length(targetProp.declarations) || target.symbol && length(target.symbol.declarations))) { const targetNode = targetProp && length(targetProp.declarations) ? targetProp.declarations![0] : target.symbol.declarations![0]; if (!getSourceFileOfNode(targetNode).hasNoDefaultLib) { addRelatedInfo(reportedDiag, createDiagnosticForNode( targetNode, Diagnostics.The_expected_type_comes_from_property_0_which_is_declared_here_on_type_1, propertyName && !(nameType.flags & TypeFlags.UniqueESSymbol) ? unescapeLeadingUnderscores(propertyName) : typeToString(nameType), typeToString(target) )); } } } } } } return reportedError; } /** * Assumes `target` type is assignable to the `Iterable` type, if `Iterable` is defined, * or that it's an array or tuple-like type, if `Iterable` is not defined. */ function elaborateIterableOrArrayLikeTargetElementwise( iterator: ElaborationIterator, source: Type, target: Type, relation: Map, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ) { const tupleOrArrayLikeTargetParts = filterType(target, isArrayOrTupleLikeType); const nonTupleOrArrayLikeTargetParts = filterType(target, t => !isArrayOrTupleLikeType(t)); // If `nonTupleOrArrayLikeTargetParts` is not `never`, then that should mean `Iterable` is defined. const iterationType = nonTupleOrArrayLikeTargetParts !== neverType ? getIterationTypeOfIterable(IterationUse.ForOf, IterationTypeKind.Yield, nonTupleOrArrayLikeTargetParts, /*errorNode*/ undefined) : undefined; let reportedError = false; for (let status = iterator.next(); !status.done; status = iterator.next()) { const { errorNode: prop, innerExpression: next, nameType, errorMessage } = status.value; let targetPropType = iterationType; const targetIndexedPropType = tupleOrArrayLikeTargetParts !== neverType ? getBestMatchIndexedAccessTypeOrUndefined(source, tupleOrArrayLikeTargetParts, nameType) : undefined; if (targetIndexedPropType && !(targetIndexedPropType.flags & TypeFlags.IndexedAccess)) { // Don't elaborate on indexes on generic variables targetPropType = iterationType ? getUnionType([iterationType, targetIndexedPropType]) : targetIndexedPropType; } if (!targetPropType) continue; let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); if (!sourcePropType) continue; const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); reportedError = true; if (!elaborated) { // Issue error on the prop itself, since the prop couldn't elaborate the error const resultObj: { errors?: Diagnostic[] } = errorOutputContainer || {}; // Use the expression type, if available const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); diagnostics.add(diag); resultObj.errors = [diag]; } else { const targetIsOptional = !!(propName && (getPropertyOfType(tupleOrArrayLikeTargetParts, propName) || unknownSymbol).flags & SymbolFlags.Optional); const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); targetPropType = removeMissingType(targetPropType, targetIsOptional); sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); if (result && specificSource !== sourcePropType) { // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); } } } } } return reportedError; } function *generateJsxAttributes(node: JsxAttributes): ElaborationIterator { if (!length(node.properties)) return; for (const prop of node.properties) { if (isJsxSpreadAttribute(prop) || isHyphenatedJsxName(idText(prop.name))) continue; yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: getStringLiteralType(idText(prop.name)) }; } } function *generateJsxChildren(node: JsxElement, getInvalidTextDiagnostic: () => DiagnosticMessage): ElaborationIterator { if (!length(node.children)) return; let memberOffset = 0; for (let i = 0; i < node.children.length; i++) { const child = node.children[i]; const nameType = getNumberLiteralType(i - memberOffset); const elem = getElaborationElementForJsxChild(child, nameType, getInvalidTextDiagnostic); if (elem) { yield elem; } else { memberOffset++; } } } function getElaborationElementForJsxChild(child: JsxChild, nameType: LiteralType, getInvalidTextDiagnostic: () => DiagnosticMessage) { switch (child.kind) { case SyntaxKind.JsxExpression: // child is of the type of the expression return { errorNode: child, innerExpression: child.expression, nameType }; case SyntaxKind.JsxText: if (child.containsOnlyTriviaWhiteSpaces) { break; // Whitespace only jsx text isn't real jsx text } // child is a string return { errorNode: child, innerExpression: undefined, nameType, errorMessage: getInvalidTextDiagnostic() }; case SyntaxKind.JsxElement: case SyntaxKind.JsxSelfClosingElement: case SyntaxKind.JsxFragment: // child is of type JSX.Element return { errorNode: child, innerExpression: child, nameType }; default: return Debug.assertNever(child, "Found invalid jsx child"); } } function elaborateJsxComponents( node: JsxAttributes, source: Type, target: Type, relation: Map, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ) { let result = elaborateElementwise(generateJsxAttributes(node), source, target, relation, containingMessageChain, errorOutputContainer); let invalidTextDiagnostic: DiagnosticMessage | undefined; if (isJsxOpeningElement(node.parent) && isJsxElement(node.parent.parent)) { const containingElement = node.parent.parent; const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); const childrenNameType = getStringLiteralType(childrenPropName); const childrenTargetType = getIndexedAccessType(target, childrenNameType); const validChildren = getSemanticJsxChildren(containingElement.children); if (!length(validChildren)) { return result; } const moreThanOneRealChildren = length(validChildren) > 1; let arrayLikeTargetParts: Type; let nonArrayLikeTargetParts: Type; const iterableType = getGlobalIterableType(/*reportErrors*/ false); if (iterableType !== emptyGenericType) { const anyIterable = createIterableType(anyType); arrayLikeTargetParts = filterType(childrenTargetType, t => isTypeAssignableTo(t, anyIterable)); nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isTypeAssignableTo(t, anyIterable)); } else { arrayLikeTargetParts = filterType(childrenTargetType, isArrayOrTupleLikeType); nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isArrayOrTupleLikeType(t)); } if (moreThanOneRealChildren) { if (arrayLikeTargetParts !== neverType) { const realSource = createTupleType(checkJsxChildren(containingElement, CheckMode.Normal)); const children = generateJsxChildren(containingElement, getInvalidTextualChildDiagnostic); result = elaborateIterableOrArrayLikeTargetElementwise(children, realSource, arrayLikeTargetParts, relation, containingMessageChain, errorOutputContainer) || result; } else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { // arity mismatch result = true; const diag = error( containingElement.openingElement.tagName, Diagnostics.This_JSX_tag_s_0_prop_expects_a_single_child_of_type_1_but_multiple_children_were_provided, childrenPropName, typeToString(childrenTargetType) ); if (errorOutputContainer && errorOutputContainer.skipLogging) { (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); } } } else { if (nonArrayLikeTargetParts !== neverType) { const child = validChildren[0]; const elem = getElaborationElementForJsxChild(child, childrenNameType, getInvalidTextualChildDiagnostic); if (elem) { result = elaborateElementwise( (function*() { yield elem; })(), source, target, relation, containingMessageChain, errorOutputContainer ) || result; } } else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { // arity mismatch result = true; const diag = error( containingElement.openingElement.tagName, Diagnostics.This_JSX_tag_s_0_prop_expects_type_1_which_requires_multiple_children_but_only_a_single_child_was_provided, childrenPropName, typeToString(childrenTargetType) ); if (errorOutputContainer && errorOutputContainer.skipLogging) { (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); } } } } return result; function getInvalidTextualChildDiagnostic() { if (!invalidTextDiagnostic) { const tagNameText = getTextOfNode(node.parent.tagName); const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); const childrenTargetType = getIndexedAccessType(target, getStringLiteralType(childrenPropName)); const diagnostic = Diagnostics._0_components_don_t_accept_text_as_child_elements_Text_in_JSX_has_the_type_string_but_the_expected_type_of_1_is_2; invalidTextDiagnostic = { ...diagnostic, key: "!!ALREADY FORMATTED!!", message: formatMessage(/*_dummy*/ undefined, diagnostic, tagNameText, childrenPropName, typeToString(childrenTargetType)) }; } return invalidTextDiagnostic; } } function *generateLimitedTupleElements(node: ArrayLiteralExpression, target: Type): ElaborationIterator { const len = length(node.elements); if (!len) return; for (let i = 0; i < len; i++) { // Skip elements which do not exist in the target - a length error on the tuple overall is likely better than an error on a mismatched index signature if (isTupleLikeType(target) && !getPropertyOfType(target, ("" + i) as __String)) continue; const elem = node.elements[i]; if (isOmittedExpression(elem)) continue; const nameType = getNumberLiteralType(i); yield { errorNode: elem, innerExpression: elem, nameType }; } } function elaborateArrayLiteral( node: ArrayLiteralExpression, source: Type, target: Type, relation: Map, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ) { if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; if (isTupleLikeType(source)) { return elaborateElementwise(generateLimitedTupleElements(node, target), source, target, relation, containingMessageChain, errorOutputContainer); } // recreate a tuple from the elements, if possible // Since we're re-doing the expression type, we need to reapply the contextual type pushContextualType(node, target, /*isCache*/ false); const tupleizedType = checkArrayLiteral(node, CheckMode.Contextual, /*forceTuple*/ true); popContextualType(); if (isTupleLikeType(tupleizedType)) { return elaborateElementwise(generateLimitedTupleElements(node, target), tupleizedType, target, relation, containingMessageChain, errorOutputContainer); } return false; } function *generateObjectLiteralElements(node: ObjectLiteralExpression): ElaborationIterator { if (!length(node.properties)) return; for (const prop of node.properties) { if (isSpreadAssignment(prop)) continue; const type = getLiteralTypeFromProperty(getSymbolOfDeclaration(prop), TypeFlags.StringOrNumberLiteralOrUnique); if (!type || (type.flags & TypeFlags.Never)) { continue; } switch (prop.kind) { case SyntaxKind.SetAccessor: case SyntaxKind.GetAccessor: case SyntaxKind.MethodDeclaration: case SyntaxKind.ShorthandPropertyAssignment: yield { errorNode: prop.name, innerExpression: undefined, nameType: type }; break; case SyntaxKind.PropertyAssignment: yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: type, errorMessage: isComputedNonLiteralName(prop.name) ? Diagnostics.Type_of_computed_property_s_value_is_0_which_is_not_assignable_to_type_1 : undefined }; break; default: Debug.assertNever(prop); } } } function elaborateObjectLiteral( node: ObjectLiteralExpression, source: Type, target: Type, relation: Map, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } | undefined ) { if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; return elaborateElementwise(generateObjectLiteralElements(node), source, target, relation, containingMessageChain, errorOutputContainer); } /** * This is *not* a bi-directional relationship. * If one needs to check both directions for comparability, use a second call to this function or 'isTypeComparableTo'. */ function checkTypeComparableTo(source: Type, target: Type, errorNode: Node, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { return checkTypeRelatedTo(source, target, comparableRelation, errorNode, headMessage, containingMessageChain); } function isSignatureAssignableTo(source: Signature, target: Signature, ignoreReturnTypes: boolean): boolean { return compareSignaturesRelated(source, target, ignoreReturnTypes ? SignatureCheckMode.IgnoreReturnTypes : SignatureCheckMode.None, /*reportErrors*/ false, /*errorReporter*/ undefined, /*errorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined) !== Ternary.False; } type ErrorReporter = (message: DiagnosticMessage, arg0?: string, arg1?: string) => void; /** * Returns true if `s` is `(...args: A) => R` where `A` is `any`, `any[]`, `never`, or `never[]`, and `R` is `any` or `unknown`. */ function isTopSignature(s: Signature) { if (!s.typeParameters && (!s.thisParameter || isTypeAny(getTypeOfParameter(s.thisParameter))) && s.parameters.length === 1 && signatureHasRestParameter(s)) { const paramType = getTypeOfParameter(s.parameters[0]); const restType = isArrayType(paramType) ? getTypeArguments(paramType)[0] : paramType; return !!(restType.flags & (TypeFlags.Any | TypeFlags.Never) && getReturnTypeOfSignature(s).flags & TypeFlags.AnyOrUnknown); } return false; } /** * See signatureRelatedTo, compareSignaturesIdentical */ function compareSignaturesRelated(source: Signature, target: Signature, checkMode: SignatureCheckMode, reportErrors: boolean, errorReporter: ErrorReporter | undefined, incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined, compareTypes: TypeComparer, reportUnreliableMarkers: TypeMapper | undefined): Ternary { // TODO (drosen): De-duplicate code between related functions. if (source === target) { return Ternary.True; } if (!(checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source)) && isTopSignature(target)) { return Ternary.True; } if (checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source) && !isTopSignature(target)) { return Ternary.False; } const targetCount = getParameterCount(target); const sourceHasMoreParameters = !hasEffectiveRestParameter(target) && (checkMode & SignatureCheckMode.StrictArity ? hasEffectiveRestParameter(source) || getParameterCount(source) > targetCount : getMinArgumentCount(source) > targetCount); if (sourceHasMoreParameters) { return Ternary.False; } if (source.typeParameters && source.typeParameters !== target.typeParameters) { target = getCanonicalSignature(target); source = instantiateSignatureInContextOf(source, target, /*inferenceContext*/ undefined, compareTypes); } const sourceCount = getParameterCount(source); const sourceRestType = getNonArrayRestType(source); const targetRestType = getNonArrayRestType(target); if (sourceRestType || targetRestType) { void instantiateType(sourceRestType || targetRestType, reportUnreliableMarkers); } const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; const strictVariance = !(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration && kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor; let result = Ternary.True; const sourceThisType = getThisTypeOfSignature(source); if (sourceThisType && sourceThisType !== voidType) { const targetThisType = getThisTypeOfSignature(target); if (targetThisType) { // void sources are assignable to anything. const related = !strictVariance && compareTypes(sourceThisType, targetThisType, /*reportErrors*/ false) || compareTypes(targetThisType, sourceThisType, reportErrors); if (!related) { if (reportErrors) { errorReporter!(Diagnostics.The_this_types_of_each_signature_are_incompatible); } return Ternary.False; } result &= related; } } const paramCount = sourceRestType || targetRestType ? Math.min(sourceCount, targetCount) : Math.max(sourceCount, targetCount); const restIndex = sourceRestType || targetRestType ? paramCount - 1 : -1; for (let i = 0; i < paramCount; i++) { const sourceType = i === restIndex ? getRestTypeAtPosition(source, i) : tryGetTypeAtPosition(source, i); const targetType = i === restIndex ? getRestTypeAtPosition(target, i) : tryGetTypeAtPosition(target, i); if (sourceType && targetType) { // In order to ensure that any generic type Foo is at least co-variant with respect to T no matter // how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions, // they naturally relate only contra-variantly). However, if the source and target parameters both have // function types with a single call signature, we know we are relating two callback parameters. In // that case it is sufficient to only relate the parameters of the signatures co-variantly because, // similar to return values, callback parameters are output positions. This means that a Promise, // where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant) // with respect to T. const sourceSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(sourceType)); const targetSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(targetType)); const callbacks = sourceSig && targetSig && !getTypePredicateOfSignature(sourceSig) && !getTypePredicateOfSignature(targetSig) && (getTypeFacts(sourceType) & TypeFacts.IsUndefinedOrNull) === (getTypeFacts(targetType) & TypeFacts.IsUndefinedOrNull); let related = callbacks ? compareSignaturesRelated(targetSig, sourceSig, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) : !(checkMode & SignatureCheckMode.Callback) && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors); // With strict arity, (x: number | undefined) => void is a subtype of (x?: number | undefined) => void if (related && checkMode & SignatureCheckMode.StrictArity && i >= getMinArgumentCount(source) && i < getMinArgumentCount(target) && compareTypes(sourceType, targetType, /*reportErrors*/ false)) { related = Ternary.False; } if (!related) { if (reportErrors) { errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible, unescapeLeadingUnderscores(getParameterNameAtPosition(source, i)), unescapeLeadingUnderscores(getParameterNameAtPosition(target, i))); } return Ternary.False; } result &= related; } } if (!(checkMode & SignatureCheckMode.IgnoreReturnTypes)) { // If a signature resolution is already in-flight, skip issuing a circularity error // here and just use the `any` type directly const targetReturnType = isResolvingReturnTypeOfSignature(target) ? anyType : target.declaration && isJSConstructor(target.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(target.declaration.symbol)) : getReturnTypeOfSignature(target); if (targetReturnType === voidType || targetReturnType === anyType) { return result; } const sourceReturnType = isResolvingReturnTypeOfSignature(source) ? anyType : source.declaration && isJSConstructor(source.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(source.declaration.symbol)) : getReturnTypeOfSignature(source); // The following block preserves behavior forbidding boolean returning functions from being assignable to type guard returning functions const targetTypePredicate = getTypePredicateOfSignature(target); if (targetTypePredicate) { const sourceTypePredicate = getTypePredicateOfSignature(source); if (sourceTypePredicate) { result &= compareTypePredicateRelatedTo(sourceTypePredicate, targetTypePredicate, reportErrors, errorReporter, compareTypes); } else if (isIdentifierTypePredicate(targetTypePredicate)) { if (reportErrors) { errorReporter!(Diagnostics.Signature_0_must_be_a_type_predicate, signatureToString(source)); } return Ternary.False; } } else { // When relating callback signatures, we still need to relate return types bi-variantly as otherwise // the containing type wouldn't be co-variant. For example, interface Foo { add(cb: () => T): void } // wouldn't be co-variant for T without this rule. result &= checkMode & SignatureCheckMode.BivariantCallback && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) || compareTypes(sourceReturnType, targetReturnType, reportErrors); if (!result && reportErrors && incompatibleErrorReporter) { incompatibleErrorReporter(sourceReturnType, targetReturnType); } } } return result; } function compareTypePredicateRelatedTo( source: TypePredicate, target: TypePredicate, reportErrors: boolean, errorReporter: ErrorReporter | undefined, compareTypes: (s: Type, t: Type, reportErrors?: boolean) => Ternary): Ternary { if (source.kind !== target.kind) { if (reportErrors) { errorReporter!(Diagnostics.A_this_based_type_guard_is_not_compatible_with_a_parameter_based_type_guard); errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); } return Ternary.False; } if (source.kind === TypePredicateKind.Identifier || source.kind === TypePredicateKind.AssertsIdentifier) { if (source.parameterIndex !== (target as IdentifierTypePredicate).parameterIndex) { if (reportErrors) { errorReporter!(Diagnostics.Parameter_0_is_not_in_the_same_position_as_parameter_1, source.parameterName, (target as IdentifierTypePredicate).parameterName); errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); } return Ternary.False; } } const related = source.type === target.type ? Ternary.True : source.type && target.type ? compareTypes(source.type, target.type, reportErrors) : Ternary.False; if (related === Ternary.False && reportErrors) { errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); } return related; } function isImplementationCompatibleWithOverload(implementation: Signature, overload: Signature): boolean { const erasedSource = getErasedSignature(implementation); const erasedTarget = getErasedSignature(overload); // First see if the return types are compatible in either direction. const sourceReturnType = getReturnTypeOfSignature(erasedSource); const targetReturnType = getReturnTypeOfSignature(erasedTarget); if (targetReturnType === voidType || isTypeRelatedTo(targetReturnType, sourceReturnType, assignableRelation) || isTypeRelatedTo(sourceReturnType, targetReturnType, assignableRelation)) { return isSignatureAssignableTo(erasedSource, erasedTarget, /*ignoreReturnTypes*/ true); } return false; } function isEmptyResolvedType(t: ResolvedType) { return t !== anyFunctionType && t.properties.length === 0 && t.callSignatures.length === 0 && t.constructSignatures.length === 0 && t.indexInfos.length === 0; } function isEmptyObjectType(type: Type): boolean { return type.flags & TypeFlags.Object ? !isGenericMappedType(type) && isEmptyResolvedType(resolveStructuredTypeMembers(type as ObjectType)) : type.flags & TypeFlags.NonPrimitive ? true : type.flags & TypeFlags.Union ? some((type as UnionType).types, isEmptyObjectType) : type.flags & TypeFlags.Intersection ? every((type as UnionType).types, isEmptyObjectType) : false; } function isEmptyAnonymousObjectType(type: Type) { return !!(getObjectFlags(type) & ObjectFlags.Anonymous && ( (type as ResolvedType).members && isEmptyResolvedType(type as ResolvedType) || type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && getMembersOfSymbol(type.symbol).size === 0)); } function isUnknownLikeUnionType(type: Type) { if (strictNullChecks && type.flags & TypeFlags.Union) { if (!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnionComputed)) { const types = (type as UnionType).types; (type as UnionType).objectFlags |= ObjectFlags.IsUnknownLikeUnionComputed | (types.length >= 3 && types[0].flags & TypeFlags.Undefined && types[1].flags & TypeFlags.Null && some(types, isEmptyAnonymousObjectType) ? ObjectFlags.IsUnknownLikeUnion : 0); } return !!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnion); } return false; } function containsUndefinedType(type: Type) { return !!((type.flags & TypeFlags.Union ? (type as UnionType).types[0] : type).flags & TypeFlags.Undefined); } function isStringIndexSignatureOnlyType(type: Type): boolean { return type.flags & TypeFlags.Object && !isGenericMappedType(type) && getPropertiesOfType(type).length === 0 && getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, stringType) || type.flags & TypeFlags.UnionOrIntersection && every((type as UnionOrIntersectionType).types, isStringIndexSignatureOnlyType) || false; } function isEnumTypeRelatedTo(source: Symbol, target: Symbol, errorReporter?: ErrorReporter) { const sourceSymbol = source.flags & SymbolFlags.EnumMember ? getParentOfSymbol(source)! : source; const targetSymbol = target.flags & SymbolFlags.EnumMember ? getParentOfSymbol(target)! : target; if (sourceSymbol === targetSymbol) { return true; } if (sourceSymbol.escapedName !== targetSymbol.escapedName || !(sourceSymbol.flags & SymbolFlags.RegularEnum) || !(targetSymbol.flags & SymbolFlags.RegularEnum)) { return false; } const id = getSymbolId(sourceSymbol) + "," + getSymbolId(targetSymbol); const entry = enumRelation.get(id); if (entry !== undefined && !(!(entry & RelationComparisonResult.Reported) && entry & RelationComparisonResult.Failed && errorReporter)) { return !!(entry & RelationComparisonResult.Succeeded); } const targetEnumType = getTypeOfSymbol(targetSymbol); for (const property of getPropertiesOfType(getTypeOfSymbol(sourceSymbol))) { if (property.flags & SymbolFlags.EnumMember) { const targetProperty = getPropertyOfType(targetEnumType, property.escapedName); if (!targetProperty || !(targetProperty.flags & SymbolFlags.EnumMember)) { if (errorReporter) { errorReporter(Diagnostics.Property_0_is_missing_in_type_1, symbolName(property), typeToString(getDeclaredTypeOfSymbol(targetSymbol), /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType)); enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); } else { enumRelation.set(id, RelationComparisonResult.Failed); } return false; } } } enumRelation.set(id, RelationComparisonResult.Succeeded); return true; } function isSimpleTypeRelatedTo(source: Type, target: Type, relation: Map, errorReporter?: ErrorReporter) { const s = source.flags; const t = target.flags; if (t & TypeFlags.Any || s & TypeFlags.Never || source === wildcardType) return true; if (t & TypeFlags.Unknown && !(relation === strictSubtypeRelation && s & TypeFlags.Any)) return true; if (t & TypeFlags.Never) return false; if (s & TypeFlags.StringLike && t & TypeFlags.String) return true; if (s & TypeFlags.StringLiteral && s & TypeFlags.EnumLiteral && t & TypeFlags.StringLiteral && !(t & TypeFlags.EnumLiteral) && (source as StringLiteralType).value === (target as StringLiteralType).value) return true; if (s & TypeFlags.NumberLike && t & TypeFlags.Number) return true; if (s & TypeFlags.NumberLiteral && s & TypeFlags.EnumLiteral && t & TypeFlags.NumberLiteral && !(t & TypeFlags.EnumLiteral) && (source as NumberLiteralType).value === (target as NumberLiteralType).value) return true; if (s & TypeFlags.BigIntLike && t & TypeFlags.BigInt) return true; if (s & TypeFlags.BooleanLike && t & TypeFlags.Boolean) return true; if (s & TypeFlags.ESSymbolLike && t & TypeFlags.ESSymbol) return true; if (s & TypeFlags.Enum && t & TypeFlags.Enum && source.symbol.escapedName === target.symbol.escapedName && isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter)) return true; if (s & TypeFlags.EnumLiteral && t & TypeFlags.EnumLiteral) { if (s & TypeFlags.Union && t & TypeFlags.Union && isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter)) return true; if (s & TypeFlags.Literal && t & TypeFlags.Literal && (source as LiteralType).value === (target as LiteralType).value && isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter)) return true; } // In non-strictNullChecks mode, `undefined` and `null` are assignable to anything except `never`. // Since unions and intersections may reduce to `never`, we exclude them here. if (s & TypeFlags.Undefined && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & (TypeFlags.Undefined | TypeFlags.Void))) return true; if (s & TypeFlags.Null && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & TypeFlags.Null)) return true; if (s & TypeFlags.Object && t & TypeFlags.NonPrimitive && !(relation === strictSubtypeRelation && isEmptyAnonymousObjectType(source) && !(getObjectFlags(source) & ObjectFlags.FreshLiteral))) return true; if (relation === assignableRelation || relation === comparableRelation) { if (s & TypeFlags.Any) return true; // Type number is assignable to any computed numeric enum type or any numeric enum literal type, and // a numeric literal type is assignable any computed numeric enum type or any numeric enum literal type // with a matching value. These rules exist such that enums can be used for bit-flag purposes. if (s & TypeFlags.Number && (t & TypeFlags.Enum || t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral)) return true; if (s & TypeFlags.NumberLiteral && !(s & TypeFlags.EnumLiteral) && (t & TypeFlags.Enum || t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral && (source as NumberLiteralType).value === (target as NumberLiteralType).value)) return true; // Anything is assignable to a union containing undefined, null, and {} if (isUnknownLikeUnionType(target)) return true; } return false; } function isTypeRelatedTo(source: Type, target: Type, relation: Map) { if (isFreshLiteralType(source)) { source = (source as FreshableType).regularType; } if (isFreshLiteralType(target)) { target = (target as FreshableType).regularType; } if (source === target) { return true; } if (relation !== identityRelation) { if (relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || isSimpleTypeRelatedTo(source, target, relation)) { return true; } } else if (!((source.flags | target.flags) & (TypeFlags.UnionOrIntersection | TypeFlags.IndexedAccess | TypeFlags.Conditional | TypeFlags.Substitution))) { // We have excluded types that may simplify to other forms, so types must have identical flags if (source.flags !== target.flags) return false; if (source.flags & TypeFlags.Singleton) return true; } if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { const related = relation.get(getRelationKey(source, target, IntersectionState.None, relation, /*ignoreConstraints*/ false)); if (related !== undefined) { return !!(related & RelationComparisonResult.Succeeded); } } if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { return checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined); } return false; } function isIgnoredJsxProperty(source: Type, sourceProp: Symbol) { return getObjectFlags(source) & ObjectFlags.JsxAttributes && isHyphenatedJsxName(sourceProp.escapedName); } function getNormalizedType(type: Type, writing: boolean): Type { while (true) { const t = isFreshLiteralType(type) ? (type as FreshableType).regularType : getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).node ? createTypeReference((type as TypeReference).target, getTypeArguments(type as TypeReference)) : getSingleBaseForNonAugmentingSubtype(type) || type : type.flags & TypeFlags.UnionOrIntersection ? getNormalizedUnionOrIntersectionType(type as UnionOrIntersectionType, writing) : type.flags & TypeFlags.Substitution ? writing ? (type as SubstitutionType).baseType : getSubstitutionIntersection(type as SubstitutionType) : type.flags & TypeFlags.Simplifiable ? getSimplifiedType(type, writing) : type; if (t === type) return t; type = t; } } function getNormalizedUnionOrIntersectionType(type: UnionOrIntersectionType, writing: boolean) { const reduced = getReducedType(type); if (reduced !== type) { return reduced; } if (type.flags & TypeFlags.Intersection && some((type as IntersectionType).types, isEmptyAnonymousObjectType)) { const normalizedTypes = sameMap(type.types, t => getNormalizedType(t, writing)); if (normalizedTypes !== type.types) { return getIntersectionType(normalizedTypes); } } return type; } /** * Checks if 'source' is related to 'target' (e.g.: is a assignable to). * @param source The left-hand-side of the relation. * @param target The right-hand-side of the relation. * @param relation The relation considered. One of 'identityRelation', 'subtypeRelation', 'assignableRelation', or 'comparableRelation'. * Used as both to determine which checks are performed and as a cache of previously computed results. * @param errorNode The suggested node upon which all errors will be reported, if defined. This may or may not be the actual node used. * @param headMessage If the error chain should be prepended by a head message, then headMessage will be used. * @param containingMessageChain A chain of errors to prepend any new errors found. * @param errorOutputContainer Return the diagnostic. Do not log if 'skipLogging' is truthy. */ function checkTypeRelatedTo( source: Type, target: Type, relation: Map, errorNode: Node | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined, errorOutputContainer?: { errors?: Diagnostic[], skipLogging?: boolean }, ): boolean { let errorInfo: DiagnosticMessageChain | undefined; let relatedInfo: [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined; let maybeKeys: string[]; let sourceStack: Type[]; let targetStack: Type[]; let maybeCount = 0; let sourceDepth = 0; let targetDepth = 0; let expandingFlags = ExpandingFlags.None; let overflow = false; let overrideNextErrorInfo = 0; // How many `reportRelationError` calls should be skipped in the elaboration pyramid let lastSkippedInfo: [Type, Type] | undefined; let incompatibleStack: [DiagnosticMessage, (string | number)?, (string | number)?, (string | number)?, (string | number)?][] | undefined; Debug.assert(relation !== identityRelation || !errorNode, "no error reporting in identity checking"); const result = isRelatedTo(source, target, RecursionFlags.Both, /*reportErrors*/ !!errorNode, headMessage); if (incompatibleStack) { reportIncompatibleStack(); } if (overflow) { tracing?.instant(tracing.Phase.CheckTypes, "checkTypeRelatedTo_DepthLimit", { sourceId: source.id, targetId: target.id, depth: sourceDepth, targetDepth }); const diag = error(errorNode || currentNode, Diagnostics.Excessive_stack_depth_comparing_types_0_and_1, typeToString(source), typeToString(target)); if (errorOutputContainer) { (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); } } else if (errorInfo) { if (containingMessageChain) { const chain = containingMessageChain(); if (chain) { concatenateDiagnosticMessageChains(chain, errorInfo); errorInfo = chain; } } let relatedInformation: DiagnosticRelatedInformation[] | undefined; // Check if we should issue an extra diagnostic to produce a quickfix for a slightly incorrect import statement if (headMessage && errorNode && !result && source.symbol) { const links = getSymbolLinks(source.symbol); if (links.originatingImport && !isImportCall(links.originatingImport)) { const helpfulRetry = checkTypeRelatedTo(getTypeOfSymbol(links.target!), target, relation, /*errorNode*/ undefined); if (helpfulRetry) { // Likely an incorrect import. Issue a helpful diagnostic to produce a quickfix to change the import const diag = createDiagnosticForNode(links.originatingImport, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead); relatedInformation = append(relatedInformation, diag); // Cause the error to appear with the error that triggered it } } } const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode!), errorNode!, errorInfo, relatedInformation); if (relatedInfo) { addRelatedInfo(diag, ...relatedInfo); } if (errorOutputContainer) { (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); } if (!errorOutputContainer || !errorOutputContainer.skipLogging) { diagnostics.add(diag); } } if (errorNode && errorOutputContainer && errorOutputContainer.skipLogging && result === Ternary.False) { Debug.assert(!!errorOutputContainer.errors, "missed opportunity to interact with error."); } return result !== Ternary.False; function resetErrorInfo(saved: ReturnType) { errorInfo = saved.errorInfo; lastSkippedInfo = saved.lastSkippedInfo; incompatibleStack = saved.incompatibleStack; overrideNextErrorInfo = saved.overrideNextErrorInfo; relatedInfo = saved.relatedInfo; } function captureErrorCalculationState() { return { errorInfo, lastSkippedInfo, incompatibleStack: incompatibleStack?.slice(), overrideNextErrorInfo, relatedInfo: relatedInfo?.slice() as [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined, }; } function reportIncompatibleError(message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number) { overrideNextErrorInfo++; // Suppress the next relation error lastSkippedInfo = undefined; // Reset skipped info cache (incompatibleStack ||= []).push([message, arg0, arg1, arg2, arg3]); } function reportIncompatibleStack() { const stack = incompatibleStack || []; incompatibleStack = undefined; const info = lastSkippedInfo; lastSkippedInfo = undefined; if (stack.length === 1) { reportError(...stack[0]); if (info) { // Actually do the last relation error reportRelationError(/*headMessage*/ undefined, ...info); } return; } // The first error will be the innermost, while the last will be the outermost - so by popping off the end, // we can build from left to right let path = ""; const secondaryRootErrors: [DiagnosticMessage, (string | number)?, (string | number)?, (string | number)?, (string | number)?][] = []; while (stack.length) { const [msg, ...args] = stack.pop()!; switch (msg.code) { case Diagnostics.Types_of_property_0_are_incompatible.code: { // Parenthesize a `new` if there is one if (path.indexOf("new ") === 0) { path = `(${path})`; } const str = "" + args[0]; // If leading, just print back the arg (irrespective of if it's a valid identifier) if (path.length === 0) { path = `${str}`; } // Otherwise write a dotted name if possible else if (isIdentifierText(str, getEmitScriptTarget(compilerOptions))) { path = `${path}.${str}`; } // Failing that, check if the name is already a computed name else if (str[0] === "[" && str[str.length - 1] === "]") { path = `${path}${str}`; } // And finally write out a computed name as a last resort else { path = `${path}[${str}]`; } break; } case Diagnostics.Call_signature_return_types_0_and_1_are_incompatible.code: case Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code: case Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: case Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: { if (path.length === 0) { // Don't flatten signature compatability errors at the start of a chain - instead prefer // to unify (the with no arguments bit is excessive for printback) and print them back let mappedMsg = msg; if (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { mappedMsg = Diagnostics.Call_signature_return_types_0_and_1_are_incompatible; } else if (msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { mappedMsg = Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible; } secondaryRootErrors.unshift([mappedMsg, args[0], args[1]]); } else { const prefix = (msg.code === Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code || msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) ? "new " : ""; const params = (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code || msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) ? "" : "..."; path = `${prefix}${path}(${params})`; } break; } case Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target.code: { secondaryRootErrors.unshift([Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, args[0], args[1]]); break; } case Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target.code: { secondaryRootErrors.unshift([Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, args[0], args[1], args[2]]); break; } default: return Debug.fail(`Unhandled Diagnostic: ${msg.code}`); } } if (path) { reportError(path[path.length - 1] === ")" ? Diagnostics.The_types_returned_by_0_are_incompatible_between_these_types : Diagnostics.The_types_of_0_are_incompatible_between_these_types, path ); } else { // Remove the innermost secondary error as it will duplicate the error already reported by `reportRelationError` on entry secondaryRootErrors.shift(); } for (const [msg, ...args] of secondaryRootErrors) { const originalValue = msg.elidedInCompatabilityPyramid; msg.elidedInCompatabilityPyramid = false; // Temporarily override elision to ensure error is reported reportError(msg, ...args); msg.elidedInCompatabilityPyramid = originalValue; } if (info) { // Actually do the last relation error reportRelationError(/*headMessage*/ undefined, ...info); } } function reportError(message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): void { Debug.assert(!!errorNode); if (incompatibleStack) reportIncompatibleStack(); if (message.elidedInCompatabilityPyramid) return; errorInfo = chainDiagnosticMessages(errorInfo, message, arg0, arg1, arg2, arg3); } function associateRelatedInfo(info: DiagnosticRelatedInformation) { Debug.assert(!!errorInfo); if (!relatedInfo) { relatedInfo = [info]; } else { relatedInfo.push(info); } } function reportRelationError(message: DiagnosticMessage | undefined, source: Type, target: Type) { if (incompatibleStack) reportIncompatibleStack(); const [sourceType, targetType] = getTypeNamesForErrorDisplay(source, target); let generalizedSource = source; let generalizedSourceType = sourceType; if (isLiteralType(source) && !typeCouldHaveTopLevelSingletonTypes(target)) { generalizedSource = getBaseTypeOfLiteralType(source); Debug.assert(!isTypeAssignableTo(generalizedSource, target), "generalized source shouldn't be assignable"); generalizedSourceType = getTypeNameForErrorDisplay(generalizedSource); } // If `target` is of indexed access type (And `source` it is not), we use the object type of `target` for better error reporting const targetFlags = target.flags & TypeFlags.IndexedAccess && !(source.flags & TypeFlags.IndexedAccess) ? (target as IndexedAccessType).objectType.flags : target.flags; if (targetFlags & TypeFlags.TypeParameter && target !== markerSuperTypeForCheck && target !== markerSubTypeForCheck) { const constraint = getBaseConstraintOfType(target); let needsOriginalSource; if (constraint && (isTypeAssignableTo(generalizedSource, constraint) || (needsOriginalSource = isTypeAssignableTo(source, constraint)))) { reportError( Diagnostics._0_is_assignable_to_the_constraint_of_type_1_but_1_could_be_instantiated_with_a_different_subtype_of_constraint_2, needsOriginalSource ? sourceType : generalizedSourceType, targetType, typeToString(constraint), ); } else { errorInfo = undefined; reportError( Diagnostics._0_could_be_instantiated_with_an_arbitrary_type_which_could_be_unrelated_to_1, targetType, generalizedSourceType ); } } if (!message) { if (relation === comparableRelation) { message = Diagnostics.Type_0_is_not_comparable_to_type_1; } else if (sourceType === targetType) { message = Diagnostics.Type_0_is_not_assignable_to_type_1_Two_different_types_with_this_name_exist_but_they_are_unrelated; } else if (exactOptionalPropertyTypes && getExactOptionalUnassignableProperties(source, target).length) { message = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; } else { if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.Union) { const suggestedType = getSuggestedTypeForNonexistentStringLiteralType(source as StringLiteralType, target as UnionType); if (suggestedType) { reportError(Diagnostics.Type_0_is_not_assignable_to_type_1_Did_you_mean_2, generalizedSourceType, targetType, typeToString(suggestedType)); return; } } message = Diagnostics.Type_0_is_not_assignable_to_type_1; } } else if (message === Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1 && exactOptionalPropertyTypes && getExactOptionalUnassignableProperties(source, target).length) { message = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; } reportError(message, generalizedSourceType, targetType); } function tryElaborateErrorsForPrimitivesAndObjects(source: Type, target: Type) { const sourceType = symbolValueDeclarationIsContextSensitive(source.symbol) ? typeToString(source, source.symbol.valueDeclaration) : typeToString(source); const targetType = symbolValueDeclarationIsContextSensitive(target.symbol) ? typeToString(target, target.symbol.valueDeclaration) : typeToString(target); if ((globalStringType === source && stringType === target) || (globalNumberType === source && numberType === target) || (globalBooleanType === source && booleanType === target) || (getGlobalESSymbolType() === source && esSymbolType === target)) { reportError(Diagnostics._0_is_a_primitive_but_1_is_a_wrapper_object_Prefer_using_0_when_possible, targetType, sourceType); } } /** * Try and elaborate array and tuple errors. Returns false * if we have found an elaboration, or we should ignore * any other elaborations when relating the `source` and * `target` types. */ function tryElaborateArrayLikeErrors(source: Type, target: Type, reportErrors: boolean): boolean { /** * The spec for elaboration is: * - If the source is a readonly tuple and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. * - If the source is a tuple then skip property elaborations if the target is an array or tuple. * - If the source is a readonly array and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. * - If the source an array then skip property elaborations if the target is a tuple. */ if (isTupleType(source)) { if (source.target.readonly && isMutableArrayOrTuple(target)) { if (reportErrors) { reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); } return false; } return isArrayOrTupleType(target); } if (isReadonlyArrayType(source) && isMutableArrayOrTuple(target)) { if (reportErrors) { reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); } return false; } if (isTupleType(target)) { return isArrayType(source); } return true; } function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { return isRelatedTo(source, target, RecursionFlags.Both, reportErrors); } /** * Compare two types and return * * Ternary.True if they are related with no assumptions, * * Ternary.Maybe if they are related with assumptions of other relationships, or * * Ternary.False if they are not related. */ function isRelatedTo(originalSource: Type, originalTarget: Type, recursionFlags: RecursionFlags = RecursionFlags.Both, reportErrors = false, headMessage?: DiagnosticMessage, intersectionState = IntersectionState.None): Ternary { // Before normalization: if `source` is type an object type, and `target` is primitive, // skip all the checks we don't need and just return `isSimpleTypeRelatedTo` result if (originalSource.flags & TypeFlags.Object && originalTarget.flags & TypeFlags.Primitive) { if (relation === comparableRelation && !(originalTarget.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(originalTarget, originalSource, relation) || isSimpleTypeRelatedTo(originalSource, originalTarget, relation, reportErrors ? reportError : undefined)) { return Ternary.True; } if (reportErrors) { reportErrorResults(originalSource, originalTarget, originalSource, originalTarget, headMessage); } return Ternary.False; } // Normalize the source and target types: Turn fresh literal types into regular literal types, // turn deferred type references into regular type references, simplify indexed access and // conditional types, and resolve substitution types to either the substitution (on the source // side) or the type variable (on the target side). const source = getNormalizedType(originalSource, /*writing*/ false); let target = getNormalizedType(originalTarget, /*writing*/ true); if (source === target) return Ternary.True; if (relation === identityRelation) { if (source.flags !== target.flags) return Ternary.False; if (source.flags & TypeFlags.Singleton) return Ternary.True; traceUnionsOrIntersectionsTooLarge(source, target); return recursiveTypeRelatedTo(source, target, /*reportErrors*/ false, IntersectionState.None, recursionFlags); } // We fastpath comparing a type parameter to exactly its constraint, as this is _super_ common, // and otherwise, for type parameters in large unions, causes us to need to compare the union to itself, // as we break down the _target_ union first, _then_ get the source constraint - so for every // member of the target, we attempt to find a match in the source. This avoids that in cases where // the target is exactly the constraint. if (source.flags & TypeFlags.TypeParameter && getConstraintOfType(source) === target) { return Ternary.True; } // See if we're relating a definitely non-nullable type to a union that includes null and/or undefined // plus a single non-nullable type. If so, remove null and/or undefined from the target type. if (source.flags & TypeFlags.DefinitelyNonNullable && target.flags & TypeFlags.Union) { const types = (target as UnionType).types; const candidate = types.length === 2 && types[0].flags & TypeFlags.Nullable ? types[1] : types.length === 3 && types[0].flags & TypeFlags.Nullable && types[1].flags & TypeFlags.Nullable ? types[2] : undefined; if (candidate && !(candidate.flags & TypeFlags.Nullable)) { target = getNormalizedType(candidate, /*writing*/ true); if (source === target) return Ternary.True; } } if (relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || isSimpleTypeRelatedTo(source, target, relation, reportErrors ? reportError : undefined)) return Ternary.True; if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { const isPerformingExcessPropertyChecks = !(intersectionState & IntersectionState.Target) && (isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral); if (isPerformingExcessPropertyChecks) { if (hasExcessProperties(source as FreshObjectLiteralType, target, reportErrors)) { if (reportErrors) { reportRelationError(headMessage, source, originalTarget.aliasSymbol ? originalTarget : target); } return Ternary.False; } } const isPerformingCommonPropertyChecks = (relation !== comparableRelation || isUnitType(source)) && !(intersectionState & IntersectionState.Target) && source.flags & (TypeFlags.Primitive | TypeFlags.Object | TypeFlags.Intersection) && source !== globalObjectType && target.flags & (TypeFlags.Object | TypeFlags.Intersection) && isWeakType(target) && (getPropertiesOfType(source).length > 0 || typeHasCallOrConstructSignatures(source)); const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); if (isPerformingCommonPropertyChecks && !hasCommonProperties(source, target, isComparingJsxAttributes)) { if (reportErrors) { const sourceString = typeToString(originalSource.aliasSymbol ? originalSource : source); const targetString = typeToString(originalTarget.aliasSymbol ? originalTarget : target); const calls = getSignaturesOfType(source, SignatureKind.Call); const constructs = getSignaturesOfType(source, SignatureKind.Construct); if (calls.length > 0 && isRelatedTo(getReturnTypeOfSignature(calls[0]), target, RecursionFlags.Source, /*reportErrors*/ false) || constructs.length > 0 && isRelatedTo(getReturnTypeOfSignature(constructs[0]), target, RecursionFlags.Source, /*reportErrors*/ false)) { reportError(Diagnostics.Value_of_type_0_has_no_properties_in_common_with_type_1_Did_you_mean_to_call_it, sourceString, targetString); } else { reportError(Diagnostics.Type_0_has_no_properties_in_common_with_type_1, sourceString, targetString); } } return Ternary.False; } traceUnionsOrIntersectionsTooLarge(source, target); const skipCaching = source.flags & TypeFlags.Union && (source as UnionType).types.length < 4 && !(target.flags & TypeFlags.Union) || target.flags & TypeFlags.Union && (target as UnionType).types.length < 4 && !(source.flags & TypeFlags.StructuredOrInstantiable); const result = skipCaching ? unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState) : recursiveTypeRelatedTo(source, target, reportErrors, intersectionState, recursionFlags); if (result) { return result; } } if (reportErrors) { reportErrorResults(originalSource, originalTarget, source, target, headMessage); } return Ternary.False; } function reportErrorResults(originalSource: Type, originalTarget: Type, source: Type, target: Type, headMessage: DiagnosticMessage | undefined) { const sourceHasBase = !!getSingleBaseForNonAugmentingSubtype(originalSource); const targetHasBase = !!getSingleBaseForNonAugmentingSubtype(originalTarget); source = (originalSource.aliasSymbol || sourceHasBase) ? originalSource : source; target = (originalTarget.aliasSymbol || targetHasBase) ? originalTarget : target; let maybeSuppress = overrideNextErrorInfo > 0; if (maybeSuppress) { overrideNextErrorInfo--; } if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { const currentError = errorInfo; tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ true); if (errorInfo !== currentError) { maybeSuppress = !!errorInfo; } } if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Primitive) { tryElaborateErrorsForPrimitivesAndObjects(source, target); } else if (source.symbol && source.flags & TypeFlags.Object && globalObjectType === source) { reportError(Diagnostics.The_Object_type_is_assignable_to_very_few_other_types_Did_you_mean_to_use_the_any_type_instead); } else if (getObjectFlags(source) & ObjectFlags.JsxAttributes && target.flags & TypeFlags.Intersection) { const targetTypes = (target as IntersectionType).types; const intrinsicAttributes = getJsxType(JsxNames.IntrinsicAttributes, errorNode); const intrinsicClassAttributes = getJsxType(JsxNames.IntrinsicClassAttributes, errorNode); if (!isErrorType(intrinsicAttributes) && !isErrorType(intrinsicClassAttributes) && (contains(targetTypes, intrinsicAttributes) || contains(targetTypes, intrinsicClassAttributes))) { // do not report top error return; } } else { errorInfo = elaborateNeverIntersection(errorInfo, originalTarget); } if (!headMessage && maybeSuppress) { lastSkippedInfo = [source, target]; // Used by, eg, missing property checking to replace the top-level message with a more informative one return; } reportRelationError(headMessage, source, target); if (source.flags & TypeFlags.TypeParameter && source.symbol?.declarations?.[0] && !getConstraintOfType(source as TypeVariable)) { const syntheticParam = cloneTypeParameter(source as TypeParameter); syntheticParam.constraint = instantiateType(target, makeUnaryTypeMapper(source, syntheticParam)); if (hasNonCircularBaseConstraint(syntheticParam)) { const targetConstraintString = typeToString(target, source.symbol.declarations[0]); associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_might_need_an_extends_0_constraint, targetConstraintString)); } } } function traceUnionsOrIntersectionsTooLarge(source: Type, target: Type): void { if (!tracing) { return; } if ((source.flags & TypeFlags.UnionOrIntersection) && (target.flags & TypeFlags.UnionOrIntersection)) { const sourceUnionOrIntersection = source as UnionOrIntersectionType; const targetUnionOrIntersection = target as UnionOrIntersectionType; if (sourceUnionOrIntersection.objectFlags & targetUnionOrIntersection.objectFlags & ObjectFlags.PrimitiveUnion) { // There's a fast path for comparing primitive unions return; } const sourceSize = sourceUnionOrIntersection.types.length; const targetSize = targetUnionOrIntersection.types.length; if (sourceSize * targetSize > 1E6) { tracing.instant(tracing.Phase.CheckTypes, "traceUnionsOrIntersectionsTooLarge_DepthLimit", { sourceId: source.id, sourceSize, targetId: target.id, targetSize, pos: errorNode?.pos, end: errorNode?.end }); } } } function getTypeOfPropertyInTypes(types: Type[], name: __String) { const appendPropType = (propTypes: Type[] | undefined, type: Type) => { type = getApparentType(type); const prop = type.flags & TypeFlags.UnionOrIntersection ? getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name) : getPropertyOfObjectType(type, name); const propType = prop && getTypeOfSymbol(prop) || getApplicableIndexInfoForName(type, name)?.type || undefinedType; return append(propTypes, propType); }; return getUnionType(reduceLeft(types, appendPropType, /*initial*/ undefined) || emptyArray); } function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean { if (!isExcessPropertyCheckTarget(target) || !noImplicitAny && getObjectFlags(target) & ObjectFlags.JSLiteral) { return false; // Disable excess property checks on JS literals to simulate having an implicit "index signature" - but only outside of noImplicitAny } const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); if ((relation === assignableRelation || relation === comparableRelation) && (isTypeSubsetOf(globalObjectType, target) || (!isComparingJsxAttributes && isEmptyObjectType(target)))) { return false; } let reducedTarget = target; let checkTypes: Type[] | undefined; if (target.flags & TypeFlags.Union) { reducedTarget = findMatchingDiscriminantType(source, target as UnionType, isRelatedTo) || filterPrimitivesIfContainsNonPrimitive(target as UnionType); checkTypes = reducedTarget.flags & TypeFlags.Union ? (reducedTarget as UnionType).types : [reducedTarget]; } for (const prop of getPropertiesOfType(source)) { if (shouldCheckAsExcessProperty(prop, source.symbol) && !isIgnoredJsxProperty(source, prop)) { if (!isKnownProperty(reducedTarget, prop.escapedName, isComparingJsxAttributes)) { if (reportErrors) { // Report error in terms of object types in the target as those are the only ones // we check in isKnownProperty. const errorTarget = filterType(reducedTarget, isExcessPropertyCheckTarget); // We know *exactly* where things went wrong when comparing the types. // Use this property as the error node as this will be more helpful in // reasoning about what went wrong. if (!errorNode) return Debug.fail(); if (isJsxAttributes(errorNode) || isJsxOpeningLikeElement(errorNode) || isJsxOpeningLikeElement(errorNode.parent)) { // JsxAttributes has an object-literal flag and undergo same type-assignablity check as normal object-literal. // However, using an object-literal error message will be very confusing to the users so we give different a message. if (prop.valueDeclaration && isJsxAttribute(prop.valueDeclaration) && getSourceFileOfNode(errorNode) === getSourceFileOfNode(prop.valueDeclaration.name)) { // Note that extraneous children (as in `extra`) don't pass this check, // since `children` is a SyntaxKind.PropertySignature instead of a SyntaxKind.JsxAttribute. errorNode = prop.valueDeclaration.name; } const propName = symbolToString(prop); const suggestionSymbol = getSuggestedSymbolForNonexistentJSXAttribute(propName, errorTarget); const suggestion = suggestionSymbol ? symbolToString(suggestionSymbol) : undefined; if (suggestion) { reportError(Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName, typeToString(errorTarget), suggestion); } else { reportError(Diagnostics.Property_0_does_not_exist_on_type_1, propName, typeToString(errorTarget)); } } else { // use the property's value declaration if the property is assigned inside the literal itself const objectLiteralDeclaration = source.symbol?.declarations && firstOrUndefined(source.symbol.declarations); let suggestion: string | undefined; if (prop.valueDeclaration && findAncestor(prop.valueDeclaration, d => d === objectLiteralDeclaration) && getSourceFileOfNode(objectLiteralDeclaration) === getSourceFileOfNode(errorNode)) { const propDeclaration = prop.valueDeclaration as ObjectLiteralElementLike; Debug.assertNode(propDeclaration, isObjectLiteralElementLike); errorNode = propDeclaration; const name = propDeclaration.name!; if (isIdentifier(name)) { suggestion = getSuggestionForNonexistentProperty(name, errorTarget); } } if (suggestion !== undefined) { reportError(Diagnostics.Object_literal_may_only_specify_known_properties_but_0_does_not_exist_in_type_1_Did_you_mean_to_write_2, symbolToString(prop), typeToString(errorTarget), suggestion); } else { reportError(Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(prop), typeToString(errorTarget)); } } } return true; } if (checkTypes && !isRelatedTo(getTypeOfSymbol(prop), getTypeOfPropertyInTypes(checkTypes, prop.escapedName), RecursionFlags.Both, reportErrors)) { if (reportErrors) { reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(prop)); } return true; } } } return false; } function shouldCheckAsExcessProperty(prop: Symbol, container: Symbol) { return prop.valueDeclaration && container.valueDeclaration && prop.valueDeclaration.parent === container.valueDeclaration; } function unionOrIntersectionRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { // Note that these checks are specifically ordered to produce correct results. In particular, // we need to deconstruct unions before intersections (because unions are always at the top), // and we need to handle "each" relations before "some" relations for the same kind of type. if (source.flags & TypeFlags.Union) { return relation === comparableRelation ? someTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState) : eachTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState); } if (target.flags & TypeFlags.Union) { return typeRelatedToSomeType(getRegularTypeOfObjectLiteral(source), target as UnionType, reportErrors && !(source.flags & TypeFlags.Primitive) && !(target.flags & TypeFlags.Primitive)); } if (target.flags & TypeFlags.Intersection) { return typeRelatedToEachType(source, target as IntersectionType, reportErrors, IntersectionState.Target); } // Source is an intersection. For the comparable relation, if the target is a primitive type we hoist the // constraints of all non-primitive types in the source into a new intersection. We do this because the // intersection may further constrain the constraints of the non-primitive types. For example, given a type // parameter 'T extends 1 | 2', the intersection 'T & 1' should be reduced to '1' such that it doesn't // appear to be comparable to '2'. if (relation === comparableRelation && target.flags & TypeFlags.Primitive) { const constraints = sameMap((source as IntersectionType).types, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(t) || unknownType : t); if (constraints !== (source as IntersectionType).types) { source = getIntersectionType(constraints); if (source.flags & TypeFlags.Never) { return Ternary.False; } if (!(source.flags & TypeFlags.Intersection)) { return isRelatedTo(source, target, RecursionFlags.Source, /*reportErrors*/ false) || isRelatedTo(target, source, RecursionFlags.Source, /*reportErrors*/ false); } } } // Check to see if any constituents of the intersection are immediately related to the target. // Don't report errors though. Elaborating on whether a source constituent is related to the target is // not actually useful and leads to some confusing error messages. Instead, we rely on the caller // checking whether the full intersection viewed as an object is related to the target. return someTypeRelatedToType(source as IntersectionType, target, /*reportErrors*/ false, IntersectionState.Source); } function eachTypeRelatedToSomeType(source: UnionOrIntersectionType, target: UnionOrIntersectionType): Ternary { let result = Ternary.True; const sourceTypes = source.types; for (const sourceType of sourceTypes) { const related = typeRelatedToSomeType(sourceType, target, /*reportErrors*/ false); if (!related) { return Ternary.False; } result &= related; } return result; } function typeRelatedToSomeType(source: Type, target: UnionOrIntersectionType, reportErrors: boolean): Ternary { const targetTypes = target.types; if (target.flags & TypeFlags.Union) { if (containsType(targetTypes, source)) { return Ternary.True; } const match = getMatchingUnionConstituentForType(target as UnionType, source); if (match) { const related = isRelatedTo(source, match, RecursionFlags.Target, /*reportErrors*/ false); if (related) { return related; } } } for (const type of targetTypes) { const related = isRelatedTo(source, type, RecursionFlags.Target, /*reportErrors*/ false); if (related) { return related; } } if (reportErrors) { // Elaborate only if we can find a best matching type in the target union const bestMatchingType = getBestMatchingType(source, target, isRelatedTo); if (bestMatchingType) { isRelatedTo(source, bestMatchingType, RecursionFlags.Target, /*reportErrors*/ true); } } return Ternary.False; } function typeRelatedToEachType(source: Type, target: IntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { let result = Ternary.True; const targetTypes = target.types; for (const targetType of targetTypes) { const related = isRelatedTo(source, targetType, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState); if (!related) { return Ternary.False; } result &= related; } return result; } function someTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { const sourceTypes = source.types; if (source.flags & TypeFlags.Union && containsType(sourceTypes, target)) { return Ternary.True; } const len = sourceTypes.length; for (let i = 0; i < len; i++) { const related = isRelatedTo(sourceTypes[i], target, RecursionFlags.Source, reportErrors && i === len - 1, /*headMessage*/ undefined, intersectionState); if (related) { return related; } } return Ternary.False; } function getUndefinedStrippedTargetIfNeeded(source: Type, target: Type) { if (source.flags & TypeFlags.Union && target.flags & TypeFlags.Union && !((source as UnionType).types[0].flags & TypeFlags.Undefined) && (target as UnionType).types[0].flags & TypeFlags.Undefined) { return extractTypesOfKind(target, ~TypeFlags.Undefined); } return target; } function eachTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { let result = Ternary.True; const sourceTypes = source.types; // We strip `undefined` from the target if the `source` trivially doesn't contain it for our correspondence-checking fastpath // since `undefined` is frequently added by optionality and would otherwise spoil a potentially useful correspondence const undefinedStrippedTarget = getUndefinedStrippedTargetIfNeeded(source, target as UnionType); for (let i = 0; i < sourceTypes.length; i++) { const sourceType = sourceTypes[i]; if (undefinedStrippedTarget.flags & TypeFlags.Union && sourceTypes.length >= (undefinedStrippedTarget as UnionType).types.length && sourceTypes.length % (undefinedStrippedTarget as UnionType).types.length === 0) { // many unions are mappings of one another; in such cases, simply comparing members at the same index can shortcut the comparison // such unions will have identical lengths, and their corresponding elements will match up. Another common scenario is where a large // union has a union of objects intersected with it. In such cases, if the input was, eg `("a" | "b" | "c") & (string | boolean | {} | {whatever})`, // the result will have the structure `"a" | "b" | "c" | "a" & {} | "b" & {} | "c" & {} | "a" & {whatever} | "b" & {whatever} | "c" & {whatever}` // - the resulting union has a length which is a multiple of the original union, and the elements correspond modulo the length of the original union const related = isRelatedTo(sourceType, (undefinedStrippedTarget as UnionType).types[i % (undefinedStrippedTarget as UnionType).types.length], RecursionFlags.Both, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); if (related) { result &= related; continue; } } const related = isRelatedTo(sourceType, target, RecursionFlags.Source, reportErrors, /*headMessage*/ undefined, intersectionState); if (!related) { return Ternary.False; } result &= related; } return result; } function typeArgumentsRelatedTo(sources: readonly Type[] = emptyArray, targets: readonly Type[] = emptyArray, variances: readonly VarianceFlags[] = emptyArray, reportErrors: boolean, intersectionState: IntersectionState): Ternary { if (sources.length !== targets.length && relation === identityRelation) { return Ternary.False; } const length = sources.length <= targets.length ? sources.length : targets.length; let result = Ternary.True; for (let i = 0; i < length; i++) { // When variance information isn't available we default to covariance. This happens // in the process of computing variance information for recursive types and when // comparing 'this' type arguments. const varianceFlags = i < variances.length ? variances[i] : VarianceFlags.Covariant; const variance = varianceFlags & VarianceFlags.VarianceMask; // We ignore arguments for independent type parameters (because they're never witnessed). if (variance !== VarianceFlags.Independent) { const s = sources[i]; const t = targets[i]; let related = Ternary.True; if (varianceFlags & VarianceFlags.Unmeasurable) { // Even an `Unmeasurable` variance works out without a structural check if the source and target are _identical_. // We can't simply assume invariance, because `Unmeasurable` marks nonlinear relations, for example, a relation tained by // the `-?` modifier in a mapped type (where, no matter how the inputs are related, the outputs still might not be) related = relation === identityRelation ? isRelatedTo(s, t, RecursionFlags.Both, /*reportErrors*/ false) : compareTypesIdentical(s, t); } else if (variance === VarianceFlags.Covariant) { related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); } else if (variance === VarianceFlags.Contravariant) { related = isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); } else if (variance === VarianceFlags.Bivariant) { // In the bivariant case we first compare contravariantly without reporting // errors. Then, if that doesn't succeed, we compare covariantly with error // reporting. Thus, error elaboration will be based on the the covariant check, // which is generally easier to reason about. related = isRelatedTo(t, s, RecursionFlags.Both, /*reportErrors*/ false); if (!related) { related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); } } else { // In the invariant case we first compare covariantly, and only when that // succeeds do we proceed to compare contravariantly. Thus, error elaboration // will typically be based on the covariant check. related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); if (related) { related &= isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); } } if (!related) { return Ternary.False; } result &= related; } } return result; } // Determine if possibly recursive types are related. First, check if the result is already available in the global cache. // Second, check if we have already started a comparison of the given two types in which case we assume the result to be true. // Third, check if both types are part of deeply nested chains of generic type instantiations and if so assume the types are // equal and infinitely expanding. Fourth, if we have reached a depth of 100 nested comparisons, assume we have runaway recursion // and issue an error. Otherwise, actually compare the structure of the two types. function recursiveTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, recursionFlags: RecursionFlags): Ternary { if (overflow) { return Ternary.False; } const id = getRelationKey(source, target, intersectionState, relation, /*ingnoreConstraints*/ false); const entry = relation.get(id); if (entry !== undefined) { if (reportErrors && entry & RelationComparisonResult.Failed && !(entry & RelationComparisonResult.Reported)) { // We are elaborating errors and the cached result is an unreported failure. The result will be reported // as a failure, and should be updated as a reported failure by the bottom of this function. } else { if (outofbandVarianceMarkerHandler) { // We're in the middle of variance checking - integrate any unmeasurable/unreliable flags from this cached component const saved = entry & RelationComparisonResult.ReportsMask; if (saved & RelationComparisonResult.ReportsUnmeasurable) { instantiateType(source, reportUnmeasurableMapper); } if (saved & RelationComparisonResult.ReportsUnreliable) { instantiateType(source, reportUnreliableMapper); } } return entry & RelationComparisonResult.Succeeded ? Ternary.True : Ternary.False; } } if (!maybeKeys) { maybeKeys = []; sourceStack = []; targetStack = []; } else { // A key that starts with "*" is an indication that we have type references that reference constrained // type parameters. For such keys we also check against the key we would have gotten if all type parameters // were unconstrained. const broadestEquivalentId = id.startsWith("*") ? getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ true) : undefined; for (let i = 0; i < maybeCount; i++) { // If source and target are already being compared, consider them related with assumptions if (id === maybeKeys[i] || broadestEquivalentId && broadestEquivalentId === maybeKeys[i]) { return Ternary.Maybe; } } if (sourceDepth === 100 || targetDepth === 100) { overflow = true; return Ternary.False; } } const maybeStart = maybeCount; maybeKeys[maybeCount] = id; maybeCount++; const saveExpandingFlags = expandingFlags; if (recursionFlags & RecursionFlags.Source) { sourceStack[sourceDepth] = source; sourceDepth++; if (!(expandingFlags & ExpandingFlags.Source) && isDeeplyNestedType(source, sourceStack, sourceDepth)) expandingFlags |= ExpandingFlags.Source; } if (recursionFlags & RecursionFlags.Target) { targetStack[targetDepth] = target; targetDepth++; if (!(expandingFlags & ExpandingFlags.Target) && isDeeplyNestedType(target, targetStack, targetDepth)) expandingFlags |= ExpandingFlags.Target; } let originalHandler: typeof outofbandVarianceMarkerHandler; let propagatingVarianceFlags = 0 as RelationComparisonResult; if (outofbandVarianceMarkerHandler) { originalHandler = outofbandVarianceMarkerHandler; outofbandVarianceMarkerHandler = onlyUnreliable => { propagatingVarianceFlags |= onlyUnreliable ? RelationComparisonResult.ReportsUnreliable : RelationComparisonResult.ReportsUnmeasurable; return originalHandler!(onlyUnreliable); }; } let result: Ternary; if (expandingFlags === ExpandingFlags.Both) { tracing?.instant(tracing.Phase.CheckTypes, "recursiveTypeRelatedTo_DepthLimit", { sourceId: source.id, sourceIdStack: sourceStack.map(t => t.id), targetId: target.id, targetIdStack: targetStack.map(t => t.id), depth: sourceDepth, targetDepth }); result = Ternary.Maybe; } else { tracing?.push(tracing.Phase.CheckTypes, "structuredTypeRelatedTo", { sourceId: source.id, targetId: target.id }); result = structuredTypeRelatedTo(source, target, reportErrors, intersectionState); tracing?.pop(); } if (outofbandVarianceMarkerHandler) { outofbandVarianceMarkerHandler = originalHandler; } if (recursionFlags & RecursionFlags.Source) { sourceDepth--; } if (recursionFlags & RecursionFlags.Target) { targetDepth--; } expandingFlags = saveExpandingFlags; if (result) { if (result === Ternary.True || (sourceDepth === 0 && targetDepth === 0)) { if (result === Ternary.True || result === Ternary.Maybe) { // If result is definitely true, record all maybe keys as having succeeded. Also, record Ternary.Maybe // results as having succeeded once we reach depth 0, but never record Ternary.Unknown results. for (let i = maybeStart; i < maybeCount; i++) { relation.set(maybeKeys[i], RelationComparisonResult.Succeeded | propagatingVarianceFlags); } } maybeCount = maybeStart; } } else { // A false result goes straight into global cache (when something is false under // assumptions it will also be false without assumptions) relation.set(id, (reportErrors ? RelationComparisonResult.Reported : 0) | RelationComparisonResult.Failed | propagatingVarianceFlags); maybeCount = maybeStart; } return result; } function structuredTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { const saveErrorInfo = captureErrorCalculationState(); let result = structuredTypeRelatedToWorker(source, target, reportErrors, intersectionState, saveErrorInfo); if (relation !== identityRelation) { // The combined constraint of an intersection type is the intersection of the constraints of // the constituents. When an intersection type contains instantiable types with union type // constraints, there are situations where we need to examine the combined constraint. One is // when the target is a union type. Another is when the intersection contains types belonging // to one of the disjoint domains. For example, given type variables T and U, each with the // constraint 'string | number', the combined constraint of 'T & U' is 'string | number' and // we need to check this constraint against a union on the target side. Also, given a type // variable V constrained to 'string | number', 'V & number' has a combined constraint of // 'string & number | number & number' which reduces to just 'number'. // This also handles type parameters, as a type parameter with a union constraint compared against a union // needs to have its constraint hoisted into an intersection with said type parameter, this way // the type param can be compared with itself in the target (with the influence of its constraint to match other parts) // For example, if `T extends 1 | 2` and `U extends 2 | 3` and we compare `T & U` to `T & U & (1 | 2 | 3)` if (!result && (source.flags & TypeFlags.Intersection || source.flags & TypeFlags.TypeParameter && target.flags & TypeFlags.Union)) { const constraint = getEffectiveConstraintOfIntersection(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types: [source], !!(target.flags & TypeFlags.Union)); if (constraint && everyType(constraint, c => c !== source)) { // Skip comparison if expansion contains the source itself // TODO: Stack errors so we get a pyramid for the "normal" comparison above, _and_ a second for this result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); } } // When the target is an intersection we need an extra property check in order to detect nested excess // properties and nested weak types. The following are motivating examples that all should be errors, but // aren't without this extra property check: // // let obj: { a: { x: string } } & { c: number } = { a: { x: 'hello', y: 2 }, c: 5 }; // Nested excess property // // declare let wrong: { a: { y: string } }; // let weak: { a?: { x?: number } } & { c?: string } = wrong; // Nested weak object type // if (result && !(intersectionState & IntersectionState.Target) && target.flags & TypeFlags.Intersection && !isGenericObjectType(target) && source.flags & (TypeFlags.Object | TypeFlags.Intersection)) { result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, IntersectionState.None); if (result && isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral) { result &= indexSignaturesRelatedTo(source, target, /*sourceIsPrimitive*/ false, reportErrors, IntersectionState.None); } } // When the source is an intersection we need an extra check of any optional properties in the target to // detect possible mismatched property types. For example: // // function foo(x: { a?: string }, y: T & { a: boolean }) { // x = y; // Mismatched property in source intersection // } // else if (result && isNonGenericObjectType(target) && !isArrayOrTupleType(target) && source.flags & TypeFlags.Intersection && getApparentType(source).flags & TypeFlags.StructuredType && !some((source as IntersectionType).types, t => t === target || !!(getObjectFlags(t) & ObjectFlags.NonInferrableType))) { result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ true, intersectionState); } } if (result) { resetErrorInfo(saveErrorInfo); } return result; } function structuredTypeRelatedToWorker(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, saveErrorInfo: ReturnType): Ternary { let result: Ternary; let originalErrorInfo: DiagnosticMessageChain | undefined; let varianceCheckFailed = false; let sourceFlags = source.flags; const targetFlags = target.flags; if (relation === identityRelation) { // We've already checked that source.flags and target.flags are identical if (sourceFlags & TypeFlags.UnionOrIntersection) { let result = eachTypeRelatedToSomeType(source as UnionOrIntersectionType, target as UnionOrIntersectionType); if (result) { result &= eachTypeRelatedToSomeType(target as UnionOrIntersectionType, source as UnionOrIntersectionType); } return result; } if (sourceFlags & TypeFlags.Index) { return isRelatedTo((source as IndexType).type, (target as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false); } if (sourceFlags & TypeFlags.IndexedAccess) { if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, /*reportErrors*/ false)) { if (result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, /*reportErrors*/ false)) { return result; } } } if (sourceFlags & TypeFlags.Conditional) { if ((source as ConditionalType).root.isDistributive === (target as ConditionalType).root.isDistributive) { if (result = isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both, /*reportErrors*/ false)) { if (result &= isRelatedTo((source as ConditionalType).extendsType, (target as ConditionalType).extendsType, RecursionFlags.Both, /*reportErrors*/ false)) { if (result &= isRelatedTo(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { if (result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { return result; } } } } } } if (sourceFlags & TypeFlags.Substitution) { if (result = isRelatedTo((source as SubstitutionType).baseType, (target as SubstitutionType).baseType, RecursionFlags.Both, /*reportErrors*/ false)) { if (result &= isRelatedTo((source as SubstitutionType).constraint, (target as SubstitutionType).constraint, RecursionFlags.Both, /*reportErrors*/ false)) { return result; } } } if (!(sourceFlags & TypeFlags.Object)) { return Ternary.False; } } else if (sourceFlags & TypeFlags.UnionOrIntersection || targetFlags & TypeFlags.UnionOrIntersection) { if (result = unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState)) { return result; } // The ordered decomposition above doesn't handle all cases. Specifically, we also need to handle: // Source is instantiable (e.g. source has union or intersection constraint). // Source is an object, target is a union (e.g. { a, b: boolean } <=> { a, b: true } | { a, b: false }). // Source is an intersection, target is an object (e.g. { a } & { b } <=> { a, b }). // Source is an intersection, target is a union (e.g. { a } & { b: boolean } <=> { a, b: true } | { a, b: false }). // Source is an intersection, target instantiable (e.g. string & { tag } <=> T["a"] constrained to string & { tag }). if (!(sourceFlags & TypeFlags.Instantiable || sourceFlags & TypeFlags.Object && targetFlags & TypeFlags.Union || sourceFlags & TypeFlags.Intersection && targetFlags & (TypeFlags.Object | TypeFlags.Union | TypeFlags.Instantiable))) { return Ternary.False; } } // We limit alias variance probing to only object and conditional types since their alias behavior // is more predictable than other, interned types, which may or may not have an alias depending on // the order in which things were checked. if (sourceFlags & (TypeFlags.Object | TypeFlags.Conditional) && source.aliasSymbol && source.aliasTypeArguments && source.aliasSymbol === target.aliasSymbol && !(isMarkerType(source) || isMarkerType(target))) { const variances = getAliasVariances(source.aliasSymbol); if (variances === emptyArray) { return Ternary.Unknown; } const params = getSymbolLinks(source.aliasSymbol).typeParameters!; const minParams = getMinTypeArgumentCount(params); const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); const varianceResult = relateVariances(sourceTypes, targetTypes, variances, intersectionState); if (varianceResult !== undefined) { return varianceResult; } } // For a generic type T and a type U that is assignable to T, [...U] is assignable to T, U is assignable to readonly [...T], // and U is assignable to [...T] when U is constrained to a mutable array or tuple type. if (isSingleElementGenericTupleType(source) && !source.target.readonly && (result = isRelatedTo(getTypeArguments(source)[0], target, RecursionFlags.Source)) || isSingleElementGenericTupleType(target) && (target.target.readonly || isMutableArrayOrTuple(getBaseConstraintOfType(source) || source)) && (result = isRelatedTo(source, getTypeArguments(target)[0], RecursionFlags.Target))) { return result; } if (targetFlags & TypeFlags.TypeParameter) { // A source type { [P in Q]: X } is related to a target type T if keyof T is related to Q and X is related to T[Q]. if (getObjectFlags(source) & ObjectFlags.Mapped && !(source as MappedType).declaration.nameType && isRelatedTo(getIndexType(target), getConstraintTypeFromMappedType(source as MappedType), RecursionFlags.Both)) { if (!(getMappedTypeModifiers(source as MappedType) & MappedTypeModifiers.IncludeOptional)) { const templateType = getTemplateTypeFromMappedType(source as MappedType); const indexedAccessType = getIndexedAccessType(target, getTypeParameterFromMappedType(source as MappedType)); if (result = isRelatedTo(templateType, indexedAccessType, RecursionFlags.Both, reportErrors)) { return result; } } } if (relation === comparableRelation && sourceFlags & TypeFlags.TypeParameter) { // This is a carve-out in comparability to essentially forbid comparing a type parameter // with another type parameter unless one extends the other. (Remember: comparability is mostly bidirectional!) let constraint = getConstraintOfTypeParameter(source); if (constraint && hasNonCircularBaseConstraint(source)) { while (constraint && someType(constraint, c => !!(c.flags & TypeFlags.TypeParameter))) { if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false)) { return result; } constraint = getConstraintOfTypeParameter(constraint); } } return Ternary.False; } } else if (targetFlags & TypeFlags.Index) { const targetType = (target as IndexType).type; // A keyof S is related to a keyof T if T is related to S. if (sourceFlags & TypeFlags.Index) { if (result = isRelatedTo(targetType, (source as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false)) { return result; } } if (isTupleType(targetType)) { // An index type can have a tuple type target when the tuple type contains variadic elements. // Check if the source is related to the known keys of the tuple type. if (result = isRelatedTo(source, getKnownKeysOfTupleType(targetType), RecursionFlags.Target, reportErrors)) { return result; } } else { // A type S is assignable to keyof T if S is assignable to keyof C, where C is the // simplified form of T or, if T doesn't simplify, the constraint of T. const constraint = getSimplifiedTypeOrConstraint(targetType); if (constraint) { // We require Ternary.True here such that circular constraints don't cause // false positives. For example, given 'T extends { [K in keyof T]: string }', // 'keyof T' has itself as its constraint and produces a Ternary.Maybe when // related to other types. if (isRelatedTo(source, getIndexType(constraint, (target as IndexType).stringsOnly), RecursionFlags.Target, reportErrors) === Ternary.True) { return Ternary.True; } } else if (isGenericMappedType(targetType)) { // generic mapped types that don't simplify or have a constraint still have a very simple set of keys we can compare against // - their nameType or constraintType. // In many ways, this comparison is a deferred version of what `getIndexTypeForMappedType` does to actually resolve the keys for _non_-generic types const nameType = getNameTypeFromMappedType(targetType); const constraintType = getConstraintTypeFromMappedType(targetType); let targetKeys; if (nameType && isMappedTypeWithKeyofConstraintDeclaration(targetType)) { // we need to get the apparent mappings and union them with the generic mappings, since some properties may be // missing from the `constraintType` which will otherwise be mapped in the object const modifiersType = getApparentType(getModifiersTypeFromMappedType(targetType)); const mappedKeys: Type[] = []; forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType( modifiersType, TypeFlags.StringOrNumberLiteralOrUnique, /*stringsOnly*/ false, t => void mappedKeys.push(instantiateType(nameType, appendTypeMapping(targetType.mapper, getTypeParameterFromMappedType(targetType), t))) ); // We still need to include the non-apparent (and thus still generic) keys in the target side of the comparison (in case they're in the source side) targetKeys = getUnionType([...mappedKeys, nameType]); } else { targetKeys = nameType || constraintType; } if (isRelatedTo(source, targetKeys, RecursionFlags.Target, reportErrors) === Ternary.True) { return Ternary.True; } } } } else if (targetFlags & TypeFlags.IndexedAccess) { if (sourceFlags & TypeFlags.IndexedAccess) { // Relate components directly before falling back to constraint relationships // A type S[K] is related to a type T[J] if S is related to T and K is related to J. if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, reportErrors)) { result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, reportErrors); } if (result) { return result; } if (reportErrors) { originalErrorInfo = errorInfo; } } // A type S is related to a type T[K] if S is related to C, where C is the base // constraint of T[K] for writing. if (relation === assignableRelation || relation === comparableRelation) { const objectType = (target as IndexedAccessType).objectType; const indexType = (target as IndexedAccessType).indexType; const baseObjectType = getBaseConstraintOfType(objectType) || objectType; const baseIndexType = getBaseConstraintOfType(indexType) || indexType; if (!isGenericObjectType(baseObjectType) && !isGenericIndexType(baseIndexType)) { const accessFlags = AccessFlags.Writing | (baseObjectType !== objectType ? AccessFlags.NoIndexSignatures : 0); const constraint = getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, accessFlags); if (constraint) { if (reportErrors && originalErrorInfo) { // create a new chain for the constraint error resetErrorInfo(saveErrorInfo); } if (result = isRelatedTo(source, constraint, RecursionFlags.Target, reportErrors, /* headMessage */ undefined, intersectionState)) { return result; } // prefer the shorter chain of the constraint comparison chain, and the direct comparison chain if (reportErrors && originalErrorInfo && errorInfo) { errorInfo = countMessageChainBreadth([originalErrorInfo]) <= countMessageChainBreadth([errorInfo]) ? originalErrorInfo : errorInfo; } } } } if (reportErrors) { originalErrorInfo = undefined; } } else if (isGenericMappedType(target) && relation !== identityRelation) { // Check if source type `S` is related to target type `{ [P in Q]: T }` or `{ [P in Q as R]: T}`. const keysRemapped = !!target.declaration.nameType; const templateType = getTemplateTypeFromMappedType(target); const modifiers = getMappedTypeModifiers(target); if (!(modifiers & MappedTypeModifiers.ExcludeOptional)) { // If the mapped type has shape `{ [P in Q]: T[P] }`, // source `S` is related to target if `T` = `S`, i.e. `S` is related to `{ [P in Q]: S[P] }`. if (!keysRemapped && templateType.flags & TypeFlags.IndexedAccess && (templateType as IndexedAccessType).objectType === source && (templateType as IndexedAccessType).indexType === getTypeParameterFromMappedType(target)) { return Ternary.True; } if (!isGenericMappedType(source)) { // If target has shape `{ [P in Q as R]: T}`, then its keys have type `R`. // If target has shape `{ [P in Q]: T }`, then its keys have type `Q`. const targetKeys = keysRemapped ? getNameTypeFromMappedType(target)! : getConstraintTypeFromMappedType(target); // Type of the keys of source type `S`, i.e. `keyof S`. const sourceKeys = getIndexType(source, /*stringsOnly*/ undefined, /*noIndexSignatures*/ true); const includeOptional = modifiers & MappedTypeModifiers.IncludeOptional; const filteredByApplicability = includeOptional ? intersectTypes(targetKeys, sourceKeys) : undefined; // A source type `S` is related to a target type `{ [P in Q]: T }` if `Q` is related to `keyof S` and `S[Q]` is related to `T`. // A source type `S` is related to a target type `{ [P in Q as R]: T }` if `R` is related to `keyof S` and `S[R]` is related to `T. // A source type `S` is related to a target type `{ [P in Q]?: T }` if some constituent `Q'` of `Q` is related to `keyof S` and `S[Q']` is related to `T`. // A source type `S` is related to a target type `{ [P in Q as R]?: T }` if some constituent `R'` of `R` is related to `keyof S` and `S[R']` is related to `T`. if (includeOptional ? !(filteredByApplicability!.flags & TypeFlags.Never) : isRelatedTo(targetKeys, sourceKeys, RecursionFlags.Both)) { const templateType = getTemplateTypeFromMappedType(target); const typeParameter = getTypeParameterFromMappedType(target); // Fastpath: When the template type has the form `Obj[P]` where `P` is the mapped type parameter, directly compare source `S` with `Obj` // to avoid creating the (potentially very large) number of new intermediate types made by manufacturing `S[P]`. const nonNullComponent = extractTypesOfKind(templateType, ~TypeFlags.Nullable); if (!keysRemapped && nonNullComponent.flags & TypeFlags.IndexedAccess && (nonNullComponent as IndexedAccessType).indexType === typeParameter) { if (result = isRelatedTo(source, (nonNullComponent as IndexedAccessType).objectType, RecursionFlags.Target, reportErrors)) { return result; } } else { // We need to compare the type of a property on the source type `S` to the type of the same property on the target type, // so we need to construct an indexing type representing a property, and then use indexing type to index the source type for comparison. // If the target type has shape `{ [P in Q]: T }`, then a property of the target has type `P`. // If the target type has shape `{ [P in Q]?: T }`, then a property of the target has type `P`, // but the property is optional, so we only want to compare properties `P` that are common between `keyof S` and `Q`. // If the target type has shape `{ [P in Q as R]: T }`, then a property of the target has type `R`. // If the target type has shape `{ [P in Q as R]?: T }`, then a property of the target has type `R`, // but the property is optional, so we only want to compare properties `R` that are common between `keyof S` and `R`. const indexingType = keysRemapped ? (filteredByApplicability || targetKeys) : filteredByApplicability ? getIntersectionType([filteredByApplicability, typeParameter]) : typeParameter; const indexedAccessType = getIndexedAccessType(source, indexingType); // Compare `S[indexingType]` to `T`, where `T` is the type of a property of the target type. if (result = isRelatedTo(indexedAccessType, templateType, RecursionFlags.Both, reportErrors)) { return result; } } } originalErrorInfo = errorInfo; resetErrorInfo(saveErrorInfo); } } } else if (targetFlags & TypeFlags.Conditional) { // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive // conditional type and bail out with a Ternary.Maybe result. if (isDeeplyNestedType(target, targetStack, targetDepth, 10)) { return Ternary.Maybe; } const c = target as ConditionalType; // We check for a relationship to a conditional type target only when the conditional type has no // 'infer' positions and is not distributive or is distributive but doesn't reference the check type // parameter in either of the result types. if (!c.root.inferTypeParameters && !isDistributionDependent(c.root)) { // Check if the conditional is always true or always false but still deferred for distribution purposes. const skipTrue = !isTypeAssignableTo(getPermissiveInstantiation(c.checkType), getPermissiveInstantiation(c.extendsType)); const skipFalse = !skipTrue && isTypeAssignableTo(getRestrictiveInstantiation(c.checkType), getRestrictiveInstantiation(c.extendsType)); // TODO: Find a nice way to include potential conditional type breakdowns in error output, if they seem good (they usually don't) if (result = skipTrue ? Ternary.True : isRelatedTo(source, getTrueTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { result &= skipFalse ? Ternary.True : isRelatedTo(source, getFalseTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); if (result) { return result; } } } } else if (targetFlags & TypeFlags.TemplateLiteral) { if (sourceFlags & TypeFlags.TemplateLiteral) { if (relation === comparableRelation) { return templateLiteralTypesDefinitelyUnrelated(source as TemplateLiteralType, target as TemplateLiteralType) ? Ternary.False : Ternary.True; } // Report unreliable variance for type variables referenced in template literal type placeholders. // For example, `foo-${number}` is related to `foo-${string}` even though number isn't related to string. instantiateType(source, reportUnreliableMapper); } if (isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)) { return Ternary.True; } } else if (target.flags & TypeFlags.StringMapping) { if (!(source.flags & TypeFlags.StringMapping)) { if (isMemberOfStringMapping(source, target)) { return Ternary.True; } } } if (sourceFlags & TypeFlags.TypeVariable) { // IndexedAccess comparisons are handled above in the `targetFlags & TypeFlage.IndexedAccess` branch if (!(sourceFlags & TypeFlags.IndexedAccess && targetFlags & TypeFlags.IndexedAccess)) { const constraint = getConstraintOfType(source as TypeVariable) || unknownType; // hi-speed no-this-instantiation check (less accurate, but avoids costly `this`-instantiation when the constraint will suffice), see #28231 for report on why this is needed if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { return result; } // slower, fuller, this-instantiated check (necessary when comparing raw `this` types from base classes), see `subclassWithPolymorphicThisIsAssignable.ts` test for example else if (result = isRelatedTo(getTypeWithThisArgument(constraint, source), target, RecursionFlags.Source, reportErrors && constraint !== unknownType && !(targetFlags & sourceFlags & TypeFlags.TypeParameter), /*headMessage*/ undefined, intersectionState)) { return result; } if (isMappedTypeGenericIndexedAccess(source)) { // For an indexed access type { [P in K]: E}[X], above we have already explored an instantiation of E with X // substituted for P. We also want to explore type { [P in K]: E }[C], where C is the constraint of X. const indexConstraint = getConstraintOfType((source as IndexedAccessType).indexType); if (indexConstraint) { if (result = isRelatedTo(getIndexedAccessType((source as IndexedAccessType).objectType, indexConstraint), target, RecursionFlags.Source, reportErrors)) { return result; } } } } } else if (sourceFlags & TypeFlags.Index) { if (result = isRelatedTo(keyofConstraintType, target, RecursionFlags.Source, reportErrors)) { return result; } } else if (sourceFlags & TypeFlags.TemplateLiteral && !(targetFlags & TypeFlags.Object)) { if (!(targetFlags & TypeFlags.TemplateLiteral)) { const constraint = getBaseConstraintOfType(source); if (constraint && constraint !== source && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { return result; } } } else if (sourceFlags & TypeFlags.StringMapping) { if (targetFlags & TypeFlags.StringMapping) { if ((source as StringMappingType).symbol !== (target as StringMappingType).symbol) { return Ternary.False; } if (result = isRelatedTo((source as StringMappingType).type, (target as StringMappingType).type, RecursionFlags.Both, reportErrors)) { return result; } } else { const constraint = getBaseConstraintOfType(source); if (constraint && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { return result; } } } else if (sourceFlags & TypeFlags.Conditional) { // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive // conditional type and bail out with a Ternary.Maybe result. if (isDeeplyNestedType(source, sourceStack, sourceDepth, 10)) { return Ternary.Maybe; } if (targetFlags & TypeFlags.Conditional) { // Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if // one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2, // and Y1 is related to Y2. const sourceParams = (source as ConditionalType).root.inferTypeParameters; let sourceExtends = (source as ConditionalType).extendsType; let mapper: TypeMapper | undefined; if (sourceParams) { // If the source has infer type parameters, we instantiate them in the context of the target const ctx = createInferenceContext(sourceParams, /*signature*/ undefined, InferenceFlags.None, isRelatedToWorker); inferTypes(ctx.inferences, (target as ConditionalType).extendsType, sourceExtends, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); sourceExtends = instantiateType(sourceExtends, ctx.mapper); mapper = ctx.mapper; } if (isTypeIdenticalTo(sourceExtends, (target as ConditionalType).extendsType) && (isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both) || isRelatedTo((target as ConditionalType).checkType, (source as ConditionalType).checkType, RecursionFlags.Both))) { if (result = isRelatedTo(instantiateType(getTrueTypeFromConditionalType(source as ConditionalType), mapper), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors)) { result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors); } if (result) { return result; } } } else { // conditionals aren't related to one another via distributive constraint as it is much too inaccurate and allows way // more assignments than are desirable (since it maps the source check type to its constraint, it loses information) const distributiveConstraint = hasNonCircularBaseConstraint(source) ? getConstraintOfDistributiveConditionalType(source as ConditionalType) : undefined; if (distributiveConstraint) { if (result = isRelatedTo(distributiveConstraint, target, RecursionFlags.Source, reportErrors)) { return result; } } } // conditionals _can_ be related to one another via normal constraint, as, eg, `A extends B ? O : never` should be assignable to `O` // when `O` is a conditional (`never` is trivially assignable to `O`, as is `O`!). const defaultConstraint = getDefaultConstraintOfConditionalType(source as ConditionalType); if (defaultConstraint) { if (result = isRelatedTo(defaultConstraint, target, RecursionFlags.Source, reportErrors)) { return result; } } } else { // An empty object type is related to any mapped type that includes a '?' modifier. if (relation !== subtypeRelation && relation !== strictSubtypeRelation && isPartialMappedType(target) && isEmptyObjectType(source)) { return Ternary.True; } if (isGenericMappedType(target)) { if (isGenericMappedType(source)) { if (result = mappedTypeRelatedTo(source, target, reportErrors)) { return result; } } return Ternary.False; } const sourceIsPrimitive = !!(sourceFlags & TypeFlags.Primitive); if (relation !== identityRelation) { source = getApparentType(source); sourceFlags = source.flags; } else if (isGenericMappedType(source)) { return Ternary.False; } if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target && !isTupleType(source) && !(isMarkerType(source) || isMarkerType(target))) { // When strictNullChecks is disabled, the element type of the empty array literal is undefinedWideningType, // and an empty array literal wouldn't be assignable to a `never[]` without this check. if (isEmptyArrayLiteralType(source)) { return Ternary.True; } // We have type references to the same generic type, and the type references are not marker // type references (which are intended by be compared structurally). Obtain the variance // information for the type parameters and relate the type arguments accordingly. const variances = getVariances((source as TypeReference).target); // We return Ternary.Maybe for a recursive invocation of getVariances (signalled by emptyArray). This // effectively means we measure variance only from type parameter occurrences that aren't nested in // recursive instantiations of the generic type. if (variances === emptyArray) { return Ternary.Unknown; } const varianceResult = relateVariances(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), variances, intersectionState); if (varianceResult !== undefined) { return varianceResult; } } else if (isReadonlyArrayType(target) ? isArrayOrTupleType(source) : isArrayType(target) && isTupleType(source) && !source.target.readonly) { if (relation !== identityRelation) { return isRelatedTo(getIndexTypeOfType(source, numberType) || anyType, getIndexTypeOfType(target, numberType) || anyType, RecursionFlags.Both, reportErrors); } else { // By flags alone, we know that the `target` is a readonly array while the source is a normal array or tuple // or `target` is an array and source is a tuple - in both cases the types cannot be identical, by construction return Ternary.False; } } // A fresh empty object type is never a subtype of a non-empty object type. This ensures fresh({}) <: { [x: string]: xxx } // but not vice-versa. Without this rule, those types would be mutual subtypes. else if ((relation === subtypeRelation || relation === strictSubtypeRelation) && isEmptyObjectType(target) && getObjectFlags(target) & ObjectFlags.FreshLiteral && !isEmptyObjectType(source)) { return Ternary.False; } // Even if relationship doesn't hold for unions, intersections, or generic type references, // it may hold in a structural comparison. // In a check of the form X = A & B, we will have previously checked if A relates to X or B relates // to X. Failing both of those we want to check if the aggregation of A and B's members structurally // relates to X. Thus, we include intersection types on the source side here. if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Object) { // Report structural errors only if we haven't reported any errors yet const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo.errorInfo && !sourceIsPrimitive; result = propertiesRelatedTo(source, target, reportStructuralErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, intersectionState); if (result) { result &= signaturesRelatedTo(source, target, SignatureKind.Call, reportStructuralErrors, intersectionState); if (result) { result &= signaturesRelatedTo(source, target, SignatureKind.Construct, reportStructuralErrors, intersectionState); if (result) { result &= indexSignaturesRelatedTo(source, target, sourceIsPrimitive, reportStructuralErrors, intersectionState); } } } if (varianceCheckFailed && result) { errorInfo = originalErrorInfo || errorInfo || saveErrorInfo.errorInfo; // Use variance error (there is no structural one) and return false } else if (result) { return result; } } // If S is an object type and T is a discriminated union, S may be related to T if // there exists a constituent of T for every combination of the discriminants of S // with respect to T. We do not report errors here, as we will use the existing // error result from checking each constituent of the union. if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Union) { const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Substitution); if (objectOnlyTarget.flags & TypeFlags.Union) { const result = typeRelatedToDiscriminatedType(source, objectOnlyTarget as UnionType); if (result) { return result; } } } } return Ternary.False; function countMessageChainBreadth(info: DiagnosticMessageChain[] | undefined): number { if (!info) return 0; return reduceLeft(info, (value, chain) => value + 1 + countMessageChainBreadth(chain.next), 0); } function relateVariances(sourceTypeArguments: readonly Type[] | undefined, targetTypeArguments: readonly Type[] | undefined, variances: VarianceFlags[], intersectionState: IntersectionState) { if (result = typeArgumentsRelatedTo(sourceTypeArguments, targetTypeArguments, variances, reportErrors, intersectionState)) { return result; } if (some(variances, v => !!(v & VarianceFlags.AllowsStructuralFallback))) { // If some type parameter was `Unmeasurable` or `Unreliable`, and we couldn't pass by assuming it was identical, then we // have to allow a structural fallback check // We elide the variance-based error elaborations, since those might not be too helpful, since we'll potentially // be assuming identity of the type parameter. originalErrorInfo = undefined; resetErrorInfo(saveErrorInfo); return undefined; } const allowStructuralFallback = targetTypeArguments && hasCovariantVoidArgument(targetTypeArguments, variances); varianceCheckFailed = !allowStructuralFallback; // The type arguments did not relate appropriately, but it may be because we have no variance // information (in which case typeArgumentsRelatedTo defaulted to covariance for all type // arguments). It might also be the case that the target type has a 'void' type argument for // a covariant type parameter that is only used in return positions within the generic type // (in which case any type argument is permitted on the source side). In those cases we proceed // with a structural comparison. Otherwise, we know for certain the instantiations aren't // related and we can return here. if (variances !== emptyArray && !allowStructuralFallback) { // In some cases generic types that are covariant in regular type checking mode become // invariant in --strictFunctionTypes mode because one or more type parameters are used in // both co- and contravariant positions. In order to make it easier to diagnose *why* such // types are invariant, if any of the type parameters are invariant we reset the reported // errors and instead force a structural comparison (which will include elaborations that // reveal the reason). // We can switch on `reportErrors` here, since varianceCheckFailed guarantees we return `False`, // we can return `False` early here to skip calculating the structural error message we don't need. if (varianceCheckFailed && !(reportErrors && some(variances, v => (v & VarianceFlags.VarianceMask) === VarianceFlags.Invariant))) { return Ternary.False; } // We remember the original error information so we can restore it in case the structural // comparison unexpectedly succeeds. This can happen when the structural comparison result // is a Ternary.Maybe for example caused by the recursion depth limiter. originalErrorInfo = errorInfo; resetErrorInfo(saveErrorInfo); } } } // A type [P in S]: X is related to a type [Q in T]: Y if T is related to S and X' is // related to Y, where X' is an instantiation of X in which P is replaced with Q. Notice // that S and T are contra-variant whereas X and Y are co-variant. function mappedTypeRelatedTo(source: MappedType, target: MappedType, reportErrors: boolean): Ternary { const modifiersRelated = relation === comparableRelation || (relation === identityRelation ? getMappedTypeModifiers(source) === getMappedTypeModifiers(target) : getCombinedMappedTypeOptionality(source) <= getCombinedMappedTypeOptionality(target)); if (modifiersRelated) { let result: Ternary; const targetConstraint = getConstraintTypeFromMappedType(target); const sourceConstraint = instantiateType(getConstraintTypeFromMappedType(source), getCombinedMappedTypeOptionality(source) < 0 ? reportUnmeasurableMapper : reportUnreliableMapper); if (result = isRelatedTo(targetConstraint, sourceConstraint, RecursionFlags.Both, reportErrors)) { const mapper = createTypeMapper([getTypeParameterFromMappedType(source)], [getTypeParameterFromMappedType(target)]); if (instantiateType(getNameTypeFromMappedType(source), mapper) === instantiateType(getNameTypeFromMappedType(target), mapper)) { return result & isRelatedTo(instantiateType(getTemplateTypeFromMappedType(source), mapper), getTemplateTypeFromMappedType(target), RecursionFlags.Both, reportErrors); } } } return Ternary.False; } function typeRelatedToDiscriminatedType(source: Type, target: UnionType) { // 1. Generate the combinations of discriminant properties & types 'source' can satisfy. // a. If the number of combinations is above a set limit, the comparison is too complex. // 2. Filter 'target' to the subset of types whose discriminants exist in the matrix. // a. If 'target' does not satisfy all discriminants in the matrix, 'source' is not related. // 3. For each type in the filtered 'target', determine if all non-discriminant properties of // 'target' are related to a property in 'source'. // // NOTE: See ~/tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithDiscriminatedUnion.ts // for examples. const sourceProperties = getPropertiesOfType(source); const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); if (!sourcePropertiesFiltered) return Ternary.False; // Though we could compute the number of combinations as we generate // the matrix, this would incur additional memory overhead due to // array allocations. To reduce this overhead, we first compute // the number of combinations to ensure we will not surpass our // fixed limit before incurring the cost of any allocations: let numCombinations = 1; for (const sourceProperty of sourcePropertiesFiltered) { numCombinations *= countTypes(getNonMissingTypeOfSymbol(sourceProperty)); if (numCombinations > 25) { // We've reached the complexity limit. tracing?.instant(tracing.Phase.CheckTypes, "typeRelatedToDiscriminatedType_DepthLimit", { sourceId: source.id, targetId: target.id, numCombinations }); return Ternary.False; } } // Compute the set of types for each discriminant property. const sourceDiscriminantTypes: Type[][] = new Array(sourcePropertiesFiltered.length); const excludedProperties = new Set<__String>(); for (let i = 0; i < sourcePropertiesFiltered.length; i++) { const sourceProperty = sourcePropertiesFiltered[i]; const sourcePropertyType = getNonMissingTypeOfSymbol(sourceProperty); sourceDiscriminantTypes[i] = sourcePropertyType.flags & TypeFlags.Union ? (sourcePropertyType as UnionType).types : [sourcePropertyType]; excludedProperties.add(sourceProperty.escapedName); } // Match each combination of the cartesian product of discriminant properties to one or more // constituents of 'target'. If any combination does not have a match then 'source' is not relatable. const discriminantCombinations = cartesianProduct(sourceDiscriminantTypes); const matchingTypes: Type[] = []; for (const combination of discriminantCombinations) { let hasMatch = false; outer: for (const type of target.types) { for (let i = 0; i < sourcePropertiesFiltered.length; i++) { const sourceProperty = sourcePropertiesFiltered[i]; const targetProperty = getPropertyOfType(type, sourceProperty.escapedName); if (!targetProperty) continue outer; if (sourceProperty === targetProperty) continue; // We compare the source property to the target in the context of a single discriminant type. const related = propertyRelatedTo(source, target, sourceProperty, targetProperty, _ => combination[i], /*reportErrors*/ false, IntersectionState.None, /*skipOptional*/ strictNullChecks || relation === comparableRelation); // If the target property could not be found, or if the properties were not related, // then this constituent is not a match. if (!related) { continue outer; } } pushIfUnique(matchingTypes, type, equateValues); hasMatch = true; } if (!hasMatch) { // We failed to match any type for this combination. return Ternary.False; } } // Compare the remaining non-discriminant properties of each match. let result = Ternary.True; for (const type of matchingTypes) { result &= propertiesRelatedTo(source, type, /*reportErrors*/ false, excludedProperties, /*optionalsOnly*/ false, IntersectionState.None); if (result) { result &= signaturesRelatedTo(source, type, SignatureKind.Call, /*reportStructuralErrors*/ false, IntersectionState.None); if (result) { result &= signaturesRelatedTo(source, type, SignatureKind.Construct, /*reportStructuralErrors*/ false, IntersectionState.None); if (result && !(isTupleType(source) && isTupleType(type))) { // Comparing numeric index types when both `source` and `type` are tuples is unnecessary as the // element types should be sufficiently covered by `propertiesRelatedTo`. It also causes problems // with index type assignability as the types for the excluded discriminants are still included // in the index type. result &= indexSignaturesRelatedTo(source, type, /*sourceIsPrimitive*/ false, /*reportStructuralErrors*/ false, IntersectionState.None); } } } if (!result) { return result; } } return result; } function excludeProperties(properties: Symbol[], excludedProperties: Set<__String> | undefined) { if (!excludedProperties || properties.length === 0) return properties; let result: Symbol[] | undefined; for (let i = 0; i < properties.length; i++) { if (!excludedProperties.has(properties[i].escapedName)) { if (result) { result.push(properties[i]); } } else if (!result) { result = properties.slice(0, i); } } return result || properties; } function isPropertySymbolTypeRelated(sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { const targetIsOptional = strictNullChecks && !!(getCheckFlags(targetProp) & CheckFlags.Partial); const effectiveTarget = addOptionality(getNonMissingTypeOfSymbol(targetProp), /*isProperty*/ false, targetIsOptional); const effectiveSource = getTypeOfSourceProperty(sourceProp); return isRelatedTo(effectiveSource, effectiveTarget, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); } function propertyRelatedTo(source: Type, target: Type, sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState, skipOptional: boolean): Ternary { const sourcePropFlags = getDeclarationModifierFlagsFromSymbol(sourceProp); const targetPropFlags = getDeclarationModifierFlagsFromSymbol(targetProp); if (sourcePropFlags & ModifierFlags.Private || targetPropFlags & ModifierFlags.Private) { if (sourceProp.valueDeclaration !== targetProp.valueDeclaration) { if (reportErrors) { if (sourcePropFlags & ModifierFlags.Private && targetPropFlags & ModifierFlags.Private) { reportError(Diagnostics.Types_have_separate_declarations_of_a_private_property_0, symbolToString(targetProp)); } else { reportError(Diagnostics.Property_0_is_private_in_type_1_but_not_in_type_2, symbolToString(targetProp), typeToString(sourcePropFlags & ModifierFlags.Private ? source : target), typeToString(sourcePropFlags & ModifierFlags.Private ? target : source)); } } return Ternary.False; } } else if (targetPropFlags & ModifierFlags.Protected) { if (!isValidOverrideOf(sourceProp, targetProp)) { if (reportErrors) { reportError(Diagnostics.Property_0_is_protected_but_type_1_is_not_a_class_derived_from_2, symbolToString(targetProp), typeToString(getDeclaringClass(sourceProp) || source), typeToString(getDeclaringClass(targetProp) || target)); } return Ternary.False; } } else if (sourcePropFlags & ModifierFlags.Protected) { if (reportErrors) { reportError(Diagnostics.Property_0_is_protected_in_type_1_but_public_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); } return Ternary.False; } // Ensure {readonly a: whatever} is not a subtype of {a: whatever}, // while {a: whatever} is a subtype of {readonly a: whatever}. // This ensures the subtype relationship is ordered, and preventing declaration order // from deciding which type "wins" in union subtype reduction. // They're still assignable to one another, since `readonly` doesn't affect assignability. // This is only applied during the strictSubtypeRelation -- currently used in subtype reduction if ( relation === strictSubtypeRelation && isReadonlySymbol(sourceProp) && !isReadonlySymbol(targetProp) ) { return Ternary.False; } // If the target comes from a partial union prop, allow `undefined` in the target type const related = isPropertySymbolTypeRelated(sourceProp, targetProp, getTypeOfSourceProperty, reportErrors, intersectionState); if (!related) { if (reportErrors) { reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(targetProp)); } return Ternary.False; } // When checking for comparability, be more lenient with optional properties. if (!skipOptional && sourceProp.flags & SymbolFlags.Optional && targetProp.flags & SymbolFlags.ClassMember && !(targetProp.flags & SymbolFlags.Optional)) { // TypeScript 1.0 spec (April 2014): 3.8.3 // S is a subtype of a type T, and T is a supertype of S if ... // S' and T are object types and, for each member M in T.. // M is a property and S' contains a property N where // if M is a required property, N is also a required property // (M - property in T) // (N - property in S) if (reportErrors) { reportError(Diagnostics.Property_0_is_optional_in_type_1_but_required_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); } return Ternary.False; } return related; } function reportUnmatchedProperty(source: Type, target: Type, unmatchedProperty: Symbol, requireOptionalProperties: boolean) { let shouldSkipElaboration = false; // give specific error in case where private names have the same description if (unmatchedProperty.valueDeclaration && isNamedDeclaration(unmatchedProperty.valueDeclaration) && isPrivateIdentifier(unmatchedProperty.valueDeclaration.name) && source.symbol && source.symbol.flags & SymbolFlags.Class) { const privateIdentifierDescription = unmatchedProperty.valueDeclaration.name.escapedText; const symbolTableKey = getSymbolNameForPrivateIdentifier(source.symbol, privateIdentifierDescription); if (symbolTableKey && getPropertyOfType(source, symbolTableKey)) { const sourceName = factory.getDeclarationName(source.symbol.valueDeclaration); const targetName = factory.getDeclarationName(target.symbol.valueDeclaration); reportError( Diagnostics.Property_0_in_type_1_refers_to_a_different_member_that_cannot_be_accessed_from_within_type_2, diagnosticName(privateIdentifierDescription), diagnosticName(sourceName.escapedText === "" ? anon : sourceName), diagnosticName(targetName.escapedText === "" ? anon : targetName)); return; } } const props = arrayFrom(getUnmatchedProperties(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false)); if (!headMessage || (headMessage.code !== Diagnostics.Class_0_incorrectly_implements_interface_1.code && headMessage.code !== Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass.code)) { shouldSkipElaboration = true; // Retain top-level error for interface implementing issues, otherwise omit it } if (props.length === 1) { const propName = symbolToString(unmatchedProperty, /*enclosingDeclaration*/ undefined, SymbolFlags.None, SymbolFormatFlags.AllowAnyNodeKind | SymbolFormatFlags.WriteComputedProps); reportError(Diagnostics.Property_0_is_missing_in_type_1_but_required_in_type_2, propName, ...getTypeNamesForErrorDisplay(source, target)); if (length(unmatchedProperty.declarations)) { associateRelatedInfo(createDiagnosticForNode(unmatchedProperty.declarations![0], Diagnostics._0_is_declared_here, propName)); } if (shouldSkipElaboration && errorInfo) { overrideNextErrorInfo++; } } else if (tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ false)) { if (props.length > 5) { // arbitrary cutoff for too-long list form reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2_and_3_more, typeToString(source), typeToString(target), map(props.slice(0, 4), p => symbolToString(p)).join(", "), props.length - 4); } else { reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2, typeToString(source), typeToString(target), map(props, p => symbolToString(p)).join(", ")); } if (shouldSkipElaboration && errorInfo) { overrideNextErrorInfo++; } } // No array like or unmatched property error - just issue top level error (errorInfo = undefined) } function propertiesRelatedTo(source: Type, target: Type, reportErrors: boolean, excludedProperties: Set<__String> | undefined, optionalsOnly: boolean, intersectionState: IntersectionState): Ternary { if (relation === identityRelation) { return propertiesIdenticalTo(source, target, excludedProperties); } let result = Ternary.True; if (isTupleType(target)) { if (isArrayOrTupleType(source)) { if (!target.target.readonly && (isReadonlyArrayType(source) || isTupleType(source) && source.target.readonly)) { return Ternary.False; } const sourceArity = getTypeReferenceArity(source); const targetArity = getTypeReferenceArity(target); const sourceRestFlag = isTupleType(source) ? source.target.combinedFlags & ElementFlags.Rest : ElementFlags.Rest; const targetRestFlag = target.target.combinedFlags & ElementFlags.Rest; const sourceMinLength = isTupleType(source) ? source.target.minLength : 0; const targetMinLength = target.target.minLength; if (!sourceRestFlag && sourceArity < targetMinLength) { if (reportErrors) { reportError(Diagnostics.Source_has_0_element_s_but_target_requires_1, sourceArity, targetMinLength); } return Ternary.False; } if (!targetRestFlag && targetArity < sourceMinLength) { if (reportErrors) { reportError(Diagnostics.Source_has_0_element_s_but_target_allows_only_1, sourceMinLength, targetArity); } return Ternary.False; } if (!targetRestFlag && (sourceRestFlag || targetArity < sourceArity)) { if (reportErrors) { if (sourceMinLength < targetMinLength) { reportError(Diagnostics.Target_requires_0_element_s_but_source_may_have_fewer, targetMinLength); } else { reportError(Diagnostics.Target_allows_only_0_element_s_but_source_may_have_more, targetArity); } } return Ternary.False; } const sourceTypeArguments = getTypeArguments(source); const targetTypeArguments = getTypeArguments(target); const targetStartCount = getStartElementCount(target.target, ElementFlags.NonRest); const targetEndCount = getEndElementCount(target.target, ElementFlags.NonRest); const targetHasRestElement = target.target.hasRestElement; let canExcludeDiscriminants = !!excludedProperties; for (let sourcePosition = 0; sourcePosition < sourceArity; sourcePosition++) { const sourceFlags = isTupleType(source) ? source.target.elementFlags[sourcePosition] : ElementFlags.Rest; const sourcePositionFromEnd = sourceArity - 1 - sourcePosition; const targetPosition = targetHasRestElement && sourcePosition >= targetStartCount ? targetArity - 1 - Math.min(sourcePositionFromEnd, targetEndCount) : sourcePosition; const targetFlags = target.target.elementFlags[targetPosition]; if (targetFlags & ElementFlags.Variadic && !(sourceFlags & ElementFlags.Variadic)) { if (reportErrors) { reportError(Diagnostics.Source_provides_no_match_for_variadic_element_at_position_0_in_target, targetPosition); } return Ternary.False; } if (sourceFlags & ElementFlags.Variadic && !(targetFlags & ElementFlags.Variable)) { if (reportErrors) { reportError(Diagnostics.Variadic_element_at_position_0_in_source_does_not_match_element_at_position_1_in_target, sourcePosition, targetPosition); } return Ternary.False; } if (targetFlags & ElementFlags.Required && !(sourceFlags & ElementFlags.Required)) { if (reportErrors) { reportError(Diagnostics.Source_provides_no_match_for_required_element_at_position_0_in_target, targetPosition); } return Ternary.False; } // We can only exclude discriminant properties if we have not yet encountered a variable-length element. if (canExcludeDiscriminants) { if (sourceFlags & ElementFlags.Variable || targetFlags & ElementFlags.Variable) { canExcludeDiscriminants = false; } if (canExcludeDiscriminants && excludedProperties?.has(("" + sourcePosition) as __String)) { continue; } } const sourceType = removeMissingType(sourceTypeArguments[sourcePosition], !!(sourceFlags & targetFlags & ElementFlags.Optional)); const targetType = targetTypeArguments[targetPosition]; const targetCheckType = sourceFlags & ElementFlags.Variadic && targetFlags & ElementFlags.Rest ? createArrayType(targetType) : removeMissingType(targetType, !!(targetFlags & ElementFlags.Optional)); const related = isRelatedTo(sourceType, targetCheckType, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); if (!related) { if (reportErrors && (targetArity > 1 || sourceArity > 1)) { if (targetHasRestElement && sourcePosition >= targetStartCount && sourcePositionFromEnd >= targetEndCount && targetStartCount !== sourceArity - targetEndCount - 1) { reportIncompatibleError(Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, targetStartCount, sourceArity - targetEndCount - 1, targetPosition); } else { reportIncompatibleError(Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, sourcePosition, targetPosition); } } return Ternary.False; } result &= related; } return result; } if (target.target.combinedFlags & ElementFlags.Variable) { return Ternary.False; } } const requireOptionalProperties = (relation === subtypeRelation || relation === strictSubtypeRelation) && !isObjectLiteralType(source) && !isEmptyArrayLiteralType(source) && !isTupleType(source); const unmatchedProperty = getUnmatchedProperty(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false); if (unmatchedProperty) { if (reportErrors && shouldReportUnmatchedPropertyError(source, target)) { reportUnmatchedProperty(source, target, unmatchedProperty, requireOptionalProperties); } return Ternary.False; } if (isObjectLiteralType(target)) { for (const sourceProp of excludeProperties(getPropertiesOfType(source), excludedProperties)) { if (!getPropertyOfObjectType(target, sourceProp.escapedName)) { const sourceType = getTypeOfSymbol(sourceProp); if (!(sourceType.flags & TypeFlags.Undefined)) { if (reportErrors) { reportError(Diagnostics.Property_0_does_not_exist_on_type_1, symbolToString(sourceProp), typeToString(target)); } return Ternary.False; } } } } // We only call this for union target types when we're attempting to do excess property checking - in those cases, we want to get _all possible props_ // from the target union, across all members const properties = getPropertiesOfType(target); const numericNamesOnly = isTupleType(source) && isTupleType(target); for (const targetProp of excludeProperties(properties, excludedProperties)) { const name = targetProp.escapedName; if (!(targetProp.flags & SymbolFlags.Prototype) && (!numericNamesOnly || isNumericLiteralName(name) || name === "length") && (!optionalsOnly || targetProp.flags & SymbolFlags.Optional)) { const sourceProp = getPropertyOfType(source, name); if (sourceProp && sourceProp !== targetProp) { const related = propertyRelatedTo(source, target, sourceProp, targetProp, getNonMissingTypeOfSymbol, reportErrors, intersectionState, relation === comparableRelation); if (!related) { return Ternary.False; } result &= related; } } } return result; } function propertiesIdenticalTo(source: Type, target: Type, excludedProperties: Set<__String> | undefined): Ternary { if (!(source.flags & TypeFlags.Object && target.flags & TypeFlags.Object)) { return Ternary.False; } const sourceProperties = excludeProperties(getPropertiesOfObjectType(source), excludedProperties); const targetProperties = excludeProperties(getPropertiesOfObjectType(target), excludedProperties); if (sourceProperties.length !== targetProperties.length) { return Ternary.False; } let result = Ternary.True; for (const sourceProp of sourceProperties) { const targetProp = getPropertyOfObjectType(target, sourceProp.escapedName); if (!targetProp) { return Ternary.False; } const related = compareProperties(sourceProp, targetProp, isRelatedTo); if (!related) { return Ternary.False; } result &= related; } return result; } function signaturesRelatedTo(source: Type, target: Type, kind: SignatureKind, reportErrors: boolean, intersectionState: IntersectionState): Ternary { if (relation === identityRelation) { return signaturesIdenticalTo(source, target, kind); } if (target === anyFunctionType || source === anyFunctionType) { return Ternary.True; } const sourceIsJSConstructor = source.symbol && isJSConstructor(source.symbol.valueDeclaration); const targetIsJSConstructor = target.symbol && isJSConstructor(target.symbol.valueDeclaration); const sourceSignatures = getSignaturesOfType(source, (sourceIsJSConstructor && kind === SignatureKind.Construct) ? SignatureKind.Call : kind); const targetSignatures = getSignaturesOfType(target, (targetIsJSConstructor && kind === SignatureKind.Construct) ? SignatureKind.Call : kind); if (kind === SignatureKind.Construct && sourceSignatures.length && targetSignatures.length) { const sourceIsAbstract = !!(sourceSignatures[0].flags & SignatureFlags.Abstract); const targetIsAbstract = !!(targetSignatures[0].flags & SignatureFlags.Abstract); if (sourceIsAbstract && !targetIsAbstract) { // An abstract constructor type is not assignable to a non-abstract constructor type // as it would otherwise be possible to new an abstract class. Note that the assignability // check we perform for an extends clause excludes construct signatures from the target, // so this check never proceeds. if (reportErrors) { reportError(Diagnostics.Cannot_assign_an_abstract_constructor_type_to_a_non_abstract_constructor_type); } return Ternary.False; } if (!constructorVisibilitiesAreCompatible(sourceSignatures[0], targetSignatures[0], reportErrors)) { return Ternary.False; } } let result = Ternary.True; const incompatibleReporter = kind === SignatureKind.Construct ? reportIncompatibleConstructSignatureReturn : reportIncompatibleCallSignatureReturn; const sourceObjectFlags = getObjectFlags(source); const targetObjectFlags = getObjectFlags(target); if (sourceObjectFlags & ObjectFlags.Instantiated && targetObjectFlags & ObjectFlags.Instantiated && source.symbol === target.symbol || sourceObjectFlags & ObjectFlags.Reference && targetObjectFlags & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target) { // We have instantiations of the same anonymous type (which typically will be the type of a // method). Simply do a pairwise comparison of the signatures in the two signature lists instead // of the much more expensive N * M comparison matrix we explore below. We erase type parameters // as they are known to always be the same. for (let i = 0; i < targetSignatures.length; i++) { const related = signatureRelatedTo(sourceSignatures[i], targetSignatures[i], /*erase*/ true, reportErrors, intersectionState, incompatibleReporter(sourceSignatures[i], targetSignatures[i])); if (!related) { return Ternary.False; } result &= related; } } else if (sourceSignatures.length === 1 && targetSignatures.length === 1) { // For simple functions (functions with a single signature) we only erase type parameters for // the comparable relation. Otherwise, if the source signature is generic, we instantiate it // in the context of the target signature before checking the relationship. Ideally we'd do // this regardless of the number of signatures, but the potential costs are prohibitive due // to the quadratic nature of the logic below. const eraseGenerics = relation === comparableRelation || !!compilerOptions.noStrictGenericChecks; const sourceSignature = first(sourceSignatures); const targetSignature = first(targetSignatures); result = signatureRelatedTo(sourceSignature, targetSignature, eraseGenerics, reportErrors, intersectionState, incompatibleReporter(sourceSignature, targetSignature)); if (!result && reportErrors && kind === SignatureKind.Construct && (sourceObjectFlags & targetObjectFlags) && (targetSignature.declaration?.kind === SyntaxKind.Constructor || sourceSignature.declaration?.kind === SyntaxKind.Constructor)) { const constructSignatureToString = (signature: Signature) => signatureToString(signature, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrowStyleSignature, kind); reportError(Diagnostics.Type_0_is_not_assignable_to_type_1, constructSignatureToString(sourceSignature), constructSignatureToString(targetSignature)); reportError(Diagnostics.Types_of_construct_signatures_are_incompatible); return result; } } else { outer: for (const t of targetSignatures) { const saveErrorInfo = captureErrorCalculationState(); // Only elaborate errors from the first failure let shouldElaborateErrors = reportErrors; for (const s of sourceSignatures) { const related = signatureRelatedTo(s, t, /*erase*/ true, shouldElaborateErrors, intersectionState, incompatibleReporter(s, t)); if (related) { result &= related; resetErrorInfo(saveErrorInfo); continue outer; } shouldElaborateErrors = false; } if (shouldElaborateErrors) { reportError(Diagnostics.Type_0_provides_no_match_for_the_signature_1, typeToString(source), signatureToString(t, /*enclosingDeclaration*/ undefined, /*flags*/ undefined, kind)); } return Ternary.False; } } return result; } function shouldReportUnmatchedPropertyError(source: Type, target: Type): boolean { const typeCallSignatures = getSignaturesOfStructuredType(source, SignatureKind.Call); const typeConstructSignatures = getSignaturesOfStructuredType(source, SignatureKind.Construct); const typeProperties = getPropertiesOfObjectType(source); if ((typeCallSignatures.length || typeConstructSignatures.length) && !typeProperties.length) { if ((getSignaturesOfType(target, SignatureKind.Call).length && typeCallSignatures.length) || (getSignaturesOfType(target, SignatureKind.Construct).length && typeConstructSignatures.length)) { return true; // target has similar signature kinds to source, still focus on the unmatched property } return false; } return true; } function reportIncompatibleCallSignatureReturn(siga: Signature, sigb: Signature) { if (siga.parameters.length === 0 && sigb.parameters.length === 0) { return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); } return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); } function reportIncompatibleConstructSignatureReturn(siga: Signature, sigb: Signature) { if (siga.parameters.length === 0 && sigb.parameters.length === 0) { return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); } return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); } /** * See signatureAssignableTo, compareSignaturesIdentical */ function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, intersectionState: IntersectionState, incompatibleReporter: (source: Type, target: Type) => void): Ternary { const checkMode = relation === subtypeRelation ? SignatureCheckMode.StrictTopSignature : relation === strictSubtypeRelation ? SignatureCheckMode.StrictTopSignature | SignatureCheckMode.StrictArity : SignatureCheckMode.None; return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target, checkMode, reportErrors, reportError, incompatibleReporter, isRelatedToWorker, reportUnreliableMapper); function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { return isRelatedTo(source, target, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); } } function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary { const sourceSignatures = getSignaturesOfType(source, kind); const targetSignatures = getSignaturesOfType(target, kind); if (sourceSignatures.length !== targetSignatures.length) { return Ternary.False; } let result = Ternary.True; for (let i = 0; i < sourceSignatures.length; i++) { const related = compareSignaturesIdentical(sourceSignatures[i], targetSignatures[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, isRelatedTo); if (!related) { return Ternary.False; } result &= related; } return result; } function membersRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { let result = Ternary.True; const keyType = targetInfo.keyType; const props = source.flags & TypeFlags.Intersection ? getPropertiesOfUnionOrIntersectionType(source as IntersectionType) : getPropertiesOfObjectType(source); for (const prop of props) { // Skip over ignored JSX and symbol-named members if (isIgnoredJsxProperty(source, prop)) { continue; } if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), keyType)) { const propType = getNonMissingTypeOfSymbol(prop); const type = exactOptionalPropertyTypes || propType.flags & TypeFlags.Undefined || keyType === numberType || !(prop.flags & SymbolFlags.Optional) ? propType : getTypeWithFacts(propType, TypeFacts.NEUndefined); const related = isRelatedTo(type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); if (!related) { if (reportErrors) { reportError(Diagnostics.Property_0_is_incompatible_with_index_signature, symbolToString(prop)); } return Ternary.False; } result &= related; } } for (const info of getIndexInfosOfType(source)) { if (isApplicableIndexType(info.keyType, keyType)) { const related = indexInfoRelatedTo(info, targetInfo, reportErrors, intersectionState); if (!related) { return Ternary.False; } result &= related; } } return result; } function indexInfoRelatedTo(sourceInfo: IndexInfo, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState) { const related = isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); if (!related && reportErrors) { if (sourceInfo.keyType === targetInfo.keyType) { reportError(Diagnostics._0_index_signatures_are_incompatible, typeToString(sourceInfo.keyType)); } else { reportError(Diagnostics._0_and_1_index_signatures_are_incompatible, typeToString(sourceInfo.keyType), typeToString(targetInfo.keyType)); } } return related; } function indexSignaturesRelatedTo(source: Type, target: Type, sourceIsPrimitive: boolean, reportErrors: boolean, intersectionState: IntersectionState): Ternary { if (relation === identityRelation) { return indexSignaturesIdenticalTo(source, target); } const indexInfos = getIndexInfosOfType(target); const targetHasStringIndex = some(indexInfos, info => info.keyType === stringType); let result = Ternary.True; for (const targetInfo of indexInfos) { const related = relation !== strictSubtypeRelation && !sourceIsPrimitive && targetHasStringIndex && targetInfo.type.flags & TypeFlags.Any ? Ternary.True : isGenericMappedType(source) && targetHasStringIndex ? isRelatedTo(getTemplateTypeFromMappedType(source), targetInfo.type, RecursionFlags.Both, reportErrors) : typeRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); if (!related) { return Ternary.False; } result &= related; } return result; } function typeRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); if (sourceInfo) { return indexInfoRelatedTo(sourceInfo, targetInfo, reportErrors, intersectionState); } // Intersection constituents are never considered to have an inferred index signature. Also, in the strict subtype relation, // only fresh object literals are considered to have inferred index signatures. This ensures { [x: string]: xxx } <: {} but // not vice-versa. Without this rule, those types would be mutual strict subtypes. if (!(intersectionState & IntersectionState.Source) && (relation !== strictSubtypeRelation || getObjectFlags(source) & ObjectFlags.FreshLiteral) && isObjectTypeWithInferableIndex(source)) { return membersRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); } if (reportErrors) { reportError(Diagnostics.Index_signature_for_type_0_is_missing_in_type_1, typeToString(targetInfo.keyType), typeToString(source)); } return Ternary.False; } function indexSignaturesIdenticalTo(source: Type, target: Type): Ternary { const sourceInfos = getIndexInfosOfType(source); const targetInfos = getIndexInfosOfType(target); if (sourceInfos.length !== targetInfos.length) { return Ternary.False; } for (const targetInfo of targetInfos) { const sourceInfo = getIndexInfoOfType(source, targetInfo.keyType); if (!(sourceInfo && isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both) && sourceInfo.isReadonly === targetInfo.isReadonly)) { return Ternary.False; } } return Ternary.True; } function constructorVisibilitiesAreCompatible(sourceSignature: Signature, targetSignature: Signature, reportErrors: boolean) { if (!sourceSignature.declaration || !targetSignature.declaration) { return true; } const sourceAccessibility = getSelectedEffectiveModifierFlags(sourceSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); const targetAccessibility = getSelectedEffectiveModifierFlags(targetSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); // A public, protected and private signature is assignable to a private signature. if (targetAccessibility === ModifierFlags.Private) { return true; } // A public and protected signature is assignable to a protected signature. if (targetAccessibility === ModifierFlags.Protected && sourceAccessibility !== ModifierFlags.Private) { return true; } // Only a public signature is assignable to public signature. if (targetAccessibility !== ModifierFlags.Protected && !sourceAccessibility) { return true; } if (reportErrors) { reportError(Diagnostics.Cannot_assign_a_0_constructor_type_to_a_1_constructor_type, visibilityToString(sourceAccessibility), visibilityToString(targetAccessibility)); } return false; } } function typeCouldHaveTopLevelSingletonTypes(type: Type): boolean { // Okay, yes, 'boolean' is a union of 'true | false', but that's not useful // in error reporting scenarios. If you need to use this function but that detail matters, // feel free to add a flag. if (type.flags & TypeFlags.Boolean) { return false; } if (type.flags & TypeFlags.UnionOrIntersection) { return !!forEach((type as IntersectionType).types, typeCouldHaveTopLevelSingletonTypes); } if (type.flags & TypeFlags.Instantiable) { const constraint = getConstraintOfType(type); if (constraint && constraint !== type) { return typeCouldHaveTopLevelSingletonTypes(constraint); } } return isUnitType(type) || !!(type.flags & TypeFlags.TemplateLiteral) || !!(type.flags & TypeFlags.StringMapping); } function getExactOptionalUnassignableProperties(source: Type, target: Type) { if (isTupleType(source) && isTupleType(target)) return emptyArray; return getPropertiesOfType(target) .filter(targetProp => isExactOptionalPropertyMismatch(getTypeOfPropertyOfType(source, targetProp.escapedName), getTypeOfSymbol(targetProp))); } function isExactOptionalPropertyMismatch(source: Type | undefined, target: Type | undefined) { return !!source && !!target && maybeTypeOfKind(source, TypeFlags.Undefined) && !!containsMissingType(target); } function getExactOptionalProperties(type: Type) { return getPropertiesOfType(type).filter(targetProp => containsMissingType(getTypeOfSymbol(targetProp))); } function getBestMatchingType(source: Type, target: UnionOrIntersectionType, isRelatedTo = compareTypesAssignable) { return findMatchingDiscriminantType(source, target, isRelatedTo, /*skipPartial*/ true) || findMatchingTypeReferenceOrTypeAliasReference(source, target) || findBestTypeForObjectLiteral(source, target) || findBestTypeForInvokable(source, target) || findMostOverlappyType(source, target); } function discriminateTypeByDiscriminableItems(target: UnionType, discriminators: [() => Type, __String][], related: (source: Type, target: Type) => boolean | Ternary, defaultValue?: undefined, skipPartial?: boolean): Type | undefined; function discriminateTypeByDiscriminableItems(target: UnionType, discriminators: [() => Type, __String][], related: (source: Type, target: Type) => boolean | Ternary, defaultValue: Type, skipPartial?: boolean): Type; function discriminateTypeByDiscriminableItems(target: UnionType, discriminators: [() => Type, __String][], related: (source: Type, target: Type) => boolean | Ternary, defaultValue?: Type, skipPartial?: boolean) { // undefined=unknown, true=discriminated, false=not discriminated // The state of each type progresses from left to right. Discriminated types stop at 'true'. const discriminable = target.types.map(_ => undefined) as (boolean | undefined)[]; for (const [getDiscriminatingType, propertyName] of discriminators) { const targetProp = getUnionOrIntersectionProperty(target, propertyName); if (skipPartial && targetProp && getCheckFlags(targetProp) & CheckFlags.ReadPartial) { continue; } let i = 0; for (const type of target.types) { const targetType = getTypeOfPropertyOfType(type, propertyName); if (targetType && related(getDiscriminatingType(), targetType)) { discriminable[i] = discriminable[i] === undefined ? true : discriminable[i]; } else { discriminable[i] = false; } i++; } } const match = discriminable.indexOf(/*searchElement*/ true); if (match === -1) { return defaultValue; } // make sure exactly 1 matches before returning it let nextMatch = discriminable.indexOf(/*searchElement*/ true, match + 1); while (nextMatch !== -1) { if (!isTypeIdenticalTo(target.types[match], target.types[nextMatch])) { return defaultValue; } nextMatch = discriminable.indexOf(/*searchElement*/ true, nextMatch + 1); } return target.types[match]; } /** * A type is 'weak' if it is an object type with at least one optional property * and no required properties, call/construct signatures or index signatures */ function isWeakType(type: Type): boolean { if (type.flags & TypeFlags.Object) { const resolved = resolveStructuredTypeMembers(type as ObjectType); return resolved.callSignatures.length === 0 && resolved.constructSignatures.length === 0 && resolved.indexInfos.length === 0 && resolved.properties.length > 0 && every(resolved.properties, p => !!(p.flags & SymbolFlags.Optional)); } if (type.flags & TypeFlags.Intersection) { return every((type as IntersectionType).types, isWeakType); } return false; } function hasCommonProperties(source: Type, target: Type, isComparingJsxAttributes: boolean) { for (const prop of getPropertiesOfType(source)) { if (isKnownProperty(target, prop.escapedName, isComparingJsxAttributes)) { return true; } } return false; } function getVariances(type: GenericType): VarianceFlags[] { // Arrays and tuples are known to be covariant, no need to spend time computing this. return type === globalArrayType || type === globalReadonlyArrayType || type.objectFlags & ObjectFlags.Tuple ? arrayVariances : getVariancesWorker(type.symbol, type.typeParameters); } function getAliasVariances(symbol: Symbol) { return getVariancesWorker(symbol, getSymbolLinks(symbol).typeParameters); } // Return an array containing the variance of each type parameter. The variance is effectively // a digest of the type comparisons that occur for each type argument when instantiations of the // generic type are structurally compared. We infer the variance information by comparing // instantiations of the generic type for type arguments with known relations. The function // returns the emptyArray singleton when invoked recursively for the given generic type. function getVariancesWorker(symbol: Symbol, typeParameters: readonly TypeParameter[] = emptyArray): VarianceFlags[] { const links = getSymbolLinks(symbol); if (!links.variances) { tracing?.push(tracing.Phase.CheckTypes, "getVariancesWorker", { arity: typeParameters.length, id: getTypeId(getDeclaredTypeOfSymbol(symbol)) }); links.variances = emptyArray; const variances = []; for (const tp of typeParameters) { const modifiers = getTypeParameterModifiers(tp); let variance = modifiers & ModifierFlags.Out ? modifiers & ModifierFlags.In ? VarianceFlags.Invariant : VarianceFlags.Covariant : modifiers & ModifierFlags.In ? VarianceFlags.Contravariant : undefined; if (variance === undefined) { let unmeasurable = false; let unreliable = false; const oldHandler = outofbandVarianceMarkerHandler; outofbandVarianceMarkerHandler = (onlyUnreliable) => onlyUnreliable ? unreliable = true : unmeasurable = true; // We first compare instantiations where the type parameter is replaced with // marker types that have a known subtype relationship. From this we can infer // invariance, covariance, contravariance or bivariance. const typeWithSuper = createMarkerType(symbol, tp, markerSuperType); const typeWithSub = createMarkerType(symbol, tp, markerSubType); variance = (isTypeAssignableTo(typeWithSub, typeWithSuper) ? VarianceFlags.Covariant : 0) | (isTypeAssignableTo(typeWithSuper, typeWithSub) ? VarianceFlags.Contravariant : 0); // If the instantiations appear to be related bivariantly it may be because the // type parameter is independent (i.e. it isn't witnessed anywhere in the generic // type). To determine this we compare instantiations where the type parameter is // replaced with marker types that are known to be unrelated. if (variance === VarianceFlags.Bivariant && isTypeAssignableTo(createMarkerType(symbol, tp, markerOtherType), typeWithSuper)) { variance = VarianceFlags.Independent; } outofbandVarianceMarkerHandler = oldHandler; if (unmeasurable || unreliable) { if (unmeasurable) { variance |= VarianceFlags.Unmeasurable; } if (unreliable) { variance |= VarianceFlags.Unreliable; } } } variances.push(variance); } links.variances = variances; tracing?.pop({ variances: variances.map(Debug.formatVariance) }); } return links.variances; } function createMarkerType(symbol: Symbol, source: TypeParameter, target: Type) { const mapper = makeUnaryTypeMapper(source, target); const type = getDeclaredTypeOfSymbol(symbol); if (isErrorType(type)) { return type; } const result = symbol.flags & SymbolFlags.TypeAlias ? getTypeAliasInstantiation(symbol, instantiateTypes(getSymbolLinks(symbol).typeParameters!, mapper)) : createTypeReference(type as GenericType, instantiateTypes((type as GenericType).typeParameters, mapper)); markerTypes.add(getTypeId(result)); return result; } function isMarkerType(type: Type) { return markerTypes.has(getTypeId(type)); } function getTypeParameterModifiers(tp: TypeParameter): ModifierFlags { return reduceLeft(tp.symbol?.declarations, (modifiers, d) => modifiers | getEffectiveModifierFlags(d), ModifierFlags.None) & (ModifierFlags.In | ModifierFlags.Out | ModifierFlags.Const); } // Return true if the given type reference has a 'void' type argument for a covariant type parameter. // See comment at call in recursiveTypeRelatedTo for when this case matters. function hasCovariantVoidArgument(typeArguments: readonly Type[], variances: VarianceFlags[]): boolean { for (let i = 0; i < variances.length; i++) { if ((variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Covariant && typeArguments[i].flags & TypeFlags.Void) { return true; } } return false; } function isUnconstrainedTypeParameter(type: Type) { return type.flags & TypeFlags.TypeParameter && !getConstraintOfTypeParameter(type as TypeParameter); } function isNonDeferredTypeReference(type: Type): type is TypeReference { return !!(getObjectFlags(type) & ObjectFlags.Reference) && !(type as TypeReference).node; } function isTypeReferenceWithGenericArguments(type: Type): boolean { return isNonDeferredTypeReference(type) && some(getTypeArguments(type), t => !!(t.flags & TypeFlags.TypeParameter) || isTypeReferenceWithGenericArguments(t)); } function getGenericTypeReferenceRelationKey(source: TypeReference, target: TypeReference, postFix: string, ignoreConstraints: boolean) { const typeParameters: Type[] = []; let constraintMarker = ""; const sourceId = getTypeReferenceId(source, 0); const targetId = getTypeReferenceId(target, 0); return `${constraintMarker}${sourceId},${targetId}${postFix}`; // getTypeReferenceId(A) returns "111=0-12=1" // where A.id=111 and number.id=12 function getTypeReferenceId(type: TypeReference, depth = 0) { let result = "" + type.target.id; for (const t of getTypeArguments(type)) { if (t.flags & TypeFlags.TypeParameter) { if (ignoreConstraints || isUnconstrainedTypeParameter(t)) { let index = typeParameters.indexOf(t); if (index < 0) { index = typeParameters.length; typeParameters.push(t); } result += "=" + index; continue; } // We mark type references that reference constrained type parameters such that we know to obtain // and look for a "broadest equivalent key" in the cache. constraintMarker = "*"; } else if (depth < 4 && isTypeReferenceWithGenericArguments(t)) { result += "<" + getTypeReferenceId(t as TypeReference, depth + 1) + ">"; continue; } result += "-" + t.id; } return result; } } /** * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters. * For other cases, the types ids are used. */ function getRelationKey(source: Type, target: Type, intersectionState: IntersectionState, relation: Map, ignoreConstraints: boolean) { if (relation === identityRelation && source.id > target.id) { const temp = source; source = target; target = temp; } const postFix = intersectionState ? ":" + intersectionState : ""; return isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target) ? getGenericTypeReferenceRelationKey(source as TypeReference, target as TypeReference, postFix, ignoreConstraints) : `${source.id},${target.id}${postFix}`; } // Invoke the callback for each underlying property symbol of the given symbol and return the first // value that isn't undefined. function forEachProperty(prop: Symbol, callback: (p: Symbol) => T): T | undefined { if (getCheckFlags(prop) & CheckFlags.Synthetic) { // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.Synthetic for (const t of (prop as TransientSymbol).links.containingType!.types) { const p = getPropertyOfType(t, prop.escapedName); const result = p && forEachProperty(p, callback); if (result) { return result; } } return undefined; } return callback(prop); } // Return the declaring class type of a property or undefined if property not declared in class function getDeclaringClass(prop: Symbol) { return prop.parent && prop.parent.flags & SymbolFlags.Class ? getDeclaredTypeOfSymbol(getParentOfSymbol(prop)!) as InterfaceType : undefined; } // Return the inherited type of the given property or undefined if property doesn't exist in a base class. function getTypeOfPropertyInBaseClass(property: Symbol) { const classType = getDeclaringClass(property); const baseClassType = classType && getBaseTypes(classType)[0]; return baseClassType && getTypeOfPropertyOfType(baseClassType, property.escapedName); } // Return true if some underlying source property is declared in a class that derives // from the given base class. function isPropertyInClassDerivedFrom(prop: Symbol, baseClass: Type | undefined) { return forEachProperty(prop, sp => { const sourceClass = getDeclaringClass(sp); return sourceClass ? hasBaseType(sourceClass, baseClass) : false; }); } // Return true if source property is a valid override of protected parts of target property. function isValidOverrideOf(sourceProp: Symbol, targetProp: Symbol) { return !forEachProperty(targetProp, tp => getDeclarationModifierFlagsFromSymbol(tp) & ModifierFlags.Protected ? !isPropertyInClassDerivedFrom(sourceProp, getDeclaringClass(tp)) : false); } // Return true if the given class derives from each of the declaring classes of the protected // constituents of the given property. function isClassDerivedFromDeclaringClasses(checkClass: T, prop: Symbol, writing: boolean) { return forEachProperty(prop, p => getDeclarationModifierFlagsFromSymbol(p, writing) & ModifierFlags.Protected ? !hasBaseType(checkClass, getDeclaringClass(p)) : false) ? undefined : checkClass; } // Return true if the given type is deeply nested. We consider this to be the case when structural type comparisons // for maxDepth or more occurrences or instantiations of the same type have been recorded on the given stack. The // "sameness" of instantiations is determined by the getRecursionIdentity function. An intersection is considered // deeply nested if any constituent of the intersection is deeply nested. It is possible, though highly unlikely, for // the deeply nested check to be true in a situation where a chain of instantiations is not infinitely expanding. // Effectively, we will generate a false positive when two types are structurally equal to at least maxDepth levels, // but unequal at some level beyond that. // In addition, this will also detect when an indexed access has been chained off of maxDepth more times (which is // essentially the dual of the structural comparison), and likewise mark the type as deeply nested, potentially adding // false positives for finite but deeply expanding indexed accesses (eg, for `Q[P1][P2][P3][P4][P5]`). // It also detects when a recursive type reference has expanded maxDepth or more times, e.g. if the true branch of // `type A = null extends T ? [A>] : [T]` // has expanded into `[A>>>>>]`. In such cases we need // to terminate the expansion, and we do so here. function isDeeplyNestedType(type: Type, stack: Type[], depth: number, maxDepth = 3): boolean { if (depth >= maxDepth) { if (type.flags & TypeFlags.Intersection) { return some((type as IntersectionType).types, t => isDeeplyNestedType(t, stack, depth, maxDepth)); } const identity = getRecursionIdentity(type); let count = 0; let lastTypeId = 0; for (let i = 0; i < depth; i++) { const t = stack[i]; if (t.flags & TypeFlags.Intersection ? some((t as IntersectionType).types, u => getRecursionIdentity(u) === identity) : getRecursionIdentity(t) === identity) { // We only count occurrences with a higher type id than the previous occurrence, since higher // type ids are an indicator of newer instantiations caused by recursion. if (t.id >= lastTypeId) { count++; if (count >= maxDepth) { return true; } } lastTypeId = t.id; } } } return false; } // The recursion identity of a type is an object identity that is shared among multiple instantiations of the type. // We track recursion identities in order to identify deeply nested and possibly infinite type instantiations with // the same origin. For example, when type parameters are in scope in an object type such as { x: T }, all // instantiations of that type have the same recursion identity. The default recursion identity is the object // identity of the type, meaning that every type is unique. Generally, types with constituents that could circularly // reference the type have a recursion identity that differs from the object identity. function getRecursionIdentity(type: Type): object { // Object and array literals are known not to contain recursive references and don't need a recursion identity. if (type.flags & TypeFlags.Object && !isObjectOrArrayLiteralType(type)) { if (getObjectFlags(type) && ObjectFlags.Reference && (type as TypeReference).node) { // Deferred type references are tracked through their associated AST node. This gives us finer // granularity than using their associated target because each manifest type reference has a // unique AST node. return (type as TypeReference).node!; } if (type.symbol && !(getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol.flags & SymbolFlags.Class)) { // We track all object types that have an associated symbol (representing the origin of the type), but // exclude the static side of classes from this check since it shares its symbol with the instance side. return type.symbol; } if (isTupleType(type)) { // Tuple types are tracked through their target type return type.target; } } if (type.flags & TypeFlags.TypeParameter) { return type.symbol; } if (type.flags & TypeFlags.IndexedAccess) { // Identity is the leftmost object type in a chain of indexed accesses, eg, in A[P][Q] it is A do { type = (type as IndexedAccessType).objectType; } while (type.flags & TypeFlags.IndexedAccess); return type; } if (type.flags & TypeFlags.Conditional) { // The root object represents the origin of the conditional type return (type as ConditionalType).root; } return type; } function isPropertyIdenticalTo(sourceProp: Symbol, targetProp: Symbol): boolean { return compareProperties(sourceProp, targetProp, compareTypesIdentical) !== Ternary.False; } function compareProperties(sourceProp: Symbol, targetProp: Symbol, compareTypes: (source: Type, target: Type) => Ternary): Ternary { // Two members are considered identical when // - they are public properties with identical names, optionality, and types, // - they are private or protected properties originating in the same declaration and having identical types if (sourceProp === targetProp) { return Ternary.True; } const sourcePropAccessibility = getDeclarationModifierFlagsFromSymbol(sourceProp) & ModifierFlags.NonPublicAccessibilityModifier; const targetPropAccessibility = getDeclarationModifierFlagsFromSymbol(targetProp) & ModifierFlags.NonPublicAccessibilityModifier; if (sourcePropAccessibility !== targetPropAccessibility) { return Ternary.False; } if (sourcePropAccessibility) { if (getTargetSymbol(sourceProp) !== getTargetSymbol(targetProp)) { return Ternary.False; } } else { if ((sourceProp.flags & SymbolFlags.Optional) !== (targetProp.flags & SymbolFlags.Optional)) { return Ternary.False; } } if (isReadonlySymbol(sourceProp) !== isReadonlySymbol(targetProp)) { return Ternary.False; } return compareTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp)); } function isMatchingSignature(source: Signature, target: Signature, partialMatch: boolean) { const sourceParameterCount = getParameterCount(source); const targetParameterCount = getParameterCount(target); const sourceMinArgumentCount = getMinArgumentCount(source); const targetMinArgumentCount = getMinArgumentCount(target); const sourceHasRestParameter = hasEffectiveRestParameter(source); const targetHasRestParameter = hasEffectiveRestParameter(target); // A source signature matches a target signature if the two signatures have the same number of required, // optional, and rest parameters. if (sourceParameterCount === targetParameterCount && sourceMinArgumentCount === targetMinArgumentCount && sourceHasRestParameter === targetHasRestParameter) { return true; } // A source signature partially matches a target signature if the target signature has no fewer required // parameters if (partialMatch && sourceMinArgumentCount <= targetMinArgumentCount) { return true; } return false; } /** * See signatureRelatedTo, compareSignaturesIdentical */ function compareSignaturesIdentical(source: Signature, target: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean, compareTypes: (s: Type, t: Type) => Ternary): Ternary { // TODO (drosen): De-duplicate code between related functions. if (source === target) { return Ternary.True; } if (!(isMatchingSignature(source, target, partialMatch))) { return Ternary.False; } // Check that the two signatures have the same number of type parameters. if (length(source.typeParameters) !== length(target.typeParameters)) { return Ternary.False; } // Check that type parameter constraints and defaults match. If they do, instantiate the source // signature with the type parameters of the target signature and continue the comparison. if (target.typeParameters) { const mapper = createTypeMapper(source.typeParameters!, target.typeParameters); for (let i = 0; i < target.typeParameters.length; i++) { const s = source.typeParameters![i]; const t = target.typeParameters[i]; if (!(s === t || compareTypes(instantiateType(getConstraintFromTypeParameter(s), mapper) || unknownType, getConstraintFromTypeParameter(t) || unknownType) && compareTypes(instantiateType(getDefaultFromTypeParameter(s), mapper) || unknownType, getDefaultFromTypeParameter(t) || unknownType))) { return Ternary.False; } } source = instantiateSignature(source, mapper, /*eraseTypeParameters*/ true); } let result = Ternary.True; if (!ignoreThisTypes) { const sourceThisType = getThisTypeOfSignature(source); if (sourceThisType) { const targetThisType = getThisTypeOfSignature(target); if (targetThisType) { const related = compareTypes(sourceThisType, targetThisType); if (!related) { return Ternary.False; } result &= related; } } } const targetLen = getParameterCount(target); for (let i = 0; i < targetLen; i++) { const s = getTypeAtPosition(source, i); const t = getTypeAtPosition(target, i); const related = compareTypes(t, s); if (!related) { return Ternary.False; } result &= related; } if (!ignoreReturnTypes) { const sourceTypePredicate = getTypePredicateOfSignature(source); const targetTypePredicate = getTypePredicateOfSignature(target); result &= sourceTypePredicate || targetTypePredicate ? compareTypePredicatesIdentical(sourceTypePredicate, targetTypePredicate, compareTypes) : compareTypes(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target)); } return result; } function compareTypePredicatesIdentical(source: TypePredicate | undefined, target: TypePredicate | undefined, compareTypes: (s: Type, t: Type) => Ternary): Ternary { return !(source && target && typePredicateKindsMatch(source, target)) ? Ternary.False : source.type === target.type ? Ternary.True : source.type && target.type ? compareTypes(source.type, target.type) : Ternary.False; } function literalTypesWithSameBaseType(types: Type[]): boolean { let commonBaseType: Type | undefined; for (const t of types) { if (!(t.flags & TypeFlags.Never)) { const baseType = getBaseTypeOfLiteralType(t); commonBaseType ??= baseType; if (baseType === t || baseType !== commonBaseType) { return false; } } } return true; } function getCombinedTypeFlags(types: Type[]): TypeFlags { return reduceLeft(types, (flags, t) => flags | (t.flags & TypeFlags.Union ? getCombinedTypeFlags((t as UnionType).types) : t.flags), 0 as TypeFlags); } function getCommonSupertype(types: Type[]): Type { if (types.length === 1) { return types[0]; } // Remove nullable types from each of the candidates. const primaryTypes = strictNullChecks ? sameMap(types, t => filterType(t, u => !(u.flags & TypeFlags.Nullable))) : types; // When the candidate types are all literal types with the same base type, return a union // of those literal types. Otherwise, return the leftmost type for which no type to the // right is a supertype. const superTypeOrUnion = literalTypesWithSameBaseType(primaryTypes) ? getUnionType(primaryTypes) : reduceLeft(primaryTypes, (s, t) => isTypeSubtypeOf(s, t) ? t : s)!; // Add any nullable types that occurred in the candidates back to the result. return primaryTypes === types ? superTypeOrUnion : getNullableType(superTypeOrUnion, getCombinedTypeFlags(types) & TypeFlags.Nullable); } // Return the leftmost type for which no type to the right is a subtype. function getCommonSubtype(types: Type[]) { return reduceLeft(types, (s, t) => isTypeSubtypeOf(t, s) ? t : s)!; } function isArrayType(type: Type): type is TypeReference { return !!(getObjectFlags(type) & ObjectFlags.Reference) && ((type as TypeReference).target === globalArrayType || (type as TypeReference).target === globalReadonlyArrayType); } function isReadonlyArrayType(type: Type): boolean { return !!(getObjectFlags(type) & ObjectFlags.Reference) && (type as TypeReference).target === globalReadonlyArrayType; } function isArrayOrTupleType(type: Type): type is TypeReference { return isArrayType(type) || isTupleType(type); } function isMutableArrayOrTuple(type: Type): boolean { return isArrayType(type) && !isReadonlyArrayType(type) || isTupleType(type) && !type.target.readonly; } function getElementTypeOfArrayType(type: Type): Type | undefined { return isArrayType(type) ? getTypeArguments(type)[0] : undefined; } function isArrayLikeType(type: Type): boolean { // A type is array-like if it is a reference to the global Array or global ReadonlyArray type, // or if it is not the undefined or null type and if it is assignable to ReadonlyArray return isArrayType(type) || !(type.flags & TypeFlags.Nullable) && isTypeAssignableTo(type, anyReadonlyArrayType); } function getSingleBaseForNonAugmentingSubtype(type: Type) { if (!(getObjectFlags(type) & ObjectFlags.Reference) || !(getObjectFlags((type as TypeReference).target) & ObjectFlags.ClassOrInterface)) { return undefined; } if (getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeCalculated) { return getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeExists ? (type as TypeReference).cachedEquivalentBaseType : undefined; } (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeCalculated; const target = (type as TypeReference).target as InterfaceType; if (getObjectFlags(target) & ObjectFlags.Class) { const baseTypeNode = getBaseTypeNodeOfClass(target); // A base type expression may circularly reference the class itself (e.g. as an argument to function call), so we only // check for base types specified as simple qualified names. if (baseTypeNode && baseTypeNode.expression.kind !== SyntaxKind.Identifier && baseTypeNode.expression.kind !== SyntaxKind.PropertyAccessExpression) { return undefined; } } const bases = getBaseTypes(target); if (bases.length !== 1) { return undefined; } if (getMembersOfSymbol(type.symbol).size) { return undefined; // If the interface has any members, they may subtype members in the base, so we should do a full structural comparison } let instantiatedBase = !length(target.typeParameters) ? bases[0] : instantiateType(bases[0], createTypeMapper(target.typeParameters!, getTypeArguments(type as TypeReference).slice(0, target.typeParameters!.length))); if (length(getTypeArguments(type as TypeReference)) > length(target.typeParameters)) { instantiatedBase = getTypeWithThisArgument(instantiatedBase, last(getTypeArguments(type as TypeReference))); } (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeExists; return (type as TypeReference).cachedEquivalentBaseType = instantiatedBase; } function isEmptyLiteralType(type: Type): boolean { return strictNullChecks ? type === implicitNeverType : type === undefinedWideningType; } function isEmptyArrayLiteralType(type: Type): boolean { const elementType = getElementTypeOfArrayType(type); return !!elementType && isEmptyLiteralType(elementType); } function isTupleLikeType(type: Type): boolean { return isTupleType(type) || !!getPropertyOfType(type, "0" as __String); } function isArrayOrTupleLikeType(type: Type): boolean { return isArrayLikeType(type) || isTupleLikeType(type); } function getTupleElementType(type: Type, index: number) { const propType = getTypeOfPropertyOfType(type, "" + index as __String); if (propType) { return propType; } if (everyType(type, isTupleType)) { return mapType(type, t => { const tupleType = t as TupleTypeReference; const restType = getRestTypeOfTupleType(tupleType); if (!restType) { return undefinedType; } if (compilerOptions.noUncheckedIndexedAccess && index >= tupleType.target.fixedLength + getEndElementCount(tupleType.target, ElementFlags.Fixed)) { return getUnionType([restType, undefinedType]); } return restType; }); } return undefined; } function isNeitherUnitTypeNorNever(type: Type): boolean { return !(type.flags & (TypeFlags.Unit | TypeFlags.Never)); } function isUnitType(type: Type): boolean { return !!(type.flags & TypeFlags.Unit); } function isUnitLikeType(type: Type): boolean { // Intersections that reduce to 'never' (e.g. 'T & null' where 'T extends {}') are not unit types. const t = getBaseConstraintOrType(type); // Scan intersections such that tagged literal types are considered unit types. return t.flags & TypeFlags.Intersection ? some((t as IntersectionType).types, isUnitType) : isUnitType(t); } function extractUnitType(type: Type) { return type.flags & TypeFlags.Intersection ? find((type as IntersectionType).types, isUnitType) || type : type; } function isLiteralType(type: Type): boolean { return type.flags & TypeFlags.Boolean ? true : type.flags & TypeFlags.Union ? type.flags & TypeFlags.EnumLiteral ? true : every((type as UnionType).types, isUnitType) : isUnitType(type); } function getBaseTypeOfLiteralType(type: Type): Type { return type.flags & TypeFlags.EnumLike ? getBaseTypeOfEnumLikeType(type as LiteralType) : type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : type.flags & TypeFlags.NumberLiteral ? numberType : type.flags & TypeFlags.BigIntLiteral ? bigintType : type.flags & TypeFlags.BooleanLiteral ? booleanType : type.flags & TypeFlags.Union ? getBaseTypeOfLiteralTypeUnion(type as UnionType) : type; } function getBaseTypeOfLiteralTypeUnion(type: UnionType) { const key = `B${getTypeId(type)}`; return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralType)); } // This like getBaseTypeOfLiteralType, but instead treats enum literals as strings/numbers instead // of returning their enum base type (which depends on the types of other literals in the enum). function getBaseTypeOfLiteralTypeForComparison(type: Type): Type { return type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : type.flags & (TypeFlags.NumberLiteral | TypeFlags.Enum) ? numberType : type.flags & TypeFlags.BigIntLiteral ? bigintType : type.flags & TypeFlags.BooleanLiteral ? booleanType : type.flags & TypeFlags.Union ? mapType(type, getBaseTypeOfLiteralTypeForComparison) : type; } function getWidenedLiteralType(type: Type): Type { return type.flags & TypeFlags.EnumLike && isFreshLiteralType(type) ? getBaseTypeOfEnumLikeType(type as LiteralType) : type.flags & TypeFlags.StringLiteral && isFreshLiteralType(type) ? stringType : type.flags & TypeFlags.NumberLiteral && isFreshLiteralType(type) ? numberType : type.flags & TypeFlags.BigIntLiteral && isFreshLiteralType(type) ? bigintType : type.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(type) ? booleanType : type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedLiteralType) : type; } function getWidenedUniqueESSymbolType(type: Type): Type { return type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedUniqueESSymbolType) : type; } function getWidenedLiteralLikeTypeForContextualType(type: Type, contextualType: Type | undefined) { if (!isLiteralOfContextualType(type, contextualType)) { type = getWidenedUniqueESSymbolType(getWidenedLiteralType(type)); } return getRegularTypeOfLiteralType(type); } function getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, isAsync: boolean) { if (type && isUnitType(type)) { const contextualType = !contextualSignatureReturnType ? undefined : isAsync ? getPromisedTypeOfPromise(contextualSignatureReturnType) : contextualSignatureReturnType; type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); } return type; } function getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, kind: IterationTypeKind, isAsyncGenerator: boolean) { if (type && isUnitType(type)) { const contextualType = !contextualSignatureReturnType ? undefined : getIterationTypeOfGeneratorFunctionReturnType(kind, contextualSignatureReturnType, isAsyncGenerator); type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); } return type; } /** * Check if a Type was written as a tuple type literal. * Prefer using isTupleLikeType() unless the use of `elementTypes`/`getTypeArguments` is required. */ function isTupleType(type: Type): type is TupleTypeReference { return !!(getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target.objectFlags & ObjectFlags.Tuple); } function isGenericTupleType(type: Type): type is TupleTypeReference { return isTupleType(type) && !!(type.target.combinedFlags & ElementFlags.Variadic); } function isSingleElementGenericTupleType(type: Type): type is TupleTypeReference { return isGenericTupleType(type) && type.target.elementFlags.length === 1; } function getRestTypeOfTupleType(type: TupleTypeReference) { return getElementTypeOfSliceOfTupleType(type, type.target.fixedLength); } function getRestArrayTypeOfTupleType(type: TupleTypeReference) { const restType = getRestTypeOfTupleType(type); return restType && createArrayType(restType); } function getElementTypeOfSliceOfTupleType(type: TupleTypeReference, index: number, endSkipCount = 0, writing = false, noReductions = false) { const length = getTypeReferenceArity(type) - endSkipCount; if (index < length) { const typeArguments = getTypeArguments(type); const elementTypes: Type[] = []; for (let i = index; i < length; i++) { const t = typeArguments[i]; elementTypes.push(type.target.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); } return writing ? getIntersectionType(elementTypes) : getUnionType(elementTypes, noReductions ? UnionReduction.None : UnionReduction.Literal); } return undefined; } function isTupleTypeStructureMatching(t1: TupleTypeReference, t2: TupleTypeReference) { return getTypeReferenceArity(t1) === getTypeReferenceArity(t2) && every(t1.target.elementFlags, (f, i) => (f & ElementFlags.Variable) === (t2.target.elementFlags[i] & ElementFlags.Variable)); } function isZeroBigInt({value}: BigIntLiteralType) { return value.base10Value === "0"; } function removeDefinitelyFalsyTypes(type: Type): Type { return filterType(type, t => !!(getTypeFacts(t) & TypeFacts.Truthy)); } function extractDefinitelyFalsyTypes(type: Type): Type { return mapType(type, getDefinitelyFalsyPartOfType); } function getDefinitelyFalsyPartOfType(type: Type): Type { return type.flags & TypeFlags.String ? emptyStringType : type.flags & TypeFlags.Number ? zeroType : type.flags & TypeFlags.BigInt ? zeroBigIntType : type === regularFalseType || type === falseType || type.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null | TypeFlags.AnyOrUnknown) || type.flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === "" || type.flags & TypeFlags.NumberLiteral && (type as NumberLiteralType).value === 0 || type.flags & TypeFlags.BigIntLiteral && isZeroBigInt(type as BigIntLiteralType) ? type : neverType; } /** * Add undefined or null or both to a type if they are missing. * @param type - type to add undefined and/or null to if not present * @param flags - Either TypeFlags.Undefined or TypeFlags.Null, or both */ function getNullableType(type: Type, flags: TypeFlags): Type { const missing = (flags & ~type.flags) & (TypeFlags.Undefined | TypeFlags.Null); return missing === 0 ? type : missing === TypeFlags.Undefined ? getUnionType([type, undefinedType]) : missing === TypeFlags.Null ? getUnionType([type, nullType]) : getUnionType([type, undefinedType, nullType]); } function getOptionalType(type: Type, isProperty = false): Type { Debug.assert(strictNullChecks); const missingOrUndefined = isProperty ? undefinedOrMissingType : undefinedType; return type === missingOrUndefined || type.flags & TypeFlags.Union && (type as UnionType).types[0] === missingOrUndefined ? type : getUnionType([type, missingOrUndefined]); } function getGlobalNonNullableTypeInstantiation(type: Type) { if (!deferredGlobalNonNullableTypeAlias) { deferredGlobalNonNullableTypeAlias = getGlobalSymbol("NonNullable" as __String, SymbolFlags.TypeAlias, /*diagnostic*/ undefined) || unknownSymbol; } return deferredGlobalNonNullableTypeAlias !== unknownSymbol ? getTypeAliasInstantiation(deferredGlobalNonNullableTypeAlias, [type]) : getIntersectionType([type, emptyObjectType]); } function getNonNullableType(type: Type): Type { return strictNullChecks ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; } function addOptionalTypeMarker(type: Type) { return strictNullChecks ? getUnionType([type, optionalType]) : type; } function removeOptionalTypeMarker(type: Type): Type { return strictNullChecks ? removeType(type, optionalType) : type; } function propagateOptionalTypeMarker(type: Type, node: OptionalChain, wasOptional: boolean) { return wasOptional ? isOutermostOptionalChain(node) ? getOptionalType(type) : addOptionalTypeMarker(type) : type; } function getOptionalExpressionType(exprType: Type, expression: Expression) { return isExpressionOfOptionalChainRoot(expression) ? getNonNullableType(exprType) : isOptionalChain(expression) ? removeOptionalTypeMarker(exprType) : exprType; } function removeMissingType(type: Type, isOptional: boolean) { return exactOptionalPropertyTypes && isOptional ? removeType(type, missingType) : type; } function containsMissingType(type: Type) { return type === missingType || !!(type.flags & TypeFlags.Union) && (type as UnionType).types[0] === missingType; } function removeMissingOrUndefinedType(type: Type): Type { return exactOptionalPropertyTypes ? removeType(type, missingType) : getTypeWithFacts(type, TypeFacts.NEUndefined); } /** * Is source potentially coercible to target type under `==`. * Assumes that `source` is a constituent of a union, hence * the boolean literal flag on the LHS, but not on the RHS. * * This does not fully replicate the semantics of `==`. The * intention is to catch cases that are clearly not right. * * Comparing (string | number) to number should not remove the * string element. * * Comparing (string | number) to 1 will remove the string * element, though this is not sound. This is a pragmatic * choice. * * @see narrowTypeByEquality * * @param source * @param target */ function isCoercibleUnderDoubleEquals(source: Type, target: Type): boolean { return ((source.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.BooleanLiteral)) !== 0) && ((target.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.Boolean)) !== 0); } /** * Return true if type was inferred from an object literal, written as an object type literal, or is the shape of a module * with no call or construct signatures. */ function isObjectTypeWithInferableIndex(type: Type): boolean { const objectFlags = getObjectFlags(type); return type.flags & TypeFlags.Intersection ? every((type as IntersectionType).types, isObjectTypeWithInferableIndex) : !!( type.symbol && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral | SymbolFlags.Enum | SymbolFlags.ValueModule)) !== 0 && !(type.symbol.flags & SymbolFlags.Class) && !typeHasCallOrConstructSignatures(type) ) || !!( objectFlags & ObjectFlags.ObjectRestType ) || !!(objectFlags & ObjectFlags.ReverseMapped && isObjectTypeWithInferableIndex((type as ReverseMappedType).source)); } function createSymbolWithType(source: Symbol, type: Type | undefined) { const symbol = createSymbol(source.flags, source.escapedName, getCheckFlags(source) & CheckFlags.Readonly); symbol.declarations = source.declarations; symbol.parent = source.parent; symbol.links.type = type; symbol.links.target = source; if (source.valueDeclaration) { symbol.valueDeclaration = source.valueDeclaration; } const nameType = getSymbolLinks(source).nameType; if (nameType) { symbol.links.nameType = nameType; } return symbol; } function transformTypeOfMembers(type: Type, f: (propertyType: Type) => Type) { const members = createSymbolTable(); for (const property of getPropertiesOfObjectType(type)) { const original = getTypeOfSymbol(property); const updated = f(original); members.set(property.escapedName, updated === original ? property : createSymbolWithType(property, updated)); } return members; } /** * If the the provided object literal is subject to the excess properties check, * create a new that is exempt. Recursively mark object literal members as exempt. * Leave signatures alone since they are not subject to the check. */ function getRegularTypeOfObjectLiteral(type: Type): Type { if (!(isObjectLiteralType(type) && getObjectFlags(type) & ObjectFlags.FreshLiteral)) { return type; } const regularType = (type as FreshObjectLiteralType).regularType; if (regularType) { return regularType; } const resolved = type as ResolvedType; const members = transformTypeOfMembers(type, getRegularTypeOfObjectLiteral); const regularNew = createAnonymousType(resolved.symbol, members, resolved.callSignatures, resolved.constructSignatures, resolved.indexInfos); regularNew.flags = resolved.flags; regularNew.objectFlags |= resolved.objectFlags & ~ObjectFlags.FreshLiteral; (type as FreshObjectLiteralType).regularType = regularNew; return regularNew; } function createWideningContext(parent: WideningContext | undefined, propertyName: __String | undefined, siblings: Type[] | undefined): WideningContext { return { parent, propertyName, siblings, resolvedProperties: undefined }; } function getSiblingsOfContext(context: WideningContext): Type[] { if (!context.siblings) { const siblings: Type[] = []; for (const type of getSiblingsOfContext(context.parent!)) { if (isObjectLiteralType(type)) { const prop = getPropertyOfObjectType(type, context.propertyName!); if (prop) { forEachType(getTypeOfSymbol(prop), t => { siblings.push(t); }); } } } context.siblings = siblings; } return context.siblings; } function getPropertiesOfContext(context: WideningContext): Symbol[] { if (!context.resolvedProperties) { const names = new Map() as UnderscoreEscapedMap; for (const t of getSiblingsOfContext(context)) { if (isObjectLiteralType(t) && !(getObjectFlags(t) & ObjectFlags.ContainsSpread)) { for (const prop of getPropertiesOfType(t)) { names.set(prop.escapedName, prop); } } } context.resolvedProperties = arrayFrom(names.values()); } return context.resolvedProperties; } function getWidenedProperty(prop: Symbol, context: WideningContext | undefined): Symbol { if (!(prop.flags & SymbolFlags.Property)) { // Since get accessors already widen their return value there is no need to // widen accessor based properties here. return prop; } const original = getTypeOfSymbol(prop); const propContext = context && createWideningContext(context, prop.escapedName, /*siblings*/ undefined); const widened = getWidenedTypeWithContext(original, propContext); return widened === original ? prop : createSymbolWithType(prop, widened); } function getUndefinedProperty(prop: Symbol) { const cached = undefinedProperties.get(prop.escapedName); if (cached) { return cached; } const result = createSymbolWithType(prop, undefinedOrMissingType); result.flags |= SymbolFlags.Optional; undefinedProperties.set(prop.escapedName, result); return result; } function getWidenedTypeOfObjectLiteral(type: Type, context: WideningContext | undefined): Type { const members = createSymbolTable(); for (const prop of getPropertiesOfObjectType(type)) { members.set(prop.escapedName, getWidenedProperty(prop, context)); } if (context) { for (const prop of getPropertiesOfContext(context)) { if (!members.has(prop.escapedName)) { members.set(prop.escapedName, getUndefinedProperty(prop)); } } } const result = createAnonymousType(type.symbol, members, emptyArray, emptyArray, sameMap(getIndexInfosOfType(type), info => createIndexInfo(info.keyType, getWidenedType(info.type), info.isReadonly))); result.objectFlags |= (getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.NonInferrableType)); // Retain js literal flag through widening return result; } function getWidenedType(type: Type) { return getWidenedTypeWithContext(type, /*context*/ undefined); } function getWidenedTypeWithContext(type: Type, context: WideningContext | undefined): Type { if (getObjectFlags(type) & ObjectFlags.RequiresWidening) { if (context === undefined && type.widened) { return type.widened; } let result: Type | undefined; if (type.flags & (TypeFlags.Any | TypeFlags.Nullable)) { result = anyType; } else if (isObjectLiteralType(type)) { result = getWidenedTypeOfObjectLiteral(type, context); } else if (type.flags & TypeFlags.Union) { const unionContext = context || createWideningContext(/*parent*/ undefined, /*propertyName*/ undefined, (type as UnionType).types); const widenedTypes = sameMap((type as UnionType).types, t => t.flags & TypeFlags.Nullable ? t : getWidenedTypeWithContext(t, unionContext)); // Widening an empty object literal transitions from a highly restrictive type to // a highly inclusive one. For that reason we perform subtype reduction here if the // union includes empty object types (e.g. reducing {} | string to just {}). result = getUnionType(widenedTypes, some(widenedTypes, isEmptyObjectType) ? UnionReduction.Subtype : UnionReduction.Literal); } else if (type.flags & TypeFlags.Intersection) { result = getIntersectionType(sameMap((type as IntersectionType).types, getWidenedType)); } else if (isArrayOrTupleType(type)) { result = createTypeReference(type.target, sameMap(getTypeArguments(type), getWidenedType)); } if (result && context === undefined) { type.widened = result; } return result || type; } return type; } /** * Reports implicit any errors that occur as a result of widening 'null' and 'undefined' * to 'any'. A call to reportWideningErrorsInType is normally accompanied by a call to * getWidenedType. But in some cases getWidenedType is called without reporting errors * (type argument inference is an example). * * The return value indicates whether an error was in fact reported. The particular circumstances * are on a best effort basis. Currently, if the null or undefined that causes widening is inside * an object literal property (arbitrarily deeply), this function reports an error. If no error is * reported, reportImplicitAnyError is a suitable fallback to report a general error. */ function reportWideningErrorsInType(type: Type): boolean { let errorReported = false; if (getObjectFlags(type) & ObjectFlags.ContainsWideningType) { if (type.flags & TypeFlags.Union) { if (some((type as UnionType).types, isEmptyObjectType)) { errorReported = true; } else { for (const t of (type as UnionType).types) { if (reportWideningErrorsInType(t)) { errorReported = true; } } } } if (isArrayOrTupleType(type)) { for (const t of getTypeArguments(type)) { if (reportWideningErrorsInType(t)) { errorReported = true; } } } if (isObjectLiteralType(type)) { for (const p of getPropertiesOfObjectType(type)) { const t = getTypeOfSymbol(p); if (getObjectFlags(t) & ObjectFlags.ContainsWideningType) { if (!reportWideningErrorsInType(t)) { error(p.valueDeclaration, Diagnostics.Object_literal_s_property_0_implicitly_has_an_1_type, symbolToString(p), typeToString(getWidenedType(t))); } errorReported = true; } } } } return errorReported; } function reportImplicitAny(declaration: Declaration, type: Type, wideningKind?: WideningKind) { const typeAsString = typeToString(getWidenedType(type)); if (isInJSFile(declaration) && !isCheckJsEnabledForFile(getSourceFileOfNode(declaration), compilerOptions)) { // Only report implicit any errors/suggestions in TS and ts-check JS files return; } let diagnostic: DiagnosticMessage; switch (declaration.kind) { case SyntaxKind.BinaryExpression: case SyntaxKind.PropertyDeclaration: case SyntaxKind.PropertySignature: diagnostic = noImplicitAny ? Diagnostics.Member_0_implicitly_has_an_1_type : Diagnostics.Member_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; break; case SyntaxKind.Parameter: const param = declaration as ParameterDeclaration; if (isIdentifier(param.name)) { const originalKeywordKind = identifierToKeywordKind(param.name); if ((isCallSignatureDeclaration(param.parent) || isMethodSignature(param.parent) || isFunctionTypeNode(param.parent)) && param.parent.parameters.indexOf(param) > -1 && (resolveName(param, param.name.escapedText, SymbolFlags.Type, undefined, param.name.escapedText, /*isUse*/ true) || originalKeywordKind && isTypeNodeKind(originalKeywordKind))) { const newName = "arg" + param.parent.parameters.indexOf(param); const typeName = declarationNameToString(param.name) + (param.dotDotDotToken ? "[]" : ""); errorOrSuggestion(noImplicitAny, declaration, Diagnostics.Parameter_has_a_name_but_no_type_Did_you_mean_0_Colon_1, newName, typeName); return; } } diagnostic = (declaration as ParameterDeclaration).dotDotDotToken ? noImplicitAny ? Diagnostics.Rest_parameter_0_implicitly_has_an_any_type : Diagnostics.Rest_parameter_0_implicitly_has_an_any_type_but_a_better_type_may_be_inferred_from_usage : noImplicitAny ? Diagnostics.Parameter_0_implicitly_has_an_1_type : Diagnostics.Parameter_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; break; case SyntaxKind.BindingElement: diagnostic = Diagnostics.Binding_element_0_implicitly_has_an_1_type; if (!noImplicitAny) { // Don't issue a suggestion for binding elements since the codefix doesn't yet support them. return; } break; case SyntaxKind.JSDocFunctionType: error(declaration, Diagnostics.Function_type_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); return; case SyntaxKind.JSDocSignature: if (noImplicitAny && isJSDocOverloadTag(declaration.parent)) { error(declaration.parent.tagName, Diagnostics.This_overload_implicitly_returns_the_type_0_because_it_lacks_a_return_type_annotation, typeAsString); } return; case SyntaxKind.FunctionDeclaration: case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: if (noImplicitAny && !(declaration as NamedDeclaration).name) { if (wideningKind === WideningKind.GeneratorYield) { error(declaration, Diagnostics.Generator_implicitly_has_yield_type_0_because_it_does_not_yield_any_values_Consider_supplying_a_return_type_annotation, typeAsString); } else { error(declaration, Diagnostics.Function_expression_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); } return; } diagnostic = !noImplicitAny ? Diagnostics._0_implicitly_has_an_1_return_type_but_a_better_type_may_be_inferred_from_usage : wideningKind === WideningKind.GeneratorYield ? Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_yield_type : Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_return_type; break; case SyntaxKind.MappedType: if (noImplicitAny) { error(declaration, Diagnostics.Mapped_object_type_implicitly_has_an_any_template_type); } return; default: diagnostic = noImplicitAny ? Diagnostics.Variable_0_implicitly_has_an_1_type : Diagnostics.Variable_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; } errorOrSuggestion(noImplicitAny, declaration, diagnostic, declarationNameToString(getNameOfDeclaration(declaration)), typeAsString); } function reportErrorsFromWidening(declaration: Declaration, type: Type, wideningKind?: WideningKind) { addLazyDiagnostic(() => { if (noImplicitAny && getObjectFlags(type) & ObjectFlags.ContainsWideningType && (!wideningKind || !getContextualSignatureForFunctionLikeDeclaration(declaration as FunctionLikeDeclaration))) { // Report implicit any error within type if possible, otherwise report error on declaration if (!reportWideningErrorsInType(type)) { reportImplicitAny(declaration, type, wideningKind); } } }); } function applyToParameterTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { const sourceCount = getParameterCount(source); const targetCount = getParameterCount(target); const sourceRestType = getEffectiveRestType(source); const targetRestType = getEffectiveRestType(target); const targetNonRestCount = targetRestType ? targetCount - 1 : targetCount; const paramCount = sourceRestType ? targetNonRestCount : Math.min(sourceCount, targetNonRestCount); const sourceThisType = getThisTypeOfSignature(source); if (sourceThisType) { const targetThisType = getThisTypeOfSignature(target); if (targetThisType) { callback(sourceThisType, targetThisType); } } for (let i = 0; i < paramCount; i++) { callback(getTypeAtPosition(source, i), getTypeAtPosition(target, i)); } if (targetRestType) { callback(getRestTypeAtPosition(source, paramCount), targetRestType); } } function applyToReturnTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { const sourceTypePredicate = getTypePredicateOfSignature(source); const targetTypePredicate = getTypePredicateOfSignature(target); if (sourceTypePredicate && targetTypePredicate && typePredicateKindsMatch(sourceTypePredicate, targetTypePredicate) && sourceTypePredicate.type && targetTypePredicate.type) { callback(sourceTypePredicate.type, targetTypePredicate.type); } else { callback(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target)); } } function createInferenceContext(typeParameters: readonly TypeParameter[], signature: Signature | undefined, flags: InferenceFlags, compareTypes?: TypeComparer): InferenceContext { return createInferenceContextWorker(typeParameters.map(createInferenceInfo), signature, flags, compareTypes || compareTypesAssignable); } function cloneInferenceContext(context: T, extraFlags: InferenceFlags = 0): InferenceContext | T & undefined { return context && createInferenceContextWorker(map(context.inferences, cloneInferenceInfo), context.signature, context.flags | extraFlags, context.compareTypes); } function createInferenceContextWorker(inferences: InferenceInfo[], signature: Signature | undefined, flags: InferenceFlags, compareTypes: TypeComparer): InferenceContext { const context: InferenceContext = { inferences, signature, flags, compareTypes, mapper: reportUnmeasurableMapper, // initialize to a noop mapper so the context object is available, but the underlying object shape is right upon construction nonFixingMapper: reportUnmeasurableMapper, }; context.mapper = makeFixingMapperForContext(context); context.nonFixingMapper = makeNonFixingMapperForContext(context); return context; } function makeFixingMapperForContext(context: InferenceContext) { return makeDeferredTypeMapper(map(context.inferences, i => i.typeParameter), map(context.inferences, (inference, i) => () => { if (!inference.isFixed) { // Before we commit to a particular inference (and thus lock out any further inferences), // we infer from any intra-expression inference sites we have collected. inferFromIntraExpressionSites(context); clearCachedInferences(context.inferences); inference.isFixed = true; } return getInferredType(context, i); })); } function makeNonFixingMapperForContext(context: InferenceContext) { return makeDeferredTypeMapper(map(context.inferences, i => i.typeParameter), map(context.inferences, (_, i) => () => { return getInferredType(context, i); })); } function clearCachedInferences(inferences: InferenceInfo[]) { for (const inference of inferences) { if (!inference.isFixed) { inference.inferredType = undefined; } } } function addIntraExpressionInferenceSite(context: InferenceContext, node: Expression | MethodDeclaration, type: Type) { (context.intraExpressionInferenceSites ??= []).push({ node, type }); } // We collect intra-expression inference sites within object and array literals to handle cases where // inferred types flow between context sensitive element expressions. For example: // // declare function foo(arg: [(n: number) => T, (x: T) => void]): void; // foo([_a => 0, n => n.toFixed()]); // // Above, both arrow functions in the tuple argument are context sensitive, thus both are omitted from the // pass that collects inferences from the non-context sensitive parts of the arguments. In the subsequent // pass where nothing is omitted, we need to commit to an inference for T in order to contextually type the // parameter in the second arrow function, but we want to first infer from the return type of the first // arrow function. This happens automatically when the arrow functions are discrete arguments (because we // infer from each argument before processing the next), but when the arrow functions are elements of an // object or array literal, we need to perform intra-expression inferences early. function inferFromIntraExpressionSites(context: InferenceContext) { if (context.intraExpressionInferenceSites) { for (const { node, type } of context.intraExpressionInferenceSites) { const contextualType = node.kind === SyntaxKind.MethodDeclaration ? getContextualTypeForObjectLiteralMethod(node as MethodDeclaration, ContextFlags.NoConstraints) : getContextualType(node, ContextFlags.NoConstraints); if (contextualType) { inferTypes(context.inferences, type, contextualType); } } context.intraExpressionInferenceSites = undefined; } } function createInferenceInfo(typeParameter: TypeParameter): InferenceInfo { return { typeParameter, candidates: undefined, contraCandidates: undefined, inferredType: undefined, priority: undefined, topLevel: true, isFixed: false, impliedArity: undefined }; } function cloneInferenceInfo(inference: InferenceInfo): InferenceInfo { return { typeParameter: inference.typeParameter, candidates: inference.candidates && inference.candidates.slice(), contraCandidates: inference.contraCandidates && inference.contraCandidates.slice(), inferredType: inference.inferredType, priority: inference.priority, topLevel: inference.topLevel, isFixed: inference.isFixed, impliedArity: inference.impliedArity }; } function cloneInferredPartOfContext(context: InferenceContext): InferenceContext | undefined { const inferences = filter(context.inferences, hasInferenceCandidates); return inferences.length ? createInferenceContextWorker(map(inferences, cloneInferenceInfo), context.signature, context.flags, context.compareTypes) : undefined; } function getMapperFromContext(context: T): TypeMapper | T & undefined { return context && context.mapper; } // Return true if the given type could possibly reference a type parameter for which // we perform type inference (i.e. a type parameter of a generic function). We cache // results for union and intersection types for performance reasons. function couldContainTypeVariables(type: Type): boolean { const objectFlags = getObjectFlags(type); if (objectFlags & ObjectFlags.CouldContainTypeVariablesComputed) { return !!(objectFlags & ObjectFlags.CouldContainTypeVariables); } const result = !!(type.flags & TypeFlags.Instantiable || type.flags & TypeFlags.Object && !isNonGenericTopLevelType(type) && ( objectFlags & ObjectFlags.Reference && ((type as TypeReference).node || forEach(getTypeArguments(type as TypeReference), couldContainTypeVariables)) || objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations || objectFlags & (ObjectFlags.Mapped | ObjectFlags.ReverseMapped | ObjectFlags.ObjectRestType | ObjectFlags.InstantiationExpressionType)) || type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && !isNonGenericTopLevelType(type) && some((type as UnionOrIntersectionType).types, couldContainTypeVariables)); if (type.flags & TypeFlags.ObjectFlagsType) { (type as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (result ? ObjectFlags.CouldContainTypeVariables : 0); } return result; } function isNonGenericTopLevelType(type: Type) { if (type.aliasSymbol && !type.aliasTypeArguments) { const declaration = getDeclarationOfKind(type.aliasSymbol, SyntaxKind.TypeAliasDeclaration); return !!(declaration && findAncestor(declaration.parent, n => n.kind === SyntaxKind.SourceFile ? true : n.kind === SyntaxKind.ModuleDeclaration ? false : "quit")); } return false; } function isTypeParameterAtTopLevel(type: Type, tp: TypeParameter, depth = 0): boolean { return !!(type === tp || type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isTypeParameterAtTopLevel(t, tp, depth)) || depth < 3 && type.flags & TypeFlags.Conditional && ( isTypeParameterAtTopLevel(getTrueTypeFromConditionalType(type as ConditionalType), tp, depth + 1) || isTypeParameterAtTopLevel(getFalseTypeFromConditionalType(type as ConditionalType), tp, depth + 1))); } function isTypeParameterAtTopLevelInReturnType(signature: Signature, typeParameter: TypeParameter) { const typePredicate = getTypePredicateOfSignature(signature); return typePredicate ? !!typePredicate.type && isTypeParameterAtTopLevel(typePredicate.type, typeParameter) : isTypeParameterAtTopLevel(getReturnTypeOfSignature(signature), typeParameter); } /** Create an object with properties named in the string literal type. Every property has type `any` */ function createEmptyObjectTypeFromStringLiteral(type: Type) { const members = createSymbolTable(); forEachType(type, t => { if (!(t.flags & TypeFlags.StringLiteral)) { return; } const name = escapeLeadingUnderscores((t as StringLiteralType).value); const literalProp = createSymbol(SymbolFlags.Property, name); literalProp.links.type = anyType; if (t.symbol) { literalProp.declarations = t.symbol.declarations; literalProp.valueDeclaration = t.symbol.valueDeclaration; } members.set(name, literalProp); }); const indexInfos = type.flags & TypeFlags.String ? [createIndexInfo(stringType, emptyObjectType, /*isReadonly*/ false)] : emptyArray; return createAnonymousType(undefined, members, emptyArray, emptyArray, indexInfos); } /** * Infer a suitable input type for a homomorphic mapped type { [P in keyof T]: X }. We construct * an object type with the same set of properties as the source type, where the type of each * property is computed by inferring from the source property type to X for the type * variable T[P] (i.e. we treat the type T[P] as the type variable we're inferring for). */ function inferTypeForHomomorphicMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { if (inInferTypeForHomomorphicMappedType) { return undefined; } const key = source.id + "," + target.id + "," + constraint.id; if (reverseMappedCache.has(key)) { return reverseMappedCache.get(key); } inInferTypeForHomomorphicMappedType = true; const type = createReverseMappedType(source, target, constraint); inInferTypeForHomomorphicMappedType = false; reverseMappedCache.set(key, type); return type; } // We consider a type to be partially inferable if it isn't marked non-inferable or if it is // an object literal type with at least one property of an inferable type. For example, an object // literal { a: 123, b: x => true } is marked non-inferable because it contains a context sensitive // arrow function, but is considered partially inferable because property 'a' has an inferable type. function isPartiallyInferableType(type: Type): boolean { return !(getObjectFlags(type) & ObjectFlags.NonInferrableType) || isObjectLiteralType(type) && some(getPropertiesOfType(type), prop => isPartiallyInferableType(getTypeOfSymbol(prop))) || isTupleType(type) && some(getTypeArguments(type), isPartiallyInferableType); } function createReverseMappedType(source: Type, target: MappedType, constraint: IndexType) { // We consider a source type reverse mappable if it has a string index signature or if // it has one or more properties and is of a partially inferable type. if (!(getIndexInfoOfType(source, stringType) || getPropertiesOfType(source).length !== 0 && isPartiallyInferableType(source))) { return undefined; } // For arrays and tuples we infer new arrays and tuples where the reverse mapping has been // applied to the element type(s). if (isArrayType(source)) { return createArrayType(inferReverseMappedType(getTypeArguments(source)[0], target, constraint), isReadonlyArrayType(source)); } if (isTupleType(source)) { const elementTypes = map(getTypeArguments(source), t => inferReverseMappedType(t, target, constraint)); const elementFlags = getMappedTypeModifiers(target) & MappedTypeModifiers.IncludeOptional ? sameMap(source.target.elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : source.target.elementFlags; return createTupleType(elementTypes, elementFlags, source.target.readonly, source.target.labeledElementDeclarations); } // For all other object types we infer a new object type where the reverse mapping has been // applied to the type of each property. const reversed = createObjectType(ObjectFlags.ReverseMapped | ObjectFlags.Anonymous, /*symbol*/ undefined) as ReverseMappedType; reversed.source = source; reversed.mappedType = target; reversed.constraintType = constraint; return reversed; } function getTypeOfReverseMappedSymbol(symbol: ReverseMappedSymbol) { const links = getSymbolLinks(symbol); if (!links.type) { links.type = inferReverseMappedType(symbol.links.propertyType, symbol.links.mappedType, symbol.links.constraintType); } return links.type; } function inferReverseMappedType(sourceType: Type, target: MappedType, constraint: IndexType): Type { const typeParameter = getIndexedAccessType(constraint.type, getTypeParameterFromMappedType(target)) as TypeParameter; const templateType = getTemplateTypeFromMappedType(target); const inference = createInferenceInfo(typeParameter); inferTypes([inference], sourceType, templateType); return getTypeFromInference(inference) || unknownType; } function* getUnmatchedProperties(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): IterableIterator { const properties = getPropertiesOfType(target); for (const targetProp of properties) { // TODO: remove this when we support static private identifier fields and find other solutions to get privateNamesAndStaticFields test to pass if (isStaticPrivateIdentifierProperty(targetProp)) { continue; } if (requireOptionalProperties || !(targetProp.flags & SymbolFlags.Optional || getCheckFlags(targetProp) & CheckFlags.Partial)) { const sourceProp = getPropertyOfType(source, targetProp.escapedName); if (!sourceProp) { yield targetProp; } else if (matchDiscriminantProperties) { const targetType = getTypeOfSymbol(targetProp); if (targetType.flags & TypeFlags.Unit) { const sourceType = getTypeOfSymbol(sourceProp); if (!(sourceType.flags & TypeFlags.Any || getRegularTypeOfLiteralType(sourceType) === getRegularTypeOfLiteralType(targetType))) { yield targetProp; } } } } } } function getUnmatchedProperty(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): Symbol | undefined { return firstOrUndefinedIterator(getUnmatchedProperties(source, target, requireOptionalProperties, matchDiscriminantProperties)); } function tupleTypesDefinitelyUnrelated(source: TupleTypeReference, target: TupleTypeReference) { return !(target.target.combinedFlags & ElementFlags.Variadic) && target.target.minLength > source.target.minLength || !target.target.hasRestElement && (source.target.hasRestElement || target.target.fixedLength < source.target.fixedLength); } function typesDefinitelyUnrelated(source: Type, target: Type) { // Two tuple types with incompatible arities are definitely unrelated. // Two object types that each have a property that is unmatched in the other are definitely unrelated. return isTupleType(source) && isTupleType(target) ? tupleTypesDefinitelyUnrelated(source, target) : !!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ true) && !!getUnmatchedProperty(target, source, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ false); } function getTypeFromInference(inference: InferenceInfo) { return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) : inference.contraCandidates ? getIntersectionType(inference.contraCandidates) : undefined; } function hasSkipDirectInferenceFlag(node: Node) { return !!getNodeLinks(node).skipDirectInference; } function isFromInferenceBlockedSource(type: Type) { return !!(type.symbol && some(type.symbol.declarations, hasSkipDirectInferenceFlag)); } function templateLiteralTypesDefinitelyUnrelated(source: TemplateLiteralType, target: TemplateLiteralType) { // Two template literal types with diffences in their starting or ending text spans are definitely unrelated. const sourceStart = source.texts[0]; const targetStart = target.texts[0]; const sourceEnd = source.texts[source.texts.length - 1]; const targetEnd = target.texts[target.texts.length - 1]; const startLen = Math.min(sourceStart.length, targetStart.length); const endLen = Math.min(sourceEnd.length, targetEnd.length); return sourceStart.slice(0, startLen) !== targetStart.slice(0, startLen) || sourceEnd.slice(sourceEnd.length - endLen) !== targetEnd.slice(targetEnd.length - endLen); } /** * Tests whether the provided string can be parsed as a number. * @param s The string to test. * @param roundTripOnly Indicates the resulting number matches the input when converted back to a string. */ function isValidNumberString(s: string, roundTripOnly: boolean): boolean { if (s === "") return false; const n = +s; return isFinite(n) && (!roundTripOnly || "" + n === s); } /** * @param text a valid bigint string excluding a trailing `n`, but including a possible prefix `-`. Use `isValidBigIntString(text, roundTripOnly)` before calling this function. */ function parseBigIntLiteralType(text: string) { return getBigIntLiteralType(parseValidBigInt(text)); } function isMemberOfStringMapping(source: Type, target: Type): boolean { if (target.flags & TypeFlags.Any) { return true; } if (target.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { return isTypeAssignableTo(source, target); } if (target.flags & TypeFlags.StringMapping) { // We need to see whether applying the same mappings of the target // onto the source would produce an identical type *and* that // it's compatible with the inner-most non-string-mapped type. // // The intuition here is that if same mappings don't affect the source at all, // and the source is compatible with the unmapped target, then they must // still reside in the same domain. const mappingStack = []; while (target.flags & TypeFlags.StringMapping) { mappingStack.unshift(target.symbol); target = (target as StringMappingType).type; } const mappedSource = reduceLeft(mappingStack, (memo, value) => getStringMappingType(value, memo), source); return mappedSource === source && isMemberOfStringMapping(source, target); } return false; } function isValidTypeForTemplateLiteralPlaceholder(source: Type, target: Type): boolean { if (source === target || target.flags & (TypeFlags.Any | TypeFlags.String)) { return true; } if (source.flags & TypeFlags.StringLiteral) { const value = (source as StringLiteralType).value; return !!(target.flags & TypeFlags.Number && isValidNumberString(value, /*roundTripOnly*/ false) || target.flags & TypeFlags.BigInt && isValidBigIntString(value, /*roundTripOnly*/ false) || target.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) && value === (target as IntrinsicType).intrinsicName || target.flags & TypeFlags.StringMapping && isMemberOfStringMapping(getStringLiteralType(value), target)); } if (source.flags & TypeFlags.TemplateLiteral) { const texts = (source as TemplateLiteralType).texts; return texts.length === 2 && texts[0] === "" && texts[1] === "" && isTypeAssignableTo((source as TemplateLiteralType).types[0], target); } return isTypeAssignableTo(source, target); } function inferTypesFromTemplateLiteralType(source: Type, target: TemplateLiteralType): Type[] | undefined { return source.flags & TypeFlags.StringLiteral ? inferFromLiteralPartsToTemplateLiteral([(source as StringLiteralType).value], emptyArray, target) : source.flags & TypeFlags.TemplateLiteral ? arraysEqual((source as TemplateLiteralType).texts, target.texts) ? map((source as TemplateLiteralType).types, getStringLikeTypeForType) : inferFromLiteralPartsToTemplateLiteral((source as TemplateLiteralType).texts, (source as TemplateLiteralType).types, target) : undefined; } function isTypeMatchedByTemplateLiteralType(source: Type, target: TemplateLiteralType): boolean { const inferences = inferTypesFromTemplateLiteralType(source, target); return !!inferences && every(inferences, (r, i) => isValidTypeForTemplateLiteralPlaceholder(r, target.types[i])); } function getStringLikeTypeForType(type: Type) { return type.flags & (TypeFlags.Any | TypeFlags.StringLike) ? type : getTemplateLiteralType(["", ""], [type]); } // This function infers from the text parts and type parts of a source literal to a target template literal. The number // of text parts is always one more than the number of type parts, and a source string literal is treated as a source // with one text part and zero type parts. The function returns an array of inferred string or template literal types // corresponding to the placeholders in the target template literal, or undefined if the source doesn't match the target. // // We first check that the starting source text part matches the starting target text part, and that the ending source // text part ends matches the ending target text part. We then iterate through the remaining target text parts, finding // a match for each in the source and inferring string or template literal types created from the segments of the source // that occur between the matches. During this iteration, seg holds the index of the current text part in the sourceTexts // array and pos holds the current character position in the current text part. // // Consider inference from type `<<${string}>.<${number}-${number}>>` to type `<${string}.${string}>`, i.e. // sourceTexts = ['<<', '>.<', '-', '>>'] // sourceTypes = [string, number, number] // target.texts = ['<', '.', '>'] // We first match '<' in the target to the start of '<<' in the source and '>' in the target to the end of '>>' in // the source. The first match for the '.' in target occurs at character 1 in the source text part at index 1, and thus // the first inference is the template literal type `<${string}>`. The remainder of the source makes up the second // inference, the template literal type `<${number}-${number}>`. function inferFromLiteralPartsToTemplateLiteral(sourceTexts: readonly string[], sourceTypes: readonly Type[], target: TemplateLiteralType): Type[] | undefined { const lastSourceIndex = sourceTexts.length - 1; const sourceStartText = sourceTexts[0]; const sourceEndText = sourceTexts[lastSourceIndex]; const targetTexts = target.texts; const lastTargetIndex = targetTexts.length - 1; const targetStartText = targetTexts[0]; const targetEndText = targetTexts[lastTargetIndex]; if (lastSourceIndex === 0 && sourceStartText.length < targetStartText.length + targetEndText.length || !sourceStartText.startsWith(targetStartText) || !sourceEndText.endsWith(targetEndText)) return undefined; const remainingEndText = sourceEndText.slice(0, sourceEndText.length - targetEndText.length); const matches: Type[] = []; let seg = 0; let pos = targetStartText.length; for (let i = 1; i < lastTargetIndex; i++) { const delim = targetTexts[i]; if (delim.length > 0) { let s = seg; let p = pos; while (true) { p = getSourceText(s).indexOf(delim, p); if (p >= 0) break; s++; if (s === sourceTexts.length) return undefined; p = 0; } addMatch(s, p); pos += delim.length; } else if (pos < getSourceText(seg).length) { addMatch(seg, pos + 1); } else if (seg < lastSourceIndex) { addMatch(seg + 1, 0); } else { return undefined; } } addMatch(lastSourceIndex, getSourceText(lastSourceIndex).length); return matches; function getSourceText(index: number) { return index < lastSourceIndex ? sourceTexts[index] : remainingEndText; } function addMatch(s: number, p: number) { const matchType = s === seg ? getStringLiteralType(getSourceText(s).slice(pos, p)) : getTemplateLiteralType( [sourceTexts[seg].slice(pos), ...sourceTexts.slice(seg + 1, s), getSourceText(s).slice(0, p)], sourceTypes.slice(seg, s)); matches.push(matchType); seg = s; pos = p; } } function inferTypes(inferences: InferenceInfo[], originalSource: Type, originalTarget: Type, priority = InferencePriority.None, contravariant = false) { let bivariant = false; let propagationType: Type; let inferencePriority: number = InferencePriority.MaxValue; let allowComplexConstraintInference = true; let visited: Map; let sourceStack: object[]; let targetStack: object[]; let expandingFlags = ExpandingFlags.None; inferFromTypes(originalSource, originalTarget); function inferFromTypes(source: Type, target: Type): void { if (!couldContainTypeVariables(target)) { return; } if (source === wildcardType) { // We are inferring from an 'any' type. We want to infer this type for every type parameter // referenced in the target type, so we record it as the propagation type and infer from the // target to itself. Then, as we find candidates we substitute the propagation type. const savePropagationType = propagationType; propagationType = source; inferFromTypes(target, target); propagationType = savePropagationType; return; } if (source.aliasSymbol && source.aliasSymbol === target.aliasSymbol) { if (source.aliasTypeArguments) { // Source and target are types originating in the same generic type alias declaration. // Simply infer from source type arguments to target type arguments, with defaults applied. const params = getSymbolLinks(source.aliasSymbol).typeParameters!; const minParams = getMinTypeArgumentCount(params); const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); inferFromTypeArguments(sourceTypes, targetTypes!, getAliasVariances(source.aliasSymbol)); } // And if there weren't any type arguments, there's no reason to run inference as the types must be the same. return; } if (source === target && source.flags & TypeFlags.UnionOrIntersection) { // When source and target are the same union or intersection type, just relate each constituent // type to itself. for (const t of (source as UnionOrIntersectionType).types) { inferFromTypes(t, t); } return; } if (target.flags & TypeFlags.Union) { // First, infer between identically matching source and target constituents and remove the // matching types. const [tempSources, tempTargets] = inferFromMatchingTypes(source.flags & TypeFlags.Union ? (source as UnionType).types : [source], (target as UnionType).types, isTypeOrBaseIdenticalTo); // Next, infer between closely matching source and target constituents and remove // the matching types. Types closely match when they are instantiations of the same // object type or instantiations of the same type alias. const [sources, targets] = inferFromMatchingTypes(tempSources, tempTargets, isTypeCloselyMatchedBy); if (targets.length === 0) { return; } target = getUnionType(targets); if (sources.length === 0) { // All source constituents have been matched and there is nothing further to infer from. // However, simply making no inferences is undesirable because it could ultimately mean // inferring a type parameter constraint. Instead, make a lower priority inference from // the full source to whatever remains in the target. For example, when inferring from // string to 'string | T', make a lower priority inference of string for T. inferWithPriority(source, target, InferencePriority.NakedTypeVariable); return; } source = getUnionType(sources); } else if (target.flags & TypeFlags.Intersection && !every((target as IntersectionType).types, isNonGenericObjectType)) { // We reduce intersection types unless they're simple combinations of object types. For example, // when inferring from 'string[] & { extra: any }' to 'string[] & T' we want to remove string[] and // infer { extra: any } for T. But when inferring to 'string[] & Iterable' we want to keep the // string[] on the source side and infer string for T. if (!(source.flags & TypeFlags.Union)) { // Infer between identically matching source and target constituents and remove the matching types. const [sources, targets] = inferFromMatchingTypes(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], (target as IntersectionType).types, isTypeIdenticalTo); if (sources.length === 0 || targets.length === 0) { return; } source = getIntersectionType(sources); target = getIntersectionType(targets); } } else if (target.flags & (TypeFlags.IndexedAccess | TypeFlags.Substitution)) { target = getActualTypeVariable(target); } if (target.flags & TypeFlags.TypeVariable) { // Skip inference if the source is "blocked", which is used by the language service to // prevent inference on nodes currently being edited. if (isFromInferenceBlockedSource(source)) { return; } const inference = getInferenceInfoForType(target); if (inference) { // If target is a type parameter, make an inference, unless the source type contains // a "non-inferrable" type. Types with this flag set are markers used to prevent inference. // // For example: // - anyFunctionType is a wildcard type that's used to avoid contextually typing functions; // it's internal, so should not be exposed to the user by adding it as a candidate. // - autoType (and autoArrayType) is a special "any" used in control flow; like anyFunctionType, // it's internal and should not be observable. // - silentNeverType is returned by getInferredType when instantiating a generic function for // inference (and a type variable has no mapping). // // This flag is infectious; if we produce Box (where never is silentNeverType), Box is // also non-inferrable. // // As a special case, also ignore nonInferrableAnyType, which is a special form of the any type // used as a stand-in for binding elements when they are being inferred. if (getObjectFlags(source) & ObjectFlags.NonInferrableType || source === nonInferrableAnyType) { return; } if (!inference.isFixed) { if (inference.priority === undefined || priority < inference.priority) { inference.candidates = undefined; inference.contraCandidates = undefined; inference.topLevel = true; inference.priority = priority; } if (priority === inference.priority) { const candidate = propagationType || source; // We make contravariant inferences only if we are in a pure contravariant position, // i.e. only if we have not descended into a bivariant position. if (contravariant && !bivariant) { if (!contains(inference.contraCandidates, candidate)) { inference.contraCandidates = append(inference.contraCandidates, candidate); clearCachedInferences(inferences); } } else if (!contains(inference.candidates, candidate)) { inference.candidates = append(inference.candidates, candidate); clearCachedInferences(inferences); } } if (!(priority & InferencePriority.ReturnType) && target.flags & TypeFlags.TypeParameter && inference.topLevel && !isTypeParameterAtTopLevel(originalTarget, target as TypeParameter)) { inference.topLevel = false; clearCachedInferences(inferences); } } inferencePriority = Math.min(inferencePriority, priority); return; } // Infer to the simplified version of an indexed access, if possible, to (hopefully) expose more bare type parameters to the inference engine const simplified = getSimplifiedType(target, /*writing*/ false); if (simplified !== target) { inferFromTypes(source, simplified); } else if (target.flags & TypeFlags.IndexedAccess) { const indexType = getSimplifiedType((target as IndexedAccessType).indexType, /*writing*/ false); // Generally simplifications of instantiable indexes are avoided to keep relationship checking correct, however if our target is an access, we can consider // that key of that access to be "instantiated", since we're looking to find the infernce goal in any way we can. if (indexType.flags & TypeFlags.Instantiable) { const simplified = distributeIndexOverObjectType(getSimplifiedType((target as IndexedAccessType).objectType, /*writing*/ false), indexType, /*writing*/ false); if (simplified && simplified !== target) { inferFromTypes(source, simplified); } } } } if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target)) && !((source as TypeReference).node && (target as TypeReference).node)) { // If source and target are references to the same generic type, infer from type arguments inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); } else if (source.flags & TypeFlags.Index && target.flags & TypeFlags.Index) { inferFromContravariantTypes((source as IndexType).type, (target as IndexType).type); } else if ((isLiteralType(source) || source.flags & TypeFlags.String) && target.flags & TypeFlags.Index) { const empty = createEmptyObjectTypeFromStringLiteral(source); inferFromContravariantTypesWithPriority(empty, (target as IndexType).type, InferencePriority.LiteralKeyof); } else if (source.flags & TypeFlags.IndexedAccess && target.flags & TypeFlags.IndexedAccess) { inferFromTypes((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType); inferFromTypes((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType); } else if (source.flags & TypeFlags.StringMapping && target.flags & TypeFlags.StringMapping) { if ((source as StringMappingType).symbol === (target as StringMappingType).symbol) { inferFromTypes((source as StringMappingType).type, (target as StringMappingType).type); } } else if (source.flags & TypeFlags.Substitution) { inferFromTypes((source as SubstitutionType).baseType, target); inferWithPriority(getSubstitutionIntersection(source as SubstitutionType), target, InferencePriority.SubstituteSource); // Make substitute inference at a lower priority } else if (target.flags & TypeFlags.Conditional) { invokeOnce(source, (target as ConditionalType), inferToConditionalType); } else if (target.flags & TypeFlags.UnionOrIntersection) { inferToMultipleTypes(source, (target as UnionOrIntersectionType).types, target.flags); } else if (source.flags & TypeFlags.Union) { // Source is a union or intersection type, infer from each constituent type const sourceTypes = (source as UnionOrIntersectionType).types; for (const sourceType of sourceTypes) { inferFromTypes(sourceType, target); } } else if (target.flags & TypeFlags.TemplateLiteral) { inferToTemplateLiteralType(source, target as TemplateLiteralType); } else { source = getReducedType(source); if (!(priority & InferencePriority.NoConstraints && source.flags & (TypeFlags.Intersection | TypeFlags.Instantiable))) { const apparentSource = getApparentType(source); // getApparentType can return _any_ type, since an indexed access or conditional may simplify to any other type. // If that occurs and it doesn't simplify to an object or intersection, we'll need to restart `inferFromTypes` // with the simplified source. if (apparentSource !== source && allowComplexConstraintInference && !(apparentSource.flags & (TypeFlags.Object | TypeFlags.Intersection))) { // TODO: The `allowComplexConstraintInference` flag is a hack! This forbids inference from complex constraints within constraints! // This isn't required algorithmically, but rather is used to lower the memory burden caused by performing inference // that is _too good_ in projects with complicated constraints (eg, fp-ts). In such cases, if we did not limit ourselves // here, we might produce more valid inferences for types, causing us to do more checks and perform more instantiations // (in addition to the extra stack depth here) which, in turn, can push the already close process over its limit. // TL;DR: If we ever become generally more memory efficient (or our resource budget ever increases), we should just // remove this `allowComplexConstraintInference` flag. allowComplexConstraintInference = false; return inferFromTypes(apparentSource, target); } source = apparentSource; } if (source.flags & (TypeFlags.Object | TypeFlags.Intersection)) { invokeOnce(source, target, inferFromObjectTypes); } } } function inferWithPriority(source: Type, target: Type, newPriority: InferencePriority) { const savePriority = priority; priority |= newPriority; inferFromTypes(source, target); priority = savePriority; } function inferFromContravariantTypesWithPriority(source: Type, target: Type, newPriority: InferencePriority) { const savePriority = priority; priority |= newPriority; inferFromContravariantTypes(source, target); priority = savePriority; } function inferToMultipleTypesWithPriority(source: Type, targets: Type[], targetFlags: TypeFlags, newPriority: InferencePriority) { const savePriority = priority; priority |= newPriority; inferToMultipleTypes(source, targets, targetFlags); priority = savePriority; } function invokeOnce(source: Source, target: Target, action: (source: Source, target: Target) => void) { const key = source.id + "," + target.id; const status = visited && visited.get(key); if (status !== undefined) { inferencePriority = Math.min(inferencePriority, status); return; } (visited || (visited = new Map())).set(key, InferencePriority.Circularity); const saveInferencePriority = inferencePriority; inferencePriority = InferencePriority.MaxValue; // We stop inferring and report a circularity if we encounter duplicate recursion identities on both // the source side and the target side. const saveExpandingFlags = expandingFlags; const sourceIdentity = getRecursionIdentity(source); const targetIdentity = getRecursionIdentity(target); if (contains(sourceStack, sourceIdentity)) expandingFlags |= ExpandingFlags.Source; if (contains(targetStack, targetIdentity)) expandingFlags |= ExpandingFlags.Target; if (expandingFlags !== ExpandingFlags.Both) { (sourceStack || (sourceStack = [])).push(sourceIdentity); (targetStack || (targetStack = [])).push(targetIdentity); action(source, target); targetStack.pop(); sourceStack.pop(); } else { inferencePriority = InferencePriority.Circularity; } expandingFlags = saveExpandingFlags; visited.set(key, inferencePriority); inferencePriority = Math.min(inferencePriority, saveInferencePriority); } function inferFromMatchingTypes(sources: Type[], targets: Type[], matches: (s: Type, t: Type) => boolean): [Type[], Type[]] { let matchedSources: Type[] | undefined; let matchedTargets: Type[] | undefined; for (const t of targets) { for (const s of sources) { if (matches(s, t)) { inferFromTypes(s, t); matchedSources = appendIfUnique(matchedSources, s); matchedTargets = appendIfUnique(matchedTargets, t); } } } return [ matchedSources ? filter(sources, t => !contains(matchedSources, t)) : sources, matchedTargets ? filter(targets, t => !contains(matchedTargets, t)) : targets, ]; } function inferFromTypeArguments(sourceTypes: readonly Type[], targetTypes: readonly Type[], variances: readonly VarianceFlags[]) { const count = sourceTypes.length < targetTypes.length ? sourceTypes.length : targetTypes.length; for (let i = 0; i < count; i++) { if (i < variances.length && (variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Contravariant) { inferFromContravariantTypes(sourceTypes[i], targetTypes[i]); } else { inferFromTypes(sourceTypes[i], targetTypes[i]); } } } function inferFromContravariantTypes(source: Type, target: Type) { contravariant = !contravariant; inferFromTypes(source, target); contravariant = !contravariant; } function inferFromContravariantTypesIfStrictFunctionTypes(source: Type, target: Type) { if (strictFunctionTypes || priority & InferencePriority.AlwaysStrict) { inferFromContravariantTypes(source, target); } else { inferFromTypes(source, target); } } function getInferenceInfoForType(type: Type) { if (type.flags & TypeFlags.TypeVariable) { for (const inference of inferences) { if (type === inference.typeParameter) { return inference; } } } return undefined; } function getSingleTypeVariableFromIntersectionTypes(types: Type[]) { let typeVariable: Type | undefined; for (const type of types) { const t = type.flags & TypeFlags.Intersection && find((type as IntersectionType).types, t => !!getInferenceInfoForType(t)); if (!t || typeVariable && t !== typeVariable) { return undefined; } typeVariable = t; } return typeVariable; } function inferToMultipleTypes(source: Type, targets: Type[], targetFlags: TypeFlags) { let typeVariableCount = 0; if (targetFlags & TypeFlags.Union) { let nakedTypeVariable: Type | undefined; const sources = source.flags & TypeFlags.Union ? (source as UnionType).types : [source]; const matched = new Array(sources.length); let inferenceCircularity = false; // First infer to types that are not naked type variables. For each source type we // track whether inferences were made from that particular type to some target with // equal priority (i.e. of equal quality) to what we would infer for a naked type // parameter. for (const t of targets) { if (getInferenceInfoForType(t)) { nakedTypeVariable = t; typeVariableCount++; } else { for (let i = 0; i < sources.length; i++) { const saveInferencePriority = inferencePriority; inferencePriority = InferencePriority.MaxValue; inferFromTypes(sources[i], t); if (inferencePriority === priority) matched[i] = true; inferenceCircularity = inferenceCircularity || inferencePriority === InferencePriority.Circularity; inferencePriority = Math.min(inferencePriority, saveInferencePriority); } } } if (typeVariableCount === 0) { // If every target is an intersection of types containing a single naked type variable, // make a lower priority inference to that type variable. This handles inferring from // 'A | B' to 'T & (X | Y)' where we want to infer 'A | B' for T. const intersectionTypeVariable = getSingleTypeVariableFromIntersectionTypes(targets); if (intersectionTypeVariable) { inferWithPriority(source, intersectionTypeVariable, InferencePriority.NakedTypeVariable); } return; } // If the target has a single naked type variable and no inference circularities were // encountered above (meaning we explored the types fully), create a union of the source // types from which no inferences have been made so far and infer from that union to the // naked type variable. if (typeVariableCount === 1 && !inferenceCircularity) { const unmatched = flatMap(sources, (s, i) => matched[i] ? undefined : s); if (unmatched.length) { inferFromTypes(getUnionType(unmatched), nakedTypeVariable!); return; } } } else { // We infer from types that are not naked type variables first so that inferences we // make from nested naked type variables and given slightly higher priority by virtue // of being first in the candidates array. for (const t of targets) { if (getInferenceInfoForType(t)) { typeVariableCount++; } else { inferFromTypes(source, t); } } } // Inferences directly to naked type variables are given lower priority as they are // less specific. For example, when inferring from Promise to T | Promise, // we want to infer string for T, not Promise | string. For intersection types // we only infer to single naked type variables. if (targetFlags & TypeFlags.Intersection ? typeVariableCount === 1 : typeVariableCount > 0) { for (const t of targets) { if (getInferenceInfoForType(t)) { inferWithPriority(source, t, InferencePriority.NakedTypeVariable); } } } } function inferToMappedType(source: Type, target: MappedType, constraintType: Type): boolean { if (constraintType.flags & TypeFlags.Union) { let result = false; for (const type of (constraintType as UnionType).types) { result = inferToMappedType(source, target, type) || result; } return result; } if (constraintType.flags & TypeFlags.Index) { // We're inferring from some source type S to a homomorphic mapped type { [P in keyof T]: X }, // where T is a type variable. Use inferTypeForHomomorphicMappedType to infer a suitable source // type and then make a secondary inference from that type to T. We make a secondary inference // such that direct inferences to T get priority over inferences to Partial, for example. const inference = getInferenceInfoForType((constraintType as IndexType).type); if (inference && !inference.isFixed && !isFromInferenceBlockedSource(source)) { const inferredType = inferTypeForHomomorphicMappedType(source, target, constraintType as IndexType); if (inferredType) { // We assign a lower priority to inferences made from types containing non-inferrable // types because we may only have a partial result (i.e. we may have failed to make // reverse inferences for some properties). inferWithPriority(inferredType, inference.typeParameter, getObjectFlags(source) & ObjectFlags.NonInferrableType ? InferencePriority.PartialHomomorphicMappedType : InferencePriority.HomomorphicMappedType); } } return true; } if (constraintType.flags & TypeFlags.TypeParameter) { // We're inferring from some source type S to a mapped type { [P in K]: X }, where K is a type // parameter. First infer from 'keyof S' to K. inferWithPriority(getIndexType(source), constraintType, InferencePriority.MappedTypeConstraint); // If K is constrained to a type C, also infer to C. Thus, for a mapped type { [P in K]: X }, // where K extends keyof T, we make the same inferences as for a homomorphic mapped type // { [P in keyof T]: X }. This enables us to make meaningful inferences when the target is a // Pick. const extendedConstraint = getConstraintOfType(constraintType); if (extendedConstraint && inferToMappedType(source, target, extendedConstraint)) { return true; } // If no inferences can be made to K's constraint, infer from a union of the property types // in the source to the template type X. const propTypes = map(getPropertiesOfType(source), getTypeOfSymbol); const indexTypes = map(getIndexInfosOfType(source), info => info !== enumNumberIndexInfo ? info.type : neverType); inferFromTypes(getUnionType(concatenate(propTypes, indexTypes)), getTemplateTypeFromMappedType(target)); return true; } return false; } function inferToConditionalType(source: Type, target: ConditionalType) { if (source.flags & TypeFlags.Conditional) { inferFromTypes((source as ConditionalType).checkType, target.checkType); inferFromTypes((source as ConditionalType).extendsType, target.extendsType); inferFromTypes(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target)); inferFromTypes(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target)); } else { const targetTypes = [getTrueTypeFromConditionalType(target), getFalseTypeFromConditionalType(target)]; inferToMultipleTypesWithPriority(source, targetTypes, target.flags, contravariant ? InferencePriority.ContravariantConditional : 0); } } function inferToTemplateLiteralType(source: Type, target: TemplateLiteralType) { const matches = inferTypesFromTemplateLiteralType(source, target); const types = target.types; // When the target template literal contains only placeholders (meaning that inference is intended to extract // single characters and remainder strings) and inference fails to produce matches, we want to infer 'never' for // each placeholder such that instantiation with the inferred value(s) produces 'never', a type for which an // assignment check will fail. If we make no inferences, we'll likely end up with the constraint 'string' which, // upon instantiation, would collapse all the placeholders to just 'string', and an assignment check might // succeed. That would be a pointless and confusing outcome. if (matches || every(target.texts, s => s.length === 0)) { for (let i = 0; i < types.length; i++) { const source = matches ? matches[i] : neverType; const target = types[i]; // If we are inferring from a string literal type to a type variable whose constraint includes one of the // allowed template literal placeholder types, infer from a literal type corresponding to the constraint. if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.TypeVariable) { const inferenceContext = getInferenceInfoForType(target); const constraint = inferenceContext ? getBaseConstraintOfType(inferenceContext.typeParameter) : undefined; if (constraint && !isTypeAny(constraint)) { const constraintTypes = constraint.flags & TypeFlags.Union ? (constraint as UnionType).types : [constraint]; let allTypeFlags: TypeFlags = reduceLeft(constraintTypes, (flags, t) => flags | t.flags, 0 as TypeFlags); // If the constraint contains `string`, we don't need to look for a more preferred type if (!(allTypeFlags & TypeFlags.String)) { const str = (source as StringLiteralType).value; // If the type contains `number` or a number literal and the string isn't a valid number, exclude numbers if (allTypeFlags & TypeFlags.NumberLike && !isValidNumberString(str, /*roundTripOnly*/ true)) { allTypeFlags &= ~TypeFlags.NumberLike; } // If the type contains `bigint` or a bigint literal and the string isn't a valid bigint, exclude bigints if (allTypeFlags & TypeFlags.BigIntLike && !isValidBigIntString(str, /*roundTripOnly*/ true)) { allTypeFlags &= ~TypeFlags.BigIntLike; } // for each type in the constraint, find the highest priority matching type const matchingType = reduceLeft(constraintTypes, (left, right) => !(right.flags & allTypeFlags) ? left : left.flags & TypeFlags.String ? left : right.flags & TypeFlags.String ? source : left.flags & TypeFlags.TemplateLiteral ? left : right.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, right as TemplateLiteralType) ? source : left.flags & TypeFlags.StringMapping ? left : right.flags & TypeFlags.StringMapping && str === applyStringMapping(right.symbol, str) ? source : left.flags & TypeFlags.StringLiteral ? left : right.flags & TypeFlags.StringLiteral && (right as StringLiteralType).value === str ? right : left.flags & TypeFlags.Number ? left : right.flags & TypeFlags.Number ? getNumberLiteralType(+str) : left.flags & TypeFlags.Enum ? left : right.flags & TypeFlags.Enum ? getNumberLiteralType(+str) : left.flags & TypeFlags.NumberLiteral ? left : right.flags & TypeFlags.NumberLiteral && (right as NumberLiteralType).value === +str ? right : left.flags & TypeFlags.BigInt ? left : right.flags & TypeFlags.BigInt ? parseBigIntLiteralType(str) : left.flags & TypeFlags.BigIntLiteral ? left : right.flags & TypeFlags.BigIntLiteral && pseudoBigIntToString((right as BigIntLiteralType).value) === str ? right : left.flags & TypeFlags.Boolean ? left : right.flags & TypeFlags.Boolean ? str === "true" ? trueType : str === "false" ? falseType : booleanType : left.flags & TypeFlags.BooleanLiteral ? left : right.flags & TypeFlags.BooleanLiteral && (right as IntrinsicType).intrinsicName === str ? right : left.flags & TypeFlags.Undefined ? left : right.flags & TypeFlags.Undefined && (right as IntrinsicType).intrinsicName === str ? right : left.flags & TypeFlags.Null ? left : right.flags & TypeFlags.Null && (right as IntrinsicType).intrinsicName === str ? right : left, neverType as Type); if (!(matchingType.flags & TypeFlags.Never)) { inferFromTypes(matchingType, target); continue; } } } } inferFromTypes(source, target); } } } function inferFromObjectTypes(source: Type, target: Type) { if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target))) { // If source and target are references to the same generic type, infer from type arguments inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); return; } if (isGenericMappedType(source) && isGenericMappedType(target)) { // The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer // from S to T and from X to Y. inferFromTypes(getConstraintTypeFromMappedType(source), getConstraintTypeFromMappedType(target)); inferFromTypes(getTemplateTypeFromMappedType(source), getTemplateTypeFromMappedType(target)); const sourceNameType = getNameTypeFromMappedType(source); const targetNameType = getNameTypeFromMappedType(target); if (sourceNameType && targetNameType) inferFromTypes(sourceNameType, targetNameType); } if (getObjectFlags(target) & ObjectFlags.Mapped && !(target as MappedType).declaration.nameType) { const constraintType = getConstraintTypeFromMappedType(target as MappedType); if (inferToMappedType(source, target as MappedType, constraintType)) { return; } } // Infer from the members of source and target only if the two types are possibly related if (!typesDefinitelyUnrelated(source, target)) { if (isArrayOrTupleType(source)) { if (isTupleType(target)) { const sourceArity = getTypeReferenceArity(source); const targetArity = getTypeReferenceArity(target); const elementTypes = getTypeArguments(target); const elementFlags = target.target.elementFlags; // When source and target are tuple types with the same structure (fixed, variadic, and rest are matched // to the same kind in each position), simply infer between the element types. if (isTupleType(source) && isTupleTypeStructureMatching(source, target)) { for (let i = 0; i < targetArity; i++) { inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); } return; } const startLength = isTupleType(source) ? Math.min(source.target.fixedLength, target.target.fixedLength) : 0; const endLength = Math.min(isTupleType(source) ? getEndElementCount(source.target, ElementFlags.Fixed) : 0, target.target.hasRestElement ? getEndElementCount(target.target, ElementFlags.Fixed) : 0); // Infer between starting fixed elements. for (let i = 0; i < startLength; i++) { inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); } if (!isTupleType(source) || sourceArity - startLength - endLength === 1 && source.target.elementFlags[startLength] & ElementFlags.Rest) { // Single rest element remains in source, infer from that to every element in target const restType = getTypeArguments(source)[startLength]; for (let i = startLength; i < targetArity - endLength; i++) { inferFromTypes(elementFlags[i] & ElementFlags.Variadic ? createArrayType(restType) : restType, elementTypes[i]); } } else { const middleLength = targetArity - startLength - endLength; if (middleLength === 2) { if (elementFlags[startLength] & elementFlags[startLength + 1] & ElementFlags.Variadic) { // Middle of target is [...T, ...U] and source is tuple type const targetInfo = getInferenceInfoForType(elementTypes[startLength]); if (targetInfo && targetInfo.impliedArity !== undefined) { // Infer slices from source based on implied arity of T. inferFromTypes(sliceTupleType(source, startLength, endLength + sourceArity - targetInfo.impliedArity), elementTypes[startLength]); inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]); } } else if (elementFlags[startLength] & ElementFlags.Variadic && elementFlags[startLength + 1] & ElementFlags.Rest) { // Middle of target is [...T, ...rest] and source is tuple type // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T const param = getInferenceInfoForType(elementTypes[startLength])?.typeParameter; const constraint = param && getBaseConstraintOfType(param); if (constraint && isTupleType(constraint) && !constraint.target.hasRestElement) { const impliedArity = constraint.target.fixedLength; inferFromTypes(sliceTupleType(source, startLength, sourceArity - (startLength + impliedArity)), elementTypes[startLength]); inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength + impliedArity, endLength)!, elementTypes[startLength + 1]); } } else if (elementFlags[startLength] & ElementFlags.Rest && elementFlags[startLength + 1] & ElementFlags.Variadic) { // Middle of target is [...rest, ...T] and source is tuple type // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T const param = getInferenceInfoForType(elementTypes[startLength + 1])?.typeParameter; const constraint = param && getBaseConstraintOfType(param); if (constraint && isTupleType(constraint) && !constraint.target.hasRestElement) { const impliedArity = constraint.target.fixedLength; const endIndex = sourceArity - getEndElementCount(target.target, ElementFlags.Fixed); const startIndex = endIndex - impliedArity; const trailingSlice = createTupleType(getTypeArguments(source).slice(startIndex, endIndex), source.target.elementFlags.slice(startIndex, endIndex), /*readonly*/ false, source.target.labeledElementDeclarations && source.target.labeledElementDeclarations.slice(startIndex, endIndex)); inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength, endLength + impliedArity)!, elementTypes[startLength]); inferFromTypes(trailingSlice, elementTypes[startLength + 1]); } } } else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Variadic) { // Middle of target is exactly one variadic element. Infer the slice between the fixed parts in the source. // If target ends in optional element(s), make a lower priority a speculative inference. const endsInOptional = target.target.elementFlags[targetArity - 1] & ElementFlags.Optional; const sourceSlice = sliceTupleType(source, startLength, endLength); inferWithPriority(sourceSlice, elementTypes[startLength], endsInOptional ? InferencePriority.SpeculativeTuple : 0); } else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Rest) { // Middle of target is exactly one rest element. If middle of source is not empty, infer union of middle element types. const restType = getElementTypeOfSliceOfTupleType(source, startLength, endLength); if (restType) { inferFromTypes(restType, elementTypes[startLength]); } } } // Infer between ending fixed elements for (let i = 0; i < endLength; i++) { inferFromTypes(getTypeArguments(source)[sourceArity - i - 1], elementTypes[targetArity - i - 1]); } return; } if (isArrayType(target)) { inferFromIndexTypes(source, target); return; } } inferFromProperties(source, target); inferFromSignatures(source, target, SignatureKind.Call); inferFromSignatures(source, target, SignatureKind.Construct); inferFromIndexTypes(source, target); } } function inferFromProperties(source: Type, target: Type) { const properties = getPropertiesOfObjectType(target); for (const targetProp of properties) { const sourceProp = getPropertyOfType(source, targetProp.escapedName); if (sourceProp && !some(sourceProp.declarations, hasSkipDirectInferenceFlag)) { inferFromTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp)); } } } function inferFromSignatures(source: Type, target: Type, kind: SignatureKind) { const sourceSignatures = getSignaturesOfType(source, kind); const targetSignatures = getSignaturesOfType(target, kind); const sourceLen = sourceSignatures.length; const targetLen = targetSignatures.length; const len = sourceLen < targetLen ? sourceLen : targetLen; for (let i = 0; i < len; i++) { inferFromSignature(getBaseSignature(sourceSignatures[sourceLen - len + i]), getErasedSignature(targetSignatures[targetLen - len + i])); } } function inferFromSignature(source: Signature, target: Signature) { const saveBivariant = bivariant; const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; // Once we descend into a bivariant signature we remain bivariant for all nested inferences bivariant = bivariant || kind === SyntaxKind.MethodDeclaration || kind === SyntaxKind.MethodSignature || kind === SyntaxKind.Constructor; applyToParameterTypes(source, target, inferFromContravariantTypesIfStrictFunctionTypes); bivariant = saveBivariant; applyToReturnTypes(source, target, inferFromTypes); } function inferFromIndexTypes(source: Type, target: Type) { // Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0; const indexInfos = getIndexInfosOfType(target); if (isObjectTypeWithInferableIndex(source)) { for (const targetInfo of indexInfos) { const propTypes: Type[] = []; for (const prop of getPropertiesOfType(source)) { if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), targetInfo.keyType)) { const propType = getTypeOfSymbol(prop); propTypes.push(prop.flags & SymbolFlags.Optional ? removeMissingOrUndefinedType(propType) : propType); } } for (const info of getIndexInfosOfType(source)) { if (isApplicableIndexType(info.keyType, targetInfo.keyType)) { propTypes.push(info.type); } } if (propTypes.length) { inferWithPriority(getUnionType(propTypes), targetInfo.type, priority); } } } for (const targetInfo of indexInfos) { const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); if (sourceInfo) { inferWithPriority(sourceInfo.type, targetInfo.type, priority); } } } } function isTypeOrBaseIdenticalTo(s: Type, t: Type) { return t === missingType ? s === t : (isTypeIdenticalTo(s, t) || !!(t.flags & TypeFlags.String && s.flags & TypeFlags.StringLiteral || t.flags & TypeFlags.Number && s.flags & TypeFlags.NumberLiteral)); } function isTypeCloselyMatchedBy(s: Type, t: Type) { return !!(s.flags & TypeFlags.Object && t.flags & TypeFlags.Object && s.symbol && s.symbol === t.symbol || s.aliasSymbol && s.aliasTypeArguments && s.aliasSymbol === t.aliasSymbol); } function hasPrimitiveConstraint(type: TypeParameter): boolean { const constraint = getConstraintOfTypeParameter(type); return !!constraint && maybeTypeOfKind(constraint.flags & TypeFlags.Conditional ? getDefaultConstraintOfConditionalType(constraint as ConditionalType) : constraint, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); } function isObjectLiteralType(type: Type) { return !!(getObjectFlags(type) & ObjectFlags.ObjectLiteral); } function isObjectOrArrayLiteralType(type: Type) { return !!(getObjectFlags(type) & (ObjectFlags.ObjectLiteral | ObjectFlags.ArrayLiteral)); } function unionObjectAndArrayLiteralCandidates(candidates: Type[]): Type[] { if (candidates.length > 1) { const objectLiterals = filter(candidates, isObjectOrArrayLiteralType); if (objectLiterals.length) { const literalsType = getUnionType(objectLiterals, UnionReduction.Subtype); return concatenate(filter(candidates, t => !isObjectOrArrayLiteralType(t)), [literalsType]); } } return candidates; } function getContravariantInference(inference: InferenceInfo) { return inference.priority! & InferencePriority.PriorityImpliesCombination ? getIntersectionType(inference.contraCandidates!) : getCommonSubtype(inference.contraCandidates!); } function getCovariantInference(inference: InferenceInfo, signature: Signature) { // Extract all object and array literal types and replace them with a single widened and normalized type. const candidates = unionObjectAndArrayLiteralCandidates(inference.candidates!); // We widen inferred literal types if // all inferences were made to top-level occurrences of the type parameter, and // the type parameter has no constraint or its constraint includes no primitive or literal types, and // the type parameter was fixed during inference or does not occur at top-level in the return type. const primitiveConstraint = hasPrimitiveConstraint(inference.typeParameter) || isConstTypeVariable(inference.typeParameter); const widenLiteralTypes = !primitiveConstraint && inference.topLevel && (inference.isFixed || !isTypeParameterAtTopLevelInReturnType(signature, inference.typeParameter)); const baseCandidates = primitiveConstraint ? sameMap(candidates, getRegularTypeOfLiteralType) : widenLiteralTypes ? sameMap(candidates, getWidenedLiteralType) : candidates; // If all inferences were made from a position that implies a combined result, infer a union type. // Otherwise, infer a common supertype. const unwidenedType = inference.priority! & InferencePriority.PriorityImpliesCombination ? getUnionType(baseCandidates, UnionReduction.Subtype) : getCommonSupertype(baseCandidates); return getWidenedType(unwidenedType); } function getInferredType(context: InferenceContext, index: number): Type { const inference = context.inferences[index]; if (!inference.inferredType) { let inferredType: Type | undefined; const signature = context.signature; if (signature) { const inferredCovariantType = inference.candidates ? getCovariantInference(inference, signature) : undefined; if (inference.contraCandidates) { // If we have both co- and contra-variant inferences, we use the co-variant inference if it is not 'never', // it is a subtype of some contra-variant inference, and no other type parameter is constrained to this type // parameter and has inferences that would conflict. Otherwise, we use the contra-variant inference. const useCovariantType = inferredCovariantType && !(inferredCovariantType.flags & TypeFlags.Never) && some(inference.contraCandidates, t => isTypeSubtypeOf(inferredCovariantType, t)) && every(context.inferences, other => other !== inference && getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter || every(other.candidates, t => isTypeSubtypeOf(t, inferredCovariantType))); inferredType = useCovariantType ? inferredCovariantType : getContravariantInference(inference); } else if (inferredCovariantType) { inferredType = inferredCovariantType; } else if (context.flags & InferenceFlags.NoDefault) { // We use silentNeverType as the wildcard that signals no inferences. inferredType = silentNeverType; } else { // Infer either the default or the empty object type when no inferences were // made. It is important to remember that in this case, inference still // succeeds, meaning there is no error for not having inference candidates. An // inference error only occurs when there are *conflicting* candidates, i.e. // candidates with no common supertype. const defaultType = getDefaultFromTypeParameter(inference.typeParameter); if (defaultType) { // Instantiate the default type. Any forward reference to a type // parameter should be instantiated to the empty object type. inferredType = instantiateType(defaultType, mergeTypeMappers(createBackreferenceMapper(context, index), context.nonFixingMapper)); } } } else { inferredType = getTypeFromInference(inference); } inference.inferredType = inferredType || getDefaultTypeArgumentType(!!(context.flags & InferenceFlags.AnyDefault)); const constraint = getConstraintOfTypeParameter(inference.typeParameter); if (constraint) { const instantiatedConstraint = instantiateType(constraint, context.nonFixingMapper); if (!inferredType || !context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) { inference.inferredType = inferredType = instantiatedConstraint; } } } return inference.inferredType; } function getDefaultTypeArgumentType(isInJavaScriptFile: boolean): Type { return isInJavaScriptFile ? anyType : unknownType; } function getInferredTypes(context: InferenceContext): Type[] { const result: Type[] = []; for (let i = 0; i < context.inferences.length; i++) { result.push(getInferredType(context, i)); } return result; } // EXPRESSION TYPE CHECKING function getCannotFindNameDiagnosticForName(node: Identifier): DiagnosticMessage { switch (node.escapedText) { case "document": case "console": return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_include_dom; case "$": return compilerOptions.types ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery_and_then_add_jquery_to_the_types_field_in_your_tsconfig : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery; case "describe": case "suite": case "it": case "test": return compilerOptions.types ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha_and_then_add_jest_or_mocha_to_the_types_field_in_your_tsconfig : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha; case "process": case "require": case "Buffer": case "module": return compilerOptions.types ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode_and_then_add_node_to_the_types_field_in_your_tsconfig : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode; case "Map": case "Set": case "Promise": case "Symbol": case "WeakMap": case "WeakSet": case "Iterator": case "AsyncIterator": case "SharedArrayBuffer": case "Atomics": case "AsyncIterable": case "AsyncIterableIterator": case "AsyncGenerator": case "AsyncGeneratorFunction": case "BigInt": case "Reflect": case "BigInt64Array": case "BigUint64Array": return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_1_or_later; case "await": if (isCallExpression(node.parent)) { return Diagnostics.Cannot_find_name_0_Did_you_mean_to_write_this_in_an_async_function; } // falls through default: if (node.parent.kind === SyntaxKind.ShorthandPropertyAssignment) { return Diagnostics.No_value_exists_in_scope_for_the_shorthand_property_0_Either_declare_one_or_provide_an_initializer; } else { return Diagnostics.Cannot_find_name_0; } } } function getResolvedSymbol(node: Identifier): Symbol { const links = getNodeLinks(node); if (!links.resolvedSymbol) { links.resolvedSymbol = !nodeIsMissing(node) && resolveName( node, node.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue, getCannotFindNameDiagnosticForName(node), node, !isWriteOnlyAccess(node), /*excludeGlobals*/ false) || unknownSymbol; } return links.resolvedSymbol; } function isInTypeQuery(node: Node): boolean { // TypeScript 1.0 spec (April 2014): 3.6.3 // A type query consists of the keyword typeof followed by an expression. // The expression is restricted to a single identifier or a sequence of identifiers separated by periods return !!findAncestor( node, n => n.kind === SyntaxKind.TypeQuery ? true : n.kind === SyntaxKind.Identifier || n.kind === SyntaxKind.QualifiedName ? false : "quit"); } function isInAmbientOrTypeNode(node: Node): boolean { return !!(node.flags & NodeFlags.Ambient || findAncestor(node, n => isInterfaceDeclaration(n) || isTypeLiteralNode(n))); } // Return the flow cache key for a "dotted name" (i.e. a sequence of identifiers // separated by dots). The key consists of the id of the symbol referenced by the // leftmost identifier followed by zero or more property names separated by dots. // The result is undefined if the reference isn't a dotted name. function getFlowCacheKey(node: Node, declaredType: Type, initialType: Type, flowContainer: Node | undefined): string | undefined { switch (node.kind) { case SyntaxKind.Identifier: if (!isThisInTypeQuery(node)) { const symbol = getResolvedSymbol(node as Identifier); return symbol !== unknownSymbol ? `${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}|${getSymbolId(symbol)}` : undefined; } // falls through case SyntaxKind.ThisKeyword: return `0|${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}`; case SyntaxKind.NonNullExpression: case SyntaxKind.ParenthesizedExpression: return getFlowCacheKey((node as NonNullExpression | ParenthesizedExpression).expression, declaredType, initialType, flowContainer); case SyntaxKind.QualifiedName: const left = getFlowCacheKey((node as QualifiedName).left, declaredType, initialType, flowContainer); return left && left + "." + (node as QualifiedName).right.escapedText; case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: const propName = getAccessedPropertyName(node as AccessExpression); if (propName !== undefined) { const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); return key && key + "." + propName; } break; case SyntaxKind.ObjectBindingPattern: case SyntaxKind.ArrayBindingPattern: case SyntaxKind.FunctionDeclaration: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: case SyntaxKind.MethodDeclaration: // Handle pseudo-references originating in getNarrowedTypeOfSymbol. return `${getNodeId(node)}#${getTypeId(declaredType)}`; } return undefined; } function isMatchingReference(source: Node, target: Node): boolean { switch (target.kind) { case SyntaxKind.ParenthesizedExpression: case SyntaxKind.NonNullExpression: return isMatchingReference(source, (target as NonNullExpression | ParenthesizedExpression).expression); case SyntaxKind.BinaryExpression: return (isAssignmentExpression(target) && isMatchingReference(source, target.left)) || (isBinaryExpression(target) && target.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source, target.right)); } switch (source.kind) { case SyntaxKind.MetaProperty: return target.kind === SyntaxKind.MetaProperty && (source as MetaProperty).keywordToken === (target as MetaProperty).keywordToken && (source as MetaProperty).name.escapedText === (target as MetaProperty).name.escapedText; case SyntaxKind.Identifier: case SyntaxKind.PrivateIdentifier: return isThisInTypeQuery(source) ? target.kind === SyntaxKind.ThisKeyword : target.kind === SyntaxKind.Identifier && getResolvedSymbol(source as Identifier) === getResolvedSymbol(target as Identifier) || (isVariableDeclaration(target) || isBindingElement(target)) && getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(source as Identifier)) === getSymbolOfDeclaration(target); case SyntaxKind.ThisKeyword: return target.kind === SyntaxKind.ThisKeyword; case SyntaxKind.SuperKeyword: return target.kind === SyntaxKind.SuperKeyword; case SyntaxKind.NonNullExpression: case SyntaxKind.ParenthesizedExpression: return isMatchingReference((source as NonNullExpression | ParenthesizedExpression).expression, target); case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: const sourcePropertyName = getAccessedPropertyName(source as AccessExpression); const targetPropertyName = isAccessExpression(target) ? getAccessedPropertyName(target) : undefined; return sourcePropertyName !== undefined && targetPropertyName !== undefined && targetPropertyName === sourcePropertyName && isMatchingReference((source as AccessExpression).expression, (target as AccessExpression).expression); case SyntaxKind.QualifiedName: return isAccessExpression(target) && (source as QualifiedName).right.escapedText === getAccessedPropertyName(target) && isMatchingReference((source as QualifiedName).left, target.expression); case SyntaxKind.BinaryExpression: return (isBinaryExpression(source) && source.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source.right, target)); } return false; } function getAccessedPropertyName(access: AccessExpression | BindingElement | ParameterDeclaration): __String | undefined { if (isPropertyAccessExpression(access)) { return access.name.escapedText; } if (isElementAccessExpression(access)) { return tryGetElementAccessExpressionName(access); } if (isBindingElement(access)) { const name = getDestructuringPropertyName(access); return name ? escapeLeadingUnderscores(name) : undefined; } if (isParameter(access)) { return ("" + access.parent.parameters.indexOf(access)) as __String; } return undefined; } function tryGetNameFromType(type: Type) { return type.flags & TypeFlags.UniqueESSymbol ? (type as UniqueESSymbolType).escapedName : type.flags & TypeFlags.StringOrNumberLiteral ? escapeLeadingUnderscores("" + (type as StringLiteralType | NumberLiteralType).value) : undefined; } function tryGetElementAccessExpressionName(node: ElementAccessExpression) { if (isStringOrNumericLiteralLike(node.argumentExpression)) { return escapeLeadingUnderscores(node.argumentExpression.text); } if (isEntityNameExpression(node.argumentExpression)) { const symbol = resolveEntityName(node.argumentExpression, SymbolFlags.Value, /*ignoreErrors*/ true); if (!symbol || !(isConstVariable(symbol) || (symbol.flags & SymbolFlags.EnumMember))) return undefined; const declaration = symbol.valueDeclaration; if (declaration === undefined) return undefined; const type = tryGetTypeFromEffectiveTypeNode(declaration); if (type) { const name = tryGetNameFromType(type); if (name !== undefined) { return name; } } if (hasOnlyExpressionInitializer(declaration) && isBlockScopedNameDeclaredBeforeUse(declaration, node.argumentExpression)) { const initializer = getEffectiveInitializer(declaration); if (initializer) { return tryGetNameFromType(getTypeOfExpression(initializer)); } if (isEnumMember(declaration)) { return getTextOfPropertyName(declaration.name); } } } return undefined; } function containsMatchingReference(source: Node, target: Node) { while (isAccessExpression(source)) { source = source.expression; if (isMatchingReference(source, target)) { return true; } } return false; } function optionalChainContainsReference(source: Node, target: Node) { while (isOptionalChain(source)) { source = source.expression; if (isMatchingReference(source, target)) { return true; } } return false; } function isDiscriminantProperty(type: Type | undefined, name: __String) { if (type && type.flags & TypeFlags.Union) { const prop = getUnionOrIntersectionProperty(type as UnionType, name); if (prop && getCheckFlags(prop) & CheckFlags.SyntheticProperty) { // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty if ((prop as TransientSymbol).links.isDiscriminantProperty === undefined) { (prop as TransientSymbol).links.isDiscriminantProperty = ((prop as TransientSymbol).links.checkFlags & CheckFlags.Discriminant) === CheckFlags.Discriminant && !isGenericType(getTypeOfSymbol(prop)); } return !!(prop as TransientSymbol).links.isDiscriminantProperty; } } return false; } function findDiscriminantProperties(sourceProperties: Symbol[], target: Type): Symbol[] | undefined { let result: Symbol[] | undefined; for (const sourceProperty of sourceProperties) { if (isDiscriminantProperty(target, sourceProperty.escapedName)) { if (result) { result.push(sourceProperty); continue; } result = [sourceProperty]; } } return result; } // Given a set of constituent types and a property name, create and return a map keyed by the literal // types of the property by that name in each constituent type. No map is returned if some key property // has a non-literal type or if less than 10 or less than 50% of the constituents have a unique key. // Entries with duplicate keys have unknownType as the value. function mapTypesByKeyProperty(types: Type[], name: __String) { const map = new Map(); let count = 0; for (const type of types) { if (type.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { const discriminant = getTypeOfPropertyOfType(type, name); if (discriminant) { if (!isLiteralType(discriminant)) { return undefined; } let duplicate = false; forEachType(discriminant, t => { const id = getTypeId(getRegularTypeOfLiteralType(t)); const existing = map.get(id); if (!existing) { map.set(id, type); } else if (existing !== unknownType) { map.set(id, unknownType); duplicate = true; } }); if (!duplicate) count++; } } } return count >= 10 && count * 2 >= types.length ? map : undefined; } // Return the name of a discriminant property for which it was possible and feasible to construct a map of // constituent types keyed by the literal types of the property by that name in each constituent type. function getKeyPropertyName(unionType: UnionType): __String | undefined { const types = unionType.types; // We only construct maps for unions with many non-primitive constituents. if (types.length < 10 || getObjectFlags(unionType) & ObjectFlags.PrimitiveUnion || countWhere(types, t => !!(t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive))) < 10) { return undefined; } if (unionType.keyPropertyName === undefined) { // The candidate key property name is the name of the first property with a unit type in one of the // constituent types. const keyPropertyName = forEach(types, t => t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) ? forEach(getPropertiesOfType(t), p => isUnitType(getTypeOfSymbol(p)) ? p.escapedName : undefined) : undefined); const mapByKeyProperty = keyPropertyName && mapTypesByKeyProperty(types, keyPropertyName); unionType.keyPropertyName = mapByKeyProperty ? keyPropertyName : "" as __String; unionType.constituentMap = mapByKeyProperty; } return (unionType.keyPropertyName as string).length ? unionType.keyPropertyName : undefined; } // Given a union type for which getKeyPropertyName returned a non-undefined result, return the constituent // that corresponds to the given key type for that property name. function getConstituentTypeForKeyType(unionType: UnionType, keyType: Type) { const result = unionType.constituentMap?.get(getTypeId(getRegularTypeOfLiteralType(keyType))); return result !== unknownType ? result : undefined; } function getMatchingUnionConstituentForType(unionType: UnionType, type: Type) { const keyPropertyName = getKeyPropertyName(unionType); const propType = keyPropertyName && getTypeOfPropertyOfType(type, keyPropertyName); return propType && getConstituentTypeForKeyType(unionType, propType); } function getMatchingUnionConstituentForObjectLiteral(unionType: UnionType, node: ObjectLiteralExpression) { const keyPropertyName = getKeyPropertyName(unionType); const propNode = keyPropertyName && find(node.properties, p => p.symbol && p.kind === SyntaxKind.PropertyAssignment && p.symbol.escapedName === keyPropertyName && isPossiblyDiscriminantValue(p.initializer)); const propType = propNode && getContextFreeTypeOfExpression((propNode as PropertyAssignment).initializer); return propType && getConstituentTypeForKeyType(unionType, propType); } function isOrContainsMatchingReference(source: Node, target: Node) { return isMatchingReference(source, target) || containsMatchingReference(source, target); } function hasMatchingArgument(expression: CallExpression | NewExpression, reference: Node) { if (expression.arguments) { for (const argument of expression.arguments) { if (isOrContainsMatchingReference(reference, argument)) { return true; } } } if (expression.expression.kind === SyntaxKind.PropertyAccessExpression && isOrContainsMatchingReference(reference, (expression.expression as PropertyAccessExpression).expression)) { return true; } return false; } function getFlowNodeId(flow: FlowNode): number { if (!flow.id || flow.id < 0) { flow.id = nextFlowId; nextFlowId++; } return flow.id; } function typeMaybeAssignableTo(source: Type, target: Type) { if (!(source.flags & TypeFlags.Union)) { return isTypeAssignableTo(source, target); } for (const t of (source as UnionType).types) { if (isTypeAssignableTo(t, target)) { return true; } } return false; } // Remove those constituent types of declaredType to which no constituent type of assignedType is assignable. // For example, when a variable of type number | string | boolean is assigned a value of type number | boolean, // we remove type string. function getAssignmentReducedType(declaredType: UnionType, assignedType: Type) { if (declaredType === assignedType) { return declaredType; } if (assignedType.flags & TypeFlags.Never) { return assignedType; } const key = `A${getTypeId(declaredType)},${getTypeId(assignedType)}`; return getCachedType(key) ?? setCachedType(key, getAssignmentReducedTypeWorker(declaredType, assignedType)); } function getAssignmentReducedTypeWorker(declaredType: UnionType, assignedType: Type) { const filteredType = filterType(declaredType, t => typeMaybeAssignableTo(assignedType, t)); // Ensure that we narrow to fresh types if the assignment is a fresh boolean literal type. const reducedType = assignedType.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(assignedType) ? mapType(filteredType, getFreshTypeOfLiteralType) : filteredType; // Our crude heuristic produces an invalid result in some cases: see GH#26130. // For now, when that happens, we give up and don't narrow at all. (This also // means we'll never narrow for erroneous assignments where the assigned type // is not assignable to the declared type.) return isTypeAssignableTo(assignedType, reducedType) ? reducedType : declaredType; } function isFunctionObjectType(type: ObjectType): boolean { // We do a quick check for a "bind" property before performing the more expensive subtype // check. This gives us a quicker out in the common case where an object type is not a function. const resolved = resolveStructuredTypeMembers(type); return !!(resolved.callSignatures.length || resolved.constructSignatures.length || resolved.members.get("bind" as __String) && isTypeSubtypeOf(type, globalFunctionType)); } function getTypeFacts(type: Type): TypeFacts { if (type.flags & (TypeFlags.Intersection | TypeFlags.Instantiable)) { type = getBaseConstraintOfType(type) || unknownType; } const flags = type.flags; if (flags & (TypeFlags.String | TypeFlags.StringMapping)) { return strictNullChecks ? TypeFacts.StringStrictFacts : TypeFacts.StringFacts; } if (flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral)) { const isEmpty = flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === ""; return strictNullChecks ? isEmpty ? TypeFacts.EmptyStringStrictFacts : TypeFacts.NonEmptyStringStrictFacts : isEmpty ? TypeFacts.EmptyStringFacts : TypeFacts.NonEmptyStringFacts; } if (flags & (TypeFlags.Number | TypeFlags.Enum)) { return strictNullChecks ? TypeFacts.NumberStrictFacts : TypeFacts.NumberFacts; } if (flags & TypeFlags.NumberLiteral) { const isZero = (type as NumberLiteralType).value === 0; return strictNullChecks ? isZero ? TypeFacts.ZeroNumberStrictFacts : TypeFacts.NonZeroNumberStrictFacts : isZero ? TypeFacts.ZeroNumberFacts : TypeFacts.NonZeroNumberFacts; } if (flags & TypeFlags.BigInt) { return strictNullChecks ? TypeFacts.BigIntStrictFacts : TypeFacts.BigIntFacts; } if (flags & TypeFlags.BigIntLiteral) { const isZero = isZeroBigInt(type as BigIntLiteralType); return strictNullChecks ? isZero ? TypeFacts.ZeroBigIntStrictFacts : TypeFacts.NonZeroBigIntStrictFacts : isZero ? TypeFacts.ZeroBigIntFacts : TypeFacts.NonZeroBigIntFacts; } if (flags & TypeFlags.Boolean) { return strictNullChecks ? TypeFacts.BooleanStrictFacts : TypeFacts.BooleanFacts; } if (flags & TypeFlags.BooleanLike) { return strictNullChecks ? (type === falseType || type === regularFalseType) ? TypeFacts.FalseStrictFacts : TypeFacts.TrueStrictFacts : (type === falseType || type === regularFalseType) ? TypeFacts.FalseFacts : TypeFacts.TrueFacts; } if (flags & TypeFlags.Object) { return getObjectFlags(type) & ObjectFlags.Anonymous && isEmptyObjectType(type as ObjectType) ? strictNullChecks ? TypeFacts.EmptyObjectStrictFacts : TypeFacts.EmptyObjectFacts : isFunctionObjectType(type as ObjectType) ? strictNullChecks ? TypeFacts.FunctionStrictFacts : TypeFacts.FunctionFacts : strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; } if (flags & TypeFlags.Void) { return TypeFacts.VoidFacts; } if (flags & TypeFlags.Undefined) { return TypeFacts.UndefinedFacts; } if (flags & TypeFlags.Null) { return TypeFacts.NullFacts; } if (flags & TypeFlags.ESSymbolLike) { return strictNullChecks ? TypeFacts.SymbolStrictFacts : TypeFacts.SymbolFacts; } if (flags & TypeFlags.NonPrimitive) { return strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; } if (flags & TypeFlags.Never) { return TypeFacts.None; } if (flags & TypeFlags.Union) { return reduceLeft((type as UnionType).types, (facts, t) => facts | getTypeFacts(t), TypeFacts.None); } if (flags & TypeFlags.Intersection) { return getIntersectionTypeFacts(type as IntersectionType); } return TypeFacts.UnknownFacts; } function getIntersectionTypeFacts(type: IntersectionType): TypeFacts { // When an intersection contains a primitive type we ignore object type constituents as they are // presumably type tags. For example, in string & { __kind__: "name" } we ignore the object type. const ignoreObjects = maybeTypeOfKind(type, TypeFlags.Primitive); // When computing the type facts of an intersection type, certain type facts are computed as `and` // and others are computed as `or`. let oredFacts = TypeFacts.None; let andedFacts = TypeFacts.All; for (const t of type.types) { if (!(ignoreObjects && t.flags & TypeFlags.Object)) { const f = getTypeFacts(t); oredFacts |= f; andedFacts &= f; } } return oredFacts & TypeFacts.OrFactsMask | andedFacts & TypeFacts.AndFactsMask; } function getTypeWithFacts(type: Type, include: TypeFacts) { return filterType(type, t => (getTypeFacts(t) & include) !== 0); } // This function is similar to getTypeWithFacts, except that in strictNullChecks mode it replaces type // unknown with the union {} | null | undefined (and reduces that accordingly), and it intersects remaining // instantiable types with {}, {} | null, or {} | undefined in order to remove null and/or undefined. function getAdjustedTypeWithFacts(type: Type, facts: TypeFacts) { const reduced = recombineUnknownType(getTypeWithFacts(strictNullChecks && type.flags & TypeFlags.Unknown ? unknownUnionType : type, facts)); if (strictNullChecks) { switch (facts) { case TypeFacts.NEUndefined: return mapType(reduced, t => getTypeFacts(t) & TypeFacts.EQUndefined ? getIntersectionType([t, getTypeFacts(t) & TypeFacts.EQNull && !maybeTypeOfKind(reduced, TypeFlags.Null) ? getUnionType([emptyObjectType, nullType]) : emptyObjectType]): t); case TypeFacts.NENull: return mapType(reduced, t => getTypeFacts(t) & TypeFacts.EQNull ? getIntersectionType([t, getTypeFacts(t) & TypeFacts.EQUndefined && !maybeTypeOfKind(reduced, TypeFlags.Undefined) ? getUnionType([emptyObjectType, undefinedType]) : emptyObjectType]): t); case TypeFacts.NEUndefinedOrNull: case TypeFacts.Truthy: return mapType(reduced, t => getTypeFacts(t) & TypeFacts.EQUndefinedOrNull ? getGlobalNonNullableTypeInstantiation(t): t); } } return reduced; } function recombineUnknownType(type: Type) { return type === unknownUnionType ? unknownType : type; } function getTypeWithDefault(type: Type, defaultExpression: Expression) { return defaultExpression ? getUnionType([getNonUndefinedType(type), getTypeOfExpression(defaultExpression)]) : type; } function getTypeOfDestructuredProperty(type: Type, name: PropertyName) { const nameType = getLiteralTypeFromPropertyName(name); if (!isTypeUsableAsPropertyName(nameType)) return errorType; const text = getPropertyNameFromType(nameType); return getTypeOfPropertyOfType(type, text) || includeUndefinedInIndexSignature(getApplicableIndexInfoForName(type, text)?.type) || errorType; } function getTypeOfDestructuredArrayElement(type: Type, index: number) { return everyType(type, isTupleLikeType) && getTupleElementType(type, index) || includeUndefinedInIndexSignature(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined)) || errorType; } function includeUndefinedInIndexSignature(type: Type | undefined): Type | undefined { if (!type) return type; return compilerOptions.noUncheckedIndexedAccess ? getUnionType([type, missingType]) : type; } function getTypeOfDestructuredSpreadExpression(type: Type) { return createArrayType(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined) || errorType); } function getAssignedTypeOfBinaryExpression(node: BinaryExpression): Type { const isDestructuringDefaultAssignment = node.parent.kind === SyntaxKind.ArrayLiteralExpression && isDestructuringAssignmentTarget(node.parent) || node.parent.kind === SyntaxKind.PropertyAssignment && isDestructuringAssignmentTarget(node.parent.parent); return isDestructuringDefaultAssignment ? getTypeWithDefault(getAssignedType(node), node.right) : getTypeOfExpression(node.right); } function isDestructuringAssignmentTarget(parent: Node) { return parent.parent.kind === SyntaxKind.BinaryExpression && (parent.parent as BinaryExpression).left === parent || parent.parent.kind === SyntaxKind.ForOfStatement && (parent.parent as ForOfStatement).initializer === parent; } function getAssignedTypeOfArrayLiteralElement(node: ArrayLiteralExpression, element: Expression): Type { return getTypeOfDestructuredArrayElement(getAssignedType(node), node.elements.indexOf(element)); } function getAssignedTypeOfSpreadExpression(node: SpreadElement): Type { return getTypeOfDestructuredSpreadExpression(getAssignedType(node.parent as ArrayLiteralExpression)); } function getAssignedTypeOfPropertyAssignment(node: PropertyAssignment | ShorthandPropertyAssignment): Type { return getTypeOfDestructuredProperty(getAssignedType(node.parent), node.name); } function getAssignedTypeOfShorthandPropertyAssignment(node: ShorthandPropertyAssignment): Type { return getTypeWithDefault(getAssignedTypeOfPropertyAssignment(node), node.objectAssignmentInitializer!); } function getAssignedType(node: Expression): Type { const { parent } = node; switch (parent.kind) { case SyntaxKind.ForInStatement: return stringType; case SyntaxKind.ForOfStatement: return checkRightHandSideOfForOf(parent as ForOfStatement) || errorType; case SyntaxKind.BinaryExpression: return getAssignedTypeOfBinaryExpression(parent as BinaryExpression); case SyntaxKind.DeleteExpression: return undefinedType; case SyntaxKind.ArrayLiteralExpression: return getAssignedTypeOfArrayLiteralElement(parent as ArrayLiteralExpression, node); case SyntaxKind.SpreadElement: return getAssignedTypeOfSpreadExpression(parent as SpreadElement); case SyntaxKind.PropertyAssignment: return getAssignedTypeOfPropertyAssignment(parent as PropertyAssignment); case SyntaxKind.ShorthandPropertyAssignment: return getAssignedTypeOfShorthandPropertyAssignment(parent as ShorthandPropertyAssignment); } return errorType; } function getInitialTypeOfBindingElement(node: BindingElement): Type { const pattern = node.parent; const parentType = getInitialType(pattern.parent as VariableDeclaration | BindingElement); const type = pattern.kind === SyntaxKind.ObjectBindingPattern ? getTypeOfDestructuredProperty(parentType, node.propertyName || node.name as Identifier) : !node.dotDotDotToken ? getTypeOfDestructuredArrayElement(parentType, pattern.elements.indexOf(node)) : getTypeOfDestructuredSpreadExpression(parentType); return getTypeWithDefault(type, node.initializer!); } function getTypeOfInitializer(node: Expression) { // Return the cached type if one is available. If the type of the variable was inferred // from its initializer, we'll already have cached the type. Otherwise we compute it now // without caching such that transient types are reflected. const links = getNodeLinks(node); return links.resolvedType || getTypeOfExpression(node); } function getInitialTypeOfVariableDeclaration(node: VariableDeclaration) { if (node.initializer) { return getTypeOfInitializer(node.initializer); } if (node.parent.parent.kind === SyntaxKind.ForInStatement) { return stringType; } if (node.parent.parent.kind === SyntaxKind.ForOfStatement) { return checkRightHandSideOfForOf(node.parent.parent) || errorType; } return errorType; } function getInitialType(node: VariableDeclaration | BindingElement) { return node.kind === SyntaxKind.VariableDeclaration ? getInitialTypeOfVariableDeclaration(node) : getInitialTypeOfBindingElement(node); } function isEmptyArrayAssignment(node: VariableDeclaration | BindingElement | Expression) { return node.kind === SyntaxKind.VariableDeclaration && (node as VariableDeclaration).initializer && isEmptyArrayLiteral((node as VariableDeclaration).initializer!) || node.kind !== SyntaxKind.BindingElement && node.parent.kind === SyntaxKind.BinaryExpression && isEmptyArrayLiteral((node.parent as BinaryExpression).right); } function getReferenceCandidate(node: Expression): Expression { switch (node.kind) { case SyntaxKind.ParenthesizedExpression: return getReferenceCandidate((node as ParenthesizedExpression).expression); case SyntaxKind.BinaryExpression: switch ((node as BinaryExpression).operatorToken.kind) { case SyntaxKind.EqualsToken: case SyntaxKind.BarBarEqualsToken: case SyntaxKind.AmpersandAmpersandEqualsToken: case SyntaxKind.QuestionQuestionEqualsToken: return getReferenceCandidate((node as BinaryExpression).left); case SyntaxKind.CommaToken: return getReferenceCandidate((node as BinaryExpression).right); } } return node; } function getReferenceRoot(node: Node): Node { const { parent } = node; return parent.kind === SyntaxKind.ParenthesizedExpression || parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && (parent as BinaryExpression).left === node || parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken && (parent as BinaryExpression).right === node ? getReferenceRoot(parent) : node; } function getTypeOfSwitchClause(clause: CaseClause | DefaultClause) { if (clause.kind === SyntaxKind.CaseClause) { return getRegularTypeOfLiteralType(getTypeOfExpression(clause.expression)); } return neverType; } function getSwitchClauseTypes(switchStatement: SwitchStatement): Type[] { const links = getNodeLinks(switchStatement); if (!links.switchTypes) { links.switchTypes = []; for (const clause of switchStatement.caseBlock.clauses) { links.switchTypes.push(getTypeOfSwitchClause(clause)); } } return links.switchTypes; } // Get the type names from all cases in a switch on `typeof`. The default clause and/or duplicate type names are // represented as undefined. Return undefined if one or more case clause expressions are not string literals. function getSwitchClauseTypeOfWitnesses(switchStatement: SwitchStatement): (string | undefined)[] | undefined { if (some(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.CaseClause && !isStringLiteralLike(clause.expression))) { return undefined; } const witnesses: (string | undefined)[] = []; for (const clause of switchStatement.caseBlock.clauses) { const text = clause.kind === SyntaxKind.CaseClause ? (clause.expression as StringLiteralLike).text : undefined; witnesses.push(text && !contains(witnesses, text) ? text : undefined); } return witnesses; } function eachTypeContainedIn(source: Type, types: Type[]) { return source.flags & TypeFlags.Union ? !forEach((source as UnionType).types, t => !contains(types, t)) : contains(types, source); } function isTypeSubsetOf(source: Type, target: Type) { return source === target || target.flags & TypeFlags.Union && isTypeSubsetOfUnion(source, target as UnionType); } function isTypeSubsetOfUnion(source: Type, target: UnionType) { if (source.flags & TypeFlags.Union) { for (const t of (source as UnionType).types) { if (!containsType(target.types, t)) { return false; } } return true; } if (source.flags & TypeFlags.EnumLike && getBaseTypeOfEnumLikeType(source as LiteralType) === target) { return true; } return containsType(target.types, source); } function forEachType(type: Type, f: (t: Type) => T | undefined): T | undefined { return type.flags & TypeFlags.Union ? forEach((type as UnionType).types, f) : f(type); } function someType(type: Type, f: (t: Type) => boolean): boolean { return type.flags & TypeFlags.Union ? some((type as UnionType).types, f) : f(type); } function everyType(type: Type, f: (t: Type) => boolean): boolean { return type.flags & TypeFlags.Union ? every((type as UnionType).types, f) : f(type); } function everyContainedType(type: Type, f: (t: Type) => boolean): boolean { return type.flags & TypeFlags.UnionOrIntersection ? every((type as UnionOrIntersectionType).types, f) : f(type); } function filterType(type: Type, f: (t: Type) => boolean): Type { if (type.flags & TypeFlags.Union) { const types = (type as UnionType).types; const filtered = filter(types, f); if (filtered === types) { return type; } const origin = (type as UnionType).origin; let newOrigin: Type | undefined; if (origin && origin.flags & TypeFlags.Union) { // If the origin type is a (denormalized) union type, filter its non-union constituents. If that ends // up removing a smaller number of types than in the normalized constituent set (meaning some of the // filtered types are within nested unions in the origin), then we can't construct a new origin type. // Otherwise, if we have exactly one type left in the origin set, return that as the filtered type. // Otherwise, construct a new filtered origin type. const originTypes = (origin as UnionType).types; const originFiltered = filter(originTypes, t => !!(t.flags & TypeFlags.Union) || f(t)); if (originTypes.length - originFiltered.length === types.length - filtered.length) { if (originFiltered.length === 1) { return originFiltered[0]; } newOrigin = createOriginUnionOrIntersectionType(TypeFlags.Union, originFiltered); } } // filtering could remove intersections so `ContainsIntersections` might be forwarded "incorrectly" // it is purely an optimization hint so there is no harm in accidentally forwarding it return getUnionTypeFromSortedList(filtered, (type as UnionType).objectFlags & (ObjectFlags.PrimitiveUnion | ObjectFlags.ContainsIntersections), /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, newOrigin); } return type.flags & TypeFlags.Never || f(type) ? type : neverType; } function removeType(type: Type, targetType: Type) { return filterType(type, t => t !== targetType); } function countTypes(type: Type) { return type.flags & TypeFlags.Union ? (type as UnionType).types.length : 1; } // Apply a mapping function to a type and return the resulting type. If the source type // is a union type, the mapping function is applied to each constituent type and a union // of the resulting types is returned. function mapType(type: Type, mapper: (t: Type) => Type, noReductions?: boolean): Type; function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined; function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined { if (type.flags & TypeFlags.Never) { return type; } if (!(type.flags & TypeFlags.Union)) { return mapper(type); } const origin = (type as UnionType).origin; const types = origin && origin.flags & TypeFlags.Union ? (origin as UnionType).types : (type as UnionType).types; let mappedTypes: Type[] | undefined; let changed = false; for (const t of types) { const mapped = t.flags & TypeFlags.Union ? mapType(t, mapper, noReductions) : mapper(t); changed ||= t !== mapped; if (mapped) { if (!mappedTypes) { mappedTypes = [mapped]; } else { mappedTypes.push(mapped); } } } return changed ? mappedTypes && getUnionType(mappedTypes, noReductions ? UnionReduction.None : UnionReduction.Literal) : type; } function mapTypeWithAlias(type: Type, mapper: (t: Type) => Type, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { return type.flags & TypeFlags.Union && aliasSymbol ? getUnionType(map((type as UnionType).types, mapper), UnionReduction.Literal, aliasSymbol, aliasTypeArguments) : mapType(type, mapper); } function extractTypesOfKind(type: Type, kind: TypeFlags) { return filterType(type, t => (t.flags & kind) !== 0); } // Return a new type in which occurrences of the string, number and bigint primitives and placeholder template // literal types in typeWithPrimitives have been replaced with occurrences of compatible and more specific types // from typeWithLiterals. This is essentially a limited form of intersection between the two types. We avoid a // true intersection because it is more costly and, when applied to union types, generates a large number of // types we don't actually care about. function replacePrimitivesWithLiterals(typeWithPrimitives: Type, typeWithLiterals: Type) { if (maybeTypeOfKind(typeWithPrimitives, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.Number | TypeFlags.BigInt) && maybeTypeOfKind(typeWithLiterals, TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping | TypeFlags.NumberLiteral | TypeFlags.BigIntLiteral)) { return mapType(typeWithPrimitives, t => t.flags & TypeFlags.String ? extractTypesOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) : isPatternLiteralType(t) && !maybeTypeOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? extractTypesOfKind(typeWithLiterals, TypeFlags.StringLiteral) : t.flags & TypeFlags.Number ? extractTypesOfKind(typeWithLiterals, TypeFlags.Number | TypeFlags.NumberLiteral) : t.flags & TypeFlags.BigInt ? extractTypesOfKind(typeWithLiterals, TypeFlags.BigInt | TypeFlags.BigIntLiteral) : t); } return typeWithPrimitives; } function isIncomplete(flowType: FlowType) { return flowType.flags === 0; } function getTypeFromFlowType(flowType: FlowType) { return flowType.flags === 0 ? flowType.type : flowType as Type; } function createFlowType(type: Type, incomplete: boolean): FlowType { return incomplete ? { flags: 0, type: type.flags & TypeFlags.Never ? silentNeverType : type } : type; } // An evolving array type tracks the element types that have so far been seen in an // 'x.push(value)' or 'x[n] = value' operation along the control flow graph. Evolving // array types are ultimately converted into manifest array types (using getFinalArrayType) // and never escape the getFlowTypeOfReference function. function createEvolvingArrayType(elementType: Type): EvolvingArrayType { const result = createObjectType(ObjectFlags.EvolvingArray) as EvolvingArrayType; result.elementType = elementType; return result; } function getEvolvingArrayType(elementType: Type): EvolvingArrayType { return evolvingArrayTypes[elementType.id] || (evolvingArrayTypes[elementType.id] = createEvolvingArrayType(elementType)); } // When adding evolving array element types we do not perform subtype reduction. Instead, // we defer subtype reduction until the evolving array type is finalized into a manifest // array type. function addEvolvingArrayElementType(evolvingArrayType: EvolvingArrayType, node: Expression): EvolvingArrayType { const elementType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(getContextFreeTypeOfExpression(node))); return isTypeSubsetOf(elementType, evolvingArrayType.elementType) ? evolvingArrayType : getEvolvingArrayType(getUnionType([evolvingArrayType.elementType, elementType])); } function createFinalArrayType(elementType: Type) { return elementType.flags & TypeFlags.Never ? autoArrayType : createArrayType(elementType.flags & TypeFlags.Union ? getUnionType((elementType as UnionType).types, UnionReduction.Subtype) : elementType); } // We perform subtype reduction upon obtaining the final array type from an evolving array type. function getFinalArrayType(evolvingArrayType: EvolvingArrayType): Type { return evolvingArrayType.finalArrayType || (evolvingArrayType.finalArrayType = createFinalArrayType(evolvingArrayType.elementType)); } function finalizeEvolvingArrayType(type: Type): Type { return getObjectFlags(type) & ObjectFlags.EvolvingArray ? getFinalArrayType(type as EvolvingArrayType) : type; } function getElementTypeOfEvolvingArrayType(type: Type) { return getObjectFlags(type) & ObjectFlags.EvolvingArray ? (type as EvolvingArrayType).elementType : neverType; } function isEvolvingArrayTypeList(types: Type[]) { let hasEvolvingArrayType = false; for (const t of types) { if (!(t.flags & TypeFlags.Never)) { if (!(getObjectFlags(t) & ObjectFlags.EvolvingArray)) { return false; } hasEvolvingArrayType = true; } } return hasEvolvingArrayType; } // Return true if the given node is 'x' in an 'x.length', x.push(value)', 'x.unshift(value)' or // 'x[n] = value' operation, where 'n' is an expression of type any, undefined, or a number-like type. function isEvolvingArrayOperationTarget(node: Node) { const root = getReferenceRoot(node); const parent = root.parent; const isLengthPushOrUnshift = isPropertyAccessExpression(parent) && ( parent.name.escapedText === "length" || parent.parent.kind === SyntaxKind.CallExpression && isIdentifier(parent.name) && isPushOrUnshiftIdentifier(parent.name)); const isElementAssignment = parent.kind === SyntaxKind.ElementAccessExpression && (parent as ElementAccessExpression).expression === root && parent.parent.kind === SyntaxKind.BinaryExpression && (parent.parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && (parent.parent as BinaryExpression).left === parent && !isAssignmentTarget(parent.parent) && isTypeAssignableToKind(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression), TypeFlags.NumberLike); return isLengthPushOrUnshift || isElementAssignment; } function isDeclarationWithExplicitTypeAnnotation(node: Declaration) { return (isVariableDeclaration(node) || isPropertyDeclaration(node) || isPropertySignature(node) || isParameter(node)) && !!(getEffectiveTypeAnnotationNode(node) || isInJSFile(node) && hasInitializer(node) && node.initializer && isFunctionExpressionOrArrowFunction(node.initializer) && getEffectiveReturnTypeNode(node.initializer)); } function getExplicitTypeOfSymbol(symbol: Symbol, diagnostic?: Diagnostic) { symbol = resolveSymbol(symbol); if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.ValueModule)) { return getTypeOfSymbol(symbol); } if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { if (getCheckFlags(symbol) & CheckFlags.Mapped) { const origin = (symbol as MappedSymbol).links.syntheticOrigin; if (origin && getExplicitTypeOfSymbol(origin)) { return getTypeOfSymbol(symbol); } } const declaration = symbol.valueDeclaration; if (declaration) { if (isDeclarationWithExplicitTypeAnnotation(declaration)) { return getTypeOfSymbol(symbol); } if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { const statement = declaration.parent.parent; const expressionType = getTypeOfDottedName(statement.expression, /*diagnostic*/ undefined); if (expressionType) { const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; return checkIteratedTypeOrElementType(use, expressionType, undefinedType, /*errorNode*/ undefined); } } if (diagnostic) { addRelatedInfo(diagnostic, createDiagnosticForNode(declaration, Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol))); } } } } // We require the dotted function name in an assertion expression to be comprised of identifiers // that reference function, method, class or value module symbols; or variable, property or // parameter symbols with declarations that have explicit type annotations. Such references are // resolvable with no possibility of triggering circularities in control flow analysis. function getTypeOfDottedName(node: Expression, diagnostic: Diagnostic | undefined): Type | undefined { if (!(node.flags & NodeFlags.InWithStatement)) { switch (node.kind) { case SyntaxKind.Identifier: const symbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(node as Identifier)); return getExplicitTypeOfSymbol(symbol, diagnostic); case SyntaxKind.ThisKeyword: return getExplicitThisType(node); case SyntaxKind.SuperKeyword: return checkSuperExpression(node); case SyntaxKind.PropertyAccessExpression: { const type = getTypeOfDottedName((node as PropertyAccessExpression).expression, diagnostic); if (type) { const name = (node as PropertyAccessExpression).name; let prop: Symbol | undefined; if (isPrivateIdentifier(name)) { if (!type.symbol) { return undefined; } prop = getPropertyOfType(type, getSymbolNameForPrivateIdentifier(type.symbol, name.escapedText)); } else { prop = getPropertyOfType(type, name.escapedText); } return prop && getExplicitTypeOfSymbol(prop, diagnostic); } return undefined; } case SyntaxKind.ParenthesizedExpression: return getTypeOfDottedName((node as ParenthesizedExpression).expression, diagnostic); } } } function getEffectsSignature(node: CallExpression) { const links = getNodeLinks(node); let signature = links.effectsSignature; if (signature === undefined) { // A call expression parented by an expression statement is a potential assertion. Other call // expressions are potential type predicate function calls. In order to avoid triggering // circularities in control flow analysis, we use getTypeOfDottedName when resolving the call // target expression of an assertion. let funcType: Type | undefined; if (node.parent.kind === SyntaxKind.ExpressionStatement) { funcType = getTypeOfDottedName(node.expression, /*diagnostic*/ undefined); } else if (node.expression.kind !== SyntaxKind.SuperKeyword) { if (isOptionalChain(node)) { funcType = checkNonNullType( getOptionalExpressionType(checkExpression(node.expression), node.expression), node.expression ); } else { funcType = checkNonNullExpression(node.expression); } } const signatures = getSignaturesOfType(funcType && getApparentType(funcType) || unknownType, SignatureKind.Call); const candidate = signatures.length === 1 && !signatures[0].typeParameters ? signatures[0] : some(signatures, hasTypePredicateOrNeverReturnType) ? getResolvedSignature(node) : undefined; signature = links.effectsSignature = candidate && hasTypePredicateOrNeverReturnType(candidate) ? candidate : unknownSignature; } return signature === unknownSignature ? undefined : signature; } function hasTypePredicateOrNeverReturnType(signature: Signature) { return !!(getTypePredicateOfSignature(signature) || signature.declaration && (getReturnTypeFromAnnotation(signature.declaration) || unknownType).flags & TypeFlags.Never); } function getTypePredicateArgument(predicate: TypePredicate, callExpression: CallExpression) { if (predicate.kind === TypePredicateKind.Identifier || predicate.kind === TypePredicateKind.AssertsIdentifier) { return callExpression.arguments[predicate.parameterIndex]; } const invokedExpression = skipParentheses(callExpression.expression); return isAccessExpression(invokedExpression) ? skipParentheses(invokedExpression.expression) : undefined; } function reportFlowControlError(node: Node) { const block = findAncestor(node, isFunctionOrModuleBlock) as Block | ModuleBlock | SourceFile; const sourceFile = getSourceFileOfNode(node); const span = getSpanOfTokenAtPosition(sourceFile, block.statements.pos); diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_containing_function_or_module_body_is_too_large_for_control_flow_analysis)); } function isReachableFlowNode(flow: FlowNode) { const result = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ false); lastFlowNode = flow; lastFlowNodeReachable = result; return result; } function isFalseExpression(expr: Expression): boolean { const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); return node.kind === SyntaxKind.FalseKeyword || node.kind === SyntaxKind.BinaryExpression && ( (node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken && (isFalseExpression((node as BinaryExpression).left) || isFalseExpression((node as BinaryExpression).right)) || (node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken && isFalseExpression((node as BinaryExpression).left) && isFalseExpression((node as BinaryExpression).right)); } function isReachableFlowNodeWorker(flow: FlowNode, noCacheCheck: boolean): boolean { while (true) { if (flow === lastFlowNode) { return lastFlowNodeReachable; } const flags = flow.flags; if (flags & FlowFlags.Shared) { if (!noCacheCheck) { const id = getFlowNodeId(flow); const reachable = flowNodeReachable[id]; return reachable !== undefined ? reachable : (flowNodeReachable[id] = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ true)); } noCacheCheck = false; } if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation)) { flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation).antecedent; } else if (flags & FlowFlags.Call) { const signature = getEffectsSignature((flow as FlowCall).node); if (signature) { const predicate = getTypePredicateOfSignature(signature); if (predicate && predicate.kind === TypePredicateKind.AssertsIdentifier && !predicate.type) { const predicateArgument = (flow as FlowCall).node.arguments[predicate.parameterIndex]; if (predicateArgument && isFalseExpression(predicateArgument)) { return false; } } if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { return false; } } flow = (flow as FlowCall).antecedent; } else if (flags & FlowFlags.BranchLabel) { // A branching point is reachable if any branch is reachable. return some((flow as FlowLabel).antecedents, f => isReachableFlowNodeWorker(f, /*noCacheCheck*/ false)); } else if (flags & FlowFlags.LoopLabel) { const antecedents = (flow as FlowLabel).antecedents; if (antecedents === undefined || antecedents.length === 0) { return false; } // A loop is reachable if the control flow path that leads to the top is reachable. flow = antecedents[0]; } else if (flags & FlowFlags.SwitchClause) { // The control flow path representing an unmatched value in a switch statement with // no default clause is unreachable if the switch statement is exhaustive. if ((flow as FlowSwitchClause).clauseStart === (flow as FlowSwitchClause).clauseEnd && isExhaustiveSwitchStatement((flow as FlowSwitchClause).switchStatement)) { return false; } flow = (flow as FlowSwitchClause).antecedent; } else if (flags & FlowFlags.ReduceLabel) { // Cache is unreliable once we start adjusting labels lastFlowNode = undefined; const target = (flow as FlowReduceLabel).target; const saveAntecedents = target.antecedents; target.antecedents = (flow as FlowReduceLabel).antecedents; const result = isReachableFlowNodeWorker((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); target.antecedents = saveAntecedents; return result; } else { return !(flags & FlowFlags.Unreachable); } } } // Return true if the given flow node is preceded by a 'super(...)' call in every possible code path // leading to the node. function isPostSuperFlowNode(flow: FlowNode, noCacheCheck: boolean): boolean { while (true) { const flags = flow.flags; if (flags & FlowFlags.Shared) { if (!noCacheCheck) { const id = getFlowNodeId(flow); const postSuper = flowNodePostSuper[id]; return postSuper !== undefined ? postSuper : (flowNodePostSuper[id] = isPostSuperFlowNode(flow, /*noCacheCheck*/ true)); } noCacheCheck = false; } if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation | FlowFlags.SwitchClause)) { flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation | FlowSwitchClause).antecedent; } else if (flags & FlowFlags.Call) { if ((flow as FlowCall).node.expression.kind === SyntaxKind.SuperKeyword) { return true; } flow = (flow as FlowCall).antecedent; } else if (flags & FlowFlags.BranchLabel) { // A branching point is post-super if every branch is post-super. return every((flow as FlowLabel).antecedents, f => isPostSuperFlowNode(f, /*noCacheCheck*/ false)); } else if (flags & FlowFlags.LoopLabel) { // A loop is post-super if the control flow path that leads to the top is post-super. flow = (flow as FlowLabel).antecedents![0]; } else if (flags & FlowFlags.ReduceLabel) { const target = (flow as FlowReduceLabel).target; const saveAntecedents = target.antecedents; target.antecedents = (flow as FlowReduceLabel).antecedents; const result = isPostSuperFlowNode((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); target.antecedents = saveAntecedents; return result; } else { // Unreachable nodes are considered post-super to silence errors return !!(flags & FlowFlags.Unreachable); } } } function isConstantReference(node: Node): boolean { switch (node.kind) { case SyntaxKind.Identifier: if (!isThisInTypeQuery(node)) { const symbol = getResolvedSymbol(node as Identifier); return isConstVariable(symbol) || isParameterOrCatchClauseVariable(symbol) && !isSymbolAssigned(symbol); } break; case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: // The resolvedSymbol property is initialized by checkPropertyAccess or checkElementAccess before we get here. return isConstantReference((node as AccessExpression).expression) && isReadonlySymbol(getNodeLinks(node).resolvedSymbol || unknownSymbol); } return false; } function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType = declaredType, flowContainer?: Node, flowNode = tryCast(reference, canHaveFlowNode)?.flowNode) { let key: string | undefined; let isKeySet = false; let flowDepth = 0; if (flowAnalysisDisabled) { return errorType; } if (!flowNode) { return declaredType; } flowInvocationCount++; const sharedFlowStart = sharedFlowCount; const evolvedType = getTypeFromFlowType(getTypeAtFlowNode(flowNode)); sharedFlowCount = sharedFlowStart; // When the reference is 'x' in an 'x.length', 'x.push(value)', 'x.unshift(value)' or x[n] = value' operation, // we give type 'any[]' to 'x' instead of using the type determined by control flow analysis such that operations // on empty arrays are possible without implicit any errors and new element types can be inferred without // type mismatch errors. const resultType = getObjectFlags(evolvedType) & ObjectFlags.EvolvingArray && isEvolvingArrayOperationTarget(reference) ? autoArrayType : finalizeEvolvingArrayType(evolvedType); if (resultType === unreachableNeverType || reference.parent && reference.parent.kind === SyntaxKind.NonNullExpression && !(resultType.flags & TypeFlags.Never) && getTypeWithFacts(resultType, TypeFacts.NEUndefinedOrNull).flags & TypeFlags.Never) { return declaredType; } // The non-null unknown type should never escape control flow analysis. return resultType === nonNullUnknownType ? unknownType : resultType; function getOrSetCacheKey() { if (isKeySet) { return key; } isKeySet = true; return key = getFlowCacheKey(reference, declaredType, initialType, flowContainer); } function getTypeAtFlowNode(flow: FlowNode): FlowType { if (flowDepth === 2000) { // We have made 2000 recursive invocations. To avoid overflowing the call stack we report an error // and disable further control flow analysis in the containing function or module body. tracing?.instant(tracing.Phase.CheckTypes, "getTypeAtFlowNode_DepthLimit", { flowId: flow.id }); flowAnalysisDisabled = true; reportFlowControlError(reference); return errorType; } flowDepth++; let sharedFlow: FlowNode | undefined; while (true) { const flags = flow.flags; if (flags & FlowFlags.Shared) { // We cache results of flow type resolution for shared nodes that were previously visited in // the same getFlowTypeOfReference invocation. A node is considered shared when it is the // antecedent of more than one node. for (let i = sharedFlowStart; i < sharedFlowCount; i++) { if (sharedFlowNodes[i] === flow) { flowDepth--; return sharedFlowTypes[i]; } } sharedFlow = flow; } let type: FlowType | undefined; if (flags & FlowFlags.Assignment) { type = getTypeAtFlowAssignment(flow as FlowAssignment); if (!type) { flow = (flow as FlowAssignment).antecedent; continue; } } else if (flags & FlowFlags.Call) { type = getTypeAtFlowCall(flow as FlowCall); if (!type) { flow = (flow as FlowCall).antecedent; continue; } } else if (flags & FlowFlags.Condition) { type = getTypeAtFlowCondition(flow as FlowCondition); } else if (flags & FlowFlags.SwitchClause) { type = getTypeAtSwitchClause(flow as FlowSwitchClause); } else if (flags & FlowFlags.Label) { if ((flow as FlowLabel).antecedents!.length === 1) { flow = (flow as FlowLabel).antecedents![0]; continue; } type = flags & FlowFlags.BranchLabel ? getTypeAtFlowBranchLabel(flow as FlowLabel) : getTypeAtFlowLoopLabel(flow as FlowLabel); } else if (flags & FlowFlags.ArrayMutation) { type = getTypeAtFlowArrayMutation(flow as FlowArrayMutation); if (!type) { flow = (flow as FlowArrayMutation).antecedent; continue; } } else if (flags & FlowFlags.ReduceLabel) { const target = (flow as FlowReduceLabel).target; const saveAntecedents = target.antecedents; target.antecedents = (flow as FlowReduceLabel).antecedents; type = getTypeAtFlowNode((flow as FlowReduceLabel).antecedent); target.antecedents = saveAntecedents; } else if (flags & FlowFlags.Start) { // Check if we should continue with the control flow of the containing function. const container = (flow as FlowStart).node; if (container && container !== flowContainer && reference.kind !== SyntaxKind.PropertyAccessExpression && reference.kind !== SyntaxKind.ElementAccessExpression && reference.kind !== SyntaxKind.ThisKeyword) { flow = container.flowNode!; continue; } // At the top of the flow we have the initial type. type = initialType; } else { // Unreachable code errors are reported in the binding phase. Here we // simply return the non-auto declared type to reduce follow-on errors. type = convertAutoToAny(declaredType); } if (sharedFlow) { // Record visited node and the associated type in the cache. sharedFlowNodes[sharedFlowCount] = sharedFlow; sharedFlowTypes[sharedFlowCount] = type; sharedFlowCount++; } flowDepth--; return type; } } function getInitialOrAssignedType(flow: FlowAssignment) { const node = flow.node; return getNarrowableTypeForReference(node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement ? getInitialType(node as VariableDeclaration | BindingElement) : getAssignedType(node), reference); } function getTypeAtFlowAssignment(flow: FlowAssignment) { const node = flow.node; // Assignments only narrow the computed type if the declared type is a union type. Thus, we // only need to evaluate the assigned type if the declared type is a union type. if (isMatchingReference(reference, node)) { if (!isReachableFlowNode(flow)) { return unreachableNeverType; } if (getAssignmentTargetKind(node) === AssignmentKind.Compound) { const flowType = getTypeAtFlowNode(flow.antecedent); return createFlowType(getBaseTypeOfLiteralType(getTypeFromFlowType(flowType)), isIncomplete(flowType)); } if (declaredType === autoType || declaredType === autoArrayType) { if (isEmptyArrayAssignment(node)) { return getEvolvingArrayType(neverType); } const assignedType = getWidenedLiteralType(getInitialOrAssignedType(flow)); return isTypeAssignableTo(assignedType, declaredType) ? assignedType : anyArrayType; } if (declaredType.flags & TypeFlags.Union) { return getAssignmentReducedType(declaredType as UnionType, getInitialOrAssignedType(flow)); } return declaredType; } // We didn't have a direct match. However, if the reference is a dotted name, this // may be an assignment to a left hand part of the reference. For example, for a // reference 'x.y.z', we may be at an assignment to 'x.y' or 'x'. In that case, // return the declared type. if (containsMatchingReference(reference, node)) { if (!isReachableFlowNode(flow)) { return unreachableNeverType; } // A matching dotted name might also be an expando property on a function *expression*, // in which case we continue control flow analysis back to the function's declaration if (isVariableDeclaration(node) && (isInJSFile(node) || isVarConst(node))) { const init = getDeclaredExpandoInitializer(node); if (init && (init.kind === SyntaxKind.FunctionExpression || init.kind === SyntaxKind.ArrowFunction)) { return getTypeAtFlowNode(flow.antecedent); } } return declaredType; } // for (const _ in ref) acts as a nonnull on ref if ( isVariableDeclaration(node) && node.parent.parent.kind === SyntaxKind.ForInStatement && (isMatchingReference(reference, node.parent.parent.expression) || optionalChainContainsReference(node.parent.parent.expression, reference)) ) { return getNonNullableTypeIfNeeded(finalizeEvolvingArrayType(getTypeFromFlowType(getTypeAtFlowNode(flow.antecedent)))); } // Assignment doesn't affect reference return undefined; } function narrowTypeByAssertion(type: Type, expr: Expression): Type { const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); if (node.kind === SyntaxKind.FalseKeyword) { return unreachableNeverType; } if (node.kind === SyntaxKind.BinaryExpression) { if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { return narrowTypeByAssertion(narrowTypeByAssertion(type, (node as BinaryExpression).left), (node as BinaryExpression).right); } if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken) { return getUnionType([narrowTypeByAssertion(type, (node as BinaryExpression).left), narrowTypeByAssertion(type, (node as BinaryExpression).right)]); } } return narrowType(type, node, /*assumeTrue*/ true); } function getTypeAtFlowCall(flow: FlowCall): FlowType | undefined { const signature = getEffectsSignature(flow.node); if (signature) { const predicate = getTypePredicateOfSignature(signature); if (predicate && (predicate.kind === TypePredicateKind.AssertsThis || predicate.kind === TypePredicateKind.AssertsIdentifier)) { const flowType = getTypeAtFlowNode(flow.antecedent); const type = finalizeEvolvingArrayType(getTypeFromFlowType(flowType)); const narrowedType = predicate.type ? narrowTypeByTypePredicate(type, predicate, flow.node, /*assumeTrue*/ true) : predicate.kind === TypePredicateKind.AssertsIdentifier && predicate.parameterIndex >= 0 && predicate.parameterIndex < flow.node.arguments.length ? narrowTypeByAssertion(type, flow.node.arguments[predicate.parameterIndex]) : type; return narrowedType === type ? flowType : createFlowType(narrowedType, isIncomplete(flowType)); } if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { return unreachableNeverType; } } return undefined; } function getTypeAtFlowArrayMutation(flow: FlowArrayMutation): FlowType | undefined { if (declaredType === autoType || declaredType === autoArrayType) { const node = flow.node; const expr = node.kind === SyntaxKind.CallExpression ? (node.expression as PropertyAccessExpression).expression : (node.left as ElementAccessExpression).expression; if (isMatchingReference(reference, getReferenceCandidate(expr))) { const flowType = getTypeAtFlowNode(flow.antecedent); const type = getTypeFromFlowType(flowType); if (getObjectFlags(type) & ObjectFlags.EvolvingArray) { let evolvedType = type as EvolvingArrayType; if (node.kind === SyntaxKind.CallExpression) { for (const arg of node.arguments) { evolvedType = addEvolvingArrayElementType(evolvedType, arg); } } else { // We must get the context free expression type so as to not recur in an uncached fashion on the LHS (which causes exponential blowup in compile time) const indexType = getContextFreeTypeOfExpression((node.left as ElementAccessExpression).argumentExpression); if (isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) { evolvedType = addEvolvingArrayElementType(evolvedType, node.right); } } return evolvedType === type ? flowType : createFlowType(evolvedType, isIncomplete(flowType)); } return flowType; } } return undefined; } function getTypeAtFlowCondition(flow: FlowCondition): FlowType { const flowType = getTypeAtFlowNode(flow.antecedent); const type = getTypeFromFlowType(flowType); if (type.flags & TypeFlags.Never) { return flowType; } // If we have an antecedent type (meaning we're reachable in some way), we first // attempt to narrow the antecedent type. If that produces the never type, and if // the antecedent type is incomplete (i.e. a transient type in a loop), then we // take the type guard as an indication that control *could* reach here once we // have the complete type. We proceed by switching to the silent never type which // doesn't report errors when operators are applied to it. Note that this is the // *only* place a silent never type is ever generated. const assumeTrue = (flow.flags & FlowFlags.TrueCondition) !== 0; const nonEvolvingType = finalizeEvolvingArrayType(type); const narrowedType = narrowType(nonEvolvingType, flow.node, assumeTrue); if (narrowedType === nonEvolvingType) { return flowType; } return createFlowType(narrowedType, isIncomplete(flowType)); } function getTypeAtSwitchClause(flow: FlowSwitchClause): FlowType { const expr = flow.switchStatement.expression; const flowType = getTypeAtFlowNode(flow.antecedent); let type = getTypeFromFlowType(flowType); if (isMatchingReference(reference, expr)) { type = narrowTypeBySwitchOnDiscriminant(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd); } else if (expr.kind === SyntaxKind.TypeOfExpression && isMatchingReference(reference, (expr as TypeOfExpression).expression)) { type = narrowTypeBySwitchOnTypeOf(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd); } else { if (strictNullChecks) { if (optionalChainContainsReference(expr, reference)) { type = narrowTypeBySwitchOptionalChainContainment(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd, t => !(t.flags & (TypeFlags.Undefined | TypeFlags.Never))); } else if (expr.kind === SyntaxKind.TypeOfExpression && optionalChainContainsReference((expr as TypeOfExpression).expression, reference)) { type = narrowTypeBySwitchOptionalChainContainment(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd, t => !(t.flags & TypeFlags.Never || t.flags & TypeFlags.StringLiteral && (t as StringLiteralType).value === "undefined")); } } const access = getDiscriminantPropertyAccess(expr, type); if (access) { type = narrowTypeBySwitchOnDiscriminantProperty(type, access, flow.switchStatement, flow.clauseStart, flow.clauseEnd); } } return createFlowType(type, isIncomplete(flowType)); } function getTypeAtFlowBranchLabel(flow: FlowLabel): FlowType { const antecedentTypes: Type[] = []; let subtypeReduction = false; let seenIncomplete = false; let bypassFlow: FlowSwitchClause | undefined; for (const antecedent of flow.antecedents!) { if (!bypassFlow && antecedent.flags & FlowFlags.SwitchClause && (antecedent as FlowSwitchClause).clauseStart === (antecedent as FlowSwitchClause).clauseEnd) { // The antecedent is the bypass branch of a potentially exhaustive switch statement. bypassFlow = antecedent as FlowSwitchClause; continue; } const flowType = getTypeAtFlowNode(antecedent); const type = getTypeFromFlowType(flowType); // If the type at a particular antecedent path is the declared type and the // reference is known to always be assigned (i.e. when declared and initial types // are the same), there is no reason to process more antecedents since the only // possible outcome is subtypes that will be removed in the final union type anyway. if (type === declaredType && declaredType === initialType) { return type; } pushIfUnique(antecedentTypes, type); // If an antecedent type is not a subset of the declared type, we need to perform // subtype reduction. This happens when a "foreign" type is injected into the control // flow using the instanceof operator or a user defined type predicate. if (!isTypeSubsetOf(type, declaredType)) { subtypeReduction = true; } if (isIncomplete(flowType)) { seenIncomplete = true; } } if (bypassFlow) { const flowType = getTypeAtFlowNode(bypassFlow); const type = getTypeFromFlowType(flowType); // If the bypass flow contributes a type we haven't seen yet and the switch statement // isn't exhaustive, process the bypass flow type. Since exhaustiveness checks increase // the risk of circularities, we only want to perform them when they make a difference. if (!(type.flags & TypeFlags.Never) && !contains(antecedentTypes, type) && !isExhaustiveSwitchStatement(bypassFlow.switchStatement)) { if (type === declaredType && declaredType === initialType) { return type; } antecedentTypes.push(type); if (!isTypeSubsetOf(type, declaredType)) { subtypeReduction = true; } if (isIncomplete(flowType)) { seenIncomplete = true; } } } return createFlowType(getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal), seenIncomplete); } function getTypeAtFlowLoopLabel(flow: FlowLabel): FlowType { // If we have previously computed the control flow type for the reference at // this flow loop junction, return the cached type. const id = getFlowNodeId(flow); const cache = flowLoopCaches[id] || (flowLoopCaches[id] = new Map()); const key = getOrSetCacheKey(); if (!key) { // No cache key is generated when binding patterns are in unnarrowable situations return declaredType; } const cached = cache.get(key); if (cached) { return cached; } // If this flow loop junction and reference are already being processed, return // the union of the types computed for each branch so far, marked as incomplete. // It is possible to see an empty array in cases where loops are nested and the // back edge of the outer loop reaches an inner loop that is already being analyzed. // In such cases we restart the analysis of the inner loop, which will then see // a non-empty in-process array for the outer loop and eventually terminate because // the first antecedent of a loop junction is always the non-looping control flow // path that leads to the top. for (let i = flowLoopStart; i < flowLoopCount; i++) { if (flowLoopNodes[i] === flow && flowLoopKeys[i] === key && flowLoopTypes[i].length) { return createFlowType(getUnionOrEvolvingArrayType(flowLoopTypes[i], UnionReduction.Literal), /*incomplete*/ true); } } // Add the flow loop junction and reference to the in-process stack and analyze // each antecedent code path. const antecedentTypes: Type[] = []; let subtypeReduction = false; let firstAntecedentType: FlowType | undefined; for (const antecedent of flow.antecedents!) { let flowType; if (!firstAntecedentType) { // The first antecedent of a loop junction is always the non-looping control // flow path that leads to the top. flowType = firstAntecedentType = getTypeAtFlowNode(antecedent); } else { // All but the first antecedent are the looping control flow paths that lead // back to the loop junction. We track these on the flow loop stack. flowLoopNodes[flowLoopCount] = flow; flowLoopKeys[flowLoopCount] = key; flowLoopTypes[flowLoopCount] = antecedentTypes; flowLoopCount++; const saveFlowTypeCache = flowTypeCache; flowTypeCache = undefined; flowType = getTypeAtFlowNode(antecedent); flowTypeCache = saveFlowTypeCache; flowLoopCount--; // If we see a value appear in the cache it is a sign that control flow analysis // was restarted and completed by checkExpressionCached. We can simply pick up // the resulting type and bail out. const cached = cache.get(key); if (cached) { return cached; } } const type = getTypeFromFlowType(flowType); pushIfUnique(antecedentTypes, type); // If an antecedent type is not a subset of the declared type, we need to perform // subtype reduction. This happens when a "foreign" type is injected into the control // flow using the instanceof operator or a user defined type predicate. if (!isTypeSubsetOf(type, declaredType)) { subtypeReduction = true; } // If the type at a particular antecedent path is the declared type there is no // reason to process more antecedents since the only possible outcome is subtypes // that will be removed in the final union type anyway. if (type === declaredType) { break; } } // The result is incomplete if the first antecedent (the non-looping control flow path) // is incomplete. const result = getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal); if (isIncomplete(firstAntecedentType!)) { return createFlowType(result, /*incomplete*/ true); } cache.set(key, result); return result; } // At flow control branch or loop junctions, if the type along every antecedent code path // is an evolving array type, we construct a combined evolving array type. Otherwise we // finalize all evolving array types. function getUnionOrEvolvingArrayType(types: Type[], subtypeReduction: UnionReduction) { if (isEvolvingArrayTypeList(types)) { return getEvolvingArrayType(getUnionType(map(types, getElementTypeOfEvolvingArrayType))); } const result = recombineUnknownType(getUnionType(sameMap(types, finalizeEvolvingArrayType), subtypeReduction)); if (result !== declaredType && result.flags & declaredType.flags & TypeFlags.Union && arraysEqual((result as UnionType).types, (declaredType as UnionType).types)) { return declaredType; } return result; } function getCandidateDiscriminantPropertyAccess(expr: Expression) { if (isBindingPattern(reference) || isFunctionExpressionOrArrowFunction(reference) || isObjectLiteralMethod(reference)) { // When the reference is a binding pattern or function or arrow expression, we are narrowing a pesudo-reference in // getNarrowedTypeOfSymbol. An identifier for a destructuring variable declared in the same binding pattern or // parameter declared in the same parameter list is a candidate. if (isIdentifier(expr)) { const symbol = getResolvedSymbol(expr); const declaration = symbol.valueDeclaration; if (declaration && (isBindingElement(declaration) || isParameter(declaration)) && reference === declaration.parent && !declaration.initializer && !declaration.dotDotDotToken) { return declaration; } } } else if (isAccessExpression(expr)) { // An access expression is a candidate if the reference matches the left hand expression. if (isMatchingReference(reference, expr.expression)) { return expr; } } else if (isIdentifier(expr)) { const symbol = getResolvedSymbol(expr); if (isConstVariable(symbol)) { const declaration = symbol.valueDeclaration!; // Given 'const x = obj.kind', allow 'x' as an alias for 'obj.kind' if (isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isAccessExpression(declaration.initializer) && isMatchingReference(reference, declaration.initializer.expression)) { return declaration.initializer; } // Given 'const { kind: x } = obj', allow 'x' as an alias for 'obj.kind' if (isBindingElement(declaration) && !declaration.initializer) { const parent = declaration.parent.parent; if (isVariableDeclaration(parent) && !parent.type && parent.initializer && (isIdentifier(parent.initializer) || isAccessExpression(parent.initializer)) && isMatchingReference(reference, parent.initializer)) { return declaration; } } } } return undefined; } function getDiscriminantPropertyAccess(expr: Expression, computedType: Type) { const type = declaredType.flags & TypeFlags.Union ? declaredType : computedType; if (type.flags & TypeFlags.Union) { const access = getCandidateDiscriminantPropertyAccess(expr); if (access) { const name = getAccessedPropertyName(access); if (name && isDiscriminantProperty(type, name)) { return access; } } } return undefined; } function narrowTypeByDiscriminant(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, narrowType: (t: Type) => Type): Type { const propName = getAccessedPropertyName(access); if (propName === undefined) { return type; } const optionalChain = isOptionalChain(access); const removeNullable = strictNullChecks && (optionalChain || isNonNullAccess(access)) && maybeTypeOfKind(type, TypeFlags.Nullable); let propType = getTypeOfPropertyOfType(removeNullable ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type, propName); if (!propType) { return type; } propType = removeNullable && optionalChain ? getOptionalType(propType) : propType; const narrowedPropType = narrowType(propType); return filterType(type, t => { const discriminantType = getTypeOfPropertyOrIndexSignature(t, propName); return !(discriminantType.flags & TypeFlags.Never) && !(narrowedPropType.flags & TypeFlags.Never) && areTypesComparable(narrowedPropType, discriminantType); }); } function narrowTypeByDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, operator: SyntaxKind, value: Expression, assumeTrue: boolean) { if ((operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) && type.flags & TypeFlags.Union) { const keyPropertyName = getKeyPropertyName(type as UnionType); if (keyPropertyName && keyPropertyName === getAccessedPropertyName(access)) { const candidate = getConstituentTypeForKeyType(type as UnionType, getTypeOfExpression(value)); if (candidate) { return operator === (assumeTrue ? SyntaxKind.EqualsEqualsEqualsToken : SyntaxKind.ExclamationEqualsEqualsToken) ? candidate : isUnitType(getTypeOfPropertyOfType(candidate, keyPropertyName) || unknownType) ? removeType(type, candidate) : type; } } } return narrowTypeByDiscriminant(type, access, t => narrowTypeByEquality(t, operator, value, assumeTrue)); } function narrowTypeBySwitchOnDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number) { if (clauseStart < clauseEnd && type.flags & TypeFlags.Union && getKeyPropertyName(type as UnionType) === getAccessedPropertyName(access)) { const clauseTypes = getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd); const candidate = getUnionType(map(clauseTypes, t => getConstituentTypeForKeyType(type as UnionType, t) || unknownType)); if (candidate !== unknownType) { return candidate; } } return narrowTypeByDiscriminant(type, access, t => narrowTypeBySwitchOnDiscriminant(t, switchStatement, clauseStart, clauseEnd)); } function narrowTypeByTruthiness(type: Type, expr: Expression, assumeTrue: boolean): Type { if (isMatchingReference(reference, expr)) { return getAdjustedTypeWithFacts(type, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy); } if (strictNullChecks && assumeTrue && optionalChainContainsReference(expr, reference)) { type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); } const access = getDiscriminantPropertyAccess(expr, type); if (access) { return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy)); } return type; } function isTypePresencePossible(type: Type, propName: __String, assumeTrue: boolean) { const prop = getPropertyOfType(type, propName); return prop ? !!(prop.flags & SymbolFlags.Optional) || assumeTrue : !!getApplicableIndexInfoForName(type, propName) || !assumeTrue; } function narrowTypeByInKeyword(type: Type, nameType: StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue: boolean) { const name = getPropertyNameFromType(nameType); const isKnownProperty = someType(type, t => isTypePresencePossible(t, name, /*assumeTrue*/ true)); if (isKnownProperty) { // If the check is for a known property (i.e. a property declared in some constituent of // the target type), we filter the target type by presence of absence of the property. return filterType(type, t => isTypePresencePossible(t, name, assumeTrue)); } if (assumeTrue) { // If the check is for an unknown property, we intersect the target type with `Record`, // where X is the name of the property. const recordSymbol = getGlobalRecordSymbol(); if (recordSymbol) { return getIntersectionType([type, getTypeAliasInstantiation(recordSymbol, [nameType, unknownType])]); } } return type; } function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { switch (expr.operatorToken.kind) { case SyntaxKind.EqualsToken: case SyntaxKind.BarBarEqualsToken: case SyntaxKind.AmpersandAmpersandEqualsToken: case SyntaxKind.QuestionQuestionEqualsToken: return narrowTypeByTruthiness(narrowType(type, expr.right, assumeTrue), expr.left, assumeTrue); case SyntaxKind.EqualsEqualsToken: case SyntaxKind.ExclamationEqualsToken: case SyntaxKind.EqualsEqualsEqualsToken: case SyntaxKind.ExclamationEqualsEqualsToken: const operator = expr.operatorToken.kind; const left = getReferenceCandidate(expr.left); const right = getReferenceCandidate(expr.right); if (left.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(right)) { return narrowTypeByTypeof(type, left as TypeOfExpression, operator, right, assumeTrue); } if (right.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(left)) { return narrowTypeByTypeof(type, right as TypeOfExpression, operator, left, assumeTrue); } if (isMatchingReference(reference, left)) { return narrowTypeByEquality(type, operator, right, assumeTrue); } if (isMatchingReference(reference, right)) { return narrowTypeByEquality(type, operator, left, assumeTrue); } if (strictNullChecks) { if (optionalChainContainsReference(left, reference)) { type = narrowTypeByOptionalChainContainment(type, operator, right, assumeTrue); } else if (optionalChainContainsReference(right, reference)) { type = narrowTypeByOptionalChainContainment(type, operator, left, assumeTrue); } } const leftAccess = getDiscriminantPropertyAccess(left, type); if (leftAccess) { return narrowTypeByDiscriminantProperty(type, leftAccess, operator, right, assumeTrue); } const rightAccess = getDiscriminantPropertyAccess(right, type); if (rightAccess) { return narrowTypeByDiscriminantProperty(type, rightAccess, operator, left, assumeTrue); } if (isMatchingConstructorReference(left)) { return narrowTypeByConstructor(type, operator, right, assumeTrue); } if (isMatchingConstructorReference(right)) { return narrowTypeByConstructor(type, operator, left, assumeTrue); } break; case SyntaxKind.InstanceOfKeyword: return narrowTypeByInstanceof(type, expr, assumeTrue); case SyntaxKind.InKeyword: if (isPrivateIdentifier(expr.left)) { return narrowTypeByPrivateIdentifierInInExpression(type, expr, assumeTrue); } const target = getReferenceCandidate(expr.right); const leftType = getTypeOfExpression(expr.left); if (leftType.flags & TypeFlags.StringOrNumberLiteralOrUnique) { if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target) && getAccessedPropertyName(reference) === getPropertyNameFromType(leftType as StringLiteralType | NumberLiteralType | UniqueESSymbolType)) { return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); } if (isMatchingReference(reference, target)) { return narrowTypeByInKeyword(type, leftType as StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue); } } break; case SyntaxKind.CommaToken: return narrowType(type, expr.right, assumeTrue); // Ordinarily we won't see && and || expressions in control flow analysis because the Binder breaks those // expressions down to individual conditional control flows. However, we may encounter them when analyzing // aliased conditional expressions. case SyntaxKind.AmpersandAmpersandToken: return assumeTrue ? narrowType(narrowType(type, expr.left, /*assumeTrue*/ true), expr.right, /*assumeTrue*/ true) : getUnionType([narrowType(type, expr.left, /*assumeTrue*/ false), narrowType(type, expr.right, /*assumeTrue*/ false)]); case SyntaxKind.BarBarToken: return assumeTrue ? getUnionType([narrowType(type, expr.left, /*assumeTrue*/ true), narrowType(type, expr.right, /*assumeTrue*/ true)]) : narrowType(narrowType(type, expr.left, /*assumeTrue*/ false), expr.right, /*assumeTrue*/ false); } return type; } function narrowTypeByPrivateIdentifierInInExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { const target = getReferenceCandidate(expr.right); if (!isMatchingReference(reference, target)) { return type; } Debug.assertNode(expr.left, isPrivateIdentifier); const symbol = getSymbolForPrivateIdentifierExpression(expr.left); if (symbol === undefined) { return type; } const classSymbol = symbol.parent!; const targetType = hasStaticModifier(Debug.checkDefined(symbol.valueDeclaration, "should always have a declaration")) ? getTypeOfSymbol(classSymbol) as InterfaceType : getDeclaredTypeOfSymbol(classSymbol); return getNarrowedType(type, targetType, assumeTrue, /*checkDerived*/ true); } function narrowTypeByOptionalChainContainment(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows: // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch. // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch. // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch. // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch. // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch. // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch. // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch. // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch. const equalsOperator = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; const nullableFlags = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? TypeFlags.Nullable : TypeFlags.Undefined; const valueType = getTypeOfExpression(value); // Note that we include any and unknown in the exclusion test because their domain includes null and undefined. const removeNullable = equalsOperator !== assumeTrue && everyType(valueType, t => !!(t.flags & nullableFlags)) || equalsOperator === assumeTrue && everyType(valueType, t => !(t.flags & (TypeFlags.AnyOrUnknown | nullableFlags))); return removeNullable ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; } function narrowTypeByEquality(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { if (type.flags & TypeFlags.Any) { return type; } if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { assumeTrue = !assumeTrue; } const valueType = getTypeOfExpression(value); const doubleEquals = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken; if (valueType.flags & TypeFlags.Nullable) { if (!strictNullChecks) { return type; } const facts = doubleEquals ? assumeTrue ? TypeFacts.EQUndefinedOrNull : TypeFacts.NEUndefinedOrNull : valueType.flags & TypeFlags.Null ? assumeTrue ? TypeFacts.EQNull : TypeFacts.NENull : assumeTrue ? TypeFacts.EQUndefined : TypeFacts.NEUndefined; return getAdjustedTypeWithFacts(type, facts); } if (assumeTrue) { if (!doubleEquals && (type.flags & TypeFlags.Unknown || someType(type, isEmptyAnonymousObjectType))) { if (valueType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) || isEmptyAnonymousObjectType(valueType)) { return valueType; } if (valueType.flags & TypeFlags.Object) { return nonPrimitiveType; } } const filteredType = filterType(type, t => areTypesComparable(t, valueType) || doubleEquals && isCoercibleUnderDoubleEquals(t, valueType)); return replacePrimitivesWithLiterals(filteredType, valueType); } if (isUnitType(valueType)) { return filterType(type, t => !(isUnitLikeType(t) && areTypesComparable(t, valueType))); } return type; } function narrowTypeByTypeof(type: Type, typeOfExpr: TypeOfExpression, operator: SyntaxKind, literal: LiteralExpression, assumeTrue: boolean): Type { // We have '==', '!=', '===', or !==' operator with 'typeof xxx' and string literal operands if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { assumeTrue = !assumeTrue; } const target = getReferenceCandidate(typeOfExpr.expression); if (!isMatchingReference(reference, target)) { if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) { type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); } const propertyAccess = getDiscriminantPropertyAccess(target, type); if (propertyAccess) { return narrowTypeByDiscriminant(type, propertyAccess, t => narrowTypeByLiteralExpression(t, literal, assumeTrue)); } return type; } return narrowTypeByLiteralExpression(type, literal, assumeTrue); } function narrowTypeByLiteralExpression(type: Type, literal: LiteralExpression, assumeTrue: boolean) { return assumeTrue ? narrowTypeByTypeName(type, literal.text) : getAdjustedTypeWithFacts(type, typeofNEFacts.get(literal.text) || TypeFacts.TypeofNEHostObject); } function narrowTypeBySwitchOptionalChainContainment(type: Type, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number, clauseCheck: (type: Type) => boolean) { const everyClauseChecks = clauseStart !== clauseEnd && every(getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd), clauseCheck); return everyClauseChecks ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; } function narrowTypeBySwitchOnDiscriminant(type: Type, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number) { // We only narrow if all case expressions specify // values with unit types, except for the case where // `type` is unknown. In this instance we map object // types to the nonPrimitive type and narrow with that. const switchTypes = getSwitchClauseTypes(switchStatement); if (!switchTypes.length) { return type; } const clauseTypes = switchTypes.slice(clauseStart, clauseEnd); const hasDefaultClause = clauseStart === clauseEnd || contains(clauseTypes, neverType); if ((type.flags & TypeFlags.Unknown) && !hasDefaultClause) { let groundClauseTypes: Type[] | undefined; for (let i = 0; i < clauseTypes.length; i += 1) { const t = clauseTypes[i]; if (t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) { if (groundClauseTypes !== undefined) { groundClauseTypes.push(t); } } else if (t.flags & TypeFlags.Object) { if (groundClauseTypes === undefined) { groundClauseTypes = clauseTypes.slice(0, i); } groundClauseTypes.push(nonPrimitiveType); } else { return type; } } return getUnionType(groundClauseTypes === undefined ? clauseTypes : groundClauseTypes); } const discriminantType = getUnionType(clauseTypes); const caseType = discriminantType.flags & TypeFlags.Never ? neverType : replacePrimitivesWithLiterals(filterType(type, t => areTypesComparable(discriminantType, t)), discriminantType); if (!hasDefaultClause) { return caseType; } const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, getRegularTypeOfLiteralType(extractUnitType(t))))); return caseType.flags & TypeFlags.Never ? defaultType : getUnionType([caseType, defaultType]); } function narrowTypeByTypeName(type: Type, typeName: string) { switch (typeName) { case "string": return narrowTypeByTypeFacts(type, stringType, TypeFacts.TypeofEQString); case "number": return narrowTypeByTypeFacts(type, numberType, TypeFacts.TypeofEQNumber); case "bigint": return narrowTypeByTypeFacts(type, bigintType, TypeFacts.TypeofEQBigInt); case "boolean": return narrowTypeByTypeFacts(type, booleanType, TypeFacts.TypeofEQBoolean); case "symbol": return narrowTypeByTypeFacts(type, esSymbolType, TypeFacts.TypeofEQSymbol); case "object": return type.flags & TypeFlags.Any ? type : getUnionType([narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQObject), narrowTypeByTypeFacts(type, nullType, TypeFacts.EQNull)]); case "function": return type.flags & TypeFlags.Any ? type : narrowTypeByTypeFacts(type, globalFunctionType, TypeFacts.TypeofEQFunction); case "undefined": return narrowTypeByTypeFacts(type, undefinedType, TypeFacts.EQUndefined); } return narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQHostObject); } function narrowTypeByTypeFacts(type: Type, impliedType: Type, facts: TypeFacts) { return mapType(type, t => // We first check if a constituent is a subtype of the implied type. If so, we either keep or eliminate // the constituent based on its type facts. We use the strict subtype relation because it treats `object` // as a subtype of `{}`, and we need the type facts check because function types are subtypes of `object`, // but are classified as "function" according to `typeof`. isTypeRelatedTo(t, impliedType, strictSubtypeRelation) ? getTypeFacts(t) & facts ? t : neverType : // We next check if the consituent is a supertype of the implied type. If so, we substitute the implied // type. This handles top types like `unknown` and `{}`, and supertypes like `{ toString(): string }`. isTypeSubtypeOf(impliedType, t) ? impliedType : // Neither the constituent nor the implied type is a subtype of the other, however their domains may still // overlap. For example, an unconstrained type parameter and type `string`. If the type facts indicate // possible overlap, we form an intersection. Otherwise, we eliminate the constituent. getTypeFacts(t) & facts ? getIntersectionType([t, impliedType]) : neverType); } function narrowTypeBySwitchOnTypeOf(type: Type, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number): Type { const witnesses = getSwitchClauseTypeOfWitnesses(switchStatement); if (!witnesses) { return type; } // Equal start and end denotes implicit fallthrough; undefined marks explicit default clause. const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); if (hasDefaultClause) { // In the default clause we filter constituents down to those that are not-equal to all handled cases. const notEqualFacts = getNotEqualFactsFromTypeofSwitch(clauseStart, clauseEnd, witnesses); return filterType(type, t => (getTypeFacts(t) & notEqualFacts) === notEqualFacts); } // In the non-default cause we create a union of the type narrowed by each of the listed cases. const clauseWitnesses = witnesses.slice(clauseStart, clauseEnd); return getUnionType(map(clauseWitnesses, text => text ? narrowTypeByTypeName(type, text) : neverType)); } function isMatchingConstructorReference(expr: Expression) { return (isPropertyAccessExpression(expr) && idText(expr.name) === "constructor" || isElementAccessExpression(expr) && isStringLiteralLike(expr.argumentExpression) && expr.argumentExpression.text === "constructor") && isMatchingReference(reference, expr.expression); } function narrowTypeByConstructor(type: Type, operator: SyntaxKind, identifier: Expression, assumeTrue: boolean): Type { // Do not narrow when checking inequality. if (assumeTrue ? (operator !== SyntaxKind.EqualsEqualsToken && operator !== SyntaxKind.EqualsEqualsEqualsToken) : (operator !== SyntaxKind.ExclamationEqualsToken && operator !== SyntaxKind.ExclamationEqualsEqualsToken)) { return type; } // Get the type of the constructor identifier expression, if it is not a function then do not narrow. const identifierType = getTypeOfExpression(identifier); if (!isFunctionType(identifierType) && !isConstructorType(identifierType)) { return type; } // Get the prototype property of the type identifier so we can find out its type. const prototypeProperty = getPropertyOfType(identifierType, "prototype" as __String); if (!prototypeProperty) { return type; } // Get the type of the prototype, if it is undefined, or the global `Object` or `Function` types then do not narrow. const prototypeType = getTypeOfSymbol(prototypeProperty); const candidate = !isTypeAny(prototypeType) ? prototypeType : undefined; if (!candidate || candidate === globalObjectType || candidate === globalFunctionType) { return type; } // If the type that is being narrowed is `any` then just return the `candidate` type since every type is a subtype of `any`. if (isTypeAny(type)) { return candidate; } // Filter out types that are not considered to be "constructed by" the `candidate` type. return filterType(type, t => isConstructedBy(t, candidate)); function isConstructedBy(source: Type, target: Type) { // If either the source or target type are a class type then we need to check that they are the same exact type. // This is because you may have a class `A` that defines some set of properties, and another class `B` // that defines the same set of properties as class `A`, in that case they are structurally the same // type, but when you do something like `instanceOfA.constructor === B` it will return false. if (source.flags & TypeFlags.Object && getObjectFlags(source) & ObjectFlags.Class || target.flags & TypeFlags.Object && getObjectFlags(target) & ObjectFlags.Class) { return source.symbol === target.symbol; } // For all other types just check that the `source` type is a subtype of the `target` type. return isTypeSubtypeOf(source, target); } } function narrowTypeByInstanceof(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { const left = getReferenceCandidate(expr.left); if (!isMatchingReference(reference, left)) { if (assumeTrue && strictNullChecks && optionalChainContainsReference(left, reference)) { return getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); } return type; } const rightType = getTypeOfExpression(expr.right); if (!isTypeDerivedFrom(rightType, globalFunctionType)) { return type; } const instanceType = mapType(rightType, getInstanceType); // Don't narrow from `any` if the target type is exactly `Object` or `Function`, and narrow // in the false branch only if the target is a non-empty object type. if (isTypeAny(type) && (instanceType === globalObjectType || instanceType === globalFunctionType) || !assumeTrue && !(instanceType.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(instanceType))) { return type; } return getNarrowedType(type, instanceType, assumeTrue, /*checkDerived*/ true); } function getInstanceType(constructorType: Type) { const prototypePropertyType = getTypeOfPropertyOfType(constructorType, "prototype" as __String); if (prototypePropertyType && !isTypeAny(prototypePropertyType)) { return prototypePropertyType; } const constructSignatures = getSignaturesOfType(constructorType, SignatureKind.Construct); if (constructSignatures.length) { return getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature)))); } // We use the empty object type to indicate we don't know the type of objects created by // this constructor function. return emptyObjectType; } function getNarrowedType(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean): Type { const key = type.flags & TypeFlags.Union ? `N${getTypeId(type)},${getTypeId(candidate)},${(assumeTrue ? 1 : 0) | (checkDerived ? 2 : 0)}` : undefined; return getCachedType(key) ?? setCachedType(key, getNarrowedTypeWorker(type, candidate, assumeTrue, checkDerived)); } function getNarrowedTypeWorker(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean) { if (!assumeTrue) { if (checkDerived) { return filterType(type, t => !isTypeDerivedFrom(t, candidate)); } const trueType = getNarrowedType(type, candidate, /*assumeTrue*/ true, /*checkDerived*/ false); return filterType(type, t => !isTypeSubsetOf(t, trueType)); } if (type.flags & TypeFlags.AnyOrUnknown) { return candidate; } // We first attempt to filter the current type, narrowing constituents as appropriate and removing // constituents that are unrelated to the candidate. const isRelated = checkDerived ? isTypeDerivedFrom : isTypeSubtypeOf; const keyPropertyName = type.flags & TypeFlags.Union ? getKeyPropertyName(type as UnionType) : undefined; const narrowedType = mapType(candidate, c => { // If a discriminant property is available, use that to reduce the type. const discriminant = keyPropertyName && getTypeOfPropertyOfType(c, keyPropertyName); const matching = discriminant && getConstituentTypeForKeyType(type as UnionType, discriminant); // For each constituent t in the current type, if t and and c are directly related, pick the most // specific of the two. When t and c are related in both directions, we prefer c for type predicates // because that is the asserted type, but t for `instanceof` because generics aren't reflected in // prototype object types. const directlyRelated = mapType(matching || type, checkDerived ? t => isTypeDerivedFrom(t, c) ? t : isTypeDerivedFrom(c, t) ? c : neverType : t => isTypeStrictSubtypeOf(t, c) ? t : isTypeStrictSubtypeOf(c, t) ? c : isTypeSubtypeOf(t, c) ? t : isTypeSubtypeOf(c, t) ? c : neverType); // If no constituents are directly related, create intersections for any generic constituents that // are related by constraint. return directlyRelated.flags & TypeFlags.Never ? mapType(type, t => maybeTypeOfKind(t, TypeFlags.Instantiable) && isRelated(c, getBaseConstraintOfType(t) || unknownType) ? getIntersectionType([t, c]) : neverType) : directlyRelated; }); // If filtering produced a non-empty type, return that. Otherwise, pick the most specific of the two // based on assignability, or as a last resort produce an intersection. return !(narrowedType.flags & TypeFlags.Never) ? narrowedType : isTypeSubtypeOf(candidate, type) ? candidate : isTypeAssignableTo(type, candidate) ? type : isTypeAssignableTo(candidate, type) ? candidate : getIntersectionType([type, candidate]); } function narrowTypeByCallExpression(type: Type, callExpression: CallExpression, assumeTrue: boolean): Type { if (hasMatchingArgument(callExpression, reference)) { const signature = assumeTrue || !isCallChain(callExpression) ? getEffectsSignature(callExpression) : undefined; const predicate = signature && getTypePredicateOfSignature(signature); if (predicate && (predicate.kind === TypePredicateKind.This || predicate.kind === TypePredicateKind.Identifier)) { return narrowTypeByTypePredicate(type, predicate, callExpression, assumeTrue); } } if (containsMissingType(type) && isAccessExpression(reference) && isPropertyAccessExpression(callExpression.expression)) { const callAccess = callExpression.expression; if (isMatchingReference(reference.expression, getReferenceCandidate(callAccess.expression)) && isIdentifier(callAccess.name) && callAccess.name.escapedText === "hasOwnProperty" && callExpression.arguments.length === 1) { const argument = callExpression.arguments[0]; if (isStringLiteralLike(argument) && getAccessedPropertyName(reference) === escapeLeadingUnderscores(argument.text)) { return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); } } } return type; } function narrowTypeByTypePredicate(type: Type, predicate: TypePredicate, callExpression: CallExpression, assumeTrue: boolean): Type { // Don't narrow from 'any' if the predicate type is exactly 'Object' or 'Function' if (predicate.type && !(isTypeAny(type) && (predicate.type === globalObjectType || predicate.type === globalFunctionType))) { const predicateArgument = getTypePredicateArgument(predicate, callExpression); if (predicateArgument) { if (isMatchingReference(reference, predicateArgument)) { return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ false); } if (strictNullChecks && assumeTrue && optionalChainContainsReference(predicateArgument, reference) && !(getTypeFacts(predicate.type) & TypeFacts.EQUndefined)) { type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); } const access = getDiscriminantPropertyAccess(predicateArgument, type); if (access) { return narrowTypeByDiscriminant(type, access, t => getNarrowedType(t, predicate.type!, assumeTrue, /*checkDerived*/ false)); } } } return type; } // Narrow the given type based on the given expression having the assumed boolean value. The returned type // will be a subtype or the same type as the argument. function narrowType(type: Type, expr: Expression, assumeTrue: boolean): Type { // for `a?.b`, we emulate a synthetic `a !== null && a !== undefined` condition for `a` if (isExpressionOfOptionalChainRoot(expr) || isBinaryExpression(expr.parent) && (expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionToken || expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionEqualsToken) && expr.parent.left === expr) { return narrowTypeByOptionality(type, expr, assumeTrue); } switch (expr.kind) { case SyntaxKind.Identifier: // When narrowing a reference to a const variable, non-assigned parameter, or readonly property, we inline // up to five levels of aliased conditional expressions that are themselves declared as const variables. if (!isMatchingReference(reference, expr) && inlineLevel < 5) { const symbol = getResolvedSymbol(expr as Identifier); if (isConstVariable(symbol)) { const declaration = symbol.valueDeclaration; if (declaration && isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isConstantReference(reference)) { inlineLevel++; const result = narrowType(type, declaration.initializer, assumeTrue); inlineLevel--; return result; } } } // falls through case SyntaxKind.ThisKeyword: case SyntaxKind.SuperKeyword: case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: return narrowTypeByTruthiness(type, expr, assumeTrue); case SyntaxKind.CallExpression: return narrowTypeByCallExpression(type, expr as CallExpression, assumeTrue); case SyntaxKind.ParenthesizedExpression: case SyntaxKind.NonNullExpression: return narrowType(type, (expr as ParenthesizedExpression | NonNullExpression).expression, assumeTrue); case SyntaxKind.BinaryExpression: return narrowTypeByBinaryExpression(type, expr as BinaryExpression, assumeTrue); case SyntaxKind.PrefixUnaryExpression: if ((expr as PrefixUnaryExpression).operator === SyntaxKind.ExclamationToken) { return narrowType(type, (expr as PrefixUnaryExpression).operand, !assumeTrue); } break; } return type; } function narrowTypeByOptionality(type: Type, expr: Expression, assumePresent: boolean): Type { if (isMatchingReference(reference, expr)) { return getAdjustedTypeWithFacts(type, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull); } const access = getDiscriminantPropertyAccess(expr, type); if (access) { return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull)); } return type; } } function getTypeOfSymbolAtLocation(symbol: Symbol, location: Node) { symbol = getExportSymbolOfValueSymbolIfExported(symbol); // If we have an identifier or a property access at the given location, if the location is // an dotted name expression, and if the location is not an assignment target, obtain the type // of the expression (which will reflect control flow analysis). If the expression indeed // resolved to the given symbol, return the narrowed type. if (location.kind === SyntaxKind.Identifier || location.kind === SyntaxKind.PrivateIdentifier) { if (isRightSideOfQualifiedNameOrPropertyAccess(location)) { location = location.parent; } if (isExpressionNode(location) && (!isAssignmentTarget(location) || isWriteAccess(location))) { const type = getTypeOfExpression(location as Expression); if (getExportSymbolOfValueSymbolIfExported(getNodeLinks(location).resolvedSymbol) === symbol) { return type; } } } if (isDeclarationName(location) && isSetAccessor(location.parent) && getAnnotatedAccessorTypeNode(location.parent)) { return getWriteTypeOfAccessors(location.parent.symbol); } // The location isn't a reference to the given symbol, meaning we're being asked // a hypothetical question of what type the symbol would have if there was a reference // to it at the given location. Since we have no control flow information for the // hypothetical reference (control flow information is created and attached by the // binder), we simply return the declared type of the symbol. return getNonMissingTypeOfSymbol(symbol); } function getControlFlowContainer(node: Node): Node { return findAncestor(node.parent, node => isFunctionLike(node) && !getImmediatelyInvokedFunctionExpression(node) || node.kind === SyntaxKind.ModuleBlock || node.kind === SyntaxKind.SourceFile || node.kind === SyntaxKind.PropertyDeclaration)!; } // Check if a parameter or catch variable is assigned anywhere function isSymbolAssigned(symbol: Symbol) { if (!symbol.valueDeclaration) { return false; } const parent = getRootDeclaration(symbol.valueDeclaration).parent; const links = getNodeLinks(parent); if (!(links.flags & NodeCheckFlags.AssignmentsMarked)) { links.flags |= NodeCheckFlags.AssignmentsMarked; if (!hasParentWithAssignmentsMarked(parent)) { markNodeAssignments(parent); } } return symbol.isAssigned || false; } function hasParentWithAssignmentsMarked(node: Node) { return !!findAncestor(node.parent, node => (isFunctionLike(node) || isCatchClause(node)) && !!(getNodeLinks(node).flags & NodeCheckFlags.AssignmentsMarked)); } function markNodeAssignments(node: Node) { if (node.kind === SyntaxKind.Identifier) { if (isAssignmentTarget(node)) { const symbol = getResolvedSymbol(node as Identifier); if (isParameterOrCatchClauseVariable(symbol)) { symbol.isAssigned = true; } } } else { forEachChild(node, markNodeAssignments); } } function isConstVariable(symbol: Symbol) { return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Const) !== 0; } function parameterInitializerContainsUndefined(declaration: ParameterDeclaration): boolean { const links = getNodeLinks(declaration); if (links.parameterInitializerContainsUndefined === undefined) { if (!pushTypeResolution(declaration, TypeSystemPropertyName.ParameterInitializerContainsUndefined)) { reportCircularityError(declaration.symbol); return true; } const containsUndefined = !!(getTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal)) & TypeFacts.IsUndefined); if (!popTypeResolution()) { reportCircularityError(declaration.symbol); return true; } links.parameterInitializerContainsUndefined = containsUndefined; } return links.parameterInitializerContainsUndefined; } /** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */ function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type { const removeUndefined = strictNullChecks && declaration.kind === SyntaxKind.Parameter && declaration.initializer && getTypeFacts(declaredType) & TypeFacts.IsUndefined && !parameterInitializerContainsUndefined(declaration); return removeUndefined ? getTypeWithFacts(declaredType, TypeFacts.NEUndefined) : declaredType; } function isConstraintPosition(type: Type, node: Node) { const parent = node.parent; // In an element access obj[x], we consider obj to be in a constraint position, except when obj is of // a generic type without a nullable constraint and x is a generic type. This is because when both obj // and x are of generic types T and K, we want the resulting type to be T[K]. return parent.kind === SyntaxKind.PropertyAccessExpression || parent.kind === SyntaxKind.QualifiedName || parent.kind === SyntaxKind.CallExpression && (parent as CallExpression).expression === node || parent.kind === SyntaxKind.ElementAccessExpression && (parent as ElementAccessExpression).expression === node && !(someType(type, isGenericTypeWithoutNullableConstraint) && isGenericIndexType(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression))); } function isGenericTypeWithUnionConstraint(type: Type): boolean { return type.flags & TypeFlags.Intersection ? some((type as IntersectionType).types, isGenericTypeWithUnionConstraint) : !!(type.flags & TypeFlags.Instantiable && getBaseConstraintOrType(type).flags & (TypeFlags.Nullable | TypeFlags.Union)); } function isGenericTypeWithoutNullableConstraint(type: Type): boolean { return type.flags & TypeFlags.Intersection ? some((type as IntersectionType).types, isGenericTypeWithoutNullableConstraint) : !!(type.flags & TypeFlags.Instantiable && !maybeTypeOfKind(getBaseConstraintOrType(type), TypeFlags.Nullable)); } function hasContextualTypeWithNoGenericTypes(node: Node, checkMode: CheckMode | undefined) { // Computing the contextual type for a child of a JSX element involves resolving the type of the // element's tag name, so we exclude that here to avoid circularities. // If check mode has `CheckMode.RestBindingElement`, we skip binding pattern contextual types, // as we want the type of a rest element to be generic when possible. const contextualType = (isIdentifier(node) || isPropertyAccessExpression(node) || isElementAccessExpression(node)) && !((isJsxOpeningElement(node.parent) || isJsxSelfClosingElement(node.parent)) && node.parent.tagName === node) && (checkMode && checkMode & CheckMode.RestBindingElement ? getContextualType(node, ContextFlags.SkipBindingPatterns) : getContextualType(node, /*contextFlags*/ undefined)); return contextualType && !isGenericType(contextualType); } function getNarrowableTypeForReference(type: Type, reference: Node, checkMode?: CheckMode) { // When the type of a reference is or contains an instantiable type with a union type constraint, and // when the reference is in a constraint position (where it is known we'll obtain the apparent type) or // has a contextual type containing no top-level instantiables (meaning constraints will determine // assignability), we substitute constraints for all instantiables in the type of the reference to give // control flow analysis an opportunity to narrow it further. For example, for a reference of a type // parameter type 'T extends string | undefined' with a contextual type 'string', we substitute // 'string | undefined' to give control flow analysis the opportunity to narrow to type 'string'. const substituteConstraints = !(checkMode && checkMode & CheckMode.Inferential) && someType(type, isGenericTypeWithUnionConstraint) && (isConstraintPosition(type, reference) || hasContextualTypeWithNoGenericTypes(reference, checkMode)); return substituteConstraints ? mapType(type, getBaseConstraintOrType) : type; } function isExportOrExportExpression(location: Node) { return !!findAncestor(location, n => { const parent = n.parent; if (parent === undefined) { return "quit"; } if (isExportAssignment(parent)) { return parent.expression === n && isEntityNameExpression(n); } if (isExportSpecifier(parent)) { return parent.name === n || parent.propertyName === n; } return false; }); } function markAliasReferenced(symbol: Symbol, location: Node) { if (compilerOptions.verbatimModuleSyntax) { return; } if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !isInTypeQuery(location) && !getTypeOnlyAliasDeclaration(symbol, SymbolFlags.Value)) { const target = resolveAlias(symbol); if (getAllSymbolFlags(target) & (SymbolFlags.Value | SymbolFlags.ExportValue)) { // An alias resolving to a const enum cannot be elided if (1) 'isolatedModules' is enabled // (because the const enum value will not be inlined), or if (2) the alias is an export // of a const enum declaration that will be preserved. if (getIsolatedModules(compilerOptions) || shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location) || !isConstEnumOrConstEnumOnlyModule(getExportSymbolOfValueSymbolIfExported(target)) ) { markAliasSymbolAsReferenced(symbol); } else { markConstEnumAliasAsReferenced(symbol); } } } } function getNarrowedTypeOfSymbol(symbol: Symbol, location: Identifier) { const type = getTypeOfSymbol(symbol); const declaration = symbol.valueDeclaration; if (declaration) { // If we have a non-rest binding element with no initializer declared as a const variable or a const-like // parameter (a parameter for which there are no assignments in the function body), and if the parent type // for the destructuring is a union type, one or more of the binding elements may represent discriminant // properties, and we want the effects of conditional checks on such discriminants to affect the types of // other binding elements from the same destructuring. Consider: // // type Action = // | { kind: 'A', payload: number } // | { kind: 'B', payload: string }; // // function f({ kind, payload }: Action) { // if (kind === 'A') { // payload.toFixed(); // } // if (kind === 'B') { // payload.toUpperCase(); // } // } // // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use // the binding pattern AST instance for '{ kind, payload }' as a pseudo-reference and narrow this reference // as if it occurred in the specified location. We then recompute the narrowed binding element type by // destructuring from the narrowed parent type. if (isBindingElement(declaration) && !declaration.initializer && !declaration.dotDotDotToken && declaration.parent.elements.length >= 2) { const parent = declaration.parent.parent; if (parent.kind === SyntaxKind.VariableDeclaration && getCombinedNodeFlags(declaration) & NodeFlags.Const || parent.kind === SyntaxKind.Parameter) { const links = getNodeLinks(parent); if (!(links.flags & NodeCheckFlags.InCheckIdentifier)) { links.flags |= NodeCheckFlags.InCheckIdentifier; const parentType = getTypeForBindingElementParent(parent, CheckMode.Normal); const parentTypeConstraint = parentType && mapType(parentType, getBaseConstraintOrType); links.flags &= ~NodeCheckFlags.InCheckIdentifier; if (parentTypeConstraint && parentTypeConstraint.flags & TypeFlags.Union && !(parent.kind === SyntaxKind.Parameter && isSymbolAssigned(symbol))) { const pattern = declaration.parent; const narrowedType = getFlowTypeOfReference(pattern, parentTypeConstraint, parentTypeConstraint, /*flowContainer*/ undefined, location.flowNode); if (narrowedType.flags & TypeFlags.Never) { return neverType; } return getBindingElementTypeFromParentType(declaration, narrowedType); } } } } // If we have a const-like parameter with no type annotation or initializer, and if the parameter is contextually // typed by a signature with a single rest parameter of a union of tuple types, one or more of the parameters may // represent discriminant tuple elements, and we want the effects of conditional checks on such discriminants to // affect the types of other parameters in the same parameter list. Consider: // // type Action = [kind: 'A', payload: number] | [kind: 'B', payload: string]; // // const f: (...args: Action) => void = (kind, payload) => { // if (kind === 'A') { // payload.toFixed(); // } // if (kind === 'B') { // payload.toUpperCase(); // } // } // // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use // the arrow function AST node for '(kind, payload) => ...' as a pseudo-reference and narrow this reference as // if it occurred in the specified location. We then recompute the narrowed parameter type by indexing into the // narrowed tuple type. if (isParameter(declaration) && !declaration.type && !declaration.initializer && !declaration.dotDotDotToken) { const func = declaration.parent; if (func.parameters.length >= 2 && isContextSensitiveFunctionOrObjectLiteralMethod(func)) { const contextualSignature = getContextualSignature(func); if (contextualSignature && contextualSignature.parameters.length === 1 && signatureHasRestParameter(contextualSignature)) { const restType = getReducedApparentType(instantiateType(getTypeOfSymbol(contextualSignature.parameters[0]), getInferenceContext(func)?.nonFixingMapper)); if (restType.flags & TypeFlags.Union && everyType(restType, isTupleType) && !isSymbolAssigned(symbol)) { const narrowedType = getFlowTypeOfReference(func, restType, restType, /*flowContainer*/ undefined, location.flowNode); const index = func.parameters.indexOf(declaration) - (getThisParameter(func) ? 1 : 0); return getIndexedAccessType(narrowedType, getNumberLiteralType(index)); } } } } } return type; } function checkIdentifier(node: Identifier, checkMode: CheckMode | undefined): Type { if (isThisInTypeQuery(node)) { return checkThisExpression(node); } const symbol = getResolvedSymbol(node); if (symbol === unknownSymbol) { return errorType; } // As noted in ECMAScript 6 language spec, arrow functions never have an arguments objects. // Although in down-level emit of arrow function, we emit it using function expression which means that // arguments objects will be bound to the inner object; emitting arrow function natively in ES6, arguments objects // will be bound to non-arrow function that contain this arrow function. This results in inconsistent behavior. // To avoid that we will give an error to users if they use arguments objects in arrow function so that they // can explicitly bound arguments objects if (symbol === argumentsSymbol) { if (isInPropertyInitializerOrClassStaticBlock(node)) { error(node, Diagnostics.arguments_cannot_be_referenced_in_property_initializers); return errorType; } const container = getContainingFunction(node)!; if (languageVersion < ScriptTarget.ES2015) { if (container.kind === SyntaxKind.ArrowFunction) { error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_arrow_function_in_ES3_and_ES5_Consider_using_a_standard_function_expression); } else if (hasSyntacticModifier(container, ModifierFlags.Async)) { error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_async_function_or_method_in_ES3_and_ES5_Consider_using_a_standard_function_or_method); } } getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; return getTypeOfSymbol(symbol); } if (shouldMarkIdentifierAliasReferenced(node)) { markAliasReferenced(symbol, node); } const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); const targetSymbol = checkDeprecatedAliasedSymbol(localOrExportSymbol, node); if (isDeprecatedSymbol(targetSymbol) && isUncalledFunctionReference(node, targetSymbol) && targetSymbol.declarations) { addDeprecatedSuggestion(node, targetSymbol.declarations, node.escapedText as string); } let declaration = localOrExportSymbol.valueDeclaration; if (declaration && localOrExportSymbol.flags & SymbolFlags.Class) { // Due to the emit for class decorators, any reference to the class from inside of the class body // must instead be rewritten to point to a temporary variable to avoid issues with the double-bind // behavior of class names in ES6. if (declaration.kind === SyntaxKind.ClassDeclaration && nodeIsDecorated(legacyDecorators, declaration as ClassDeclaration)) { let container = getContainingClass(node); while (container !== undefined) { if (container === declaration && container.name !== node) { getNodeLinks(declaration).flags |= NodeCheckFlags.ClassWithConstructorReference; getNodeLinks(node).flags |= NodeCheckFlags.ConstructorReferenceInClass; break; } container = getContainingClass(container); } } else if (declaration.kind === SyntaxKind.ClassExpression) { // When we emit a class expression with static members that contain a reference // to the constructor in the initializer, we will need to substitute that // binding with an alias as the class name is not in scope. let container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); while (container.kind !== SyntaxKind.SourceFile) { if (container.parent === declaration) { if (isPropertyDeclaration(container) && isStatic(container) || isClassStaticBlockDeclaration(container)) { getNodeLinks(declaration).flags |= NodeCheckFlags.ClassWithConstructorReference; getNodeLinks(node).flags |= NodeCheckFlags.ConstructorReferenceInClass; } break; } container = getThisContainer(container, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); } } } checkNestedBlockScopedBinding(node, symbol); let type = getNarrowedTypeOfSymbol(localOrExportSymbol, node); const assignmentKind = getAssignmentTargetKind(node); if (assignmentKind) { if (!(localOrExportSymbol.flags & SymbolFlags.Variable) && !(isInJSFile(node) && localOrExportSymbol.flags & SymbolFlags.ValueModule)) { const assignmentError = localOrExportSymbol.flags & SymbolFlags.Enum ? Diagnostics.Cannot_assign_to_0_because_it_is_an_enum : localOrExportSymbol.flags & SymbolFlags.Class ? Diagnostics.Cannot_assign_to_0_because_it_is_a_class : localOrExportSymbol.flags & SymbolFlags.Module ? Diagnostics.Cannot_assign_to_0_because_it_is_a_namespace : localOrExportSymbol.flags & SymbolFlags.Function ? Diagnostics.Cannot_assign_to_0_because_it_is_a_function : localOrExportSymbol.flags & SymbolFlags.Alias ? Diagnostics.Cannot_assign_to_0_because_it_is_an_import : Diagnostics.Cannot_assign_to_0_because_it_is_not_a_variable; error(node, assignmentError, symbolToString(symbol)); return errorType; } if (isReadonlySymbol(localOrExportSymbol)) { if (localOrExportSymbol.flags & SymbolFlags.Variable) { error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant, symbolToString(symbol)); } else { error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(symbol)); } return errorType; } } const isAlias = localOrExportSymbol.flags & SymbolFlags.Alias; // We only narrow variables and parameters occurring in a non-assignment position. For all other // entities we simply return the declared type. if (localOrExportSymbol.flags & SymbolFlags.Variable) { if (assignmentKind === AssignmentKind.Definite) { return type; } } else if (isAlias) { declaration = getDeclarationOfAliasSymbol(symbol); } else { return type; } if (!declaration) { return type; } type = getNarrowableTypeForReference(type, node, checkMode); // The declaration container is the innermost function that encloses the declaration of the variable // or parameter. The flow container is the innermost function starting with which we analyze the control // flow graph to determine the control flow based type. const isParameter = getRootDeclaration(declaration).kind === SyntaxKind.Parameter; const declarationContainer = getControlFlowContainer(declaration); let flowContainer = getControlFlowContainer(node); const isOuterVariable = flowContainer !== declarationContainer; const isSpreadDestructuringAssignmentTarget = node.parent && node.parent.parent && isSpreadAssignment(node.parent) && isDestructuringAssignmentTarget(node.parent.parent); const isModuleExports = symbol.flags & SymbolFlags.ModuleExports; // When the control flow originates in a function expression or arrow function and we are referencing // a const variable or parameter from an outer function, we extend the origin of the control flow // analysis to include the immediately enclosing function. while (flowContainer !== declarationContainer && (flowContainer.kind === SyntaxKind.FunctionExpression || flowContainer.kind === SyntaxKind.ArrowFunction || isObjectLiteralOrClassExpressionMethodOrAccessor(flowContainer)) && (isConstVariable(localOrExportSymbol) && type !== autoArrayType || isParameter && !isSymbolAssigned(localOrExportSymbol))) { flowContainer = getControlFlowContainer(flowContainer); } // We only look for uninitialized variables in strict null checking mode, and only when we can analyze // the entire control flow graph from the variable's declaration (i.e. when the flow container and // declaration container are the same). const assumeInitialized = isParameter || isAlias || isOuterVariable || isSpreadDestructuringAssignmentTarget || isModuleExports || isSameScopedBindingElement(node, declaration) || type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void)) !== 0 || isInTypeQuery(node) || isInAmbientOrTypeNode(node) || node.parent.kind === SyntaxKind.ExportSpecifier) || node.parent.kind === SyntaxKind.NonNullExpression || declaration.kind === SyntaxKind.VariableDeclaration && (declaration as VariableDeclaration).exclamationToken || declaration.flags & NodeFlags.Ambient; const initialType = assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, declaration as VariableLikeDeclaration) : type) : type === autoType || type === autoArrayType ? undefinedType : getOptionalType(type); const flowType = getFlowTypeOfReference(node, type, initialType, flowContainer); // A variable is considered uninitialized when it is possible to analyze the entire control flow graph // from declaration to use, and when the variable's declared type doesn't include undefined but the // control flow based type does include undefined. if (!isEvolvingArrayOperationTarget(node) && (type === autoType || type === autoArrayType)) { if (flowType === autoType || flowType === autoArrayType) { if (noImplicitAny) { error(getNameOfDeclaration(declaration), Diagnostics.Variable_0_implicitly_has_type_1_in_some_locations_where_its_type_cannot_be_determined, symbolToString(symbol), typeToString(flowType)); error(node, Diagnostics.Variable_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); } return convertAutoToAny(flowType); } } else if (!assumeInitialized && !containsUndefinedType(type) && containsUndefinedType(flowType)) { error(node, Diagnostics.Variable_0_is_used_before_being_assigned, symbolToString(symbol)); // Return the declared type to reduce follow-on errors return type; } return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; } function isSameScopedBindingElement(node: Identifier, declaration: Declaration) { if (isBindingElement(declaration)) { const bindingElement = findAncestor(node, isBindingElement); return bindingElement && getRootDeclaration(bindingElement) === getRootDeclaration(declaration); } } function shouldMarkIdentifierAliasReferenced(node: Identifier): boolean { const parent = node.parent; if (parent) { // A property access expression LHS? checkPropertyAccessExpression will handle that. if (isPropertyAccessExpression(parent) && parent.expression === node) { return false; } // Next two check for an identifier inside a type only export. if (isExportSpecifier(parent) && parent.isTypeOnly) { return false; } const greatGrandparent = parent.parent?.parent; if (greatGrandparent && isExportDeclaration(greatGrandparent) && greatGrandparent.isTypeOnly) { return false; } } return true; } function isInsideFunctionOrInstancePropertyInitializer(node: Node, threshold: Node): boolean { return !!findAncestor(node, n => n === threshold ? "quit" : isFunctionLike(n) || ( n.parent && isPropertyDeclaration(n.parent) && !hasStaticModifier(n.parent) && n.parent.initializer === n )); } function getPartOfForStatementContainingNode(node: Node, container: ForStatement) { return findAncestor(node, n => n === container ? "quit" : n === container.initializer || n === container.condition || n === container.incrementor || n === container.statement); } function getEnclosingIterationStatement(node: Node): Node | undefined { return findAncestor(node, n => (!n || nodeStartsNewLexicalEnvironment(n)) ? "quit" : isIterationStatement(n, /*lookInLabeledStatements*/ false)); } function checkNestedBlockScopedBinding(node: Identifier, symbol: Symbol): void { if (languageVersion >= ScriptTarget.ES2015 || (symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.Class)) === 0 || !symbol.valueDeclaration || isSourceFile(symbol.valueDeclaration) || symbol.valueDeclaration.parent.kind === SyntaxKind.CatchClause) { return; } // 1. walk from the use site up to the declaration and check // if there is anything function like between declaration and use-site (is binding/class is captured in function). // 2. walk from the declaration up to the boundary of lexical environment and check // if there is an iteration statement in between declaration and boundary (is binding/class declared inside iteration statement) const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); const isCaptured = isInsideFunctionOrInstancePropertyInitializer(node, container); const enclosingIterationStatement = getEnclosingIterationStatement(container); if (enclosingIterationStatement) { if (isCaptured) { // mark iteration statement as containing block-scoped binding captured in some function let capturesBlockScopeBindingInLoopBody = true; if (isForStatement(container)) { const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); if (varDeclList && varDeclList.parent === container) { const part = getPartOfForStatementContainingNode(node.parent, container); if (part) { const links = getNodeLinks(part); links.flags |= NodeCheckFlags.ContainsCapturedBlockScopeBinding; const capturedBindings = links.capturedBlockScopeBindings || (links.capturedBlockScopeBindings = []); pushIfUnique(capturedBindings, symbol); if (part === container.initializer) { capturesBlockScopeBindingInLoopBody = false; // Initializer is outside of loop body } } } } if (capturesBlockScopeBindingInLoopBody) { getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; } } // mark variables that are declared in loop initializer and reassigned inside the body of ForStatement. // if body of ForStatement will be converted to function then we'll need a extra machinery to propagate reassigned values back. if (isForStatement(container)) { const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); if (varDeclList && varDeclList.parent === container && isAssignedInBodyOfForStatement(node, container)) { getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.NeedsLoopOutParameter; } } // set 'declared inside loop' bit on the block-scoped binding getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.BlockScopedBindingInLoop; } if (isCaptured) { getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.CapturedBlockScopedBinding; } } function isBindingCapturedByNode(node: Node, decl: VariableDeclaration | BindingElement) { const links = getNodeLinks(node); return !!links && contains(links.capturedBlockScopeBindings, getSymbolOfDeclaration(decl)); } function isAssignedInBodyOfForStatement(node: Identifier, container: ForStatement): boolean { // skip parenthesized nodes let current: Node = node; while (current.parent.kind === SyntaxKind.ParenthesizedExpression) { current = current.parent; } // check if node is used as LHS in some assignment expression let isAssigned = false; if (isAssignmentTarget(current)) { isAssigned = true; } else if ((current.parent.kind === SyntaxKind.PrefixUnaryExpression || current.parent.kind === SyntaxKind.PostfixUnaryExpression)) { const expr = current.parent as PrefixUnaryExpression | PostfixUnaryExpression; isAssigned = expr.operator === SyntaxKind.PlusPlusToken || expr.operator === SyntaxKind.MinusMinusToken; } if (!isAssigned) { return false; } // at this point we know that node is the target of assignment // now check that modification happens inside the statement part of the ForStatement return !!findAncestor(current, n => n === container ? "quit" : n === container.statement); } function captureLexicalThis(node: Node, container: Node): void { getNodeLinks(node).flags |= NodeCheckFlags.LexicalThis; if (container.kind === SyntaxKind.PropertyDeclaration || container.kind === SyntaxKind.Constructor) { const classNode = container.parent; getNodeLinks(classNode).flags |= NodeCheckFlags.CaptureThis; } else { getNodeLinks(container).flags |= NodeCheckFlags.CaptureThis; } } function findFirstSuperCall(node: Node): SuperCall | undefined { return isSuperCall(node) ? node : isFunctionLike(node) ? undefined : forEachChild(node, findFirstSuperCall); } /** * Check if the given class-declaration extends null then return true. * Otherwise, return false * @param classDecl a class declaration to check if it extends null */ function classDeclarationExtendsNull(classDecl: ClassDeclaration): boolean { const classSymbol = getSymbolOfDeclaration(classDecl); const classInstanceType = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; const baseConstructorType = getBaseConstructorTypeOfClass(classInstanceType); return baseConstructorType === nullWideningType; } function checkThisBeforeSuper(node: Node, container: Node, diagnosticMessage: DiagnosticMessage) { const containingClassDecl = container.parent as ClassDeclaration; const baseTypeNode = getClassExtendsHeritageElement(containingClassDecl); // If a containing class does not have extends clause or the class extends null // skip checking whether super statement is called before "this" accessing. if (baseTypeNode && !classDeclarationExtendsNull(containingClassDecl)) { if (canHaveFlowNode(node) && node.flowNode && !isPostSuperFlowNode(node.flowNode, /*noCacheCheck*/ false)) { error(node, diagnosticMessage); } } } function checkThisInStaticClassFieldInitializerInDecoratedClass(thisExpression: Node, container: Node) { if (isPropertyDeclaration(container) && hasStaticModifier(container) && legacyDecorators && container.initializer && textRangeContainsPositionInclusive(container.initializer, thisExpression.pos) && hasDecorators(container.parent)) { error(thisExpression, Diagnostics.Cannot_use_this_in_a_static_property_initializer_of_a_decorated_class); } } function checkThisExpression(node: Node): Type { const isNodeInTypeQuery = isInTypeQuery(node); // Stop at the first arrow function so that we can // tell whether 'this' needs to be captured. let container = getThisContainer(node, /* includeArrowFunctions */ true, /*includeClassComputedPropertyName*/ true); let capturedByArrowFunction = false; let thisInComputedPropertyName = false; if (container.kind === SyntaxKind.Constructor) { checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_this_in_the_constructor_of_a_derived_class); } while (true) { // Now skip arrow functions to get the "real" owner of 'this'. if (container.kind === SyntaxKind.ArrowFunction) { container = getThisContainer(container, /* includeArrowFunctions */ false, !thisInComputedPropertyName); capturedByArrowFunction = true; } if (container.kind === SyntaxKind.ComputedPropertyName) { container = getThisContainer(container, !capturedByArrowFunction, /*includeClassComputedPropertyName*/ false); thisInComputedPropertyName = true; continue; } break; } checkThisInStaticClassFieldInitializerInDecoratedClass(node, container); if (thisInComputedPropertyName) { error(node, Diagnostics.this_cannot_be_referenced_in_a_computed_property_name); } else { switch (container.kind) { case SyntaxKind.ModuleDeclaration: error(node, Diagnostics.this_cannot_be_referenced_in_a_module_or_namespace_body); // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks break; case SyntaxKind.EnumDeclaration: error(node, Diagnostics.this_cannot_be_referenced_in_current_location); // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks break; case SyntaxKind.Constructor: if (isInConstructorArgumentInitializer(node, container)) { error(node, Diagnostics.this_cannot_be_referenced_in_constructor_arguments); // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks } break; } } // When targeting es6, mark that we'll need to capture `this` in its lexically bound scope. if (!isNodeInTypeQuery && capturedByArrowFunction && languageVersion < ScriptTarget.ES2015) { captureLexicalThis(node, container); } const type = tryGetThisTypeAt(node, /*includeGlobalThis*/ true, container); if (noImplicitThis) { const globalThisType = getTypeOfSymbol(globalThisSymbol); if (type === globalThisType && capturedByArrowFunction) { error(node, Diagnostics.The_containing_arrow_function_captures_the_global_value_of_this); } else if (!type) { // With noImplicitThis, functions may not reference 'this' if it has type 'any' const diag = error(node, Diagnostics.this_implicitly_has_type_any_because_it_does_not_have_a_type_annotation); if (!isSourceFile(container)) { const outsideThis = tryGetThisTypeAt(container); if (outsideThis && outsideThis !== globalThisType) { addRelatedInfo(diag, createDiagnosticForNode(container, Diagnostics.An_outer_value_of_this_is_shadowed_by_this_container)); } } } } return type || anyType; } function tryGetThisTypeAt(node: Node, includeGlobalThis = true, container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)): Type | undefined { const isInJS = isInJSFile(node); if (isFunctionLike(container) && (!isInParameterInitializerBeforeContainingFunction(node) || getThisParameter(container))) { let thisType = getThisTypeOfDeclaration(container) || isInJS && getTypeForThisExpressionFromJSDoc(container); // Note: a parameter initializer should refer to class-this unless function-this is explicitly annotated. // If this is a function in a JS file, it might be a class method. if (!thisType) { const className = getClassNameFromPrototypeMethod(container); if (isInJS && className) { const classSymbol = checkExpression(className).symbol; if (classSymbol && classSymbol.members && (classSymbol.flags & SymbolFlags.Function)) { thisType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType; } } else if (isJSConstructor(container)) { thisType = (getDeclaredTypeOfSymbol(getMergedSymbol(container.symbol)) as InterfaceType).thisType; } thisType ||= getContextualThisParameterType(container); } if (thisType) { return getFlowTypeOfReference(node, thisType); } } if (isClassLike(container.parent)) { const symbol = getSymbolOfDeclaration(container.parent); const type = isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; return getFlowTypeOfReference(node, type); } if (isSourceFile(container)) { // look up in the source file's locals or exports if (container.commonJsModuleIndicator) { const fileSymbol = getSymbolOfDeclaration(container); return fileSymbol && getTypeOfSymbol(fileSymbol); } else if (container.externalModuleIndicator) { // TODO: Maybe issue a better error than 'object is possibly undefined' return undefinedType; } else if (includeGlobalThis) { return getTypeOfSymbol(globalThisSymbol); } } } function getExplicitThisType(node: Expression) { const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); if (isFunctionLike(container)) { const signature = getSignatureFromDeclaration(container); if (signature.thisParameter) { return getExplicitTypeOfSymbol(signature.thisParameter); } } if (isClassLike(container.parent)) { const symbol = getSymbolOfDeclaration(container.parent); return isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; } } function getClassNameFromPrototypeMethod(container: Node) { // Check if it's the RHS of a x.prototype.y = function [name]() { .... } if (container.kind === SyntaxKind.FunctionExpression && isBinaryExpression(container.parent) && getAssignmentDeclarationKind(container.parent) === AssignmentDeclarationKind.PrototypeProperty) { // Get the 'x' of 'x.prototype.y = container' return ((container.parent // x.prototype.y = container .left as PropertyAccessExpression) // x.prototype.y .expression as PropertyAccessExpression) // x.prototype .expression; // x } // x.prototype = { method() { } } else if (container.kind === SyntaxKind.MethodDeclaration && container.parent.kind === SyntaxKind.ObjectLiteralExpression && isBinaryExpression(container.parent.parent) && getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.Prototype) { return (container.parent.parent.left as PropertyAccessExpression).expression; } // x.prototype = { method: function() { } } else if (container.kind === SyntaxKind.FunctionExpression && container.parent.kind === SyntaxKind.PropertyAssignment && container.parent.parent.kind === SyntaxKind.ObjectLiteralExpression && isBinaryExpression(container.parent.parent.parent) && getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.Prototype) { return (container.parent.parent.parent.left as PropertyAccessExpression).expression; } // Object.defineProperty(x, "method", { value: function() { } }); // Object.defineProperty(x, "method", { set: (x: () => void) => void }); // Object.defineProperty(x, "method", { get: () => function() { }) }); else if (container.kind === SyntaxKind.FunctionExpression && isPropertyAssignment(container.parent) && isIdentifier(container.parent.name) && (container.parent.name.escapedText === "value" || container.parent.name.escapedText === "get" || container.parent.name.escapedText === "set") && isObjectLiteralExpression(container.parent.parent) && isCallExpression(container.parent.parent.parent) && container.parent.parent.parent.arguments[2] === container.parent.parent && getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty) { return (container.parent.parent.parent.arguments[0] as PropertyAccessExpression).expression; } // Object.defineProperty(x, "method", { value() { } }); // Object.defineProperty(x, "method", { set(x: () => void) {} }); // Object.defineProperty(x, "method", { get() { return () => {} } }); else if (isMethodDeclaration(container) && isIdentifier(container.name) && (container.name.escapedText === "value" || container.name.escapedText === "get" || container.name.escapedText === "set") && isObjectLiteralExpression(container.parent) && isCallExpression(container.parent.parent) && container.parent.parent.arguments[2] === container.parent && getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty) { return (container.parent.parent.arguments[0] as PropertyAccessExpression).expression; } } function getTypeForThisExpressionFromJSDoc(node: Node) { const jsdocType = getJSDocType(node); if (jsdocType && jsdocType.kind === SyntaxKind.JSDocFunctionType) { const jsDocFunctionType = jsdocType as JSDocFunctionType; if (jsDocFunctionType.parameters.length > 0 && jsDocFunctionType.parameters[0].name && (jsDocFunctionType.parameters[0].name as Identifier).escapedText === InternalSymbolName.This) { return getTypeFromTypeNode(jsDocFunctionType.parameters[0].type!); } } const thisTag = getJSDocThisTag(node); if (thisTag && thisTag.typeExpression) { return getTypeFromTypeNode(thisTag.typeExpression); } } function isInConstructorArgumentInitializer(node: Node, constructorDecl: Node): boolean { return !!findAncestor(node, n => isFunctionLikeDeclaration(n) ? "quit" : n.kind === SyntaxKind.Parameter && n.parent === constructorDecl); } function checkSuperExpression(node: Node): Type { const isCallExpression = node.parent.kind === SyntaxKind.CallExpression && (node.parent as CallExpression).expression === node; const immediateContainer = getSuperContainer(node, /*stopOnFunctions*/ true); let container = immediateContainer; let needToCaptureLexicalThis = false; let inAsyncFunction = false; // adjust the container reference in case if super is used inside arrow functions with arbitrarily deep nesting if (!isCallExpression) { while (container && container.kind === SyntaxKind.ArrowFunction) { if (hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; container = getSuperContainer(container, /*stopOnFunctions*/ true); needToCaptureLexicalThis = languageVersion < ScriptTarget.ES2015; } if (container && hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; } let nodeCheckFlag: NodeCheckFlags = 0; if (!container || !isLegalUsageOfSuperExpression(container)) { // issue more specific error if super is used in computed property name // class A { foo() { return "1" }} // class B { // [super.foo()]() {} // } const current = findAncestor(node, n => n === container ? "quit" : n.kind === SyntaxKind.ComputedPropertyName); if (current && current.kind === SyntaxKind.ComputedPropertyName) { error(node, Diagnostics.super_cannot_be_referenced_in_a_computed_property_name); } else if (isCallExpression) { error(node, Diagnostics.Super_calls_are_not_permitted_outside_constructors_or_in_nested_functions_inside_constructors); } else if (!container || !container.parent || !(isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression)) { error(node, Diagnostics.super_can_only_be_referenced_in_members_of_derived_classes_or_object_literal_expressions); } else { error(node, Diagnostics.super_property_access_is_permitted_only_in_a_constructor_member_function_or_member_accessor_of_a_derived_class); } return errorType; } if (!isCallExpression && immediateContainer!.kind === SyntaxKind.Constructor) { checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_a_property_of_super_in_the_constructor_of_a_derived_class); } if (isStatic(container) || isCallExpression) { nodeCheckFlag = NodeCheckFlags.SuperStatic; if (!isCallExpression && languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 && (isPropertyDeclaration(container) || isClassStaticBlockDeclaration(container))) { // for `super.x` or `super[x]` in a static initializer, mark all enclosing // block scope containers so that we can report potential collisions with // `Reflect`. forEachEnclosingBlockScopeContainer(node.parent, current => { if (!isSourceFile(current) || isExternalOrCommonJsModule(current)) { getNodeLinks(current).flags |= NodeCheckFlags.ContainsSuperPropertyInStaticInitializer; } }); } } else { nodeCheckFlag = NodeCheckFlags.SuperInstance; } getNodeLinks(node).flags |= nodeCheckFlag; // Due to how we emit async functions, we need to specialize the emit for an async method that contains a `super` reference. // This is due to the fact that we emit the body of an async function inside of a generator function. As generator // functions cannot reference `super`, we emit a helper inside of the method body, but outside of the generator. This helper // uses an arrow function, which is permitted to reference `super`. // // There are two primary ways we can access `super` from within an async method. The first is getting the value of a property // or indexed access on super, either as part of a right-hand-side expression or call expression. The second is when setting the value // of a property or indexed access, either as part of an assignment expression or destructuring assignment. // // The simplest case is reading a value, in which case we will emit something like the following: // // // ts // ... // async asyncMethod() { // let x = await super.asyncMethod(); // return x; // } // ... // // // js // ... // asyncMethod() { // const _super = Object.create(null, { // asyncMethod: { get: () => super.asyncMethod }, // }); // return __awaiter(this, arguments, Promise, function *() { // let x = yield _super.asyncMethod.call(this); // return x; // }); // } // ... // // The more complex case is when we wish to assign a value, especially as part of a destructuring assignment. As both cases // are legal in ES6, but also likely less frequent, we only emit setters if there is an assignment: // // // ts // ... // async asyncMethod(ar: Promise) { // [super.a, super.b] = await ar; // } // ... // // // js // ... // asyncMethod(ar) { // const _super = Object.create(null, { // a: { get: () => super.a, set: (v) => super.a = v }, // b: { get: () => super.b, set: (v) => super.b = v } // }; // return __awaiter(this, arguments, Promise, function *() { // [_super.a, _super.b] = yield ar; // }); // } // ... // // Creating an object that has getter and setters instead of just an accessor function is required for destructuring assignments // as a call expression cannot be used as the target of a destructuring assignment while a property access can. // // For element access expressions (`super[x]`), we emit a generic helper that forwards the element access in both situations. if (container.kind === SyntaxKind.MethodDeclaration && inAsyncFunction) { if (isSuperProperty(node.parent) && isAssignmentTarget(node.parent)) { getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync; } else { getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAccessInAsync; } } if (needToCaptureLexicalThis) { // call expressions are allowed only in constructors so they should always capture correct 'this' // super property access expressions can also appear in arrow functions - // in this case they should also use correct lexical this captureLexicalThis(node.parent, container); } if (container.parent.kind === SyntaxKind.ObjectLiteralExpression) { if (languageVersion < ScriptTarget.ES2015) { error(node, Diagnostics.super_is_only_allowed_in_members_of_object_literal_expressions_when_option_target_is_ES2015_or_higher); return errorType; } else { // for object literal assume that type of 'super' is 'any' return anyType; } } // at this point the only legal case for parent is ClassLikeDeclaration const classLikeDeclaration = container.parent as ClassLikeDeclaration; if (!getClassExtendsHeritageElement(classLikeDeclaration)) { error(node, Diagnostics.super_can_only_be_referenced_in_a_derived_class); return errorType; } const classType = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(classLikeDeclaration)) as InterfaceType; const baseClassType = classType && getBaseTypes(classType)[0]; if (!baseClassType) { return errorType; } if (container.kind === SyntaxKind.Constructor && isInConstructorArgumentInitializer(node, container)) { // issue custom error message for super property access in constructor arguments (to be aligned with old compiler) error(node, Diagnostics.super_cannot_be_referenced_in_constructor_arguments); return errorType; } return nodeCheckFlag === NodeCheckFlags.SuperStatic ? getBaseConstructorTypeOfClass(classType) : getTypeWithThisArgument(baseClassType, classType.thisType); function isLegalUsageOfSuperExpression(container: Node): boolean { if (isCallExpression) { // TS 1.0 SPEC (April 2014): 4.8.1 // Super calls are only permitted in constructors of derived classes return container.kind === SyntaxKind.Constructor; } else { // TS 1.0 SPEC (April 2014) // 'super' property access is allowed // - In a constructor, instance member function, instance member accessor, or instance member variable initializer where this references a derived class instance // - In a static member function or static member accessor // topmost container must be something that is directly nested in the class declaration\object literal expression if (isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression) { if (isStatic(container)) { return container.kind === SyntaxKind.MethodDeclaration || container.kind === SyntaxKind.MethodSignature || container.kind === SyntaxKind.GetAccessor || container.kind === SyntaxKind.SetAccessor || container.kind === SyntaxKind.PropertyDeclaration || container.kind === SyntaxKind.ClassStaticBlockDeclaration; } else { return container.kind === SyntaxKind.MethodDeclaration || container.kind === SyntaxKind.MethodSignature || container.kind === SyntaxKind.GetAccessor || container.kind === SyntaxKind.SetAccessor || container.kind === SyntaxKind.PropertyDeclaration || container.kind === SyntaxKind.PropertySignature || container.kind === SyntaxKind.Constructor; } } } return false; } } function getContainingObjectLiteral(func: SignatureDeclaration): ObjectLiteralExpression | undefined { return (func.kind === SyntaxKind.MethodDeclaration || func.kind === SyntaxKind.GetAccessor || func.kind === SyntaxKind.SetAccessor) && func.parent.kind === SyntaxKind.ObjectLiteralExpression ? func.parent : func.kind === SyntaxKind.FunctionExpression && func.parent.kind === SyntaxKind.PropertyAssignment ? func.parent.parent as ObjectLiteralExpression : undefined; } function getThisTypeArgument(type: Type): Type | undefined { return getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target === globalThisType ? getTypeArguments(type as TypeReference)[0] : undefined; } function getThisTypeFromContextualType(type: Type): Type | undefined { return mapType(type, t => { return t.flags & TypeFlags.Intersection ? forEach((t as IntersectionType).types, getThisTypeArgument) : getThisTypeArgument(t); }); } function getContextualThisParameterType(func: SignatureDeclaration): Type | undefined { if (func.kind === SyntaxKind.ArrowFunction) { return undefined; } if (isContextSensitiveFunctionOrObjectLiteralMethod(func)) { const contextualSignature = getContextualSignature(func); if (contextualSignature) { const thisParameter = contextualSignature.thisParameter; if (thisParameter) { return getTypeOfSymbol(thisParameter); } } } const inJs = isInJSFile(func); if (noImplicitThis || inJs) { const containingLiteral = getContainingObjectLiteral(func); if (containingLiteral) { // We have an object literal method. Check if the containing object literal has a contextual type // that includes a ThisType. If so, T is the contextual type for 'this'. We continue looking in // any directly enclosing object literals. const contextualType = getApparentTypeOfContextualType(containingLiteral, /*contextFlags*/ undefined); let literal = containingLiteral; let type = contextualType; while (type) { const thisType = getThisTypeFromContextualType(type); if (thisType) { return instantiateType(thisType, getMapperFromContext(getInferenceContext(containingLiteral))); } if (literal.parent.kind !== SyntaxKind.PropertyAssignment) { break; } literal = literal.parent.parent as ObjectLiteralExpression; type = getApparentTypeOfContextualType(literal, /*contextFlags*/ undefined); } // There was no contextual ThisType for the containing object literal, so the contextual type // for 'this' is the non-null form of the contextual type for the containing object literal or // the type of the object literal itself. return getWidenedType(contextualType ? getNonNullableType(contextualType) : checkExpressionCached(containingLiteral)); } // In an assignment of the form 'obj.xxx = function(...)' or 'obj[xxx] = function(...)', the // contextual type for 'this' is 'obj'. const parent = walkUpParenthesizedExpressions(func.parent); if (parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { const target = (parent as BinaryExpression).left; if (isAccessExpression(target)) { const { expression } = target; // Don't contextually type `this` as `exports` in `exports.Point = function(x, y) { this.x = x; this.y = y; }` if (inJs && isIdentifier(expression)) { const sourceFile = getSourceFileOfNode(parent); if (sourceFile.commonJsModuleIndicator && getResolvedSymbol(expression) === sourceFile.symbol) { return undefined; } } return getWidenedType(checkExpressionCached(expression)); } } } return undefined; } // Return contextual type of parameter or undefined if no contextual type is available function getContextuallyTypedParameterType(parameter: ParameterDeclaration): Type | undefined { const func = parameter.parent; if (!isContextSensitiveFunctionOrObjectLiteralMethod(func)) { return undefined; } const iife = getImmediatelyInvokedFunctionExpression(func); if (iife && iife.arguments) { const args = getEffectiveCallArguments(iife); const indexOfParameter = func.parameters.indexOf(parameter); if (parameter.dotDotDotToken) { return getSpreadArgumentType(args, indexOfParameter, args.length, anyType, /*context*/ undefined, CheckMode.Normal); } const links = getNodeLinks(iife); const cached = links.resolvedSignature; links.resolvedSignature = anySignature; const type = indexOfParameter < args.length ? getWidenedLiteralType(checkExpression(args[indexOfParameter])) : parameter.initializer ? undefined : undefinedWideningType; links.resolvedSignature = cached; return type; } const contextualSignature = getContextualSignature(func); if (contextualSignature) { const index = func.parameters.indexOf(parameter) - (getThisParameter(func) ? 1 : 0); return parameter.dotDotDotToken && lastOrUndefined(func.parameters) === parameter ? getRestTypeAtPosition(contextualSignature, index) : tryGetTypeAtPosition(contextualSignature, index); } } function getContextualTypeForVariableLikeDeclaration(declaration: VariableLikeDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { const typeNode = getEffectiveTypeAnnotationNode(declaration) || (isInJSFile(declaration) ? tryGetJSDocSatisfiesTypeNode(declaration) : undefined); if (typeNode) { return getTypeFromTypeNode(typeNode); } switch (declaration.kind) { case SyntaxKind.Parameter: return getContextuallyTypedParameterType(declaration); case SyntaxKind.BindingElement: return getContextualTypeForBindingElement(declaration, contextFlags); case SyntaxKind.PropertyDeclaration: if (isStatic(declaration)) { return getContextualTypeForStaticPropertyDeclaration(declaration, contextFlags); } // By default, do nothing and return undefined - only the above cases have context implied by a parent } } function getContextualTypeForBindingElement(declaration: BindingElement, contextFlags: ContextFlags | undefined): Type | undefined { const parent = declaration.parent.parent; const name = declaration.propertyName || declaration.name; const parentType = getContextualTypeForVariableLikeDeclaration(parent, contextFlags) || parent.kind !== SyntaxKind.BindingElement && parent.initializer && checkDeclarationInitializer(parent, declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal); if (!parentType || isBindingPattern(name) || isComputedNonLiteralName(name)) return undefined; if (parent.name.kind === SyntaxKind.ArrayBindingPattern) { const index = indexOfNode(declaration.parent.elements, declaration); if (index < 0) return undefined; return getContextualTypeForElementExpression(parentType, index); } const nameType = getLiteralTypeFromPropertyName(name); if (isTypeUsableAsPropertyName(nameType)) { const text = getPropertyNameFromType(nameType); return getTypeOfPropertyOfType(parentType, text); } } function getContextualTypeForStaticPropertyDeclaration(declaration: PropertyDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { const parentType = isExpression(declaration.parent) && getContextualType(declaration.parent, contextFlags); if (!parentType) return undefined; return getTypeOfPropertyOfContextualType(parentType, getSymbolOfDeclaration(declaration).escapedName); } // In a variable, parameter or property declaration with a type annotation, // the contextual type of an initializer expression is the type of the variable, parameter or property. // Otherwise, in a parameter declaration of a contextually typed function expression, // the contextual type of an initializer expression is the contextual type of the parameter. // Otherwise, in a variable or parameter declaration with a binding pattern name, // the contextual type of an initializer expression is the type implied by the binding pattern. // Otherwise, in a binding pattern inside a variable or parameter declaration, // the contextual type of an initializer expression is the type annotation of the containing declaration, if present. function getContextualTypeForInitializerExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { const declaration = node.parent as VariableLikeDeclaration; if (hasInitializer(declaration) && node === declaration.initializer) { const result = getContextualTypeForVariableLikeDeclaration(declaration, contextFlags); if (result) { return result; } if (!(contextFlags! & ContextFlags.SkipBindingPatterns) && isBindingPattern(declaration.name) && declaration.name.elements.length > 0) { return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ true, /*reportErrors*/ false); } } return undefined; } function getContextualTypeForReturnExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { const func = getContainingFunction(node); if (func) { let contextualReturnType = getContextualReturnType(func, contextFlags); if (contextualReturnType) { const functionFlags = getFunctionFlags(func); if (functionFlags & FunctionFlags.Generator) { // Generator or AsyncGenerator function const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; if (contextualReturnType.flags & TypeFlags.Union) { contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); } const iterationReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, contextualReturnType, (functionFlags & FunctionFlags.Async) !== 0); if (!iterationReturnType) { return undefined; } contextualReturnType = iterationReturnType; // falls through to unwrap Promise for AsyncGenerators } if (functionFlags & FunctionFlags.Async) { // Async function or AsyncGenerator function // Get the awaited type without the `Awaited` alias const contextualAwaitedType = mapType(contextualReturnType, getAwaitedTypeNoAlias); return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); } return contextualReturnType; // Regular function or Generator function } } return undefined; } function getContextualTypeForAwaitOperand(node: AwaitExpression, contextFlags: ContextFlags | undefined): Type | undefined { const contextualType = getContextualType(node, contextFlags); if (contextualType) { const contextualAwaitedType = getAwaitedTypeNoAlias(contextualType); return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); } return undefined; } function getContextualTypeForYieldOperand(node: YieldExpression, contextFlags: ContextFlags | undefined): Type | undefined { const func = getContainingFunction(node); if (func) { const functionFlags = getFunctionFlags(func); let contextualReturnType = getContextualReturnType(func, contextFlags); if (contextualReturnType) { const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; if (!node.asteriskToken && contextualReturnType.flags & TypeFlags.Union) { contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); } return node.asteriskToken ? contextualReturnType : getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, contextualReturnType, isAsyncGenerator); } } return undefined; } function isInParameterInitializerBeforeContainingFunction(node: Node) { let inBindingInitializer = false; while (node.parent && !isFunctionLike(node.parent)) { if (isParameter(node.parent) && (inBindingInitializer || node.parent.initializer === node)) { return true; } if (isBindingElement(node.parent) && node.parent.initializer === node) { inBindingInitializer = true; } node = node.parent; } return false; } function getContextualIterationType(kind: IterationTypeKind, functionDecl: SignatureDeclaration): Type | undefined { const isAsync = !!(getFunctionFlags(functionDecl) & FunctionFlags.Async); const contextualReturnType = getContextualReturnType(functionDecl, /*contextFlags*/ undefined); if (contextualReturnType) { return getIterationTypeOfGeneratorFunctionReturnType(kind, contextualReturnType, isAsync) || undefined; } return undefined; } function getContextualReturnType(functionDecl: SignatureDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { // If the containing function has a return type annotation, is a constructor, or is a get accessor whose // corresponding set accessor has a type annotation, return statements in the function are contextually typed const returnType = getReturnTypeFromAnnotation(functionDecl); if (returnType) { return returnType; } // Otherwise, if the containing function is contextually typed by a function type with exactly one call signature // and that call signature is non-generic, return statements are contextually typed by the return type of the signature const signature = getContextualSignatureForFunctionLikeDeclaration(functionDecl as FunctionExpression); if (signature && !isResolvingReturnTypeOfSignature(signature)) { return getReturnTypeOfSignature(signature); } const iife = getImmediatelyInvokedFunctionExpression(functionDecl); if (iife) { return getContextualType(iife, contextFlags); } return undefined; } // In a typed function call, an argument or substitution expression is contextually typed by the type of the corresponding parameter. function getContextualTypeForArgument(callTarget: CallLikeExpression, arg: Expression): Type | undefined { const args = getEffectiveCallArguments(callTarget); const argIndex = args.indexOf(arg); // -1 for e.g. the expression of a CallExpression, or the tag of a TaggedTemplateExpression return argIndex === -1 ? undefined : getContextualTypeForArgumentAtIndex(callTarget, argIndex); } function getContextualTypeForArgumentAtIndex(callTarget: CallLikeExpression, argIndex: number): Type { if (isImportCall(callTarget)) { return argIndex === 0 ? stringType : argIndex === 1 ? getGlobalImportCallOptionsType(/*reportErrors*/ false) : anyType; } // If we're already in the process of resolving the given signature, don't resolve again as // that could cause infinite recursion. Instead, return anySignature. const signature = getNodeLinks(callTarget).resolvedSignature === resolvingSignature ? resolvingSignature : getResolvedSignature(callTarget); if (isJsxOpeningLikeElement(callTarget) && argIndex === 0) { return getEffectiveFirstArgumentForJsxSignature(signature, callTarget); } const restIndex = signature.parameters.length - 1; return signatureHasRestParameter(signature) && argIndex >= restIndex ? getIndexedAccessType(getTypeOfSymbol(signature.parameters[restIndex]), getNumberLiteralType(argIndex - restIndex), AccessFlags.Contextual) : getTypeAtPosition(signature, argIndex); } function getContextualTypeForDecorator(decorator: Decorator): Type | undefined { const signature = getDecoratorCallSignature(decorator); return signature ? getOrCreateTypeFromSignature(signature) : undefined; } function getContextualTypeForSubstitutionExpression(template: TemplateExpression, substitutionExpression: Expression) { if (template.parent.kind === SyntaxKind.TaggedTemplateExpression) { return getContextualTypeForArgument(template.parent as TaggedTemplateExpression, substitutionExpression); } return undefined; } function getContextualTypeForBinaryOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { const binaryExpression = node.parent as BinaryExpression; const { left, operatorToken, right } = binaryExpression; switch (operatorToken.kind) { case SyntaxKind.EqualsToken: case SyntaxKind.AmpersandAmpersandEqualsToken: case SyntaxKind.BarBarEqualsToken: case SyntaxKind.QuestionQuestionEqualsToken: return node === right ? getContextualTypeForAssignmentDeclaration(binaryExpression) : undefined; case SyntaxKind.BarBarToken: case SyntaxKind.QuestionQuestionToken: // When an || expression has a contextual type, the operands are contextually typed by that type, except // when that type originates in a binding pattern, the right operand is contextually typed by the type of // the left operand. When an || expression has no contextual type, the right operand is contextually typed // by the type of the left operand, except for the special case of Javascript declarations of the form // `namespace.prop = namespace.prop || {}`. const type = getContextualType(binaryExpression, contextFlags); return node === right && (type && type.pattern || !type && !isDefaultedExpandoInitializer(binaryExpression)) ? getTypeOfExpression(left) : type; case SyntaxKind.AmpersandAmpersandToken: case SyntaxKind.CommaToken: return node === right ? getContextualType(binaryExpression, contextFlags) : undefined; default: return undefined; } } /** * Try to find a resolved symbol for an expression without also resolving its type, as * getSymbolAtLocation would (as that could be reentrant into contextual typing) */ function getSymbolForExpression(e: Expression) { if (canHaveSymbol(e) && e.symbol) { return e.symbol; } if (isIdentifier(e)) { return getResolvedSymbol(e); } if (isPropertyAccessExpression(e)) { const lhsType = getTypeOfExpression(e.expression); return isPrivateIdentifier(e.name) ? tryGetPrivateIdentifierPropertyOfType(lhsType, e.name) : getPropertyOfType(lhsType, e.name.escapedText); } if (isElementAccessExpression(e)) { const propType = checkExpressionCached(e.argumentExpression); if (!isTypeUsableAsPropertyName(propType)) { return undefined; } const lhsType = getTypeOfExpression(e.expression); return getPropertyOfType(lhsType, getPropertyNameFromType(propType)); } return undefined; function tryGetPrivateIdentifierPropertyOfType(type: Type, id: PrivateIdentifier) { const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(id.escapedText, id); return lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(type, lexicallyScopedSymbol); } } // In an assignment expression, the right operand is contextually typed by the type of the left operand. // Don't do this for assignment declarations unless there is a type tag on the assignment, to avoid circularity from checking the right operand. function getContextualTypeForAssignmentDeclaration(binaryExpression: BinaryExpression): Type | undefined { const kind = getAssignmentDeclarationKind(binaryExpression); switch (kind) { case AssignmentDeclarationKind.None: case AssignmentDeclarationKind.ThisProperty: const lhsSymbol = getSymbolForExpression(binaryExpression.left); const decl = lhsSymbol && lhsSymbol.valueDeclaration; // Unannotated, uninitialized property declarations have a type implied by their usage in the constructor. // We avoid calling back into `getTypeOfExpression` and reentering contextual typing to avoid a bogus circularity error in that case. if (decl && (isPropertyDeclaration(decl) || isPropertySignature(decl))) { const overallAnnotation = getEffectiveTypeAnnotationNode(decl); return (overallAnnotation && instantiateType(getTypeFromTypeNode(overallAnnotation), getSymbolLinks(lhsSymbol).mapper)) || (isPropertyDeclaration(decl) ? decl.initializer && getTypeOfExpression(binaryExpression.left) : undefined); } if (kind === AssignmentDeclarationKind.None) { return getTypeOfExpression(binaryExpression.left); } return getContextualTypeForThisPropertyAssignment(binaryExpression); case AssignmentDeclarationKind.Property: if (isPossiblyAliasedThisProperty(binaryExpression, kind)) { return getContextualTypeForThisPropertyAssignment(binaryExpression); } // If `binaryExpression.left` was assigned a symbol, then this is a new declaration; otherwise it is an assignment to an existing declaration. // See `bindStaticPropertyAssignment` in `binder.ts`. else if (!canHaveSymbol(binaryExpression.left) || !binaryExpression.left.symbol) { return getTypeOfExpression(binaryExpression.left); } else { const decl = binaryExpression.left.symbol.valueDeclaration; if (!decl) { return undefined; } const lhs = cast(binaryExpression.left, isAccessExpression); const overallAnnotation = getEffectiveTypeAnnotationNode(decl); if (overallAnnotation) { return getTypeFromTypeNode(overallAnnotation); } else if (isIdentifier(lhs.expression)) { const id = lhs.expression; const parentSymbol = resolveName(id, id.escapedText, SymbolFlags.Value, undefined, id.escapedText, /*isUse*/ true); if (parentSymbol) { const annotated = parentSymbol.valueDeclaration && getEffectiveTypeAnnotationNode(parentSymbol.valueDeclaration); if (annotated) { const nameStr = getElementOrPropertyAccessName(lhs); if (nameStr !== undefined) { return getTypeOfPropertyOfContextualType(getTypeFromTypeNode(annotated), nameStr); } } return undefined; } } return isInJSFile(decl) ? undefined : getTypeOfExpression(binaryExpression.left); } case AssignmentDeclarationKind.ExportsProperty: case AssignmentDeclarationKind.Prototype: case AssignmentDeclarationKind.PrototypeProperty: case AssignmentDeclarationKind.ModuleExports: let valueDeclaration: Declaration | undefined; if (kind !== AssignmentDeclarationKind.ModuleExports) { valueDeclaration = canHaveSymbol(binaryExpression.left) ? binaryExpression.left.symbol?.valueDeclaration : undefined; } valueDeclaration ||= binaryExpression.symbol?.valueDeclaration; const annotated = valueDeclaration && getEffectiveTypeAnnotationNode(valueDeclaration); return annotated ? getTypeFromTypeNode(annotated) : undefined; case AssignmentDeclarationKind.ObjectDefinePropertyValue: case AssignmentDeclarationKind.ObjectDefinePropertyExports: case AssignmentDeclarationKind.ObjectDefinePrototypeProperty: return Debug.fail("Does not apply"); default: return Debug.assertNever(kind); } } function isPossiblyAliasedThisProperty(declaration: BinaryExpression, kind = getAssignmentDeclarationKind(declaration)) { if (kind === AssignmentDeclarationKind.ThisProperty) { return true; } if (!isInJSFile(declaration) || kind !== AssignmentDeclarationKind.Property || !isIdentifier((declaration.left as AccessExpression).expression)) { return false; } const name = ((declaration.left as AccessExpression).expression as Identifier).escapedText; const symbol = resolveName(declaration.left, name, SymbolFlags.Value, undefined, undefined, /*isUse*/ true, /*excludeGlobals*/ true); return isThisInitializedDeclaration(symbol?.valueDeclaration); } function getContextualTypeForThisPropertyAssignment(binaryExpression: BinaryExpression): Type | undefined { if (!binaryExpression.symbol) return getTypeOfExpression(binaryExpression.left); if (binaryExpression.symbol.valueDeclaration) { const annotated = getEffectiveTypeAnnotationNode(binaryExpression.symbol.valueDeclaration); if (annotated) { const type = getTypeFromTypeNode(annotated); if (type) { return type; } } } const thisAccess = cast(binaryExpression.left, isAccessExpression); if (!isObjectLiteralMethod(getThisContainer(thisAccess.expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false))) { return undefined; } const thisType = checkThisExpression(thisAccess.expression); const nameStr = getElementOrPropertyAccessName(thisAccess); return nameStr !== undefined && getTypeOfPropertyOfContextualType(thisType, nameStr) || undefined; } function isCircularMappedProperty(symbol: Symbol) { return !!(getCheckFlags(symbol) & CheckFlags.Mapped && !(symbol as MappedSymbol).links.type && findResolutionCycleStartIndex(symbol, TypeSystemPropertyName.Type) >= 0); } function getTypeOfPropertyOfContextualType(type: Type, name: __String, nameType?: Type) { return mapType(type, t => { if (isGenericMappedType(t) && !t.declaration.nameType) { const constraint = getConstraintTypeFromMappedType(t); const constraintOfConstraint = getBaseConstraintOfType(constraint) || constraint; const propertyNameType = nameType || getStringLiteralType(unescapeLeadingUnderscores(name)); if (isTypeAssignableTo(propertyNameType, constraintOfConstraint)) { return substituteIndexedMappedType(t, propertyNameType); } } else if (t.flags & TypeFlags.StructuredType) { const prop = getPropertyOfType(t, name); if (prop) { return isCircularMappedProperty(prop) ? undefined : getTypeOfSymbol(prop); } if (isTupleType(t) && isNumericLiteralName(name) && +name >= 0) { const restType = getElementTypeOfSliceOfTupleType(t, t.target.fixedLength, /*endSkipCount*/ 0, /*writing*/ false, /*noReductions*/ true); if (restType) { return restType; } } return findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType || getStringLiteralType(unescapeLeadingUnderscores(name)))?.type; } return undefined; }, /*noReductions*/ true); } // In an object literal contextually typed by a type T, the contextual type of a property assignment is the type of // the matching property in T, if one exists. Otherwise, it is the type of the numeric index signature in T, if one // exists. Otherwise, it is the type of the string index signature in T, if one exists. function getContextualTypeForObjectLiteralMethod(node: MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { Debug.assert(isObjectLiteralMethod(node)); if (node.flags & NodeFlags.InWithStatement) { // We cannot answer semantic questions within a with block, do not proceed any further return undefined; } return getContextualTypeForObjectLiteralElement(node, contextFlags); } function getContextualTypeForObjectLiteralElement(element: ObjectLiteralElementLike, contextFlags: ContextFlags | undefined) { const objectLiteral = element.parent as ObjectLiteralExpression; const propertyAssignmentType = isPropertyAssignment(element) && getContextualTypeForVariableLikeDeclaration(element, contextFlags); if (propertyAssignmentType) { return propertyAssignmentType; } const type = getApparentTypeOfContextualType(objectLiteral, contextFlags); if (type) { if (hasBindableName(element)) { // For a (non-symbol) computed property, there is no reason to look up the name // in the type. It will just be "__computed", which does not appear in any // SymbolTable. const symbol = getSymbolOfDeclaration(element); return getTypeOfPropertyOfContextualType(type, symbol.escapedName, getSymbolLinks(symbol).nameType); } if (element.name) { const nameType = getLiteralTypeFromPropertyName(element.name); // We avoid calling getApplicableIndexInfo here because it performs potentially expensive intersection reduction. return mapType(type, t => findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType)?.type, /*noReductions*/ true); } } return undefined; } // In an array literal contextually typed by a type T, the contextual type of an element expression at index N is // the type of the property with the numeric name N in T, if one exists. Otherwise, if T has a numeric index signature, // it is the type of the numeric index signature in T. Otherwise, in ES6 and higher, the contextual type is the iterated // type of T. function getContextualTypeForElementExpression(arrayContextualType: Type | undefined, index: number): Type | undefined { return arrayContextualType && ( index >= 0 && getTypeOfPropertyOfContextualType(arrayContextualType, "" + index as __String) || mapType(arrayContextualType, t => isTupleType(t) ? getElementTypeOfSliceOfTupleType(t, 0, /*endSkipCount*/ 0, /*writing*/ false, /*noReductions*/ true) : getIteratedTypeOrElementType(IterationUse.Element, t, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false), /*noReductions*/ true)); } // In a contextually typed conditional expression, the true/false expressions are contextually typed by the same type. function getContextualTypeForConditionalOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { const conditional = node.parent as ConditionalExpression; return node === conditional.whenTrue || node === conditional.whenFalse ? getContextualType(conditional, contextFlags) : undefined; } function getContextualTypeForChildJsxExpression(node: JsxElement, child: JsxChild, contextFlags: ContextFlags | undefined) { const attributesType = getApparentTypeOfContextualType(node.openingElement.tagName, contextFlags); // JSX expression is in children of JSX Element, we will look for an "children" attribute (we get the name from JSX.ElementAttributesProperty) const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); if (!(attributesType && !isTypeAny(attributesType) && jsxChildrenPropertyName && jsxChildrenPropertyName !== "")) { return undefined; } const realChildren = getSemanticJsxChildren(node.children); const childIndex = realChildren.indexOf(child); const childFieldType = getTypeOfPropertyOfContextualType(attributesType, jsxChildrenPropertyName); return childFieldType && (realChildren.length === 1 ? childFieldType : mapType(childFieldType, t => { if (isArrayLikeType(t)) { return getIndexedAccessType(t, getNumberLiteralType(childIndex)); } else { return t; } }, /*noReductions*/ true)); } function getContextualTypeForJsxExpression(node: JsxExpression, contextFlags: ContextFlags | undefined): Type | undefined { const exprParent = node.parent; return isJsxAttributeLike(exprParent) ? getContextualType(node, contextFlags) : isJsxElement(exprParent) ? getContextualTypeForChildJsxExpression(exprParent, node, contextFlags) : undefined; } function getContextualTypeForJsxAttribute(attribute: JsxAttribute | JsxSpreadAttribute, contextFlags: ContextFlags | undefined): Type | undefined { // When we trying to resolve JsxOpeningLikeElement as a stateless function element, we will already give its attributes a contextual type // which is a type of the parameter of the signature we are trying out. // If there is no contextual type (e.g. we are trying to resolve stateful component), get attributes type from resolving element's tagName if (isJsxAttribute(attribute)) { const attributesType = getApparentTypeOfContextualType(attribute.parent, contextFlags); if (!attributesType || isTypeAny(attributesType)) { return undefined; } return getTypeOfPropertyOfContextualType(attributesType, attribute.name.escapedText); } else { return getContextualType(attribute.parent, contextFlags); } } // Return true if the given expression is possibly a discriminant value. We limit the kinds of // expressions we check to those that don't depend on their contextual type in order not to cause // recursive (and possibly infinite) invocations of getContextualType. function isPossiblyDiscriminantValue(node: Expression): boolean { switch (node.kind) { case SyntaxKind.StringLiteral: case SyntaxKind.NumericLiteral: case SyntaxKind.BigIntLiteral: case SyntaxKind.NoSubstitutionTemplateLiteral: case SyntaxKind.TrueKeyword: case SyntaxKind.FalseKeyword: case SyntaxKind.NullKeyword: case SyntaxKind.Identifier: case SyntaxKind.UndefinedKeyword: return true; case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ParenthesizedExpression: return isPossiblyDiscriminantValue((node as PropertyAccessExpression | ParenthesizedExpression).expression); case SyntaxKind.JsxExpression: return !(node as JsxExpression).expression || isPossiblyDiscriminantValue((node as JsxExpression).expression!); } return false; } function discriminateContextualTypeByObjectMembers(node: ObjectLiteralExpression, contextualType: UnionType) { return getMatchingUnionConstituentForObjectLiteral(contextualType, node) || discriminateTypeByDiscriminableItems(contextualType, concatenate( map( filter(node.properties, p => !!p.symbol && p.kind === SyntaxKind.PropertyAssignment && isPossiblyDiscriminantValue(p.initializer) && isDiscriminantProperty(contextualType, p.symbol.escapedName)), prop => ([() => getContextFreeTypeOfExpression((prop as PropertyAssignment).initializer), prop.symbol.escapedName] as [() => Type, __String]) ), map( filter(getPropertiesOfType(contextualType), s => !!(s.flags & SymbolFlags.Optional) && !!node?.symbol?.members && !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName)), s => [() => undefinedType, s.escapedName] as [() => Type, __String] ) ), isTypeAssignableTo, contextualType ); } function discriminateContextualTypeByJSXAttributes(node: JsxAttributes, contextualType: UnionType) { return discriminateTypeByDiscriminableItems(contextualType, concatenate( map( filter(node.properties, p => !!p.symbol && p.kind === SyntaxKind.JsxAttribute && isDiscriminantProperty(contextualType, p.symbol.escapedName) && (!p.initializer || isPossiblyDiscriminantValue(p.initializer))), prop => ([!(prop as JsxAttribute).initializer ? (() => trueType) : (() => getContextFreeTypeOfExpression((prop as JsxAttribute).initializer!)), prop.symbol.escapedName] as [() => Type, __String]) ), map( filter(getPropertiesOfType(contextualType), s => !!(s.flags & SymbolFlags.Optional) && !!node?.symbol?.members && !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName)), s => [() => undefinedType, s.escapedName] as [() => Type, __String] ) ), isTypeAssignableTo, contextualType ); } // Return the contextual type for a given expression node. During overload resolution, a contextual type may temporarily // be "pushed" onto a node using the contextualType property. function getApparentTypeOfContextualType(node: Expression | MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { const contextualType = isObjectLiteralMethod(node) ? getContextualTypeForObjectLiteralMethod(node, contextFlags) : getContextualType(node, contextFlags); const instantiatedType = instantiateContextualType(contextualType, node, contextFlags); if (instantiatedType && !(contextFlags && contextFlags & ContextFlags.NoConstraints && instantiatedType.flags & TypeFlags.TypeVariable)) { const apparentType = mapType(instantiatedType, getApparentType, /*noReductions*/ true); return apparentType.flags & TypeFlags.Union && isObjectLiteralExpression(node) ? discriminateContextualTypeByObjectMembers(node, apparentType as UnionType) : apparentType.flags & TypeFlags.Union && isJsxAttributes(node) ? discriminateContextualTypeByJSXAttributes(node, apparentType as UnionType) : apparentType; } } // If the given contextual type contains instantiable types and if a mapper representing // return type inferences is available, instantiate those types using that mapper. function instantiateContextualType(contextualType: Type | undefined, node: Node, contextFlags: ContextFlags | undefined): Type | undefined { if (contextualType && maybeTypeOfKind(contextualType, TypeFlags.Instantiable)) { const inferenceContext = getInferenceContext(node); // If no inferences have been made, and none of the type parameters for which we are inferring // specify default types, nothing is gained from instantiating as type parameters would just be // replaced with their constraints similar to the apparent type. if (inferenceContext && contextFlags! & ContextFlags.Signature && some(inferenceContext.inferences, hasInferenceCandidatesOrDefault)) { // For contextual signatures we incorporate all inferences made so far, e.g. from return // types as well as arguments to the left in a function call. return instantiateInstantiableTypes(contextualType, inferenceContext.nonFixingMapper); } if (inferenceContext?.returnMapper) { // For other purposes (e.g. determining whether to produce literal types) we only // incorporate inferences made from the return type in a function call. We remove // the 'boolean' type from the contextual type such that contextually typed boolean // literals actually end up widening to 'boolean' (see #48363). const type = instantiateInstantiableTypes(contextualType, inferenceContext.returnMapper); return type.flags & TypeFlags.Union && containsType((type as UnionType).types, regularFalseType) && containsType((type as UnionType).types, regularTrueType) ? filterType(type, t => t !== regularFalseType && t !== regularTrueType) : type; } } return contextualType; } // This function is similar to instantiateType, except that (a) it only instantiates types that // are classified as instantiable (i.e. it doesn't instantiate object types), and (b) it performs // no reductions on instantiated union types. function instantiateInstantiableTypes(type: Type, mapper: TypeMapper): Type { if (type.flags & TypeFlags.Instantiable) { return instantiateType(type, mapper); } if (type.flags & TypeFlags.Union) { return getUnionType(map((type as UnionType).types, t => instantiateInstantiableTypes(t, mapper)), UnionReduction.None); } if (type.flags & TypeFlags.Intersection) { return getIntersectionType(map((type as IntersectionType).types, t => instantiateInstantiableTypes(t, mapper))); } return type; } /** * Whoa! Do you really want to use this function? * * Unless you're trying to get the *non-apparent* type for a * value-literal type or you're authoring relevant portions of this algorithm, * you probably meant to use 'getApparentTypeOfContextualType'. * Otherwise this may not be very useful. * * In cases where you *are* working on this function, you should understand * when it is appropriate to use 'getContextualType' and 'getApparentTypeOfContextualType'. * * - Use 'getContextualType' when you are simply going to propagate the result to the expression. * - Use 'getApparentTypeOfContextualType' when you're going to need the members of the type. * * @param node the expression whose contextual type will be returned. * @returns the contextual type of an expression. */ function getContextualType(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { if (node.flags & NodeFlags.InWithStatement) { // We cannot answer semantic questions within a with block, do not proceed any further return undefined; } // Cached contextual types are obtained with no ContextFlags, so we can only consult them for // requests with no ContextFlags. const index = findContextualNode(node, /*includeCaches*/ !contextFlags); if (index >= 0) { return contextualTypes[index]; } const { parent } = node; switch (parent.kind) { case SyntaxKind.VariableDeclaration: case SyntaxKind.Parameter: case SyntaxKind.PropertyDeclaration: case SyntaxKind.PropertySignature: case SyntaxKind.BindingElement: return getContextualTypeForInitializerExpression(node, contextFlags); case SyntaxKind.ArrowFunction: case SyntaxKind.ReturnStatement: return getContextualTypeForReturnExpression(node, contextFlags); case SyntaxKind.YieldExpression: return getContextualTypeForYieldOperand(parent as YieldExpression, contextFlags); case SyntaxKind.AwaitExpression: return getContextualTypeForAwaitOperand(parent as AwaitExpression, contextFlags); case SyntaxKind.CallExpression: case SyntaxKind.NewExpression: return getContextualTypeForArgument(parent as CallExpression | NewExpression | Decorator, node); case SyntaxKind.Decorator: return getContextualTypeForDecorator(parent as Decorator); case SyntaxKind.TypeAssertionExpression: case SyntaxKind.AsExpression: return isConstTypeReference((parent as AssertionExpression).type) ? getContextualType(parent as AssertionExpression, contextFlags) : getTypeFromTypeNode((parent as AssertionExpression).type); case SyntaxKind.BinaryExpression: return getContextualTypeForBinaryOperand(node, contextFlags); case SyntaxKind.PropertyAssignment: case SyntaxKind.ShorthandPropertyAssignment: return getContextualTypeForObjectLiteralElement(parent as PropertyAssignment | ShorthandPropertyAssignment, contextFlags); case SyntaxKind.SpreadAssignment: return getContextualType(parent.parent as ObjectLiteralExpression, contextFlags); case SyntaxKind.ArrayLiteralExpression: { const arrayLiteral = parent as ArrayLiteralExpression; const type = getApparentTypeOfContextualType(arrayLiteral, contextFlags); // The index of an array literal element doesn't necessarily line up with the index of the corresponding // element in a contextual tuple type when there are preceding spread elements in the array literal. For // this reason we only pass indices for elements that precede the first spread element. const spreadIndex = getNodeLinks(arrayLiteral).firstSpreadIndex ??= findIndex(arrayLiteral.elements, isSpreadElement); const elementIndex = indexOfNode(arrayLiteral.elements, node); return getContextualTypeForElementExpression(type, spreadIndex < 0 || elementIndex < spreadIndex ? elementIndex : -1); } case SyntaxKind.ConditionalExpression: return getContextualTypeForConditionalOperand(node, contextFlags); case SyntaxKind.TemplateSpan: Debug.assert(parent.parent.kind === SyntaxKind.TemplateExpression); return getContextualTypeForSubstitutionExpression(parent.parent as TemplateExpression, node); case SyntaxKind.ParenthesizedExpression: { if (isInJSFile(parent)) { if (isJSDocSatisfiesExpression(parent)) { return getTypeFromTypeNode(getJSDocSatisfiesExpressionType(parent)); } // Like in `checkParenthesizedExpression`, an `/** @type {xyz} */` comment before a parenthesized expression acts as a type cast. const typeTag = getJSDocTypeTag(parent); if (typeTag && !isConstTypeReference(typeTag.typeExpression.type)) { return getTypeFromTypeNode(typeTag.typeExpression.type); } } return getContextualType(parent as ParenthesizedExpression, contextFlags); } case SyntaxKind.NonNullExpression: return getContextualType(parent as NonNullExpression, contextFlags); case SyntaxKind.SatisfiesExpression: return getTypeFromTypeNode((parent as SatisfiesExpression).type); case SyntaxKind.ExportAssignment: return tryGetTypeFromEffectiveTypeNode(parent as ExportAssignment); case SyntaxKind.JsxExpression: return getContextualTypeForJsxExpression(parent as JsxExpression, contextFlags); case SyntaxKind.JsxAttribute: case SyntaxKind.JsxSpreadAttribute: return getContextualTypeForJsxAttribute(parent as JsxAttribute | JsxSpreadAttribute, contextFlags); case SyntaxKind.JsxOpeningElement: case SyntaxKind.JsxSelfClosingElement: return getContextualJsxElementAttributesType(parent as JsxOpeningLikeElement, contextFlags); } return undefined; } function pushCachedContextualType(node: Expression) { pushContextualType(node, getContextualType(node, /*contextFlags*/ undefined), /*isCache*/ true); } function pushContextualType(node: Expression, type: Type | undefined, isCache: boolean) { contextualTypeNodes[contextualTypeCount] = node; contextualTypes[contextualTypeCount] = type; contextualIsCache[contextualTypeCount] = isCache; contextualTypeCount++; } function popContextualType() { contextualTypeCount--; } function findContextualNode(node: Node, includeCaches: boolean) { for (let i = contextualTypeCount - 1; i >= 0; i--) { if (node === contextualTypeNodes[i] && (includeCaches || !contextualIsCache[i])) { return i; } } return -1; } function pushInferenceContext(node: Node, inferenceContext: InferenceContext | undefined) { inferenceContextNodes[inferenceContextCount] = node; inferenceContexts[inferenceContextCount] = inferenceContext; inferenceContextCount++; } function popInferenceContext() { inferenceContextCount--; } function getInferenceContext(node: Node) { for (let i = inferenceContextCount - 1; i >= 0; i--) { if (isNodeDescendantOf(node, inferenceContextNodes[i])) { return inferenceContexts[i]; } } } function getContextualJsxElementAttributesType(node: JsxOpeningLikeElement, contextFlags: ContextFlags | undefined) { if (isJsxOpeningElement(node) && contextFlags !== ContextFlags.Completions) { const index = findContextualNode(node.parent, /*includeCaches*/ !contextFlags); if (index >= 0) { // Contextually applied type is moved from attributes up to the outer jsx attributes so when walking up from the children they get hit // _However_ to hit them from the _attributes_ we must look for them here; otherwise we'll used the declared type // (as below) instead! return contextualTypes[index]; } } return getContextualTypeForArgumentAtIndex(node, 0); } function getEffectiveFirstArgumentForJsxSignature(signature: Signature, node: JsxOpeningLikeElement) { return getJsxReferenceKind(node) !== JsxReferenceKind.Component ? getJsxPropsTypeFromCallSignature(signature, node) : getJsxPropsTypeFromClassType(signature, node); } function getJsxPropsTypeFromCallSignature(sig: Signature, context: JsxOpeningLikeElement) { let propsType = getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType); propsType = getJsxManagedAttributesFromLocatedAttributes(context, getJsxNamespaceAt(context), propsType); const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); if (!isErrorType(intrinsicAttribs)) { propsType = intersectTypes(intrinsicAttribs, propsType); } return propsType; } function getJsxPropsTypeForSignatureFromMember(sig: Signature, forcedLookupLocation: __String) { if (sig.compositeSignatures) { // JSX Elements using the legacy `props`-field based lookup (eg, react class components) need to treat the `props` member as an input // instead of an output position when resolving the signature. We need to go back to the input signatures of the composite signature, // get the type of `props` on each return type individually, and then _intersect them_, rather than union them (as would normally occur // for a union signature). It's an unfortunate quirk of looking in the output of the signature for the type we want to use for the input. // The default behavior of `getTypeOfFirstParameterOfSignatureWithFallback` when no `props` member name is defined is much more sane. const results: Type[] = []; for (const signature of sig.compositeSignatures) { const instance = getReturnTypeOfSignature(signature); if (isTypeAny(instance)) { return instance; } const propType = getTypeOfPropertyOfType(instance, forcedLookupLocation); if (!propType) { return; } results.push(propType); } return getIntersectionType(results); // Same result for both union and intersection signatures } const instanceType = getReturnTypeOfSignature(sig); return isTypeAny(instanceType) ? instanceType : getTypeOfPropertyOfType(instanceType, forcedLookupLocation); } function getStaticTypeOfReferencedJsxConstructor(context: JsxOpeningLikeElement) { if (isJsxIntrinsicIdentifier(context.tagName)) { const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(context); const fakeSignature = createSignatureForJSXIntrinsic(context, result); return getOrCreateTypeFromSignature(fakeSignature); } const tagType = checkExpressionCached(context.tagName); if (tagType.flags & TypeFlags.StringLiteral) { const result = getIntrinsicAttributesTypeFromStringLiteralType(tagType as StringLiteralType, context); if (!result) { return errorType; } const fakeSignature = createSignatureForJSXIntrinsic(context, result); return getOrCreateTypeFromSignature(fakeSignature); } return tagType; } function getJsxManagedAttributesFromLocatedAttributes(context: JsxOpeningLikeElement, ns: Symbol, attributesType: Type) { const managedSym = getJsxLibraryManagedAttributes(ns); if (managedSym) { const declaredManagedType = getDeclaredTypeOfSymbol(managedSym); // fetches interface type, or initializes symbol links type parmaeters const ctorType = getStaticTypeOfReferencedJsxConstructor(context); if (managedSym.flags & SymbolFlags.TypeAlias) { const params = getSymbolLinks(managedSym).typeParameters; if (length(params) >= 2) { const args = fillMissingTypeArguments([ctorType, attributesType], params, 2, isInJSFile(context)); return getTypeAliasInstantiation(managedSym, args); } } if (length((declaredManagedType as GenericType).typeParameters) >= 2) { const args = fillMissingTypeArguments([ctorType, attributesType], (declaredManagedType as GenericType).typeParameters, 2, isInJSFile(context)); return createTypeReference((declaredManagedType as GenericType), args); } } return attributesType; } function getJsxPropsTypeFromClassType(sig: Signature, context: JsxOpeningLikeElement) { const ns = getJsxNamespaceAt(context); const forcedLookupLocation = getJsxElementPropertiesName(ns); let attributesType = forcedLookupLocation === undefined // If there is no type ElementAttributesProperty, return the type of the first parameter of the signature, which should be the props type ? getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType) : forcedLookupLocation === "" // If there is no e.g. 'props' member in ElementAttributesProperty, use the element class type instead ? getReturnTypeOfSignature(sig) // Otherwise get the type of the property on the signature return type : getJsxPropsTypeForSignatureFromMember(sig, forcedLookupLocation); if (!attributesType) { // There is no property named 'props' on this instance type if (!!forcedLookupLocation && !!length(context.attributes.properties)) { error(context, Diagnostics.JSX_element_class_does_not_support_attributes_because_it_does_not_have_a_0_property, unescapeLeadingUnderscores(forcedLookupLocation)); } return unknownType; } attributesType = getJsxManagedAttributesFromLocatedAttributes(context, ns, attributesType); if (isTypeAny(attributesType)) { // Props is of type 'any' or unknown return attributesType; } else { // Normal case -- add in IntrinsicClassElements and IntrinsicElements let apparentAttributesType = attributesType; const intrinsicClassAttribs = getJsxType(JsxNames.IntrinsicClassAttributes, context); if (!isErrorType(intrinsicClassAttribs)) { const typeParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(intrinsicClassAttribs.symbol); const hostClassType = getReturnTypeOfSignature(sig); let libraryManagedAttributeType: Type; if (typeParams) { // apply JSX.IntrinsicClassElements const inferredArgs = fillMissingTypeArguments([hostClassType], typeParams, getMinTypeArgumentCount(typeParams), isInJSFile(context)); libraryManagedAttributeType = instantiateType(intrinsicClassAttribs, createTypeMapper(typeParams, inferredArgs)); } // or JSX.IntrinsicClassElements has no generics. else libraryManagedAttributeType = intrinsicClassAttribs; apparentAttributesType = intersectTypes(libraryManagedAttributeType, apparentAttributesType); } const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); if (!isErrorType(intrinsicAttribs)) { apparentAttributesType = intersectTypes(intrinsicAttribs, apparentAttributesType); } return apparentAttributesType; } } function getIntersectedSignatures(signatures: readonly Signature[]) { return getStrictOptionValue(compilerOptions, "noImplicitAny") ? reduceLeft( signatures, (left: Signature | undefined, right) => left === right || !left ? left : compareTypeParametersIdentical(left.typeParameters, right!.typeParameters) ? combineSignaturesOfIntersectionMembers(left, right!) : undefined) : undefined; } function combineIntersectionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { if (!left || !right) { return left || right; } // A signature `this` type might be a read or a write position... It's very possible that it should be invariant // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be // pessimistic when contextual typing, for now, we'll union the `this` types. const thisType = getUnionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); return createSymbolWithType(left, thisType); } function combineIntersectionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { const leftCount = getParameterCount(left); const rightCount = getParameterCount(right); const longest = leftCount >= rightCount ? left : right; const shorter = longest === left ? right : left; const longestCount = longest === left ? leftCount : rightCount; const eitherHasEffectiveRest = (hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right)); const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); for (let i = 0; i < longestCount; i++) { let longestParamType = tryGetTypeAtPosition(longest, i)!; if (longest === right) { longestParamType = instantiateType(longestParamType, mapper); } let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; if (shorter === right) { shorterParamType = instantiateType(shorterParamType, mapper); } const unionParamType = getUnionType([longestParamType, shorterParamType]); const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); const paramName = leftName === rightName ? leftName : !leftName ? rightName : !rightName ? leftName : undefined; const paramSymbol = createSymbol( SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), paramName || `arg${i}` as __String ); paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; params[i] = paramSymbol; } if (needsExtraRestElement) { const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String); restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); if (shorter === right) { restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); } params[longestCount] = restParamSymbol; } return params; } function combineSignaturesOfIntersectionMembers(left: Signature, right: Signature): Signature { const typeParams = left.typeParameters || right.typeParameters; let paramMapper: TypeMapper | undefined; if (left.typeParameters && right.typeParameters) { paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); // We just use the type parameter defaults from the first signature } const declaration = left.declaration; const params = combineIntersectionParameters(left, right, paramMapper); const thisParam = combineIntersectionThisParam(left.thisParameter, right.thisParameter, paramMapper); const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); const result = createSignature( declaration, typeParams, thisParam, params, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, minArgCount, (left.flags | right.flags) & SignatureFlags.PropagatingFlags ); result.compositeKind = TypeFlags.Intersection; result.compositeSignatures = concatenate(left.compositeKind === TypeFlags.Intersection && left.compositeSignatures || [left], [right]); if (paramMapper) { result.mapper = left.compositeKind === TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; } return result; } // If the given type is an object or union type with a single signature, and if that signature has at // least as many parameters as the given function, return the signature. Otherwise return undefined. function getContextualCallSignature(type: Type, node: SignatureDeclaration): Signature | undefined { const signatures = getSignaturesOfType(type, SignatureKind.Call); const applicableByArity = filter(signatures, s => !isAritySmaller(s, node)); return applicableByArity.length === 1 ? applicableByArity[0] : getIntersectedSignatures(applicableByArity); } /** If the contextual signature has fewer parameters than the function expression, do not use it */ function isAritySmaller(signature: Signature, target: SignatureDeclaration) { let targetParameterCount = 0; for (; targetParameterCount < target.parameters.length; targetParameterCount++) { const param = target.parameters[targetParameterCount]; if (param.initializer || param.questionToken || param.dotDotDotToken || isJSDocOptionalParameter(param)) { break; } } if (target.parameters.length && parameterIsThisKeyword(target.parameters[0])) { targetParameterCount--; } return !hasEffectiveRestParameter(signature) && getParameterCount(signature) < targetParameterCount; } function getContextualSignatureForFunctionLikeDeclaration(node: FunctionLikeDeclaration): Signature | undefined { // Only function expressions, arrow functions, and object literal methods are contextually typed. return isFunctionExpressionOrArrowFunction(node) || isObjectLiteralMethod(node) ? getContextualSignature(node as FunctionExpression) : undefined; } // Return the contextual signature for a given expression node. A contextual type provides a // contextual signature if it has a single call signature and if that call signature is non-generic. // If the contextual type is a union type, get the signature from each type possible and if they are // all identical ignoring their return type, the result is same signature but with return type as // union type of return types from these signatures function getContextualSignature(node: FunctionExpression | ArrowFunction | MethodDeclaration): Signature | undefined { Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); const typeTagSignature = getSignatureOfTypeTag(node); if (typeTagSignature) { return typeTagSignature; } const type = getApparentTypeOfContextualType(node, ContextFlags.Signature); if (!type) { return undefined; } if (!(type.flags & TypeFlags.Union)) { return getContextualCallSignature(type, node); } let signatureList: Signature[] | undefined; const types = (type as UnionType).types; for (const current of types) { const signature = getContextualCallSignature(current, node); if (signature) { if (!signatureList) { // This signature will contribute to contextual union signature signatureList = [signature]; } else if (!compareSignaturesIdentical(signatureList[0], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ true, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { // Signatures aren't identical, do not use return undefined; } else { // Use this signature for contextual union signature signatureList.push(signature); } } } // Result is union of signatures collected (return type is union of return types of this signature set) if (signatureList) { return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList); } } function checkSpreadExpression(node: SpreadElement, checkMode?: CheckMode): Type { if (languageVersion < ScriptTarget.ES2015) { checkExternalEmitHelpers(node, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); } const arrayOrIterableType = checkExpression(node.expression, checkMode); return checkIteratedTypeOrElementType(IterationUse.Spread, arrayOrIterableType, undefinedType, node.expression); } function checkSyntheticExpression(node: SyntheticExpression): Type { return node.isSpread ? getIndexedAccessType(node.type, numberType) : node.type; } function hasDefaultValue(node: BindingElement | Expression): boolean { return (node.kind === SyntaxKind.BindingElement && !!(node as BindingElement).initializer) || (node.kind === SyntaxKind.BinaryExpression && (node as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken); } function checkArrayLiteral(node: ArrayLiteralExpression, checkMode: CheckMode | undefined, forceTuple: boolean | undefined): Type { const elements = node.elements; const elementCount = elements.length; const elementTypes: Type[] = []; const elementFlags: ElementFlags[] = []; pushCachedContextualType(node); const inDestructuringPattern = isAssignmentTarget(node); const inConstContext = isConstContext(node); const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); const inTupleContext = !!contextualType && someType(contextualType, isTupleLikeType); let hasOmittedExpression = false; for (let i = 0; i < elementCount; i++) { const e = elements[i]; if (e.kind === SyntaxKind.SpreadElement) { if (languageVersion < ScriptTarget.ES2015) { checkExternalEmitHelpers(e, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); } const spreadType = checkExpression((e as SpreadElement).expression, checkMode, forceTuple); if (isArrayLikeType(spreadType)) { elementTypes.push(spreadType); elementFlags.push(ElementFlags.Variadic); } else if (inDestructuringPattern) { // Given the following situation: // var c: {}; // [...c] = ["", 0]; // // c is represented in the tree as a spread element in an array literal. // But c really functions as a rest element, and its purpose is to provide // a contextual type for the right hand side of the assignment. Therefore, // instead of calling checkExpression on "...c", which will give an error // if c is not iterable/array-like, we need to act as if we are trying to // get the contextual element type from it. So we do something similar to // getContextualTypeForElementExpression, which will crucially not error // if there is no index type / iterated type. const restElementType = getIndexTypeOfType(spreadType, numberType) || getIteratedTypeOrElementType(IterationUse.Destructuring, spreadType, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false) || unknownType; elementTypes.push(restElementType); elementFlags.push(ElementFlags.Rest); } else { elementTypes.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, (e as SpreadElement).expression)); elementFlags.push(ElementFlags.Rest); } } else if (exactOptionalPropertyTypes && e.kind === SyntaxKind.OmittedExpression) { hasOmittedExpression = true; elementTypes.push(undefinedOrMissingType); elementFlags.push(ElementFlags.Optional); } else { const type = checkExpressionForMutableLocation(e, checkMode, forceTuple); elementTypes.push(addOptionality(type, /*isProperty*/ true, hasOmittedExpression)); elementFlags.push(hasOmittedExpression ? ElementFlags.Optional : ElementFlags.Required); if (inTupleContext && checkMode && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(e)) { const inferenceContext = getInferenceContext(node); Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context addIntraExpressionInferenceSite(inferenceContext, e, type); } } } popContextualType(); if (inDestructuringPattern) { return createTupleType(elementTypes, elementFlags); } if (forceTuple || inConstContext || inTupleContext) { return createArrayLiteralType(createTupleType(elementTypes, elementFlags, /*readonly*/ inConstContext)); } return createArrayLiteralType(createArrayType(elementTypes.length ? getUnionType(sameMap(elementTypes, (t, i) => elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessTypeOrUndefined(t, numberType) || anyType : t), UnionReduction.Subtype) : strictNullChecks ? implicitNeverType : undefinedWideningType, inConstContext)); } function createArrayLiteralType(type: Type) { if (!(getObjectFlags(type) & ObjectFlags.Reference)) { return type; } let literalType = (type as TypeReference).literalType; if (!literalType) { literalType = (type as TypeReference).literalType = cloneTypeReference(type as TypeReference); literalType.objectFlags |= ObjectFlags.ArrayLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; } return literalType; } function isNumericName(name: DeclarationName): boolean { switch (name.kind) { case SyntaxKind.ComputedPropertyName: return isNumericComputedName(name); case SyntaxKind.Identifier: return isNumericLiteralName(name.escapedText); case SyntaxKind.NumericLiteral: case SyntaxKind.StringLiteral: return isNumericLiteralName(name.text); default: return false; } } function isNumericComputedName(name: ComputedPropertyName): boolean { // It seems odd to consider an expression of type Any to result in a numeric name, // but this behavior is consistent with checkIndexedAccess return isTypeAssignableToKind(checkComputedPropertyName(name), TypeFlags.NumberLike); } function checkComputedPropertyName(node: ComputedPropertyName): Type { const links = getNodeLinks(node.expression); if (!links.resolvedType) { if ((isTypeLiteralNode(node.parent.parent) || isClassLike(node.parent.parent) || isInterfaceDeclaration(node.parent.parent)) && isBinaryExpression(node.expression) && node.expression.operatorToken.kind === SyntaxKind.InKeyword && node.parent.kind !== SyntaxKind.GetAccessor && node.parent.kind !== SyntaxKind.SetAccessor) { return links.resolvedType = errorType; } links.resolvedType = checkExpression(node.expression); // The computed property name of a non-static class field within a loop must be stored in a block-scoped binding. // (It needs to be bound at class evaluation time.) if (isPropertyDeclaration(node.parent) && !hasStaticModifier(node.parent) && isClassExpression(node.parent.parent)) { const container = getEnclosingBlockScopeContainer(node.parent.parent); const enclosingIterationStatement = getEnclosingIterationStatement(container); if (enclosingIterationStatement) { // The computed field name will use a block scoped binding which can be unique for each iteration of the loop. getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; // The generated variable which stores the computed field name must be block-scoped. getNodeLinks(node).flags |= NodeCheckFlags.BlockScopedBindingInLoop; // The generated variable which stores the class must be block-scoped. getNodeLinks(node.parent.parent).flags |= NodeCheckFlags.BlockScopedBindingInLoop; } } // This will allow types number, string, symbol or any. It will also allow enums, the unknown // type, and any union of these types (like string | number). if (links.resolvedType.flags & TypeFlags.Nullable || !isTypeAssignableToKind(links.resolvedType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike) && !isTypeAssignableTo(links.resolvedType, stringNumberSymbolType)) { error(node, Diagnostics.A_computed_property_name_must_be_of_type_string_number_symbol_or_any); } } return links.resolvedType; } function isSymbolWithNumericName(symbol: Symbol) { const firstDecl = symbol.declarations?.[0]; return isNumericLiteralName(symbol.escapedName) || (firstDecl && isNamedDeclaration(firstDecl) && isNumericName(firstDecl.name)); } function isSymbolWithSymbolName(symbol: Symbol) { const firstDecl = symbol.declarations?.[0]; return isKnownSymbol(symbol) || (firstDecl && isNamedDeclaration(firstDecl) && isComputedPropertyName(firstDecl.name) && isTypeAssignableToKind(checkComputedPropertyName(firstDecl.name), TypeFlags.ESSymbol)); } function getObjectLiteralIndexInfo(node: ObjectLiteralExpression, offset: number, properties: Symbol[], keyType: Type): IndexInfo { const propTypes: Type[] = []; for (let i = offset; i < properties.length; i++) { const prop = properties[i]; if (keyType === stringType && !isSymbolWithSymbolName(prop) || keyType === numberType && isSymbolWithNumericName(prop) || keyType === esSymbolType && isSymbolWithSymbolName(prop)) { propTypes.push(getTypeOfSymbol(properties[i])); } } const unionType = propTypes.length ? getUnionType(propTypes, UnionReduction.Subtype) : undefinedType; return createIndexInfo(keyType, unionType, isConstContext(node)); } function getImmediateAliasedSymbol(symbol: Symbol): Symbol | undefined { Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); const links = getSymbolLinks(symbol); if (!links.immediateTarget) { const node = getDeclarationOfAliasSymbol(symbol); if (!node) return Debug.fail(); links.immediateTarget = getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true); } return links.immediateTarget; } function checkObjectLiteral(node: ObjectLiteralExpression, checkMode?: CheckMode): Type { const inDestructuringPattern = isAssignmentTarget(node); // Grammar checking checkGrammarObjectLiteralExpression(node, inDestructuringPattern); const allPropertiesTable = strictNullChecks ? createSymbolTable() : undefined; let propertiesTable = createSymbolTable(); let propertiesArray: Symbol[] = []; let spread: Type = emptyObjectType; pushCachedContextualType(node); const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); const contextualTypeHasPattern = contextualType && contextualType.pattern && (contextualType.pattern.kind === SyntaxKind.ObjectBindingPattern || contextualType.pattern.kind === SyntaxKind.ObjectLiteralExpression); const inConstContext = isConstContext(node); const checkFlags = inConstContext ? CheckFlags.Readonly : 0; const isInJavascript = isInJSFile(node) && !isInJsonFile(node); const enumTag = getJSDocEnumTag(node); const isJSObjectLiteral = !contextualType && isInJavascript && !enumTag; let objectFlags: ObjectFlags = freshObjectLiteralFlag; let patternWithComputedProperties = false; let hasComputedStringProperty = false; let hasComputedNumberProperty = false; let hasComputedSymbolProperty = false; // Spreads may cause an early bail; ensure computed names are always checked (this is cached) // As otherwise they may not be checked until exports for the type at this position are retrieved, // which may never occur. for (const elem of node.properties) { if (elem.name && isComputedPropertyName(elem.name)) { checkComputedPropertyName(elem.name); } } let offset = 0; for (const memberDecl of node.properties) { let member = getSymbolOfDeclaration(memberDecl); const computedNameType = memberDecl.name && memberDecl.name.kind === SyntaxKind.ComputedPropertyName ? checkComputedPropertyName(memberDecl.name) : undefined; if (memberDecl.kind === SyntaxKind.PropertyAssignment || memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment || isObjectLiteralMethod(memberDecl)) { let type = memberDecl.kind === SyntaxKind.PropertyAssignment ? checkPropertyAssignment(memberDecl, checkMode) : // avoid resolving the left side of the ShorthandPropertyAssignment outside of the destructuring // for error recovery purposes. For example, if a user wrote `{ a = 100 }` instead of `{ a: 100 }`. // we don't want to say "could not find 'a'". memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment ? checkExpressionForMutableLocation(!inDestructuringPattern && memberDecl.objectAssignmentInitializer ? memberDecl.objectAssignmentInitializer : memberDecl.name, checkMode) : checkObjectLiteralMethod(memberDecl, checkMode); if (isInJavascript) { const jsDocType = getTypeForDeclarationFromJSDocComment(memberDecl); if (jsDocType) { checkTypeAssignableTo(type, jsDocType, memberDecl); type = jsDocType; } else if (enumTag && enumTag.typeExpression) { checkTypeAssignableTo(type, getTypeFromTypeNode(enumTag.typeExpression), memberDecl); } } objectFlags |= getObjectFlags(type) & ObjectFlags.PropagatingFlags; const nameType = computedNameType && isTypeUsableAsPropertyName(computedNameType) ? computedNameType : undefined; const prop = nameType ? createSymbol(SymbolFlags.Property | member.flags, getPropertyNameFromType(nameType), checkFlags | CheckFlags.Late) : createSymbol(SymbolFlags.Property | member.flags, member.escapedName, checkFlags); if (nameType) { prop.links.nameType = nameType; } if (inDestructuringPattern) { // If object literal is an assignment pattern and if the assignment pattern specifies a default value // for the property, make the property optional. const isOptional = (memberDecl.kind === SyntaxKind.PropertyAssignment && hasDefaultValue(memberDecl.initializer)) || (memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment && memberDecl.objectAssignmentInitializer); if (isOptional) { prop.flags |= SymbolFlags.Optional; } } else if (contextualTypeHasPattern && !(getObjectFlags(contextualType) & ObjectFlags.ObjectLiteralPatternWithComputedProperties)) { // If object literal is contextually typed by the implied type of a binding pattern, and if the // binding pattern specifies a default value for the property, make the property optional. const impliedProp = getPropertyOfType(contextualType, member.escapedName); if (impliedProp) { prop.flags |= impliedProp.flags & SymbolFlags.Optional; } else if (!compilerOptions.suppressExcessPropertyErrors && !getIndexInfoOfType(contextualType, stringType)) { error(memberDecl.name, Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(member), typeToString(contextualType)); } } prop.declarations = member.declarations; prop.parent = member.parent; if (member.valueDeclaration) { prop.valueDeclaration = member.valueDeclaration; } prop.links.type = type; prop.links.target = member; member = prop; allPropertiesTable?.set(prop.escapedName, prop); if (contextualType && checkMode && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && (memberDecl.kind === SyntaxKind.PropertyAssignment || memberDecl.kind === SyntaxKind.MethodDeclaration) && isContextSensitive(memberDecl)) { const inferenceContext = getInferenceContext(node); Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context const inferenceNode = memberDecl.kind === SyntaxKind.PropertyAssignment ? memberDecl.initializer : memberDecl; addIntraExpressionInferenceSite(inferenceContext, inferenceNode, type); } } else if (memberDecl.kind === SyntaxKind.SpreadAssignment) { if (languageVersion < ScriptTarget.ES2015) { checkExternalEmitHelpers(memberDecl, ExternalEmitHelpers.Assign); } if (propertiesArray.length > 0) { spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); propertiesArray = []; propertiesTable = createSymbolTable(); hasComputedStringProperty = false; hasComputedNumberProperty = false; hasComputedSymbolProperty = false; } const type = getReducedType(checkExpression(memberDecl.expression)); if (isValidSpreadType(type)) { const mergedType = tryMergeUnionOfObjectTypeAndEmptyObject(type, inConstContext); if (allPropertiesTable) { checkSpreadPropOverrides(mergedType, allPropertiesTable, memberDecl); } offset = propertiesArray.length; if (isErrorType(spread)) { continue; } spread = getSpreadType(spread, mergedType, node.symbol, objectFlags, inConstContext); } else { error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types); spread = errorType; } continue; } else { // TypeScript 1.0 spec (April 2014) // A get accessor declaration is processed in the same manner as // an ordinary function declaration(section 6.1) with no parameters. // A set accessor declaration is processed in the same manner // as an ordinary function declaration with a single parameter and a Void return type. Debug.assert(memberDecl.kind === SyntaxKind.GetAccessor || memberDecl.kind === SyntaxKind.SetAccessor); checkNodeDeferred(memberDecl); } if (computedNameType && !(computedNameType.flags & TypeFlags.StringOrNumberLiteralOrUnique)) { if (isTypeAssignableTo(computedNameType, stringNumberSymbolType)) { if (isTypeAssignableTo(computedNameType, numberType)) { hasComputedNumberProperty = true; } else if (isTypeAssignableTo(computedNameType, esSymbolType)) { hasComputedSymbolProperty = true; } else { hasComputedStringProperty = true; } if (inDestructuringPattern) { patternWithComputedProperties = true; } } } else { propertiesTable.set(member.escapedName, member); } propertiesArray.push(member); } popContextualType(); // If object literal is contextually typed by the implied type of a binding pattern, augment the result // type with those properties for which the binding pattern specifies a default value. // If the object literal is spread into another object literal, skip this step and let the top-level object // literal handle it instead. Note that this might require full traversal to the root pattern's parent // as it's the guaranteed to be the common ancestor of the pattern node and the current object node. // It's not possible to check if the immediate parent node is a spread assignment // since the type flows in non-obvious ways through conditional expressions, IIFEs and more. if (contextualTypeHasPattern) { const rootPatternParent = findAncestor(contextualType.pattern!.parent, n => n.kind === SyntaxKind.VariableDeclaration || n.kind === SyntaxKind.BinaryExpression || n.kind === SyntaxKind.Parameter ); const spreadOrOutsideRootObject = findAncestor(node, n => n === rootPatternParent || n.kind === SyntaxKind.SpreadAssignment )!; if (spreadOrOutsideRootObject.kind !== SyntaxKind.SpreadAssignment) { for (const prop of getPropertiesOfType(contextualType)) { if (!propertiesTable.get(prop.escapedName) && !getPropertyOfType(spread, prop.escapedName)) { if (!(prop.flags & SymbolFlags.Optional)) { error(prop.valueDeclaration || tryCast(prop, isTransientSymbol)?.links.bindingElement, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value); } propertiesTable.set(prop.escapedName, prop); propertiesArray.push(prop); } } } } if (isErrorType(spread)) { return errorType; } if (spread !== emptyObjectType) { if (propertiesArray.length > 0) { spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); propertiesArray = []; propertiesTable = createSymbolTable(); hasComputedStringProperty = false; hasComputedNumberProperty = false; } // remap the raw emptyObjectType fed in at the top into a fresh empty object literal type, unique to this use site return mapType(spread, t => t === emptyObjectType ? createObjectLiteralType() : t); } return createObjectLiteralType(); function createObjectLiteralType() { const indexInfos = []; if (hasComputedStringProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, stringType)); if (hasComputedNumberProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, numberType)); if (hasComputedSymbolProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, esSymbolType)); const result = createAnonymousType(node.symbol, propertiesTable, emptyArray, emptyArray, indexInfos); result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; if (isJSObjectLiteral) { result.objectFlags |= ObjectFlags.JSLiteral; } if (patternWithComputedProperties) { result.objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; } if (inDestructuringPattern) { result.pattern = node; } return result; } } function isValidSpreadType(type: Type): boolean { const t = removeDefinitelyFalsyTypes(mapType(type, getBaseConstraintOrType)); return !!(t.flags & (TypeFlags.Any | TypeFlags.NonPrimitive | TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) || t.flags & TypeFlags.UnionOrIntersection && every((t as UnionOrIntersectionType).types, isValidSpreadType)); } function checkJsxSelfClosingElementDeferred(node: JsxSelfClosingElement) { checkJsxOpeningLikeElementOrOpeningFragment(node); } function checkJsxSelfClosingElement(node: JsxSelfClosingElement, _checkMode: CheckMode | undefined): Type { checkNodeDeferred(node); return getJsxElementTypeAt(node) || anyType; } function checkJsxElementDeferred(node: JsxElement) { // Check attributes checkJsxOpeningLikeElementOrOpeningFragment(node.openingElement); // Perform resolution on the closing tag so that rename/go to definition/etc work if (isJsxIntrinsicIdentifier(node.closingElement.tagName)) { getIntrinsicTagSymbol(node.closingElement); } else { checkExpression(node.closingElement.tagName); } checkJsxChildren(node); } function checkJsxElement(node: JsxElement, _checkMode: CheckMode | undefined): Type { checkNodeDeferred(node); return getJsxElementTypeAt(node) || anyType; } function checkJsxFragment(node: JsxFragment): Type { checkJsxOpeningLikeElementOrOpeningFragment(node.openingFragment); // by default, jsx:'react' will use jsxFactory = React.createElement and jsxFragmentFactory = React.Fragment // if jsxFactory compiler option is provided, ensure jsxFragmentFactory compiler option or @jsxFrag pragma is provided too const nodeSourceFile = getSourceFileOfNode(node); if (getJSXTransformEnabled(compilerOptions) && (compilerOptions.jsxFactory || nodeSourceFile.pragmas.has("jsx")) && !compilerOptions.jsxFragmentFactory && !nodeSourceFile.pragmas.has("jsxfrag")) { error(node, compilerOptions.jsxFactory ? Diagnostics.The_jsxFragmentFactory_compiler_option_must_be_provided_to_use_JSX_fragments_with_the_jsxFactory_compiler_option : Diagnostics.An_jsxFrag_pragma_is_required_when_using_an_jsx_pragma_with_JSX_fragments); } checkJsxChildren(node); return getJsxElementTypeAt(node) || anyType; } function isHyphenatedJsxName(name: string | __String) { return stringContains(name as string, "-"); } /** * Returns true iff React would emit this tag name as a string rather than an identifier or qualified name */ function isJsxIntrinsicIdentifier(tagName: JsxTagNameExpression): boolean { return tagName.kind === SyntaxKind.Identifier && isIntrinsicJsxName(tagName.escapedText); } function checkJsxAttribute(node: JsxAttribute, checkMode?: CheckMode) { return node.initializer ? checkExpressionForMutableLocation(node.initializer, checkMode) : trueType; // is sugar for } /** * Get attributes type of the JSX opening-like element. The result is from resolving "attributes" property of the opening-like element. * * @param openingLikeElement a JSX opening-like element * @param filter a function to remove attributes that will not participate in checking whether attributes are assignable * @return an anonymous type (similar to the one returned by checkObjectLiteral) in which its properties are attributes property. * @remarks Because this function calls getSpreadType, it needs to use the same checks as checkObjectLiteral, * which also calls getSpreadType. */ function createJsxAttributesTypeFromAttributesProperty(openingLikeElement: JsxOpeningLikeElement, checkMode: CheckMode | undefined) { const attributes = openingLikeElement.attributes; const attributesType = getContextualType(attributes, ContextFlags.None); const allAttributesTable = strictNullChecks ? createSymbolTable() : undefined; let attributesTable = createSymbolTable(); let spread: Type = emptyJsxObjectType; let hasSpreadAnyType = false; let typeToIntersect: Type | undefined; let explicitlySpecifyChildrenAttribute = false; let objectFlags: ObjectFlags = ObjectFlags.JsxAttributes; const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(openingLikeElement)); for (const attributeDecl of attributes.properties) { const member = attributeDecl.symbol; if (isJsxAttribute(attributeDecl)) { const exprType = checkJsxAttribute(attributeDecl, checkMode); objectFlags |= getObjectFlags(exprType) & ObjectFlags.PropagatingFlags; const attributeSymbol = createSymbol(SymbolFlags.Property | member.flags, member.escapedName); attributeSymbol.declarations = member.declarations; attributeSymbol.parent = member.parent; if (member.valueDeclaration) { attributeSymbol.valueDeclaration = member.valueDeclaration; } attributeSymbol.links.type = exprType; attributeSymbol.links.target = member; attributesTable.set(attributeSymbol.escapedName, attributeSymbol); allAttributesTable?.set(attributeSymbol.escapedName, attributeSymbol); if (attributeDecl.name.escapedText === jsxChildrenPropertyName) { explicitlySpecifyChildrenAttribute = true; } if (attributesType) { const prop = getPropertyOfType(attributesType, member.escapedName); if (prop && prop.declarations && isDeprecatedSymbol(prop)) { addDeprecatedSuggestion(attributeDecl.name, prop.declarations, attributeDecl.name.escapedText as string); } } } else { Debug.assert(attributeDecl.kind === SyntaxKind.JsxSpreadAttribute); if (attributesTable.size > 0) { spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); attributesTable = createSymbolTable(); } const exprType = getReducedType(checkExpressionCached(attributeDecl.expression, checkMode)); if (isTypeAny(exprType)) { hasSpreadAnyType = true; } if (isValidSpreadType(exprType)) { spread = getSpreadType(spread, exprType, attributes.symbol, objectFlags, /*readonly*/ false); if (allAttributesTable) { checkSpreadPropOverrides(exprType, allAttributesTable, attributeDecl); } } else { error(attributeDecl.expression, Diagnostics.Spread_types_may_only_be_created_from_object_types); typeToIntersect = typeToIntersect ? getIntersectionType([typeToIntersect, exprType]) : exprType; } } } if (!hasSpreadAnyType) { if (attributesTable.size > 0) { spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); } } // Handle children attribute const parent = openingLikeElement.parent.kind === SyntaxKind.JsxElement ? openingLikeElement.parent as JsxElement : undefined; // We have to check that openingElement of the parent is the one we are visiting as this may not be true for selfClosingElement if (parent && parent.openingElement === openingLikeElement && parent.children.length > 0) { const childrenTypes: Type[] = checkJsxChildren(parent, checkMode); if (!hasSpreadAnyType && jsxChildrenPropertyName && jsxChildrenPropertyName !== "") { // Error if there is a attribute named "children" explicitly specified and children element. // This is because children element will overwrite the value from attributes. // Note: we will not warn "children" attribute overwritten if "children" attribute is specified in object spread. if (explicitlySpecifyChildrenAttribute) { error(attributes, Diagnostics._0_are_specified_twice_The_attribute_named_0_will_be_overwritten, unescapeLeadingUnderscores(jsxChildrenPropertyName)); } const contextualType = getApparentTypeOfContextualType(openingLikeElement.attributes, /*contextFlags*/ undefined); const childrenContextualType = contextualType && getTypeOfPropertyOfContextualType(contextualType, jsxChildrenPropertyName); // If there are children in the body of JSX element, create dummy attribute "children" with the union of children types so that it will pass the attribute checking process const childrenPropSymbol = createSymbol(SymbolFlags.Property, jsxChildrenPropertyName); childrenPropSymbol.links.type = childrenTypes.length === 1 ? childrenTypes[0] : childrenContextualType && someType(childrenContextualType, isTupleLikeType) ? createTupleType(childrenTypes) : createArrayType(getUnionType(childrenTypes)); // Fake up a property declaration for the children childrenPropSymbol.valueDeclaration = factory.createPropertySignature(/*modifiers*/ undefined, unescapeLeadingUnderscores(jsxChildrenPropertyName), /*questionToken*/ undefined, /*type*/ undefined); setParent(childrenPropSymbol.valueDeclaration, attributes); childrenPropSymbol.valueDeclaration.symbol = childrenPropSymbol; const childPropMap = createSymbolTable(); childPropMap.set(jsxChildrenPropertyName, childrenPropSymbol); spread = getSpreadType(spread, createAnonymousType(attributes.symbol, childPropMap, emptyArray, emptyArray, emptyArray), attributes.symbol, objectFlags, /*readonly*/ false); } } if (hasSpreadAnyType) { return anyType; } if (typeToIntersect && spread !== emptyJsxObjectType) { return getIntersectionType([typeToIntersect, spread]); } return typeToIntersect || (spread === emptyJsxObjectType ? createJsxAttributesType() : spread); /** * Create anonymous type from given attributes symbol table. * @param symbol a symbol of JsxAttributes containing attributes corresponding to attributesTable * @param attributesTable a symbol table of attributes property */ function createJsxAttributesType() { objectFlags |= freshObjectLiteralFlag; const result = createAnonymousType(attributes.symbol, attributesTable, emptyArray, emptyArray, emptyArray); result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; return result; } } function checkJsxChildren(node: JsxElement | JsxFragment, checkMode?: CheckMode) { const childrenTypes: Type[] = []; for (const child of node.children) { // In React, JSX text that contains only whitespaces will be ignored so we don't want to type-check that // because then type of children property will have constituent of string type. if (child.kind === SyntaxKind.JsxText) { if (!child.containsOnlyTriviaWhiteSpaces) { childrenTypes.push(stringType); } } else if (child.kind === SyntaxKind.JsxExpression && !child.expression) { continue; // empty jsx expressions don't *really* count as present children } else { childrenTypes.push(checkExpressionForMutableLocation(child, checkMode)); } } return childrenTypes; } function checkSpreadPropOverrides(type: Type, props: SymbolTable, spread: SpreadAssignment | JsxSpreadAttribute) { for (const right of getPropertiesOfType(type)) { if (!(right.flags & SymbolFlags.Optional)) { const left = props.get(right.escapedName); if (left) { const diagnostic = error(left.valueDeclaration, Diagnostics._0_is_specified_more_than_once_so_this_usage_will_be_overwritten, unescapeLeadingUnderscores(left.escapedName)); addRelatedInfo(diagnostic, createDiagnosticForNode(spread, Diagnostics.This_spread_always_overwrites_this_property)); } } } } /** * Check attributes property of opening-like element. This function is called during chooseOverload to get call signature of a JSX opening-like element. * (See "checkApplicableSignatureForJsxOpeningLikeElement" for how the function is used) * @param node a JSXAttributes to be resolved of its type */ function checkJsxAttributes(node: JsxAttributes, checkMode: CheckMode | undefined) { return createJsxAttributesTypeFromAttributesProperty(node.parent, checkMode); } function getJsxType(name: __String, location: Node | undefined) { const namespace = getJsxNamespaceAt(location); const exports = namespace && getExportsOfSymbol(namespace); const typeSymbol = exports && getSymbol(exports, name, SymbolFlags.Type); return typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType; } /** * Looks up an intrinsic tag name and returns a symbol that either points to an intrinsic * property (in which case nodeLinks.jsxFlags will be IntrinsicNamedElement) or an intrinsic * string index signature (in which case nodeLinks.jsxFlags will be IntrinsicIndexedElement). * May also return unknownSymbol if both of these lookups fail. */ function getIntrinsicTagSymbol(node: JsxOpeningLikeElement | JsxClosingElement): Symbol { const links = getNodeLinks(node); if (!links.resolvedSymbol) { const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, node); if (!isErrorType(intrinsicElementsType)) { // Property case if (!isIdentifier(node.tagName)) return Debug.fail(); const intrinsicProp = getPropertyOfType(intrinsicElementsType, node.tagName.escapedText); if (intrinsicProp) { links.jsxFlags |= JsxFlags.IntrinsicNamedElement; return links.resolvedSymbol = intrinsicProp; } // Intrinsic string indexer case const indexSignatureType = getIndexTypeOfType(intrinsicElementsType, stringType); if (indexSignatureType) { links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; return links.resolvedSymbol = intrinsicElementsType.symbol; } // Wasn't found error(node, Diagnostics.Property_0_does_not_exist_on_type_1, idText(node.tagName), "JSX." + JsxNames.IntrinsicElements); return links.resolvedSymbol = unknownSymbol; } else { if (noImplicitAny) { error(node, Diagnostics.JSX_element_implicitly_has_type_any_because_no_interface_JSX_0_exists, unescapeLeadingUnderscores(JsxNames.IntrinsicElements)); } return links.resolvedSymbol = unknownSymbol; } } return links.resolvedSymbol; } function getJsxNamespaceContainerForImplicitImport(location: Node | undefined): Symbol | undefined { const file = location && getSourceFileOfNode(location); const links = file && getNodeLinks(file); if (links && links.jsxImplicitImportContainer === false) { return undefined; } if (links && links.jsxImplicitImportContainer) { return links.jsxImplicitImportContainer; } const runtimeImportSpecifier = getJSXRuntimeImport(getJSXImplicitImportBase(compilerOptions, file), compilerOptions); if (!runtimeImportSpecifier) { return undefined; } const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; const errorMessage = isClassic ? Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; const mod = resolveExternalModule(location!, runtimeImportSpecifier, errorMessage, location!); const result = mod && mod !== unknownSymbol ? getMergedSymbol(resolveSymbol(mod)) : undefined; if (links) { links.jsxImplicitImportContainer = result || false; } return result; } function getJsxNamespaceAt(location: Node | undefined): Symbol { const links = location && getNodeLinks(location); if (links && links.jsxNamespace) { return links.jsxNamespace; } if (!links || links.jsxNamespace !== false) { let resolvedNamespace = getJsxNamespaceContainerForImplicitImport(location); if (!resolvedNamespace || resolvedNamespace === unknownSymbol) { const namespaceName = getJsxNamespace(location); resolvedNamespace = resolveName(location, namespaceName, SymbolFlags.Namespace, /*diagnosticMessage*/ undefined, namespaceName, /*isUse*/ false); } if (resolvedNamespace) { const candidate = resolveSymbol(getSymbol(getExportsOfSymbol(resolveSymbol(resolvedNamespace)), JsxNames.JSX, SymbolFlags.Namespace)); if (candidate && candidate !== unknownSymbol) { if (links) { links.jsxNamespace = candidate; } return candidate; } } if (links) { links.jsxNamespace = false; } } // JSX global fallback const s = resolveSymbol(getGlobalSymbol(JsxNames.JSX, SymbolFlags.Namespace, /*diagnosticMessage*/ undefined)); if (s === unknownSymbol) { return undefined!; // TODO: GH#18217 } return s!; // TODO: GH#18217 } /** * Look into JSX namespace and then look for container with matching name as nameOfAttribPropContainer. * Get a single property from that container if existed. Report an error if there are more than one property. * * @param nameOfAttribPropContainer a string of value JsxNames.ElementAttributesPropertyNameContainer or JsxNames.ElementChildrenAttributeNameContainer * if other string is given or the container doesn't exist, return undefined. */ function getNameFromJsxElementAttributesContainer(nameOfAttribPropContainer: __String, jsxNamespace: Symbol): __String | undefined { // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [symbol] const jsxElementAttribPropInterfaceSym = jsxNamespace && getSymbol(jsxNamespace.exports!, nameOfAttribPropContainer, SymbolFlags.Type); // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [type] const jsxElementAttribPropInterfaceType = jsxElementAttribPropInterfaceSym && getDeclaredTypeOfSymbol(jsxElementAttribPropInterfaceSym); // The properties of JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute const propertiesOfJsxElementAttribPropInterface = jsxElementAttribPropInterfaceType && getPropertiesOfType(jsxElementAttribPropInterfaceType); if (propertiesOfJsxElementAttribPropInterface) { // Element Attributes has zero properties, so the element attributes type will be the class instance type if (propertiesOfJsxElementAttribPropInterface.length === 0) { return "" as __String; } // Element Attributes has one property, so the element attributes type will be the type of the corresponding // property of the class instance type else if (propertiesOfJsxElementAttribPropInterface.length === 1) { return propertiesOfJsxElementAttribPropInterface[0].escapedName; } else if (propertiesOfJsxElementAttribPropInterface.length > 1 && jsxElementAttribPropInterfaceSym.declarations) { // More than one property on ElementAttributesProperty is an error error(jsxElementAttribPropInterfaceSym.declarations[0], Diagnostics.The_global_type_JSX_0_may_not_have_more_than_one_property, unescapeLeadingUnderscores(nameOfAttribPropContainer)); } } return undefined; } function getJsxLibraryManagedAttributes(jsxNamespace: Symbol) { // JSX.LibraryManagedAttributes [symbol] return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.LibraryManagedAttributes, SymbolFlags.Type); } /// e.g. "props" for React.d.ts, /// or 'undefined' if ElementAttributesProperty doesn't exist (which means all /// non-intrinsic elements' attributes type is 'any'), /// or '' if it has 0 properties (which means every /// non-intrinsic elements' attributes type is the element instance type) function getJsxElementPropertiesName(jsxNamespace: Symbol) { return getNameFromJsxElementAttributesContainer(JsxNames.ElementAttributesPropertyNameContainer, jsxNamespace); } function getJsxElementChildrenPropertyName(jsxNamespace: Symbol): __String | undefined { return getNameFromJsxElementAttributesContainer(JsxNames.ElementChildrenAttributeNameContainer, jsxNamespace); } function getUninstantiatedJsxSignaturesOfType(elementType: Type, caller: JsxOpeningLikeElement): readonly Signature[] { if (elementType.flags & TypeFlags.String) { return [anySignature]; } else if (elementType.flags & TypeFlags.StringLiteral) { const intrinsicType = getIntrinsicAttributesTypeFromStringLiteralType(elementType as StringLiteralType, caller); if (!intrinsicType) { error(caller, Diagnostics.Property_0_does_not_exist_on_type_1, (elementType as StringLiteralType).value, "JSX." + JsxNames.IntrinsicElements); return emptyArray; } else { const fakeSignature = createSignatureForJSXIntrinsic(caller, intrinsicType); return [fakeSignature]; } } const apparentElemType = getApparentType(elementType); // Resolve the signatures, preferring constructor let signatures = getSignaturesOfType(apparentElemType, SignatureKind.Construct); if (signatures.length === 0) { // No construct signatures, try call signatures signatures = getSignaturesOfType(apparentElemType, SignatureKind.Call); } if (signatures.length === 0 && apparentElemType.flags & TypeFlags.Union) { // If each member has some combination of new/call signatures; make a union signature list for those signatures = getUnionSignatures(map((apparentElemType as UnionType).types, t => getUninstantiatedJsxSignaturesOfType(t, caller))); } return signatures; } function getIntrinsicAttributesTypeFromStringLiteralType(type: StringLiteralType, location: Node): Type | undefined { // If the elemType is a stringLiteral type, we can then provide a check to make sure that the string literal type is one of the Jsx intrinsic element type // For example: // var CustomTag: "h1" = "h1"; // Hello World const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, location); if (!isErrorType(intrinsicElementsType)) { const stringLiteralTypeName = type.value; const intrinsicProp = getPropertyOfType(intrinsicElementsType, escapeLeadingUnderscores(stringLiteralTypeName)); if (intrinsicProp) { return getTypeOfSymbol(intrinsicProp); } const indexSignatureType = getIndexTypeOfType(intrinsicElementsType, stringType); if (indexSignatureType) { return indexSignatureType; } return undefined; } // If we need to report an error, we already done so here. So just return any to prevent any more error downstream return anyType; } function checkJsxReturnAssignableToAppropriateBound(refKind: JsxReferenceKind, elemInstanceType: Type, openingLikeElement: JsxOpeningLikeElement) { if (refKind === JsxReferenceKind.Function) { const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); if (sfcReturnConstraint) { checkTypeRelatedTo(elemInstanceType, sfcReturnConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_return_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); } } else if (refKind === JsxReferenceKind.Component) { const classConstraint = getJsxElementClassTypeAt(openingLikeElement); if (classConstraint) { // Issue an error if this return type isn't assignable to JSX.ElementClass, failing that checkTypeRelatedTo(elemInstanceType, classConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_instance_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); } } else { // Mixed const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); const classConstraint = getJsxElementClassTypeAt(openingLikeElement); if (!sfcReturnConstraint || !classConstraint) { return; } const combined = getUnionType([sfcReturnConstraint, classConstraint]); checkTypeRelatedTo(elemInstanceType, combined, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_element_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); } function generateInitialErrorChain(): DiagnosticMessageChain { const componentName = getTextOfNode(openingLikeElement.tagName); return chainDiagnosticMessages(/* details */ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); } } /** * Get attributes type of the given intrinsic opening-like Jsx element by resolving the tag name. * The function is intended to be called from a function which has checked that the opening element is an intrinsic element. * @param node an intrinsic JSX opening-like element */ function getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node: JsxOpeningLikeElement): Type { Debug.assert(isJsxIntrinsicIdentifier(node.tagName)); const links = getNodeLinks(node); if (!links.resolvedJsxElementAttributesType) { const symbol = getIntrinsicTagSymbol(node); if (links.jsxFlags & JsxFlags.IntrinsicNamedElement) { return links.resolvedJsxElementAttributesType = getTypeOfSymbol(symbol) || errorType; } else if (links.jsxFlags & JsxFlags.IntrinsicIndexedElement) { return links.resolvedJsxElementAttributesType = getIndexTypeOfType(getJsxType(JsxNames.IntrinsicElements, node), stringType) || errorType; } else { return links.resolvedJsxElementAttributesType = errorType; } } return links.resolvedJsxElementAttributesType; } function getJsxElementClassTypeAt(location: Node): Type | undefined { const type = getJsxType(JsxNames.ElementClass, location); if (isErrorType(type)) return undefined; return type; } function getJsxElementTypeAt(location: Node): Type { return getJsxType(JsxNames.Element, location); } function getJsxStatelessElementTypeAt(location: Node): Type | undefined { const jsxElementType = getJsxElementTypeAt(location); if (jsxElementType) { return getUnionType([jsxElementType, nullType]); } } /** * Returns all the properties of the Jsx.IntrinsicElements interface */ function getJsxIntrinsicTagNamesAt(location: Node): Symbol[] { const intrinsics = getJsxType(JsxNames.IntrinsicElements, location); return intrinsics ? getPropertiesOfType(intrinsics) : emptyArray; } function checkJsxPreconditions(errorNode: Node) { // Preconditions for using JSX if ((compilerOptions.jsx || JsxEmit.None) === JsxEmit.None) { error(errorNode, Diagnostics.Cannot_use_JSX_unless_the_jsx_flag_is_provided); } if (getJsxElementTypeAt(errorNode) === undefined) { if (noImplicitAny) { error(errorNode, Diagnostics.JSX_element_implicitly_has_type_any_because_the_global_type_JSX_Element_does_not_exist); } } } function checkJsxOpeningLikeElementOrOpeningFragment(node: JsxOpeningLikeElement | JsxOpeningFragment) { const isNodeOpeningLikeElement = isJsxOpeningLikeElement(node); if (isNodeOpeningLikeElement) { checkGrammarJsxElement(node); } checkJsxPreconditions(node); if (!getJsxNamespaceContainerForImplicitImport(node)) { // The reactNamespace/jsxFactory's root symbol should be marked as 'used' so we don't incorrectly elide its import. // And if there is no reactNamespace/jsxFactory's symbol in scope when targeting React emit, we should issue an error. const jsxFactoryRefErr = diagnostics && compilerOptions.jsx === JsxEmit.React ? Diagnostics.Cannot_find_name_0 : undefined; const jsxFactoryNamespace = getJsxNamespace(node); const jsxFactoryLocation = isNodeOpeningLikeElement ? node.tagName : node; // allow null as jsxFragmentFactory let jsxFactorySym: Symbol | undefined; if (!(isJsxOpeningFragment(node) && jsxFactoryNamespace === "null")) { jsxFactorySym = resolveName(jsxFactoryLocation, jsxFactoryNamespace, SymbolFlags.Value, jsxFactoryRefErr, jsxFactoryNamespace, /*isUse*/ true); } if (jsxFactorySym) { // Mark local symbol as referenced here because it might not have been marked // if jsx emit was not jsxFactory as there wont be error being emitted jsxFactorySym.isReferenced = SymbolFlags.All; // If react/jsxFactory symbol is alias, mark it as refereced if (!compilerOptions.verbatimModuleSyntax && jsxFactorySym.flags & SymbolFlags.Alias && !getTypeOnlyAliasDeclaration(jsxFactorySym)) { markAliasSymbolAsReferenced(jsxFactorySym); } } // For JsxFragment, mark jsx pragma as referenced via resolveName if (isJsxOpeningFragment(node)) { const file = getSourceFileOfNode(node); const localJsxNamespace = getLocalJsxNamespace(file); if (localJsxNamespace) { resolveName(jsxFactoryLocation, localJsxNamespace, SymbolFlags.Value, jsxFactoryRefErr, localJsxNamespace, /*isUse*/ true); } } } if (isNodeOpeningLikeElement) { const jsxOpeningLikeNode = node ; const sig = getResolvedSignature(jsxOpeningLikeNode); checkDeprecatedSignature(sig, node); checkJsxReturnAssignableToAppropriateBound(getJsxReferenceKind(jsxOpeningLikeNode), getReturnTypeOfSignature(sig), jsxOpeningLikeNode); } } /** * Check if a property with the given name is known anywhere in the given type. In an object type, a property * is considered known if * 1. the object type is empty and the check is for assignability, or * 2. if the object type has index signatures, or * 3. if the property is actually declared in the object type * (this means that 'toString', for example, is not usually a known property). * 4. In a union or intersection type, * a property is considered known if it is known in any constituent type. * @param targetType a type to search a given name in * @param name a property name to search * @param isComparingJsxAttributes a boolean flag indicating whether we are searching in JsxAttributesType */ function isKnownProperty(targetType: Type, name: __String, isComparingJsxAttributes: boolean): boolean { if (targetType.flags & TypeFlags.Object) { // For backwards compatibility a symbol-named property is satisfied by a string index signature. This // is incorrect and inconsistent with element access expressions, where it is an error, so eventually // we should remove this exception. if (getPropertyOfObjectType(targetType, name) || getApplicableIndexInfoForName(targetType, name) || isLateBoundName(name) && getIndexInfoOfType(targetType, stringType) || isComparingJsxAttributes && isHyphenatedJsxName(name)) { // For JSXAttributes, if the attribute has a hyphenated name, consider that the attribute to be known. return true; } } else if (targetType.flags & TypeFlags.UnionOrIntersection && isExcessPropertyCheckTarget(targetType)) { for (const t of (targetType as UnionOrIntersectionType).types) { if (isKnownProperty(t, name, isComparingJsxAttributes)) { return true; } } } return false; } function isExcessPropertyCheckTarget(type: Type): boolean { return !!(type.flags & TypeFlags.Object && !(getObjectFlags(type) & ObjectFlags.ObjectLiteralPatternWithComputedProperties) || type.flags & TypeFlags.NonPrimitive || type.flags & TypeFlags.Union && some((type as UnionType).types, isExcessPropertyCheckTarget) || type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isExcessPropertyCheckTarget)); } function checkJsxExpression(node: JsxExpression, checkMode?: CheckMode) { checkGrammarJsxExpression(node); if (node.expression) { const type = checkExpression(node.expression, checkMode); if (node.dotDotDotToken && type !== anyType && !isArrayType(type)) { error(node, Diagnostics.JSX_spread_child_must_be_an_array_type); } return type; } else { return errorType; } } function getDeclarationNodeFlagsFromSymbol(s: Symbol): NodeFlags { return s.valueDeclaration ? getCombinedNodeFlags(s.valueDeclaration) : 0; } /** * Return whether this symbol is a member of a prototype somewhere * Note that this is not tracked well within the compiler, so the answer may be incorrect. */ function isPrototypeProperty(symbol: Symbol) { if (symbol.flags & SymbolFlags.Method || getCheckFlags(symbol) & CheckFlags.SyntheticMethod) { return true; } if (isInJSFile(symbol.valueDeclaration)) { const parent = symbol.valueDeclaration!.parent; return parent && isBinaryExpression(parent) && getAssignmentDeclarationKind(parent) === AssignmentDeclarationKind.PrototypeProperty; } } /** * Check whether the requested property access is valid. * Returns true if node is a valid property access, and false otherwise. * @param node The node to be checked. * @param isSuper True if the access is from `super.`. * @param type The type of the object whose property is being accessed. (Not the type of the property.) * @param prop The symbol for the property being accessed. */ function checkPropertyAccessibility( node: PropertyAccessExpression | QualifiedName | PropertyAccessExpression | VariableDeclaration | ParameterDeclaration | ImportTypeNode | PropertyAssignment | ShorthandPropertyAssignment | BindingElement, isSuper: boolean, writing: boolean, type: Type, prop: Symbol, reportError = true): boolean { const errorNode = !reportError ? undefined : node.kind === SyntaxKind.QualifiedName ? node.right : node.kind === SyntaxKind.ImportType ? node : node.kind === SyntaxKind.BindingElement && node.propertyName ? node.propertyName : node.name; return checkPropertyAccessibilityAtLocation(node, isSuper, writing, type, prop, errorNode); } /** * Check whether the requested property can be accessed at the requested location. * Returns true if node is a valid property access, and false otherwise. * @param location The location node where we want to check if the property is accessible. * @param isSuper True if the access is from `super.`. * @param writing True if this is a write property access, false if it is a read property access. * @param containingType The type of the object whose property is being accessed. (Not the type of the property.) * @param prop The symbol for the property being accessed. * @param errorNode The node where we should report an invalid property access error, or undefined if we should not report errors. */ function checkPropertyAccessibilityAtLocation(location: Node, isSuper: boolean, writing: boolean, containingType: Type, prop: Symbol, errorNode?: Node): boolean { const flags = getDeclarationModifierFlagsFromSymbol(prop, writing); if (isSuper) { // TS 1.0 spec (April 2014): 4.8.2 // - In a constructor, instance member function, instance member accessor, or // instance member variable initializer where this references a derived class instance, // a super property access is permitted and must specify a public instance member function of the base class. // - In a static member function or static member accessor // where this references the constructor function object of a derived class, // a super property access is permitted and must specify a public static member function of the base class. if (languageVersion < ScriptTarget.ES2015) { if (symbolHasNonMethodDeclaration(prop)) { if (errorNode) { error(errorNode, Diagnostics.Only_public_and_protected_methods_of_the_base_class_are_accessible_via_the_super_keyword); } return false; } } if (flags & ModifierFlags.Abstract) { // A method cannot be accessed in a super property access if the method is abstract. // This error could mask a private property access error. But, a member // cannot simultaneously be private and abstract, so this will trigger an // additional error elsewhere. if (errorNode) { error(errorNode, Diagnostics.Abstract_method_0_in_class_1_cannot_be_accessed_via_super_expression, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); } return false; } } // Referencing abstract properties within their own constructors is not allowed if ((flags & ModifierFlags.Abstract) && symbolHasNonMethodDeclaration(prop) && (isThisProperty(location) || isThisInitializedObjectBindingExpression(location) || isObjectBindingPattern(location.parent) && isThisInitializedDeclaration(location.parent.parent))) { const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!); if (declaringClassDeclaration && isNodeUsedDuringClassInitialization(location)) { if (errorNode) { error(errorNode, Diagnostics.Abstract_property_0_in_class_1_cannot_be_accessed_in_the_constructor, symbolToString(prop), getTextOfIdentifierOrLiteral(declaringClassDeclaration.name!)); } return false; } } // Public properties are otherwise accessible. if (!(flags & ModifierFlags.NonPublicAccessibilityModifier)) { return true; } // Property is known to be private or protected at this point // Private property is accessible if the property is within the declaring class if (flags & ModifierFlags.Private) { const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!)!; if (!isNodeWithinClass(location, declaringClassDeclaration)) { if (errorNode) { error(errorNode, Diagnostics.Property_0_is_private_and_only_accessible_within_class_1, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); } return false; } return true; } // Property is known to be protected at this point // All protected properties of a supertype are accessible in a super access if (isSuper) { return true; } // Find the first enclosing class that has the declaring classes of the protected constituents // of the property as base classes let enclosingClass = forEachEnclosingClass(location, enclosingDeclaration => { const enclosingClass = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(enclosingDeclaration)!) as InterfaceType; return isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); }); // A protected property is accessible if the property is within the declaring class or classes derived from it if (!enclosingClass) { // allow PropertyAccessibility if context is in function with this parameter // static member access is disallowed enclosingClass = getEnclosingClassFromThisParameter(location); enclosingClass = enclosingClass && isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); if (flags & ModifierFlags.Static || !enclosingClass) { if (errorNode) { error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_within_class_1_and_its_subclasses, symbolToString(prop), typeToString(getDeclaringClass(prop) || containingType)); } return false; } } // No further restrictions for static properties if (flags & ModifierFlags.Static) { return true; } if (containingType.flags & TypeFlags.TypeParameter) { // get the original type -- represented as the type constraint of the 'this' type containingType = (containingType as TypeParameter).isThisType ? getConstraintOfTypeParameter(containingType as TypeParameter)! : getBaseConstraintOfType(containingType as TypeParameter)!; // TODO: GH#18217 Use a different variable that's allowed to be undefined } if (!containingType || !hasBaseType(containingType, enclosingClass)) { if (errorNode) { error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1_This_is_an_instance_of_class_2, symbolToString(prop), typeToString(enclosingClass), typeToString(containingType)); } return false; } return true; } function getEnclosingClassFromThisParameter(node: Node): InterfaceType | undefined { const thisParameter = getThisParameterFromNodeContext(node); let thisType = thisParameter?.type && getTypeFromTypeNode(thisParameter.type); if (thisType && thisType.flags & TypeFlags.TypeParameter) { thisType = getConstraintOfTypeParameter(thisType as TypeParameter); } if (thisType && getObjectFlags(thisType) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { return getTargetType(thisType) as InterfaceType; } return undefined; } function getThisParameterFromNodeContext(node: Node) { const thisContainer = getThisContainer(node, /* includeArrowFunctions */ false, /*includeClassComputedPropertyName*/ false); return thisContainer && isFunctionLike(thisContainer) ? getThisParameter(thisContainer) : undefined; } function symbolHasNonMethodDeclaration(symbol: Symbol) { return !!forEachProperty(symbol, prop => !(prop.flags & SymbolFlags.Method)); } function checkNonNullExpression(node: Expression | QualifiedName) { return checkNonNullType(checkExpression(node), node); } function isNullableType(type: Type) { return !!(getTypeFacts(type) & TypeFacts.IsUndefinedOrNull); } function getNonNullableTypeIfNeeded(type: Type) { return isNullableType(type) ? getNonNullableType(type) : type; } function reportObjectPossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { const nodeText = isEntityNameExpression(node) ? entityNameToString(node) : undefined; if (node.kind === SyntaxKind.NullKeyword) { error(node, Diagnostics.The_value_0_cannot_be_used_here, "null"); return; } if (nodeText !== undefined && nodeText.length < 100) { if (isIdentifier(node) && nodeText === "undefined") { error(node, Diagnostics.The_value_0_cannot_be_used_here, "undefined"); return; } error(node, facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? Diagnostics._0_is_possibly_null_or_undefined : Diagnostics._0_is_possibly_undefined : Diagnostics._0_is_possibly_null, nodeText ); } else { error(node, facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? Diagnostics.Object_is_possibly_null_or_undefined : Diagnostics.Object_is_possibly_undefined : Diagnostics.Object_is_possibly_null ); } } function reportCannotInvokePossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { error(node, facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? Diagnostics.Cannot_invoke_an_object_which_is_possibly_null_or_undefined : Diagnostics.Cannot_invoke_an_object_which_is_possibly_undefined : Diagnostics.Cannot_invoke_an_object_which_is_possibly_null ); } function checkNonNullTypeWithReporter( type: Type, node: Node, reportError: (node: Node, facts: TypeFacts) => void ): Type { if (strictNullChecks && type.flags & TypeFlags.Unknown) { if (isEntityNameExpression(node)) { const nodeText = entityNameToString(node); if (nodeText.length < 100) { error(node, Diagnostics._0_is_of_type_unknown, nodeText); return errorType; } } error(node, Diagnostics.Object_is_of_type_unknown); return errorType; } const facts = getTypeFacts(type); if (facts & TypeFacts.IsUndefinedOrNull) { reportError(node, facts); const t = getNonNullableType(type); return t.flags & (TypeFlags.Nullable | TypeFlags.Never) ? errorType : t; } return type; } function checkNonNullType(type: Type, node: Node) { return checkNonNullTypeWithReporter(type, node, reportObjectPossiblyNullOrUndefinedError); } function checkNonNullNonVoidType(type: Type, node: Node): Type { const nonNullType = checkNonNullType(type, node); if (nonNullType.flags & TypeFlags.Void) { if (isEntityNameExpression(node)) { const nodeText = entityNameToString(node); if (isIdentifier(node) && nodeText === "undefined") { error(node, Diagnostics.The_value_0_cannot_be_used_here, nodeText); return nonNullType; } if (nodeText.length < 100) { error(node, Diagnostics._0_is_possibly_undefined, nodeText); return nonNullType; } } error(node, Diagnostics.Object_is_possibly_undefined); } return nonNullType; } function checkPropertyAccessExpression(node: PropertyAccessExpression, checkMode: CheckMode | undefined) { return node.flags & NodeFlags.OptionalChain ? checkPropertyAccessChain(node as PropertyAccessChain, checkMode) : checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullExpression(node.expression), node.name, checkMode); } function checkPropertyAccessChain(node: PropertyAccessChain, checkMode: CheckMode | undefined) { const leftType = checkExpression(node.expression); const nonOptionalType = getOptionalExpressionType(leftType, node.expression); return propagateOptionalTypeMarker(checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullType(nonOptionalType, node.expression), node.name, checkMode), node, nonOptionalType !== leftType); } function checkQualifiedName(node: QualifiedName, checkMode: CheckMode | undefined) { const leftType = isPartOfTypeQuery(node) && isThisIdentifier(node.left) ? checkNonNullType(checkThisExpression(node.left), node.left) : checkNonNullExpression(node.left); return checkPropertyAccessExpressionOrQualifiedName(node, node.left, leftType, node.right, checkMode); } function isMethodAccessForCall(node: Node) { while (node.parent.kind === SyntaxKind.ParenthesizedExpression) { node = node.parent; } return isCallOrNewExpression(node.parent) && node.parent.expression === node; } // Lookup the private identifier lexically. function lookupSymbolForPrivateIdentifierDeclaration(propName: __String, location: Node): Symbol | undefined { for (let containingClass = getContainingClass(location); !!containingClass; containingClass = getContainingClass(containingClass)) { const { symbol } = containingClass; const name = getSymbolNameForPrivateIdentifier(symbol, propName); const prop = (symbol.members && symbol.members.get(name)) || (symbol.exports && symbol.exports.get(name)); if (prop) { return prop; } } } function checkGrammarPrivateIdentifierExpression(privId: PrivateIdentifier): boolean { if (!getContainingClass(privId)) { return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); } if (!isForInStatement(privId.parent)) { if (!isExpressionNode(privId)) { return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_only_allowed_in_class_bodies_and_may_only_be_used_as_part_of_a_class_member_declaration_property_access_or_on_the_left_hand_side_of_an_in_expression); } const isInOperation = isBinaryExpression(privId.parent) && privId.parent.operatorToken.kind === SyntaxKind.InKeyword; if (!getSymbolForPrivateIdentifierExpression(privId) && !isInOperation) { return grammarErrorOnNode(privId, Diagnostics.Cannot_find_name_0, idText(privId)); } } return false; } function checkPrivateIdentifierExpression(privId: PrivateIdentifier): Type { checkGrammarPrivateIdentifierExpression(privId); const symbol = getSymbolForPrivateIdentifierExpression(privId); if (symbol) { markPropertyAsReferenced(symbol, /* nodeForCheckWriteOnly: */ undefined, /* isThisAccess: */ false); } return anyType; } function getSymbolForPrivateIdentifierExpression(privId: PrivateIdentifier): Symbol | undefined { if (!isExpressionNode(privId)) { return undefined; } const links = getNodeLinks(privId); if (links.resolvedSymbol === undefined) { links.resolvedSymbol = lookupSymbolForPrivateIdentifierDeclaration(privId.escapedText, privId); } return links.resolvedSymbol; } function getPrivateIdentifierPropertyOfType(leftType: Type, lexicallyScopedIdentifier: Symbol): Symbol | undefined { return getPropertyOfType(leftType, lexicallyScopedIdentifier.escapedName); } function checkPrivateIdentifierPropertyAccess(leftType: Type, right: PrivateIdentifier, lexicallyScopedIdentifier: Symbol | undefined): boolean { // Either the identifier could not be looked up in the lexical scope OR the lexically scoped identifier did not exist on the type. // Find a private identifier with the same description on the type. let propertyOnType: Symbol | undefined; const properties = getPropertiesOfType(leftType); if (properties) { forEach(properties, (symbol: Symbol) => { const decl = symbol.valueDeclaration; if (decl && isNamedDeclaration(decl) && isPrivateIdentifier(decl.name) && decl.name.escapedText === right.escapedText) { propertyOnType = symbol; return true; } }); } const diagName = diagnosticName(right); if (propertyOnType) { const typeValueDecl = Debug.checkDefined(propertyOnType.valueDeclaration); const typeClass = Debug.checkDefined(getContainingClass(typeValueDecl)); // We found a private identifier property with the same description. // Either: // - There is a lexically scoped private identifier AND it shadows the one we found on the type. // - It is an attempt to access the private identifier outside of the class. if (lexicallyScopedIdentifier?.valueDeclaration) { const lexicalValueDecl = lexicallyScopedIdentifier.valueDeclaration; const lexicalClass = getContainingClass(lexicalValueDecl); Debug.assert(!!lexicalClass); if (findAncestor(lexicalClass, n => typeClass === n)) { const diagnostic = error( right, Diagnostics.The_property_0_cannot_be_accessed_on_type_1_within_this_class_because_it_is_shadowed_by_another_private_identifier_with_the_same_spelling, diagName, typeToString(leftType) ); addRelatedInfo( diagnostic, createDiagnosticForNode( lexicalValueDecl, Diagnostics.The_shadowing_declaration_of_0_is_defined_here, diagName ), createDiagnosticForNode( typeValueDecl, Diagnostics.The_declaration_of_0_that_you_probably_intended_to_use_is_defined_here, diagName ) ); return true; } } error( right, Diagnostics.Property_0_is_not_accessible_outside_class_1_because_it_has_a_private_identifier, diagName, diagnosticName(typeClass.name || anon) ); return true; } return false; } function isThisPropertyAccessInConstructor(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol) { return (isConstructorDeclaredProperty(prop) || isThisProperty(node) && isAutoTypedProperty(prop)) && getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ false) === getDeclaringConstructor(prop); } function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, leftType: Type, right: Identifier | PrivateIdentifier, checkMode: CheckMode | undefined) { const parentSymbol = getNodeLinks(left).resolvedSymbol; const assignmentKind = getAssignmentTargetKind(node); const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType); const isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType; let prop: Symbol | undefined; if (isPrivateIdentifier(right)) { if (languageVersion < ScriptTarget.ESNext) { if (assignmentKind !== AssignmentKind.None) { checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldSet); } if (assignmentKind !== AssignmentKind.Definite) { checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldGet); } } const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); if (assignmentKind && lexicallyScopedSymbol && lexicallyScopedSymbol.valueDeclaration && isMethodDeclaration(lexicallyScopedSymbol.valueDeclaration)) { grammarErrorOnNode(right, Diagnostics.Cannot_assign_to_private_method_0_Private_methods_are_not_writable, idText(right)); } if (isAnyLike) { if (lexicallyScopedSymbol) { return isErrorType(apparentType) ? errorType : apparentType; } if (!getContainingClass(right)) { grammarErrorOnNode(right, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); return anyType; } } prop = lexicallyScopedSymbol ? getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedSymbol) : undefined; // Check for private-identifier-specific shadowing and lexical-scoping errors. if (!prop && checkPrivateIdentifierPropertyAccess(leftType, right, lexicallyScopedSymbol)) { return errorType; } else { const isSetonlyAccessor = prop && prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); if (isSetonlyAccessor && assignmentKind !== AssignmentKind.Definite) { error(node, Diagnostics.Private_accessor_was_defined_without_a_getter); } } } else { if (isAnyLike) { if (isIdentifier(left) && parentSymbol) { markAliasReferenced(parentSymbol, node); } return isErrorType(apparentType) ? errorType : apparentType; } prop = getPropertyOfType(apparentType, right.escapedText, /*skipObjectFunctionPropertyAugment*/ false, /*includeTypeOnlyMembers*/ node.kind === SyntaxKind.QualifiedName); } // In `Foo.Bar.Baz`, 'Foo' is not referenced if 'Bar' is a const enum or a module containing only const enums. // `Foo` is also not referenced in `enum FooCopy { Bar = Foo.Bar }`, because the enum member value gets inlined // here even if `Foo` is not a const enum. // // The exceptions are: // 1. if 'isolatedModules' is enabled, because the const enum value will not be inlined, and // 2. if 'preserveConstEnums' is enabled and the expression is itself an export, e.g. `export = Foo.Bar.Baz`. if (isIdentifier(left) && parentSymbol && ( getIsolatedModules(compilerOptions) || !(prop && (isConstEnumOrConstEnumOnlyModule(prop) || prop.flags & SymbolFlags.EnumMember && node.parent.kind === SyntaxKind.EnumMember)) || shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(node) )) { markAliasReferenced(parentSymbol, node); } let propType: Type; if (!prop) { const indexInfo = !isPrivateIdentifier(right) && (assignmentKind === AssignmentKind.None || !isGenericObjectType(leftType) || isThisTypeParameter(leftType)) ? getApplicableIndexInfoForName(apparentType, right.escapedText) : undefined; if (!(indexInfo && indexInfo.type)) { const isUncheckedJS = isUncheckedJSSuggestion(node, leftType.symbol, /*excludeClasses*/ true); if (!isUncheckedJS && isJSLiteralType(leftType)) { return anyType; } if (leftType.symbol === globalThisSymbol) { if (globalThisSymbol.exports!.has(right.escapedText) && (globalThisSymbol.exports!.get(right.escapedText)!.flags & SymbolFlags.BlockScoped)) { error(right, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(right.escapedText), typeToString(leftType)); } else if (noImplicitAny) { error(right, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature, typeToString(leftType)); } return anyType; } if (right.escapedText && !checkAndReportErrorForExtendingInterface(node)) { reportNonexistentProperty(right, isThisTypeParameter(leftType) ? apparentType : leftType, isUncheckedJS); } return errorType; } if (indexInfo.isReadonly && (isAssignmentTarget(node) || isDeleteTarget(node))) { error(node, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(apparentType)); } propType = (compilerOptions.noUncheckedIndexedAccess && !isAssignmentTarget(node)) ? getUnionType([indexInfo.type, missingType]) : indexInfo.type; if (compilerOptions.noPropertyAccessFromIndexSignature && isPropertyAccessExpression(node)) { error(right, Diagnostics.Property_0_comes_from_an_index_signature_so_it_must_be_accessed_with_0, unescapeLeadingUnderscores(right.escapedText)); } if (indexInfo.declaration && getCombinedNodeFlags(indexInfo.declaration) & NodeFlags.Deprecated) { addDeprecatedSuggestion(right, [indexInfo.declaration], right.escapedText as string); } } else { if (isDeprecatedSymbol(prop) && isUncalledFunctionReference(node, prop) && prop.declarations) { addDeprecatedSuggestion(right, prop.declarations, right.escapedText as string); } checkPropertyNotUsedBeforeDeclaration(prop, node, right); markPropertyAsReferenced(prop, node, isSelfTypeAccess(left, parentSymbol)); getNodeLinks(node).resolvedSymbol = prop; const writing = isWriteAccess(node); checkPropertyAccessibility(node, left.kind === SyntaxKind.SuperKeyword, writing, apparentType, prop); if (isAssignmentToReadonlyEntity(node as Expression, prop, assignmentKind)) { error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, idText(right)); return errorType; } propType = isThisPropertyAccessInConstructor(node, prop) ? autoType : writing ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); } return getFlowTypeOfAccessExpression(node, prop, propType, right, checkMode); } /** * Determines whether a did-you-mean error should be a suggestion in an unchecked JS file. * Only applies to unchecked JS files without checkJS, // @ts-check or // @ts-nocheck * It does not suggest when the suggestion: * - Is from a global file that is different from the reference file, or * - (optionally) Is a class, or is a this.x property access expression */ function isUncheckedJSSuggestion(node: Node | undefined, suggestion: Symbol | undefined, excludeClasses: boolean): boolean { const file = getSourceFileOfNode(node); if (file) { if (compilerOptions.checkJs === undefined && file.checkJsDirective === undefined && (file.scriptKind === ScriptKind.JS || file.scriptKind === ScriptKind.JSX)) { const declarationFile = forEach(suggestion?.declarations, getSourceFileOfNode); return !(file !== declarationFile && !!declarationFile && isGlobalSourceFile(declarationFile)) && !(excludeClasses && suggestion && suggestion.flags & SymbolFlags.Class) && !(!!node && excludeClasses && isPropertyAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword); } } return false; } function getFlowTypeOfAccessExpression(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol | undefined, propType: Type, errorNode: Node, checkMode: CheckMode | undefined) { // Only compute control flow type if this is a property access expression that isn't an // assignment target, and the referenced property was declared as a variable, property, // accessor, or optional method. const assignmentKind = getAssignmentTargetKind(node); if (assignmentKind === AssignmentKind.Definite) { return removeMissingType(propType, !!(prop && prop.flags & SymbolFlags.Optional)); } if (prop && !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) && !(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union) && !isDuplicatedCommonJSExport(prop.declarations)) { return propType; } if (propType === autoType) { return getFlowTypeOfProperty(node, prop); } propType = getNarrowableTypeForReference(propType, node, checkMode); // If strict null checks and strict property initialization checks are enabled, if we have // a this.xxx property access, if the property is an instance property without an initializer, // and if we are in a constructor of the same class as the property declaration, assume that // the property is uninitialized at the top of the control flow. let assumeUninitialized = false; if (strictNullChecks && strictPropertyInitialization && isAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword) { const declaration = prop && prop.valueDeclaration; if (declaration && isPropertyWithoutInitializer(declaration)) { if (!isStatic(declaration)) { const flowContainer = getControlFlowContainer(node); if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent && !(declaration.flags & NodeFlags.Ambient)) { assumeUninitialized = true; } } } } else if (strictNullChecks && prop && prop.valueDeclaration && isPropertyAccessExpression(prop.valueDeclaration) && getAssignmentDeclarationPropertyAccessKind(prop.valueDeclaration) && getControlFlowContainer(node) === getControlFlowContainer(prop.valueDeclaration)) { assumeUninitialized = true; } const flowType = getFlowTypeOfReference(node, propType, assumeUninitialized ? getOptionalType(propType) : propType); if (assumeUninitialized && !containsUndefinedType(propType) && containsUndefinedType(flowType)) { error(errorNode, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(prop!)); // TODO: GH#18217 // Return the declared type to reduce follow-on errors return propType; } return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; } function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier | PrivateIdentifier): void { const { valueDeclaration } = prop; if (!valueDeclaration || getSourceFileOfNode(node).isDeclarationFile) { return; } let diagnosticMessage; const declarationName = idText(right); if (isInPropertyInitializerOrClassStaticBlock(node) && !isOptionalPropertyDeclaration(valueDeclaration) && !(isAccessExpression(node) && isAccessExpression(node.expression)) && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) && !(isMethodDeclaration(valueDeclaration) && getCombinedModifierFlags(valueDeclaration) & ModifierFlags.Static) && (compilerOptions.useDefineForClassFields || !isPropertyDeclaredInAncestorClass(prop))) { diagnosticMessage = error(right, Diagnostics.Property_0_is_used_before_its_initialization, declarationName); } else if (valueDeclaration.kind === SyntaxKind.ClassDeclaration && node.parent.kind !== SyntaxKind.TypeReference && !(valueDeclaration.flags & NodeFlags.Ambient) && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right)) { diagnosticMessage = error(right, Diagnostics.Class_0_used_before_its_declaration, declarationName); } if (diagnosticMessage) { addRelatedInfo(diagnosticMessage, createDiagnosticForNode(valueDeclaration, Diagnostics._0_is_declared_here, declarationName) ); } } function isInPropertyInitializerOrClassStaticBlock(node: Node): boolean { return !!findAncestor(node, node => { switch (node.kind) { case SyntaxKind.PropertyDeclaration: return true; case SyntaxKind.PropertyAssignment: case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.SpreadAssignment: case SyntaxKind.ComputedPropertyName: case SyntaxKind.TemplateSpan: case SyntaxKind.JsxExpression: case SyntaxKind.JsxAttribute: case SyntaxKind.JsxAttributes: case SyntaxKind.JsxSpreadAttribute: case SyntaxKind.JsxOpeningElement: case SyntaxKind.ExpressionWithTypeArguments: case SyntaxKind.HeritageClause: return false; case SyntaxKind.ArrowFunction: case SyntaxKind.ExpressionStatement: return isBlock(node.parent) && isClassStaticBlockDeclaration(node.parent.parent) ? true : "quit"; default: return isExpressionNode(node) ? false : "quit"; } }); } /** * It's possible that "prop.valueDeclaration" is a local declaration, but the property was also declared in a superclass. * In that case we won't consider it used before its declaration, because it gets its value from the superclass' declaration. */ function isPropertyDeclaredInAncestorClass(prop: Symbol): boolean { if (!(prop.parent!.flags & SymbolFlags.Class)) { return false; } let classType: InterfaceType | undefined = getTypeOfSymbol(prop.parent!) as InterfaceType; while (true) { classType = classType.symbol && getSuperClass(classType) as InterfaceType | undefined; if (!classType) { return false; } const superProperty = getPropertyOfType(classType, prop.escapedName); if (superProperty && superProperty.valueDeclaration) { return true; } } } function getSuperClass(classType: InterfaceType): Type | undefined { const x = getBaseTypes(classType); if (x.length === 0) { return undefined; } return getIntersectionType(x); } function reportNonexistentProperty(propNode: Identifier | PrivateIdentifier, containingType: Type, isUncheckedJS: boolean) { let errorInfo: DiagnosticMessageChain | undefined; let relatedInfo: Diagnostic | undefined; if (!isPrivateIdentifier(propNode) && containingType.flags & TypeFlags.Union && !(containingType.flags & TypeFlags.Primitive)) { for (const subtype of (containingType as UnionType).types) { if (!getPropertyOfType(subtype, propNode.escapedText) && !getApplicableIndexInfoForName(subtype, propNode.escapedText)) { errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(subtype)); break; } } } if (typeHasStaticProperty(propNode.escapedText, containingType)) { const propName = declarationNameToString(propNode); const typeName = typeToString(containingType); errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName, typeName, typeName + "." + propName); } else { const promisedType = getPromisedTypeOfPromise(containingType); if (promisedType && getPropertyOfType(promisedType, propNode.escapedText)) { errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(containingType)); relatedInfo = createDiagnosticForNode(propNode, Diagnostics.Did_you_forget_to_use_await); } else { const missingProperty = declarationNameToString(propNode); const container = typeToString(containingType); const libSuggestion = getSuggestedLibForNonExistentProperty(missingProperty, containingType); if (libSuggestion !== undefined) { errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_2_or_later, missingProperty, container, libSuggestion); } else { const suggestion = getSuggestedSymbolForNonexistentProperty(propNode, containingType); if (suggestion !== undefined) { const suggestedName = symbolName(suggestion); const message = isUncheckedJS ? Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2 : Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2; errorInfo = chainDiagnosticMessages(errorInfo, message, missingProperty, container, suggestedName); relatedInfo = suggestion.valueDeclaration && createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestedName); } else { const diagnostic = containerSeemsToBeEmptyDomElement(containingType) ? Diagnostics.Property_0_does_not_exist_on_type_1_Try_changing_the_lib_compiler_option_to_include_dom : Diagnostics.Property_0_does_not_exist_on_type_1; errorInfo = chainDiagnosticMessages(elaborateNeverIntersection(errorInfo, containingType), diagnostic, missingProperty, container); } } } } const resultDiagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(propNode), propNode, errorInfo); if (relatedInfo) { addRelatedInfo(resultDiagnostic, relatedInfo); } addErrorOrSuggestion(!isUncheckedJS || errorInfo.code !== Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2.code, resultDiagnostic); } function containerSeemsToBeEmptyDomElement(containingType: Type) { return (compilerOptions.lib && !compilerOptions.lib.includes("dom")) && everyContainedType(containingType, type => type.symbol && /^(EventTarget|Node|((HTML[a-zA-Z]*)?Element))$/.test(unescapeLeadingUnderscores(type.symbol.escapedName))) && isEmptyObjectType(containingType); } function typeHasStaticProperty(propName: __String, containingType: Type): boolean { const prop = containingType.symbol && getPropertyOfType(getTypeOfSymbol(containingType.symbol), propName); return prop !== undefined && !!prop.valueDeclaration && isStatic(prop.valueDeclaration); } function getSuggestedLibForNonExistentName(name: __String | Identifier) { const missingName = diagnosticName(name); const allFeatures = getScriptTargetFeatures(); const typeFeatures = allFeatures.get(missingName); return typeFeatures && firstIterator(typeFeatures.keys()); } function getSuggestedLibForNonExistentProperty(missingProperty: string, containingType: Type) { const container = getApparentType(containingType).symbol; if (!container) { return undefined; } const containingTypeName = symbolName(container); const allFeatures = getScriptTargetFeatures(); const typeFeatures = allFeatures.get(containingTypeName); if (typeFeatures) { for (const [libTarget, featuresOfType] of typeFeatures) { if (contains(featuresOfType, missingProperty)) { return libTarget; } } } } function getSuggestedSymbolForNonexistentClassMember(name: string, baseType: Type): Symbol | undefined { return getSpellingSuggestionForName(name, getPropertiesOfType(baseType), SymbolFlags.ClassMember); } function getSuggestedSymbolForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { let props = getPropertiesOfType(containingType); if (typeof name !== "string") { const parent = name.parent; if (isPropertyAccessExpression(parent)) { props = filter(props, prop => isValidPropertyAccessForCompletions(parent, containingType, prop)); } name = idText(name); } return getSpellingSuggestionForName(name, props, SymbolFlags.Value); } function getSuggestedSymbolForNonexistentJSXAttribute(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { const strName = isString(name) ? name : idText(name); const properties = getPropertiesOfType(containingType); const jsxSpecific = strName === "for" ? find(properties, x => symbolName(x) === "htmlFor") : strName === "class" ? find(properties, x => symbolName(x) === "className") : undefined; return jsxSpecific ?? getSpellingSuggestionForName(strName, properties, SymbolFlags.Value); } function getSuggestionForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): string | undefined { const suggestion = getSuggestedSymbolForNonexistentProperty(name, containingType); return suggestion && symbolName(suggestion); } function getSuggestedSymbolForNonexistentSymbol(location: Node | undefined, outerName: __String, meaning: SymbolFlags): Symbol | undefined { Debug.assert(outerName !== undefined, "outername should always be defined"); const result = resolveNameHelper(location, outerName, meaning, /*nameNotFoundMessage*/ undefined, outerName, /*isUse*/ false, /*excludeGlobals*/ false, /*getSpellingSuggestions*/ true, (symbols, name, meaning) => { Debug.assertEqual(outerName, name, "name should equal outerName"); const symbol = getSymbol(symbols, name, meaning); // Sometimes the symbol is found when location is a return type of a function: `typeof x` and `x` is declared in the body of the function // So the table *contains* `x` but `x` isn't actually in scope. // However, resolveNameHelper will continue and call this callback again, so we'll eventually get a correct suggestion. if (symbol) return symbol; let candidates: Symbol[]; if (symbols === globals) { const primitives = mapDefined( ["string", "number", "boolean", "object", "bigint", "symbol"], s => symbols.has((s.charAt(0).toUpperCase() + s.slice(1)) as __String) ? createSymbol(SymbolFlags.TypeAlias, s as __String) as Symbol : undefined); candidates = primitives.concat(arrayFrom(symbols.values())); } else { candidates = arrayFrom(symbols.values()); } return getSpellingSuggestionForName(unescapeLeadingUnderscores(name), candidates, meaning); }); return result; } function getSuggestionForNonexistentSymbol(location: Node | undefined, outerName: __String, meaning: SymbolFlags): string | undefined { const symbolResult = getSuggestedSymbolForNonexistentSymbol(location, outerName, meaning); return symbolResult && symbolName(symbolResult); } function getSuggestedSymbolForNonexistentModule(name: Identifier, targetModule: Symbol): Symbol | undefined { return targetModule.exports && getSpellingSuggestionForName(idText(name), getExportsOfModuleAsArray(targetModule), SymbolFlags.ModuleMember); } function getSuggestionForNonexistentExport(name: Identifier, targetModule: Symbol): string | undefined { const suggestion = getSuggestedSymbolForNonexistentModule(name, targetModule); return suggestion && symbolName(suggestion); } function getSuggestionForNonexistentIndexSignature(objectType: Type, expr: ElementAccessExpression, keyedType: Type): string | undefined { // check if object type has setter or getter function hasProp(name: "set" | "get") { const prop = getPropertyOfObjectType(objectType, name as __String); if (prop) { const s = getSingleCallSignature(getTypeOfSymbol(prop)); return !!s && getMinArgumentCount(s) >= 1 && isTypeAssignableTo(keyedType, getTypeAtPosition(s, 0)); } return false; } const suggestedMethod = isAssignmentTarget(expr) ? "set" : "get"; if (!hasProp(suggestedMethod)) { return undefined; } let suggestion = tryGetPropertyAccessOrIdentifierToString(expr.expression); if (suggestion === undefined) { suggestion = suggestedMethod; } else { suggestion += "." + suggestedMethod; } return suggestion; } function getSuggestedTypeForNonexistentStringLiteralType(source: StringLiteralType, target: UnionType): StringLiteralType | undefined { const candidates = target.types.filter((type): type is StringLiteralType => !!(type.flags & TypeFlags.StringLiteral)); return getSpellingSuggestion(source.value, candidates, type => type.value); } /** * Given a name and a list of symbols whose names are *not* equal to the name, return a spelling suggestion if there is one that is close enough. * Names less than length 3 only check for case-insensitive equality, not levenshtein distance. * * If there is a candidate that's the same except for case, return that. * If there is a candidate that's within one edit of the name, return that. * Otherwise, return the candidate with the smallest Levenshtein distance, * except for candidates: * * With no name * * Whose meaning doesn't match the `meaning` parameter. * * Whose length differs from the target name by more than 0.34 of the length of the name. * * Whose levenshtein distance is more than 0.4 of the length of the name * (0.4 allows 1 substitution/transposition for every 5 characters, * and 1 insertion/deletion at 3 characters) */ function getSpellingSuggestionForName(name: string, symbols: Symbol[], meaning: SymbolFlags): Symbol | undefined { return getSpellingSuggestion(name, symbols, getCandidateName); function getCandidateName(candidate: Symbol) { const candidateName = symbolName(candidate); if (startsWith(candidateName, "\"")) { return undefined; } if (candidate.flags & meaning) { return candidateName; } if (candidate.flags & SymbolFlags.Alias) { const alias = tryResolveAlias(candidate); if (alias && alias.flags & meaning) { return candidateName; } } return undefined; } } function markPropertyAsReferenced(prop: Symbol, nodeForCheckWriteOnly: Node | undefined, isSelfTypeAccess: boolean) { const valueDeclaration = prop && (prop.flags & SymbolFlags.ClassMember) && prop.valueDeclaration; if (!valueDeclaration) { return; } const hasPrivateModifier = hasEffectiveModifier(valueDeclaration, ModifierFlags.Private); const hasPrivateIdentifier = prop.valueDeclaration && isNamedDeclaration(prop.valueDeclaration) && isPrivateIdentifier(prop.valueDeclaration.name); if (!hasPrivateModifier && !hasPrivateIdentifier) { return; } if (nodeForCheckWriteOnly && isWriteOnlyAccess(nodeForCheckWriteOnly) && !(prop.flags & SymbolFlags.SetAccessor)) { return; } if (isSelfTypeAccess) { // Find any FunctionLikeDeclaration because those create a new 'this' binding. But this should only matter for methods (or getters/setters). const containingMethod = findAncestor(nodeForCheckWriteOnly, isFunctionLikeDeclaration); if (containingMethod && containingMethod.symbol === prop) { return; } } (getCheckFlags(prop) & CheckFlags.Instantiated ? getSymbolLinks(prop).target : prop)!.isReferenced = SymbolFlags.All; } function isSelfTypeAccess(name: Expression | QualifiedName, parent: Symbol | undefined) { return name.kind === SyntaxKind.ThisKeyword || !!parent && isEntityNameExpression(name) && parent === getResolvedSymbol(getFirstIdentifier(name)); } function isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName | ImportTypeNode, propertyName: __String): boolean { switch (node.kind) { case SyntaxKind.PropertyAccessExpression: return isValidPropertyAccessWithType(node, node.expression.kind === SyntaxKind.SuperKeyword, propertyName, getWidenedType(checkExpression(node.expression))); case SyntaxKind.QualifiedName: return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getWidenedType(checkExpression(node.left))); case SyntaxKind.ImportType: return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getTypeFromTypeNode(node)); } } /** * Checks if an existing property access is valid for completions purposes. * @param node a property access-like node where we want to check if we can access a property. * This node does not need to be an access of the property we are checking. * e.g. in completions, this node will often be an incomplete property access node, as in `foo.`. * Besides providing a location (i.e. scope) used to check property accessibility, we use this node for * computing whether this is a `super` property access. * @param type the type whose property we are checking. * @param property the accessed property's symbol. */ function isValidPropertyAccessForCompletions(node: PropertyAccessExpression | ImportTypeNode | QualifiedName, type: Type, property: Symbol): boolean { return isPropertyAccessible(node, node.kind === SyntaxKind.PropertyAccessExpression && node.expression.kind === SyntaxKind.SuperKeyword, /* isWrite */ false, type, property); // Previously we validated the 'this' type of methods but this adversely affected performance. See #31377 for more context. } function isValidPropertyAccessWithType( node: PropertyAccessExpression | QualifiedName | ImportTypeNode, isSuper: boolean, propertyName: __String, type: Type): boolean { // Short-circuiting for improved performance. if (isTypeAny(type)) { return true; } const prop = getPropertyOfType(type, propertyName); return !!prop && isPropertyAccessible(node, isSuper, /* isWrite */ false, type, prop); } /** * Checks if a property can be accessed in a location. * The location is given by the `node` parameter. * The node does not need to be a property access. * @param node location where to check property accessibility * @param isSuper whether to consider this a `super` property access, e.g. `super.foo`. * @param isWrite whether this is a write access, e.g. `++foo.x`. * @param containingType type where the property comes from. * @param property property symbol. */ function isPropertyAccessible( node: Node, isSuper: boolean, isWrite: boolean, containingType: Type, property: Symbol): boolean { // Short-circuiting for improved performance. if (isTypeAny(containingType)) { return true; } // A #private property access in an optional chain is an error dealt with by the parser. // The checker does not check for it, so we need to do our own check here. if (property.valueDeclaration && isPrivateIdentifierClassElementDeclaration(property.valueDeclaration)) { const declClass = getContainingClass(property.valueDeclaration); return !isOptionalChain(node) && !!findAncestor(node, parent => parent === declClass); } return checkPropertyAccessibilityAtLocation(node, isSuper, isWrite, containingType, property); } /** * Return the symbol of the for-in variable declared or referenced by the given for-in statement. */ function getForInVariableSymbol(node: ForInStatement): Symbol | undefined { const initializer = node.initializer; if (initializer.kind === SyntaxKind.VariableDeclarationList) { const variable = (initializer as VariableDeclarationList).declarations[0]; if (variable && !isBindingPattern(variable.name)) { return getSymbolOfDeclaration(variable); } } else if (initializer.kind === SyntaxKind.Identifier) { return getResolvedSymbol(initializer as Identifier); } return undefined; } /** * Return true if the given type is considered to have numeric property names. */ function hasNumericPropertyNames(type: Type) { return getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, numberType); } /** * Return true if given node is an expression consisting of an identifier (possibly parenthesized) * that references a for-in variable for an object with numeric property names. */ function isForInVariableForNumericPropertyNames(expr: Expression) { const e = skipParentheses(expr); if (e.kind === SyntaxKind.Identifier) { const symbol = getResolvedSymbol(e as Identifier); if (symbol.flags & SymbolFlags.Variable) { let child: Node = expr; let node = expr.parent; while (node) { if (node.kind === SyntaxKind.ForInStatement && child === (node as ForInStatement).statement && getForInVariableSymbol(node as ForInStatement) === symbol && hasNumericPropertyNames(getTypeOfExpression((node as ForInStatement).expression))) { return true; } child = node; node = node.parent; } } } return false; } function checkIndexedAccess(node: ElementAccessExpression, checkMode: CheckMode | undefined): Type { return node.flags & NodeFlags.OptionalChain ? checkElementAccessChain(node as ElementAccessChain, checkMode) : checkElementAccessExpression(node, checkNonNullExpression(node.expression), checkMode); } function checkElementAccessChain(node: ElementAccessChain, checkMode: CheckMode | undefined) { const exprType = checkExpression(node.expression); const nonOptionalType = getOptionalExpressionType(exprType, node.expression); return propagateOptionalTypeMarker(checkElementAccessExpression(node, checkNonNullType(nonOptionalType, node.expression), checkMode), node, nonOptionalType !== exprType); } function checkElementAccessExpression(node: ElementAccessExpression, exprType: Type, checkMode: CheckMode | undefined): Type { const objectType = getAssignmentTargetKind(node) !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(exprType) : exprType; const indexExpression = node.argumentExpression; const indexType = checkExpression(indexExpression); if (isErrorType(objectType) || objectType === silentNeverType) { return objectType; } if (isConstEnumObjectType(objectType) && !isStringLiteralLike(indexExpression)) { error(indexExpression, Diagnostics.A_const_enum_member_can_only_be_accessed_using_a_string_literal); return errorType; } const effectiveIndexType = isForInVariableForNumericPropertyNames(indexExpression) ? numberType : indexType; const accessFlags = isAssignmentTarget(node) ? AccessFlags.Writing | (isGenericObjectType(objectType) && !isThisTypeParameter(objectType) ? AccessFlags.NoIndexSignatures : 0) : AccessFlags.ExpressionPosition; const indexedAccessType = getIndexedAccessTypeOrUndefined(objectType, effectiveIndexType, accessFlags, node) || errorType; return checkIndexedAccessIndexType(getFlowTypeOfAccessExpression(node, getNodeLinks(node).resolvedSymbol, indexedAccessType, indexExpression, checkMode), node); } function callLikeExpressionMayHaveTypeArguments(node: CallLikeExpression): node is CallExpression | NewExpression | TaggedTemplateExpression | JsxOpeningElement { return isCallOrNewExpression(node) || isTaggedTemplateExpression(node) || isJsxOpeningLikeElement(node); } function resolveUntypedCall(node: CallLikeExpression): Signature { if (callLikeExpressionMayHaveTypeArguments(node)) { // Check type arguments even though we will give an error that untyped calls may not accept type arguments. // This gets us diagnostics for the type arguments and marks them as referenced. forEach(node.typeArguments, checkSourceElement); } if (node.kind === SyntaxKind.TaggedTemplateExpression) { checkExpression(node.template); } else if (isJsxOpeningLikeElement(node)) { checkExpression(node.attributes); } else if (node.kind !== SyntaxKind.Decorator) { forEach((node as CallExpression).arguments, argument => { checkExpression(argument); }); } return anySignature; } function resolveErrorCall(node: CallLikeExpression): Signature { resolveUntypedCall(node); return unknownSignature; } // Re-order candidate signatures into the result array. Assumes the result array to be empty. // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order // A nit here is that we reorder only signatures that belong to the same symbol, // so order how inherited signatures are processed is still preserved. // interface A { (x: string): void } // interface B extends A { (x: 'foo'): string } // const b: B; // b('foo') // <- here overloads should be processed as [(x:'foo'): string, (x: string): void] function reorderCandidates(signatures: readonly Signature[], result: Signature[], callChainFlags: SignatureFlags): void { let lastParent: Node | undefined; let lastSymbol: Symbol | undefined; let cutoffIndex = 0; let index: number | undefined; let specializedIndex = -1; let spliceIndex: number; Debug.assert(!result.length); for (const signature of signatures) { const symbol = signature.declaration && getSymbolOfDeclaration(signature.declaration); const parent = signature.declaration && signature.declaration.parent; if (!lastSymbol || symbol === lastSymbol) { if (lastParent && parent === lastParent) { index = index! + 1; } else { lastParent = parent; index = cutoffIndex; } } else { // current declaration belongs to a different symbol // set cutoffIndex so re-orderings in the future won't change result set from 0 to cutoffIndex index = cutoffIndex = result.length; lastParent = parent; } lastSymbol = symbol; // specialized signatures always need to be placed before non-specialized signatures regardless // of the cutoff position; see GH#1133 if (signatureHasLiteralTypes(signature)) { specializedIndex++; spliceIndex = specializedIndex; // The cutoff index always needs to be greater than or equal to the specialized signature index // in order to prevent non-specialized signatures from being added before a specialized // signature. cutoffIndex++; } else { spliceIndex = index; } result.splice(spliceIndex, 0, callChainFlags ? getOptionalCallSignature(signature, callChainFlags) : signature); } } function isSpreadArgument(arg: Expression | undefined): arg is Expression { return !!arg && (arg.kind === SyntaxKind.SpreadElement || arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).isSpread); } function getSpreadArgumentIndex(args: readonly Expression[]): number { return findIndex(args, isSpreadArgument); } function acceptsVoid(t: Type): boolean { return !!(t.flags & TypeFlags.Void); } function acceptsVoidUndefinedUnknownOrAny(t: Type): boolean { return !!(t.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Unknown | TypeFlags.Any)); } function hasCorrectArity(node: CallLikeExpression, args: readonly Expression[], signature: Signature, signatureHelpTrailingComma = false) { let argCount: number; let callIsIncomplete = false; // In incomplete call we want to be lenient when we have too few arguments let effectiveParameterCount = getParameterCount(signature); let effectiveMinimumArguments = getMinArgumentCount(signature); if (node.kind === SyntaxKind.TaggedTemplateExpression) { argCount = args.length; if (node.template.kind === SyntaxKind.TemplateExpression) { // If a tagged template expression lacks a tail literal, the call is incomplete. // Specifically, a template only can end in a TemplateTail or a Missing literal. const lastSpan = last(node.template.templateSpans); // we should always have at least one span. callIsIncomplete = nodeIsMissing(lastSpan.literal) || !!lastSpan.literal.isUnterminated; } else { // If the template didn't end in a backtick, or its beginning occurred right prior to EOF, // then this might actually turn out to be a TemplateHead in the future; // so we consider the call to be incomplete. const templateLiteral = node.template as LiteralExpression; Debug.assert(templateLiteral.kind === SyntaxKind.NoSubstitutionTemplateLiteral); callIsIncomplete = !!templateLiteral.isUnterminated; } } else if (node.kind === SyntaxKind.Decorator) { argCount = getDecoratorArgumentCount(node, signature); } else if (isJsxOpeningLikeElement(node)) { callIsIncomplete = node.attributes.end === node.end; if (callIsIncomplete) { return true; } argCount = effectiveMinimumArguments === 0 ? args.length : 1; effectiveParameterCount = args.length === 0 ? effectiveParameterCount : 1; // class may have argumentless ctor functions - still resolve ctor and compare vs props member type effectiveMinimumArguments = Math.min(effectiveMinimumArguments, 1); // sfc may specify context argument - handled by framework and not typechecked } else if (!node.arguments) { // This only happens when we have something of the form: 'new C' Debug.assert(node.kind === SyntaxKind.NewExpression); return getMinArgumentCount(signature) === 0; } else { argCount = signatureHelpTrailingComma ? args.length + 1 : args.length; // If we are missing the close parenthesis, the call is incomplete. callIsIncomplete = node.arguments.end === node.end; // If a spread argument is present, check that it corresponds to a rest parameter or at least that it's in the valid range. const spreadArgIndex = getSpreadArgumentIndex(args); if (spreadArgIndex >= 0) { return spreadArgIndex >= getMinArgumentCount(signature) && (hasEffectiveRestParameter(signature) || spreadArgIndex < getParameterCount(signature)); } } // Too many arguments implies incorrect arity. if (!hasEffectiveRestParameter(signature) && argCount > effectiveParameterCount) { return false; } // If the call is incomplete, we should skip the lower bound check. // JSX signatures can have extra parameters provided by the library which we don't check if (callIsIncomplete || argCount >= effectiveMinimumArguments) { return true; } for (let i = argCount; i < effectiveMinimumArguments; i++) { const type = getTypeAtPosition(signature, i); if (filterType(type, isInJSFile(node) && !strictNullChecks ? acceptsVoidUndefinedUnknownOrAny : acceptsVoid).flags & TypeFlags.Never) { return false; } } return true; } function hasCorrectTypeArgumentArity(signature: Signature, typeArguments: NodeArray | undefined) { // If the user supplied type arguments, but the number of type arguments does not match // the declared number of type parameters, the call has an incorrect arity. const numTypeParameters = length(signature.typeParameters); const minTypeArgumentCount = getMinTypeArgumentCount(signature.typeParameters); return !some(typeArguments) || (typeArguments.length >= minTypeArgumentCount && typeArguments.length <= numTypeParameters); } // If type has a single call signature and no other members, return that signature. Otherwise, return undefined. function getSingleCallSignature(type: Type): Signature | undefined { return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false); } function getSingleCallOrConstructSignature(type: Type): Signature | undefined { return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false) || getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ false); } function getSingleSignature(type: Type, kind: SignatureKind, allowMembers: boolean): Signature | undefined { if (type.flags & TypeFlags.Object) { const resolved = resolveStructuredTypeMembers(type as ObjectType); if (allowMembers || resolved.properties.length === 0 && resolved.indexInfos.length === 0) { if (kind === SignatureKind.Call && resolved.callSignatures.length === 1 && resolved.constructSignatures.length === 0) { return resolved.callSignatures[0]; } if (kind === SignatureKind.Construct && resolved.constructSignatures.length === 1 && resolved.callSignatures.length === 0) { return resolved.constructSignatures[0]; } } } return undefined; } // Instantiate a generic signature in the context of a non-generic signature (section 3.8.5 in TypeScript spec) function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, inferenceContext?: InferenceContext, compareTypes?: TypeComparer): Signature { const context = createInferenceContext(signature.typeParameters!, signature, InferenceFlags.None, compareTypes); // We clone the inferenceContext to avoid fixing. For example, when the source signature is (x: T) => T[] and // the contextual signature is (...args: A) => B, we want to infer the element type of A's constraint (say 'any') // for T but leave it possible to later infer '[any]' back to A. const restType = getEffectiveRestType(contextualSignature); const mapper = inferenceContext && (restType && restType.flags & TypeFlags.TypeParameter ? inferenceContext.nonFixingMapper : inferenceContext.mapper); const sourceSignature = mapper ? instantiateSignature(contextualSignature, mapper) : contextualSignature; applyToParameterTypes(sourceSignature, signature, (source, target) => { // Type parameters from outer context referenced by source type are fixed by instantiation of the source type inferTypes(context.inferences, source, target); }); if (!inferenceContext) { applyToReturnTypes(contextualSignature, signature, (source, target) => { inferTypes(context.inferences, source, target, InferencePriority.ReturnType); }); } return getSignatureInstantiation(signature, getInferredTypes(context), isInJSFile(contextualSignature.declaration)); } function inferJsxTypeArguments(node: JsxOpeningLikeElement, signature: Signature, checkMode: CheckMode, context: InferenceContext): Type[] { const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); const checkAttrType = checkExpressionWithContextualType(node.attributes, paramType, context, checkMode); inferTypes(context.inferences, checkAttrType, paramType); return getInferredTypes(context); } function getThisArgumentType(thisArgumentNode: LeftHandSideExpression | undefined) { if (!thisArgumentNode) { return voidType; } const thisArgumentType = checkExpression(thisArgumentNode); return isOptionalChainRoot(thisArgumentNode.parent) ? getNonNullableType(thisArgumentType) : isOptionalChain(thisArgumentNode.parent) ? removeOptionalTypeMarker(thisArgumentType) : thisArgumentType; } function inferTypeArguments(node: CallLikeExpression, signature: Signature, args: readonly Expression[], checkMode: CheckMode, context: InferenceContext): Type[] { if (isJsxOpeningLikeElement(node)) { return inferJsxTypeArguments(node, signature, checkMode, context); } // If a contextual type is available, infer from that type to the return type of the call expression. For // example, given a 'function wrap(cb: (x: T) => U): (x: T) => U' and a call expression // 'let f: (x: string) => number = wrap(s => s.length)', we infer from the declared type of 'f' to the // return type of 'wrap'. if (node.kind !== SyntaxKind.Decorator) { const skipBindingPatterns = every(signature.typeParameters, p => !!getDefaultFromTypeParameter(p)); const contextualType = getContextualType(node, skipBindingPatterns ? ContextFlags.SkipBindingPatterns : ContextFlags.None); if (contextualType) { const inferenceTargetType = getReturnTypeOfSignature(signature); if (couldContainTypeVariables(inferenceTargetType)) { const outerContext = getInferenceContext(node); const isFromBindingPattern = !skipBindingPatterns && getContextualType(node, ContextFlags.SkipBindingPatterns) !== contextualType; // A return type inference from a binding pattern can be used in instantiating the contextual // type of an argument later in inference, but cannot stand on its own as the final return type. // It is incorporated into `context.returnMapper` which is used in `instantiateContextualType`, // but doesn't need to go into `context.inferences`. This allows a an array binding pattern to // produce a tuple for `T` in // declare function f(cb: () => T): T; // const [e1, e2, e3] = f(() => [1, "hi", true]); // but does not produce any inference for `T` in // declare function f(): T; // const [e1, e2, e3] = f(); if (!isFromBindingPattern) { // We clone the inference context to avoid disturbing a resolution in progress for an // outer call expression. Effectively we just want a snapshot of whatever has been // inferred for any outer call expression so far. const outerMapper = getMapperFromContext(cloneInferenceContext(outerContext, InferenceFlags.NoDefault)); const instantiatedType = instantiateType(contextualType, outerMapper); // If the contextual type is a generic function type with a single call signature, we // instantiate the type with its own type parameters and type arguments. This ensures that // the type parameters are not erased to type any during type inference such that they can // be inferred as actual types from the contextual type. For example: // declare function arrayMap(f: (x: T) => U): (a: T[]) => U[]; // const boxElements: (a: A[]) => { value: A }[] = arrayMap(value => ({ value })); // Above, the type of the 'value' parameter is inferred to be 'A'. const contextualSignature = getSingleCallSignature(instantiatedType); const inferenceSourceType = contextualSignature && contextualSignature.typeParameters ? getOrCreateTypeFromSignature(getSignatureInstantiationWithoutFillingInTypeArguments(contextualSignature, contextualSignature.typeParameters)) : instantiatedType; // Inferences made from return types have lower priority than all other inferences. inferTypes(context.inferences, inferenceSourceType, inferenceTargetType, InferencePriority.ReturnType); } // Create a type mapper for instantiating generic contextual types using the inferences made // from the return type. We need a separate inference pass here because (a) instantiation of // the source type uses the outer context's return mapper (which excludes inferences made from // outer arguments), and (b) we don't want any further inferences going into this context. const returnContext = createInferenceContext(signature.typeParameters!, signature, context.flags); const returnSourceType = instantiateType(contextualType, outerContext && outerContext.returnMapper); inferTypes(returnContext.inferences, returnSourceType, inferenceTargetType); context.returnMapper = some(returnContext.inferences, hasInferenceCandidates) ? getMapperFromContext(cloneInferredPartOfContext(returnContext)) : undefined; } } } const restType = getNonArrayRestType(signature); const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; if (restType && restType.flags & TypeFlags.TypeParameter) { const info = find(context.inferences, info => info.typeParameter === restType); if (info) { info.impliedArity = findIndex(args, isSpreadArgument, argCount) < 0 ? args.length - argCount : undefined; } } const thisType = getThisTypeOfSignature(signature); if (thisType && couldContainTypeVariables(thisType)) { const thisArgumentNode = getThisArgumentOfCall(node); inferTypes(context.inferences, getThisArgumentType(thisArgumentNode), thisType); } for (let i = 0; i < argCount; i++) { const arg = args[i]; if (arg.kind !== SyntaxKind.OmittedExpression && !(checkMode & CheckMode.IsForStringLiteralArgumentCompletions && hasSkipDirectInferenceFlag(arg))) { const paramType = getTypeAtPosition(signature, i); if (couldContainTypeVariables(paramType)) { const argType = checkExpressionWithContextualType(arg, paramType, context, checkMode); inferTypes(context.inferences, argType, paramType); } } } if (restType && couldContainTypeVariables(restType)) { const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, context, checkMode); inferTypes(context.inferences, spreadType, restType); } return getInferredTypes(context); } function getMutableArrayOrTupleType(type: Type) { return type.flags & TypeFlags.Union ? mapType(type, getMutableArrayOrTupleType) : type.flags & TypeFlags.Any || isMutableArrayOrTuple(getBaseConstraintOfType(type) || type) ? type : isTupleType(type) ? createTupleType(getTypeArguments(type), type.target.elementFlags, /*readonly*/ false, type.target.labeledElementDeclarations) : createTupleType([type], [ElementFlags.Variadic]); } function getSpreadArgumentType(args: readonly Expression[], index: number, argCount: number, restType: Type, context: InferenceContext | undefined, checkMode: CheckMode) { if (index >= argCount - 1) { const arg = args[argCount - 1]; if (isSpreadArgument(arg)) { // We are inferring from a spread expression in the last argument position, i.e. both the parameter // and the argument are ...x forms. return getMutableArrayOrTupleType(arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : checkExpressionWithContextualType((arg as SpreadElement).expression, restType, context, checkMode)); } } const types = []; const flags = []; const names = []; const inConstContext = isConstTypeVariable(restType); for (let i = index; i < argCount; i++) { const arg = args[i]; if (isSpreadArgument(arg)) { const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : checkExpression((arg as SpreadElement).expression); if (isArrayLikeType(spreadType)) { types.push(spreadType); flags.push(ElementFlags.Variadic); } else { types.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg)); flags.push(ElementFlags.Rest); } } else { const contextualType = getIndexedAccessType(restType, getNumberLiteralType(i - index), AccessFlags.Contextual); const argType = checkExpressionWithContextualType(arg, contextualType, context, checkMode); const hasPrimitiveContextualType = inConstContext || maybeTypeOfKind(contextualType, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); types.push(hasPrimitiveContextualType ? getRegularTypeOfLiteralType(argType) : getWidenedLiteralType(argType)); flags.push(ElementFlags.Required); } if (arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).tupleNameSource) { names.push((arg as SyntheticExpression).tupleNameSource!); } } return createTupleType(types, flags, inConstContext, length(names) === length(types) ? names : undefined); } function checkTypeArguments(signature: Signature, typeArgumentNodes: readonly TypeNode[], reportErrors: boolean, headMessage?: DiagnosticMessage): Type[] | undefined { const isJavascript = isInJSFile(signature.declaration); const typeParameters = signature.typeParameters!; const typeArgumentTypes = fillMissingTypeArguments(map(typeArgumentNodes, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isJavascript); let mapper: TypeMapper | undefined; for (let i = 0; i < typeArgumentNodes.length; i++) { Debug.assert(typeParameters[i] !== undefined, "Should not call checkTypeArguments with too many type arguments"); const constraint = getConstraintOfTypeParameter(typeParameters[i]); if (constraint) { const errorInfo = reportErrors && headMessage ? (() => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Type_0_does_not_satisfy_the_constraint_1)) : undefined; const typeArgumentHeadMessage = headMessage || Diagnostics.Type_0_does_not_satisfy_the_constraint_1; if (!mapper) { mapper = createTypeMapper(typeParameters, typeArgumentTypes); } const typeArgument = typeArgumentTypes[i]; if (!checkTypeAssignableTo( typeArgument, getTypeWithThisArgument(instantiateType(constraint, mapper), typeArgument), reportErrors ? typeArgumentNodes[i] : undefined, typeArgumentHeadMessage, errorInfo)) { return undefined; } } } return typeArgumentTypes; } function getJsxReferenceKind(node: JsxOpeningLikeElement): JsxReferenceKind { if (isJsxIntrinsicIdentifier(node.tagName)) { return JsxReferenceKind.Mixed; } const tagType = getApparentType(checkExpression(node.tagName)); if (length(getSignaturesOfType(tagType, SignatureKind.Construct))) { return JsxReferenceKind.Component; } if (length(getSignaturesOfType(tagType, SignatureKind.Call))) { return JsxReferenceKind.Function; } return JsxReferenceKind.Mixed; } /** * Check if the given signature can possibly be a signature called by the JSX opening-like element. * @param node a JSX opening-like element we are trying to figure its call signature * @param signature a candidate signature we are trying whether it is a call signature * @param relation a relationship to check parameter and argument type */ function checkApplicableSignatureForJsxOpeningLikeElement( node: JsxOpeningLikeElement, signature: Signature, relation: Map, checkMode: CheckMode, reportErrors: boolean, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } ) { // Stateless function components can have maximum of three arguments: "props", "context", and "updater". // However "context" and "updater" are implicit and can't be specify by users. Only the first parameter, props, // can be specified by users through attributes property. const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); const attributesType = checkExpressionWithContextualType(node.attributes, paramType, /*inferenceContext*/ undefined, checkMode); return checkTagNameDoesNotExpectTooManyArguments() && checkTypeRelatedToAndOptionallyElaborate( attributesType, paramType, relation, reportErrors ? node.tagName : undefined, node.attributes, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); function checkTagNameDoesNotExpectTooManyArguments(): boolean { if (getJsxNamespaceContainerForImplicitImport(node)) { return true; // factory is implicitly jsx/jsxdev - assume it fits the bill, since we don't strongly look for the jsx/jsxs/jsxDEV factory APIs anywhere else (at least not yet) } const tagType = isJsxOpeningElement(node) || isJsxSelfClosingElement(node) && !isJsxIntrinsicIdentifier(node.tagName) ? checkExpression(node.tagName) : undefined; if (!tagType) { return true; } const tagCallSignatures = getSignaturesOfType(tagType, SignatureKind.Call); if (!length(tagCallSignatures)) { return true; } const factory = getJsxFactoryEntity(node); if (!factory) { return true; } const factorySymbol = resolveEntityName(factory, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ false, node); if (!factorySymbol) { return true; } const factoryType = getTypeOfSymbol(factorySymbol); const callSignatures = getSignaturesOfType(factoryType, SignatureKind.Call); if (!length(callSignatures)) { return true; } let hasFirstParamSignatures = false; let maxParamCount = 0; // Check that _some_ first parameter expects a FC-like thing, and that some overload of the SFC expects an acceptable number of arguments for (const sig of callSignatures) { const firstparam = getTypeAtPosition(sig, 0); const signaturesOfParam = getSignaturesOfType(firstparam, SignatureKind.Call); if (!length(signaturesOfParam)) continue; for (const paramSig of signaturesOfParam) { hasFirstParamSignatures = true; if (hasEffectiveRestParameter(paramSig)) { return true; // some signature has a rest param, so function components can have an arbitrary number of arguments } const paramCount = getParameterCount(paramSig); if (paramCount > maxParamCount) { maxParamCount = paramCount; } } } if (!hasFirstParamSignatures) { // Not a single signature had a first parameter which expected a signature - for back compat, and // to guard against generic factories which won't have signatures directly, do not error return true; } let absoluteMinArgCount = Infinity; for (const tagSig of tagCallSignatures) { const tagRequiredArgCount = getMinArgumentCount(tagSig); if (tagRequiredArgCount < absoluteMinArgCount) { absoluteMinArgCount = tagRequiredArgCount; } } if (absoluteMinArgCount <= maxParamCount) { return true; // some signature accepts the number of arguments the function component provides } if (reportErrors) { const diag = createDiagnosticForNode(node.tagName, Diagnostics.Tag_0_expects_at_least_1_arguments_but_the_JSX_factory_2_provides_at_most_3, entityNameToString(node.tagName), absoluteMinArgCount, entityNameToString(factory), maxParamCount); const tagNameDeclaration = getSymbolAtLocation(node.tagName)?.valueDeclaration; if (tagNameDeclaration) { addRelatedInfo(diag, createDiagnosticForNode(tagNameDeclaration, Diagnostics._0_is_declared_here, entityNameToString(node.tagName))); } if (errorOutputContainer && errorOutputContainer.skipLogging) { (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); } if (!errorOutputContainer.skipLogging) { diagnostics.add(diag); } } return false; } } function getSignatureApplicabilityError( node: CallLikeExpression, args: readonly Expression[], signature: Signature, relation: Map, checkMode: CheckMode, reportErrors: boolean, containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, ): readonly Diagnostic[] | undefined { const errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } = { errors: undefined, skipLogging: true }; if (isJsxOpeningLikeElement(node)) { if (!checkApplicableSignatureForJsxOpeningLikeElement(node, signature, relation, checkMode, reportErrors, containingMessageChain, errorOutputContainer)) { Debug.assert(!reportErrors || !!errorOutputContainer.errors, "jsx should have errors when reporting errors"); return errorOutputContainer.errors || emptyArray; } return undefined; } const thisType = getThisTypeOfSignature(signature); if (thisType && thisType !== voidType && !(isNewExpression(node) || isCallExpression(node) && isSuperProperty(node.expression))) { // If the called expression is not of the form `x.f` or `x["f"]`, then sourceType = voidType // If the signature's 'this' type is voidType, then the check is skipped -- anything is compatible. // If the expression is a new expression or super call expression, then the check is skipped. const thisArgumentNode = getThisArgumentOfCall(node); const thisArgumentType = getThisArgumentType(thisArgumentNode); const errorNode = reportErrors ? (thisArgumentNode || node) : undefined; const headMessage = Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1; if (!checkTypeRelatedTo(thisArgumentType, thisType, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer)) { Debug.assert(!reportErrors || !!errorOutputContainer.errors, "this parameter should have errors when reporting errors"); return errorOutputContainer.errors || emptyArray; } } const headMessage = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1; const restType = getNonArrayRestType(signature); const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; for (let i = 0; i < argCount; i++) { const arg = args[i]; if (arg.kind !== SyntaxKind.OmittedExpression) { const paramType = getTypeAtPosition(signature, i); const argType = checkExpressionWithContextualType(arg, paramType, /*inferenceContext*/ undefined, checkMode); // If one or more arguments are still excluded (as indicated by CheckMode.SkipContextSensitive), // we obtain the regular type of any object literal arguments because we may not have inferred complete // parameter types yet and therefore excess property checks may yield false positives (see #17041). const checkArgType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(argType) : argType; if (!checkTypeRelatedToAndOptionallyElaborate(checkArgType, paramType, relation, reportErrors ? arg : undefined, arg, headMessage, containingMessageChain, errorOutputContainer)) { Debug.assert(!reportErrors || !!errorOutputContainer.errors, "parameter should have errors when reporting errors"); maybeAddMissingAwaitInfo(arg, checkArgType, paramType); return errorOutputContainer.errors || emptyArray; } } } if (restType) { const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, /*context*/ undefined, checkMode); const restArgCount = args.length - argCount; const errorNode = !reportErrors ? undefined : restArgCount === 0 ? node : restArgCount === 1 ? args[argCount] : setTextRangePosEnd(createSyntheticExpression(node, spreadType), args[argCount].pos, args[args.length - 1].end); if (!checkTypeRelatedTo(spreadType, restType, relation, errorNode, headMessage, /*containingMessageChain*/ undefined, errorOutputContainer)) { Debug.assert(!reportErrors || !!errorOutputContainer.errors, "rest parameter should have errors when reporting errors"); maybeAddMissingAwaitInfo(errorNode, spreadType, restType); return errorOutputContainer.errors || emptyArray; } } return undefined; function maybeAddMissingAwaitInfo(errorNode: Node | undefined, source: Type, target: Type) { if (errorNode && reportErrors && errorOutputContainer.errors && errorOutputContainer.errors.length) { // Bail if target is Promise-like---something else is wrong if (getAwaitedTypeOfPromise(target)) { return; } const awaitedTypeOfSource = getAwaitedTypeOfPromise(source); if (awaitedTypeOfSource && isTypeRelatedTo(awaitedTypeOfSource, target, relation)) { addRelatedInfo(errorOutputContainer.errors[0], createDiagnosticForNode(errorNode, Diagnostics.Did_you_forget_to_use_await)); } } } } /** * Returns the this argument in calls like x.f(...) and x[f](...). Undefined otherwise. */ function getThisArgumentOfCall(node: CallLikeExpression): LeftHandSideExpression | undefined { const expression = node.kind === SyntaxKind.CallExpression ? node.expression : node.kind === SyntaxKind.TaggedTemplateExpression ? node.tag : undefined; if (expression) { const callee = skipOuterExpressions(expression); if (isAccessExpression(callee)) { return callee.expression; } } } function createSyntheticExpression(parent: Node, type: Type, isSpread?: boolean, tupleNameSource?: ParameterDeclaration | NamedTupleMember) { const result = parseNodeFactory.createSyntheticExpression(type, isSpread, tupleNameSource); setTextRange(result, parent); setParent(result, parent); return result; } /** * Returns the effective arguments for an expression that works like a function invocation. */ function getEffectiveCallArguments(node: CallLikeExpression): readonly Expression[] { if (node.kind === SyntaxKind.TaggedTemplateExpression) { const template = node.template; const args: Expression[] = [createSyntheticExpression(template, getGlobalTemplateStringsArrayType())]; if (template.kind === SyntaxKind.TemplateExpression) { forEach(template.templateSpans, span => { args.push(span.expression); }); } return args; } if (node.kind === SyntaxKind.Decorator) { return getEffectiveDecoratorArguments(node); } if (isJsxOpeningLikeElement(node)) { return node.attributes.properties.length > 0 || (isJsxOpeningElement(node) && node.parent.children.length > 0) ? [node.attributes] : emptyArray; } const args = node.arguments || emptyArray; const spreadIndex = getSpreadArgumentIndex(args); if (spreadIndex >= 0) { // Create synthetic arguments from spreads of tuple types. const effectiveArgs = args.slice(0, spreadIndex); for (let i = spreadIndex; i < args.length; i++) { const arg = args[i]; // We can call checkExpressionCached because spread expressions never have a contextual type. const spreadType = arg.kind === SyntaxKind.SpreadElement && (flowLoopCount ? checkExpression((arg as SpreadElement).expression) : checkExpressionCached((arg as SpreadElement).expression)); if (spreadType && isTupleType(spreadType)) { forEach(getTypeArguments(spreadType), (t, i) => { const flags = spreadType.target.elementFlags[i]; const syntheticArg = createSyntheticExpression(arg, flags & ElementFlags.Rest ? createArrayType(t) : t, !!(flags & ElementFlags.Variable), spreadType.target.labeledElementDeclarations?.[i]); effectiveArgs.push(syntheticArg); }); } else { effectiveArgs.push(arg); } } return effectiveArgs; } return args; } /** * Returns the synthetic argument list for a decorator invocation. */ function getEffectiveDecoratorArguments(node: Decorator): readonly Expression[] { const expr = node.expression; const signature = getDecoratorCallSignature(node); if (signature) { const args: Expression[] = []; for (const param of signature.parameters) { const type = getTypeOfSymbol(param); args.push(createSyntheticExpression(expr, type)); } return args; } return Debug.fail(); } /** * Returns the argument count for a decorator node that works like a function invocation. */ function getDecoratorArgumentCount(node: Decorator, signature: Signature) { return compilerOptions.experimentalDecorators ? getLegacyDecoratorArgumentCount(node, signature) : 2; } /** * Returns the argument count for a decorator node that works like a function invocation. */ function getLegacyDecoratorArgumentCount(node: Decorator, signature: Signature) { switch (node.parent.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: return 1; case SyntaxKind.PropertyDeclaration: return hasAccessorModifier(node.parent) ? 3 : 2; case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: // For ES3 or decorators with only two parameters we supply only two arguments return languageVersion === ScriptTarget.ES3 || signature.parameters.length <= 2 ? 2 : 3; case SyntaxKind.Parameter: return 3; default: return Debug.fail(); } } function getDiagnosticSpanForCallNode(node: CallExpression, doNotIncludeArguments?: boolean) { let start: number; let length: number; const sourceFile = getSourceFileOfNode(node); if (isPropertyAccessExpression(node.expression)) { const nameSpan = getErrorSpanForNode(sourceFile, node.expression.name); start = nameSpan.start; length = doNotIncludeArguments ? nameSpan.length : node.end - start; } else { const expressionSpan = getErrorSpanForNode(sourceFile, node.expression); start = expressionSpan.start; length = doNotIncludeArguments ? expressionSpan.length : node.end - start; } return { start, length, sourceFile }; } function getDiagnosticForCallNode(node: CallLikeExpression, message: DiagnosticMessage | DiagnosticMessageChain, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): DiagnosticWithLocation { if (isCallExpression(node)) { const { sourceFile, start, length } = getDiagnosticSpanForCallNode(node); if ("message" in message) { // eslint-disable-line local/no-in-operator return createFileDiagnostic(sourceFile, start, length, message, arg0, arg1, arg2, arg3); } return createDiagnosticForFileFromMessageChain(sourceFile, message); } else { if ("message" in message) { // eslint-disable-line local/no-in-operator return createDiagnosticForNode(node, message, arg0, arg1, arg2, arg3); } return createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), node, message); } } function isPromiseResolveArityError(node: CallLikeExpression) { if (!isCallExpression(node) || !isIdentifier(node.expression)) return false; const symbol = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, undefined, undefined, false); const decl = symbol?.valueDeclaration; if (!decl || !isParameter(decl) || !isFunctionExpressionOrArrowFunction(decl.parent) || !isNewExpression(decl.parent.parent) || !isIdentifier(decl.parent.parent.expression)) { return false; } const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); if (!globalPromiseSymbol) return false; const constructorSymbol = getSymbolAtLocation(decl.parent.parent.expression, /*ignoreErrors*/ true); return constructorSymbol === globalPromiseSymbol; } function getArgumentArityError(node: CallLikeExpression, signatures: readonly Signature[], args: readonly Expression[], headMessage?: DiagnosticMessage) { const spreadIndex = getSpreadArgumentIndex(args); if (spreadIndex > -1) { return createDiagnosticForNode(args[spreadIndex], Diagnostics.A_spread_argument_must_either_have_a_tuple_type_or_be_passed_to_a_rest_parameter); } let min = Number.POSITIVE_INFINITY; // smallest parameter count let max = Number.NEGATIVE_INFINITY; // largest parameter count let maxBelow = Number.NEGATIVE_INFINITY; // largest parameter count that is smaller than the number of arguments let minAbove = Number.POSITIVE_INFINITY; // smallest parameter count that is larger than the number of arguments let closestSignature: Signature | undefined; for (const sig of signatures) { const minParameter = getMinArgumentCount(sig); const maxParameter = getParameterCount(sig); // smallest/largest parameter counts if (minParameter < min) { min = minParameter; closestSignature = sig; } max = Math.max(max, maxParameter); // shortest parameter count *longer than the call*/longest parameter count *shorter than the call* if (minParameter < args.length && minParameter > maxBelow) maxBelow = minParameter; if (args.length < maxParameter && maxParameter < minAbove) minAbove = maxParameter; } const hasRestParameter = some(signatures, hasEffectiveRestParameter); const parameterRange = hasRestParameter ? min : min < max ? min + "-" + max : min; const isVoidPromiseError = !hasRestParameter && parameterRange === 1 && args.length === 0 && isPromiseResolveArityError(node); if (isVoidPromiseError && isInJSFile(node)) { return getDiagnosticForCallNode(node, Diagnostics.Expected_1_argument_but_got_0_new_Promise_needs_a_JSDoc_hint_to_produce_a_resolve_that_can_be_called_without_arguments); } const error = isDecorator(node) ? hasRestParameter ? Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_at_least_0 : Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_0 : hasRestParameter ? Diagnostics.Expected_at_least_0_arguments_but_got_1 : isVoidPromiseError ? Diagnostics.Expected_0_arguments_but_got_1_Did_you_forget_to_include_void_in_your_type_argument_to_Promise : Diagnostics.Expected_0_arguments_but_got_1; if (min < args.length && args.length < max) { // between min and max, but with no matching overload if (headMessage) { let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); chain = chainDiagnosticMessages(chain, headMessage); return getDiagnosticForCallNode(node, chain); } return getDiagnosticForCallNode(node, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); } else if (args.length < min) { // too short: put the error span on the call expression, not any of the args let diagnostic: Diagnostic; if (headMessage) { let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); chain = chainDiagnosticMessages(chain, headMessage); diagnostic = getDiagnosticForCallNode(node, chain); } else { diagnostic = getDiagnosticForCallNode(node, error, parameterRange, args.length); } const parameter = closestSignature?.declaration?.parameters[closestSignature.thisParameter ? args.length + 1 : args.length]; if (parameter) { const parameterError = createDiagnosticForNode( parameter, isBindingPattern(parameter.name) ? Diagnostics.An_argument_matching_this_binding_pattern_was_not_provided : isRestParameter(parameter) ? Diagnostics.Arguments_for_the_rest_parameter_0_were_not_provided : Diagnostics.An_argument_for_0_was_not_provided, !parameter.name ? args.length : !isBindingPattern(parameter.name) ? idText(getFirstIdentifier(parameter.name)) : undefined ); return addRelatedInfo(diagnostic, parameterError); } return diagnostic; } else { // too long; error goes on the excess parameters const errorSpan = factory.createNodeArray(args.slice(max)); const pos = first(errorSpan).pos; let end = last(errorSpan).end; if (end === pos) { end++; } setTextRangePosEnd(errorSpan, pos, end); if (headMessage) { let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); chain = chainDiagnosticMessages(chain, headMessage); return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), errorSpan, chain); } return createDiagnosticForNodeArray(getSourceFileOfNode(node), errorSpan, error, parameterRange, args.length); } } function getTypeArgumentArityError(node: Node, signatures: readonly Signature[], typeArguments: NodeArray, headMessage?: DiagnosticMessage) { const argCount = typeArguments.length; // No overloads exist if (signatures.length === 1) { const sig = signatures[0]; const min = getMinTypeArgumentCount(sig.typeParameters); const max = length(sig.typeParameters); if (headMessage) { let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min , argCount); chain = chainDiagnosticMessages(chain, headMessage); return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); } return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min , argCount); } // Overloads exist let belowArgCount = -Infinity; let aboveArgCount = Infinity; for (const sig of signatures) { const min = getMinTypeArgumentCount(sig.typeParameters); const max = length(sig.typeParameters); if (min > argCount) { aboveArgCount = Math.min(aboveArgCount, min); } else if (max < argCount) { belowArgCount = Math.max(belowArgCount, max); } } if (belowArgCount !== -Infinity && aboveArgCount !== Infinity) { if (headMessage) { let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); chain = chainDiagnosticMessages(chain, headMessage); return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); } return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); } if (headMessage) { let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); chain = chainDiagnosticMessages(chain, headMessage); return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); } return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); } function resolveCall(node: CallLikeExpression, signatures: readonly Signature[], candidatesOutArray: Signature[] | undefined, checkMode: CheckMode, callChainFlags: SignatureFlags, headMessage?: DiagnosticMessage): Signature { const isTaggedTemplate = node.kind === SyntaxKind.TaggedTemplateExpression; const isDecorator = node.kind === SyntaxKind.Decorator; const isJsxOpeningOrSelfClosingElement = isJsxOpeningLikeElement(node); const reportErrors = !isInferencePartiallyBlocked && !candidatesOutArray; let typeArguments: NodeArray | undefined; if (!isDecorator && !isSuperCall(node)) { typeArguments = (node as CallExpression).typeArguments; // We already perform checking on the type arguments on the class declaration itself. if (isTaggedTemplate || isJsxOpeningOrSelfClosingElement || (node as CallExpression).expression.kind !== SyntaxKind.SuperKeyword) { forEach(typeArguments, checkSourceElement); } } const candidates = candidatesOutArray || []; // reorderCandidates fills up the candidates array directly reorderCandidates(signatures, candidates, callChainFlags); if (!candidates.length) { if (reportErrors) { diagnostics.add(getDiagnosticForCallNode(node, Diagnostics.Call_target_does_not_contain_any_signatures)); } return resolveErrorCall(node); } const args = getEffectiveCallArguments(node); // The excludeArgument array contains true for each context sensitive argument (an argument // is context sensitive it is susceptible to a one-time permanent contextual typing). // // The idea is that we will perform type argument inference & assignability checking once // without using the susceptible parameters that are functions, and once more for those // parameters, contextually typing each as we go along. // // For a tagged template, then the first argument be 'undefined' if necessary because it // represents a TemplateStringsArray. // // For a decorator, no arguments are susceptible to contextual typing due to the fact // decorators are applied to a declaration by the emitter, and not to an expression. const isSingleNonGenericCandidate = candidates.length === 1 && !candidates[0].typeParameters; let argCheckMode = !isDecorator && !isSingleNonGenericCandidate && some(args, isContextSensitive) ? CheckMode.SkipContextSensitive : CheckMode.Normal; argCheckMode |= checkMode & CheckMode.IsForStringLiteralArgumentCompletions; // The following variables are captured and modified by calls to chooseOverload. // If overload resolution or type argument inference fails, we want to report the // best error possible. The best error is one which says that an argument was not // assignable to a parameter. This implies that everything else about the overload // was fine. So if there is any overload that is only incorrect because of an // argument, we will report an error on that one. // // function foo(s: string): void; // function foo(n: number): void; // Report argument error on this overload // function foo(): void; // foo(true); // // If none of the overloads even made it that far, there are two possibilities. // There was a problem with type arguments for some overload, in which case // report an error on that. Or none of the overloads even had correct arity, // in which case give an arity error. // // function foo(x: T): void; // Report type argument error // function foo(): void; // foo(0); // let candidatesForArgumentError: Signature[] | undefined; let candidateForArgumentArityError: Signature | undefined; let candidateForTypeArgumentError: Signature | undefined; let result: Signature | undefined; // If we are in signature help, a trailing comma indicates that we intend to provide another argument, // so we will only accept overloads with arity at least 1 higher than the current number of provided arguments. const signatureHelpTrailingComma = !!(checkMode & CheckMode.IsForSignatureHelp) && node.kind === SyntaxKind.CallExpression && node.arguments.hasTrailingComma; // Section 4.12.1: // if the candidate list contains one or more signatures for which the type of each argument // expression is a subtype of each corresponding parameter type, the return type of the first // of those signatures becomes the return type of the function call. // Otherwise, the return type of the first signature in the candidate list becomes the return // type of the function call. // // Whether the call is an error is determined by assignability of the arguments. The subtype pass // is just important for choosing the best signature. So in the case where there is only one // signature, the subtype pass is useless. So skipping it is an optimization. if (candidates.length > 1) { result = chooseOverload(candidates, subtypeRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); } if (!result) { result = chooseOverload(candidates, assignableRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); } if (result) { return result; } result = getCandidateForOverloadFailure(node, candidates, args, !!candidatesOutArray, checkMode); // Preemptively cache the result; getResolvedSignature will do this after we return, but // we need to ensure that the result is present for the error checks below so that if // this signature is encountered again, we handle the circularity (rather than producing a // different result which may produce no errors and assert). Callers of getResolvedSignature // don't hit this issue because they only observe this result after it's had a chance to // be cached, but the error reporting code below executes before getResolvedSignature sets // resolvedSignature. getNodeLinks(node).resolvedSignature = result; // No signatures were applicable. Now report errors based on the last applicable signature with // no arguments excluded from assignability checks. // If candidate is undefined, it means that no candidates had a suitable arity. In that case, // skip the checkApplicableSignature check. if (reportErrors) { if (candidatesForArgumentError) { if (candidatesForArgumentError.length === 1 || candidatesForArgumentError.length > 3) { const last = candidatesForArgumentError[candidatesForArgumentError.length - 1]; let chain: DiagnosticMessageChain | undefined; if (candidatesForArgumentError.length > 3) { chain = chainDiagnosticMessages(chain, Diagnostics.The_last_overload_gave_the_following_error); chain = chainDiagnosticMessages(chain, Diagnostics.No_overload_matches_this_call); } if (headMessage) { chain = chainDiagnosticMessages(chain, headMessage); } const diags = getSignatureApplicabilityError(node, args, last, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, () => chain); if (diags) { for (const d of diags) { if (last.declaration && candidatesForArgumentError.length > 3) { addRelatedInfo(d, createDiagnosticForNode(last.declaration, Diagnostics.The_last_overload_is_declared_here)); } addImplementationSuccessElaboration(last, d); diagnostics.add(d); } } else { Debug.fail("No error for last overload signature"); } } else { const allDiagnostics: (readonly DiagnosticRelatedInformation[])[] = []; let max = 0; let min = Number.MAX_VALUE; let minIndex = 0; let i = 0; for (const c of candidatesForArgumentError) { const chain = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Overload_0_of_1_2_gave_the_following_error, i + 1, candidates.length, signatureToString(c)); const diags = getSignatureApplicabilityError(node, args, c, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, chain); if (diags) { if (diags.length <= min) { min = diags.length; minIndex = i; } max = Math.max(max, diags.length); allDiagnostics.push(diags); } else { Debug.fail("No error for 3 or fewer overload signatures"); } i++; } const diags = max > 1 ? allDiagnostics[minIndex] : flatten(allDiagnostics); Debug.assert(diags.length > 0, "No errors reported for 3 or fewer overload signatures"); let chain = chainDiagnosticMessages( map(diags, createDiagnosticMessageChainFromDiagnostic), Diagnostics.No_overload_matches_this_call); if (headMessage) { chain = chainDiagnosticMessages(chain, headMessage); } // The below is a spread to guarantee we get a new (mutable) array - our `flatMap` helper tries to do "smart" optimizations where it reuses input // arrays and the emptyArray singleton where possible, which is decidedly not what we want while we're still constructing this diagnostic const related = [...flatMap(diags, d => (d as Diagnostic).relatedInformation) as DiagnosticRelatedInformation[]]; let diag: Diagnostic; if (every(diags, d => d.start === diags[0].start && d.length === diags[0].length && d.file === diags[0].file)) { const { file, start, length } = diags[0]; diag = { file, start, length, code: chain.code, category: chain.category, messageText: chain, relatedInformation: related }; } else { diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), node, chain, related); } addImplementationSuccessElaboration(candidatesForArgumentError[0], diag); diagnostics.add(diag); } } else if (candidateForArgumentArityError) { diagnostics.add(getArgumentArityError(node, [candidateForArgumentArityError], args, headMessage)); } else if (candidateForTypeArgumentError) { checkTypeArguments(candidateForTypeArgumentError, (node as CallExpression | TaggedTemplateExpression | JsxOpeningLikeElement).typeArguments!, /*reportErrors*/ true, headMessage); } else { const signaturesWithCorrectTypeArgumentArity = filter(signatures, s => hasCorrectTypeArgumentArity(s, typeArguments)); if (signaturesWithCorrectTypeArgumentArity.length === 0) { diagnostics.add(getTypeArgumentArityError(node, signatures, typeArguments!, headMessage)); } else { diagnostics.add(getArgumentArityError(node, signaturesWithCorrectTypeArgumentArity, args, headMessage)); } } } return result; function addImplementationSuccessElaboration(failed: Signature, diagnostic: Diagnostic) { const oldCandidatesForArgumentError = candidatesForArgumentError; const oldCandidateForArgumentArityError = candidateForArgumentArityError; const oldCandidateForTypeArgumentError = candidateForTypeArgumentError; const failedSignatureDeclarations = failed.declaration?.symbol?.declarations || emptyArray; const isOverload = failedSignatureDeclarations.length > 1; const implDecl = isOverload ? find(failedSignatureDeclarations, d => isFunctionLikeDeclaration(d) && nodeIsPresent(d.body)) : undefined; if (implDecl) { const candidate = getSignatureFromDeclaration(implDecl as FunctionLikeDeclaration); const isSingleNonGenericCandidate = !candidate.typeParameters; if (chooseOverload([candidate], assignableRelation, isSingleNonGenericCandidate)) { addRelatedInfo(diagnostic, createDiagnosticForNode(implDecl, Diagnostics.The_call_would_have_succeeded_against_this_implementation_but_implementation_signatures_of_overloads_are_not_externally_visible)); } } candidatesForArgumentError = oldCandidatesForArgumentError; candidateForArgumentArityError = oldCandidateForArgumentArityError; candidateForTypeArgumentError = oldCandidateForTypeArgumentError; } function chooseOverload(candidates: Signature[], relation: Map, isSingleNonGenericCandidate: boolean, signatureHelpTrailingComma = false) { candidatesForArgumentError = undefined; candidateForArgumentArityError = undefined; candidateForTypeArgumentError = undefined; if (isSingleNonGenericCandidate) { const candidate = candidates[0]; if (some(typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { return undefined; } if (getSignatureApplicabilityError(node, args, candidate, relation, CheckMode.Normal, /*reportErrors*/ false, /*containingMessageChain*/ undefined)) { candidatesForArgumentError = [candidate]; return undefined; } return candidate; } for (let candidateIndex = 0; candidateIndex < candidates.length; candidateIndex++) { const candidate = candidates[candidateIndex]; if (!hasCorrectTypeArgumentArity(candidate, typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { continue; } let checkCandidate: Signature; let inferenceContext: InferenceContext | undefined; if (candidate.typeParameters) { let typeArgumentTypes: Type[] | undefined; if (some(typeArguments)) { typeArgumentTypes = checkTypeArguments(candidate, typeArguments, /*reportErrors*/ false); if (!typeArgumentTypes) { candidateForTypeArgumentError = candidate; continue; } } else { inferenceContext = createInferenceContext(candidate.typeParameters, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); typeArgumentTypes = inferTypeArguments(node, candidate, args, argCheckMode | CheckMode.SkipGenericFunctions, inferenceContext); argCheckMode |= inferenceContext.flags & InferenceFlags.SkippedGenericFunction ? CheckMode.SkipGenericFunctions : CheckMode.Normal; } checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext && inferenceContext.inferredTypeParameters); // If the original signature has a generic rest type, instantiation may produce a // signature with different arity and we need to perform another arity check. if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { candidateForArgumentArityError = checkCandidate; continue; } } else { checkCandidate = candidate; } if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined)) { // Give preference to error candidates that have no rest parameters (as they are more specific) (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); continue; } if (argCheckMode) { // If one or more context sensitive arguments were excluded, we start including // them now (and keeping do so for any subsequent candidates) and perform a second // round of type inference and applicability checking for this particular candidate. argCheckMode = checkMode & CheckMode.IsForStringLiteralArgumentCompletions; if (inferenceContext) { const typeArgumentTypes = inferTypeArguments(node, candidate, args, argCheckMode, inferenceContext); checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext.inferredTypeParameters); // If the original signature has a generic rest type, instantiation may produce a // signature with different arity and we need to perform another arity check. if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { candidateForArgumentArityError = checkCandidate; continue; } } if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined)) { // Give preference to error candidates that have no rest parameters (as they are more specific) (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); continue; } } candidates[candidateIndex] = checkCandidate; return checkCandidate; } return undefined; } } // No signature was applicable. We have already reported the errors for the invalid signature. function getCandidateForOverloadFailure( node: CallLikeExpression, candidates: Signature[], args: readonly Expression[], hasCandidatesOutArray: boolean, checkMode: CheckMode, ): Signature { Debug.assert(candidates.length > 0); // Else should not have called this. checkNodeDeferred(node); // Normally we will combine overloads. Skip this if they have type parameters since that's hard to combine. // Don't do this if there is a `candidatesOutArray`, // because then we want the chosen best candidate to be one of the overloads, not a combination. return hasCandidatesOutArray || candidates.length === 1 || candidates.some(c => !!c.typeParameters) ? pickLongestCandidateSignature(node, candidates, args, checkMode) : createUnionOfSignaturesForOverloadFailure(candidates); } function createUnionOfSignaturesForOverloadFailure(candidates: readonly Signature[]): Signature { const thisParameters = mapDefined(candidates, c => c.thisParameter); let thisParameter: Symbol | undefined; if (thisParameters.length) { thisParameter = createCombinedSymbolFromTypes(thisParameters, thisParameters.map(getTypeOfParameter)); } const { min: minArgumentCount, max: maxNonRestParam } = minAndMax(candidates, getNumNonRestParameters); const parameters: Symbol[] = []; for (let i = 0; i < maxNonRestParam; i++) { const symbols = mapDefined(candidates, s => signatureHasRestParameter(s) ? i < s.parameters.length - 1 ? s.parameters[i] : last(s.parameters) : i < s.parameters.length ? s.parameters[i] : undefined); Debug.assert(symbols.length !== 0); parameters.push(createCombinedSymbolFromTypes(symbols, mapDefined(candidates, candidate => tryGetTypeAtPosition(candidate, i)))); } const restParameterSymbols = mapDefined(candidates, c => signatureHasRestParameter(c) ? last(c.parameters) : undefined); let flags = SignatureFlags.None; if (restParameterSymbols.length !== 0) { const type = createArrayType(getUnionType(mapDefined(candidates, tryGetRestTypeOfSignature), UnionReduction.Subtype)); parameters.push(createCombinedSymbolForOverloadFailure(restParameterSymbols, type)); flags |= SignatureFlags.HasRestParameter; } if (candidates.some(signatureHasLiteralTypes)) { flags |= SignatureFlags.HasLiteralTypes; } return createSignature( candidates[0].declaration, /*typeParameters*/ undefined, // Before calling this we tested for `!candidates.some(c => !!c.typeParameters)`. thisParameter, parameters, /*resolvedReturnType*/ getIntersectionType(candidates.map(getReturnTypeOfSignature)), /*typePredicate*/ undefined, minArgumentCount, flags); } function getNumNonRestParameters(signature: Signature): number { const numParams = signature.parameters.length; return signatureHasRestParameter(signature) ? numParams - 1 : numParams; } function createCombinedSymbolFromTypes(sources: readonly Symbol[], types: Type[]): Symbol { return createCombinedSymbolForOverloadFailure(sources, getUnionType(types, UnionReduction.Subtype)); } function createCombinedSymbolForOverloadFailure(sources: readonly Symbol[], type: Type): Symbol { // This function is currently only used for erroneous overloads, so it's good enough to just use the first source. return createSymbolWithType(first(sources), type); } function pickLongestCandidateSignature(node: CallLikeExpression, candidates: Signature[], args: readonly Expression[], checkMode: CheckMode): Signature { // Pick the longest signature. This way we can get a contextual type for cases like: // declare function f(a: { xa: number; xb: number; }, b: number); // f({ | // Also, use explicitly-supplied type arguments if they are provided, so we can get a contextual signature in cases like: // declare function f(k: keyof T); // f(" const bestIndex = getLongestCandidateIndex(candidates, apparentArgumentCount === undefined ? args.length : apparentArgumentCount); const candidate = candidates[bestIndex]; const { typeParameters } = candidate; if (!typeParameters) { return candidate; } const typeArgumentNodes: readonly TypeNode[] | undefined = callLikeExpressionMayHaveTypeArguments(node) ? node.typeArguments : undefined; const instantiated = typeArgumentNodes ? createSignatureInstantiation(candidate, getTypeArgumentsFromNodes(typeArgumentNodes, typeParameters, isInJSFile(node))) : inferSignatureInstantiationForOverloadFailure(node, typeParameters, candidate, args, checkMode); candidates[bestIndex] = instantiated; return instantiated; } function getTypeArgumentsFromNodes(typeArgumentNodes: readonly TypeNode[], typeParameters: readonly TypeParameter[], isJs: boolean): readonly Type[] { const typeArguments = typeArgumentNodes.map(getTypeOfNode); while (typeArguments.length > typeParameters.length) { typeArguments.pop(); } while (typeArguments.length < typeParameters.length) { typeArguments.push(getDefaultFromTypeParameter(typeParameters[typeArguments.length]) || getConstraintOfTypeParameter(typeParameters[typeArguments.length]) || getDefaultTypeArgumentType(isJs)); } return typeArguments; } function inferSignatureInstantiationForOverloadFailure(node: CallLikeExpression, typeParameters: readonly TypeParameter[], candidate: Signature, args: readonly Expression[], checkMode: CheckMode): Signature { const inferenceContext = createInferenceContext(typeParameters, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); const typeArgumentTypes = inferTypeArguments(node, candidate, args, checkMode | CheckMode.SkipContextSensitive | CheckMode.SkipGenericFunctions, inferenceContext); return createSignatureInstantiation(candidate, typeArgumentTypes); } function getLongestCandidateIndex(candidates: Signature[], argsCount: number): number { let maxParamsIndex = -1; let maxParams = -1; for (let i = 0; i < candidates.length; i++) { const candidate = candidates[i]; const paramCount = getParameterCount(candidate); if (hasEffectiveRestParameter(candidate) || paramCount >= argsCount) { return i; } if (paramCount > maxParams) { maxParams = paramCount; maxParamsIndex = i; } } return maxParamsIndex; } function resolveCallExpression(node: CallExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { if (node.expression.kind === SyntaxKind.SuperKeyword) { const superType = checkSuperExpression(node.expression); if (isTypeAny(superType)) { for (const arg of node.arguments) { checkExpression(arg); // Still visit arguments so they get marked for visibility, etc } return anySignature; } if (!isErrorType(superType)) { // In super call, the candidate signatures are the matching arity signatures of the base constructor function instantiated // with the type arguments specified in the extends clause. const baseTypeNode = getEffectiveBaseTypeNode(getContainingClass(node)!); if (baseTypeNode) { const baseConstructors = getInstantiatedConstructorsForTypeArguments(superType, baseTypeNode.typeArguments, baseTypeNode); return resolveCall(node, baseConstructors, candidatesOutArray, checkMode, SignatureFlags.None); } } return resolveUntypedCall(node); } let callChainFlags: SignatureFlags; let funcType = checkExpression(node.expression); if (isCallChain(node)) { const nonOptionalType = getOptionalExpressionType(funcType, node.expression); callChainFlags = nonOptionalType === funcType ? SignatureFlags.None : isOutermostOptionalChain(node) ? SignatureFlags.IsOuterCallChain : SignatureFlags.IsInnerCallChain; funcType = nonOptionalType; } else { callChainFlags = SignatureFlags.None; } funcType = checkNonNullTypeWithReporter( funcType, node.expression, reportCannotInvokePossiblyNullOrUndefinedError ); if (funcType === silentNeverType) { return silentNeverSignature; } const apparentType = getApparentType(funcType); if (isErrorType(apparentType)) { // Another error has already been reported return resolveErrorCall(node); } // Technically, this signatures list may be incomplete. We are taking the apparent type, // but we are not including call signatures that may have been added to the Object or // Function interface, since they have none by default. This is a bit of a leap of faith // that the user will not add any. const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; // TS 1.0 Spec: 4.12 // In an untyped function call no TypeArgs are permitted, Args can be any argument list, no contextual // types are provided for the argument expressions, and the result is always of type Any. if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { // The unknownType indicates that an error already occurred (and was reported). No // need to report another error in this case. if (!isErrorType(funcType) && node.typeArguments) { error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); } return resolveUntypedCall(node); } // If FuncExpr's apparent type(section 3.8.1) is a function type, the call is a typed function call. // TypeScript employs overload resolution in typed function calls in order to support functions // with multiple call signatures. if (!callSignatures.length) { if (numConstructSignatures) { error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); } else { let relatedInformation: DiagnosticRelatedInformation | undefined; if (node.arguments.length === 1) { const text = getSourceFileOfNode(node).text; if (isLineBreak(text.charCodeAt(skipTrivia(text, node.expression.end, /* stopAfterLineBreak */ true) - 1))) { relatedInformation = createDiagnosticForNode(node.expression, Diagnostics.Are_you_missing_a_semicolon); } } invocationError(node.expression, apparentType, SignatureKind.Call, relatedInformation); } return resolveErrorCall(node); } // When a call to a generic function is an argument to an outer call to a generic function for which // inference is in process, we have a choice to make. If the inner call relies on inferences made from // its contextual type to its return type, deferring the inner call processing allows the best possible // contextual type to accumulate. But if the outer call relies on inferences made from the return type of // the inner call, the inner call should be processed early. There's no sure way to know which choice is // right (only a full unification algorithm can determine that), so we resort to the following heuristic: // If no type arguments are specified in the inner call and at least one call signature is generic and // returns a function type, we choose to defer processing. This narrowly permits function composition // operators to flow inferences through return types, but otherwise processes calls right away. We // use the resolvingSignature singleton to indicate that we deferred processing. This result will be // propagated out and eventually turned into silentNeverType (a type that is assignable to anything and // from which we never make inferences). if (checkMode & CheckMode.SkipGenericFunctions && !node.typeArguments && callSignatures.some(isGenericFunctionReturningFunction)) { skippedGenericFunction(node, checkMode); return resolvingSignature; } // If the function is explicitly marked with `@class`, then it must be constructed. if (callSignatures.some(sig => isInJSFile(sig.declaration) && !!getJSDocClassTag(sig.declaration!))) { error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); return resolveErrorCall(node); } return resolveCall(node, callSignatures, candidatesOutArray, checkMode, callChainFlags); } function isGenericFunctionReturningFunction(signature: Signature) { return !!(signature.typeParameters && isFunctionType(getReturnTypeOfSignature(signature))); } /** * TS 1.0 spec: 4.12 * If FuncExpr is of type Any, or of an object type that has no call or construct signatures * but is a subtype of the Function interface, the call is an untyped function call. */ function isUntypedFunctionCall(funcType: Type, apparentFuncType: Type, numCallSignatures: number, numConstructSignatures: number): boolean { // We exclude union types because we may have a union of function types that happen to have no common signatures. return isTypeAny(funcType) || isTypeAny(apparentFuncType) && !!(funcType.flags & TypeFlags.TypeParameter) || !numCallSignatures && !numConstructSignatures && !(apparentFuncType.flags & TypeFlags.Union) && !(getReducedType(apparentFuncType).flags & TypeFlags.Never) && isTypeAssignableTo(funcType, globalFunctionType); } function resolveNewExpression(node: NewExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { if (node.arguments && languageVersion < ScriptTarget.ES5) { const spreadIndex = getSpreadArgumentIndex(node.arguments); if (spreadIndex >= 0) { error(node.arguments[spreadIndex], Diagnostics.Spread_operator_in_new_expressions_is_only_available_when_targeting_ECMAScript_5_and_higher); } } let expressionType = checkNonNullExpression(node.expression); if (expressionType === silentNeverType) { return silentNeverSignature; } // If expressionType's apparent type(section 3.8.1) is an object type with one or // more construct signatures, the expression is processed in the same manner as a // function call, but using the construct signatures as the initial set of candidate // signatures for overload resolution. The result type of the function call becomes // the result type of the operation. expressionType = getApparentType(expressionType); if (isErrorType(expressionType)) { // Another error has already been reported return resolveErrorCall(node); } // TS 1.0 spec: 4.11 // If expressionType is of type Any, Args can be any argument // list and the result of the operation is of type Any. if (isTypeAny(expressionType)) { if (node.typeArguments) { error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); } return resolveUntypedCall(node); } // Technically, this signatures list may be incomplete. We are taking the apparent type, // but we are not including construct signatures that may have been added to the Object or // Function interface, since they have none by default. This is a bit of a leap of faith // that the user will not add any. const constructSignatures = getSignaturesOfType(expressionType, SignatureKind.Construct); if (constructSignatures.length) { if (!isConstructorAccessible(node, constructSignatures[0])) { return resolveErrorCall(node); } // If the expression is a class of abstract type, or an abstract construct signature, // then it cannot be instantiated. // In the case of a merged class-module or class-interface declaration, // only the class declaration node will have the Abstract flag set. if (someSignature(constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract))) { error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); return resolveErrorCall(node); } const valueDecl = expressionType.symbol && getClassLikeDeclarationOfSymbol(expressionType.symbol); if (valueDecl && hasSyntacticModifier(valueDecl, ModifierFlags.Abstract)) { error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); return resolveErrorCall(node); } return resolveCall(node, constructSignatures, candidatesOutArray, checkMode, SignatureFlags.None); } // If expressionType's apparent type is an object type with no construct signatures but // one or more call signatures, the expression is processed as a function call. A compile-time // error occurs if the result of the function call is not Void. The type of the result of the // operation is Any. It is an error to have a Void this type. const callSignatures = getSignaturesOfType(expressionType, SignatureKind.Call); if (callSignatures.length) { const signature = resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); if (!noImplicitAny) { if (signature.declaration && !isJSConstructor(signature.declaration) && getReturnTypeOfSignature(signature) !== voidType) { error(node, Diagnostics.Only_a_void_function_can_be_called_with_the_new_keyword); } if (getThisTypeOfSignature(signature) === voidType) { error(node, Diagnostics.A_function_that_is_called_with_the_new_keyword_cannot_have_a_this_type_that_is_void); } } return signature; } invocationError(node.expression, expressionType, SignatureKind.Construct); return resolveErrorCall(node); } function someSignature(signatures: Signature | readonly Signature[], f: (s: Signature) => boolean): boolean { if (isArray(signatures)) { return some(signatures, signature => someSignature(signature, f)); } return signatures.compositeKind === TypeFlags.Union ? some(signatures.compositeSignatures, f) : f(signatures); } function typeHasProtectedAccessibleBase(target: Symbol, type: InterfaceType): boolean { const baseTypes = getBaseTypes(type); if (!length(baseTypes)) { return false; } const firstBase = baseTypes[0]; if (firstBase.flags & TypeFlags.Intersection) { const types = (firstBase as IntersectionType).types; const mixinFlags = findMixins(types); let i = 0; for (const intersectionMember of (firstBase as IntersectionType).types) { // We want to ignore mixin ctors if (!mixinFlags[i]) { if (getObjectFlags(intersectionMember) & (ObjectFlags.Class | ObjectFlags.Interface)) { if (intersectionMember.symbol === target) { return true; } if (typeHasProtectedAccessibleBase(target, intersectionMember as InterfaceType)) { return true; } } } i++; } return false; } if (firstBase.symbol === target) { return true; } return typeHasProtectedAccessibleBase(target, firstBase as InterfaceType); } function isConstructorAccessible(node: NewExpression, signature: Signature) { if (!signature || !signature.declaration) { return true; } const declaration = signature.declaration; const modifiers = getSelectedEffectiveModifierFlags(declaration, ModifierFlags.NonPublicAccessibilityModifier); // (1) Public constructors and (2) constructor functions are always accessible. if (!modifiers || declaration.kind !== SyntaxKind.Constructor) { return true; } const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(declaration.parent.symbol)!; const declaringClass = getDeclaredTypeOfSymbol(declaration.parent.symbol) as InterfaceType; // A private or protected constructor can only be instantiated within its own class (or a subclass, for protected) if (!isNodeWithinClass(node, declaringClassDeclaration)) { const containingClass = getContainingClass(node); if (containingClass && modifiers & ModifierFlags.Protected) { const containingType = getTypeOfNode(containingClass); if (typeHasProtectedAccessibleBase(declaration.parent.symbol, containingType as InterfaceType)) { return true; } } if (modifiers & ModifierFlags.Private) { error(node, Diagnostics.Constructor_of_class_0_is_private_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); } if (modifiers & ModifierFlags.Protected) { error(node, Diagnostics.Constructor_of_class_0_is_protected_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); } return false; } return true; } function invocationErrorDetails(errorTarget: Node, apparentType: Type, kind: SignatureKind): { messageChain: DiagnosticMessageChain, relatedMessage: DiagnosticMessage | undefined } { let errorInfo: DiagnosticMessageChain | undefined; const isCall = kind === SignatureKind.Call; const awaitedType = getAwaitedType(apparentType); const maybeMissingAwait = awaitedType && getSignaturesOfType(awaitedType, kind).length > 0; if (apparentType.flags & TypeFlags.Union) { const types = (apparentType as UnionType).types; let hasSignatures = false; for (const constituent of types) { const signatures = getSignaturesOfType(constituent, kind); if (signatures.length !== 0) { hasSignatures = true; if (errorInfo) { // Bail early if we already have an error, no chance of "No constituent of type is callable" break; } } else { // Error on the first non callable constituent only if (!errorInfo) { errorInfo = chainDiagnosticMessages( errorInfo, isCall ? Diagnostics.Type_0_has_no_call_signatures : Diagnostics.Type_0_has_no_construct_signatures, typeToString(constituent) ); errorInfo = chainDiagnosticMessages( errorInfo, isCall ? Diagnostics.Not_all_constituents_of_type_0_are_callable : Diagnostics.Not_all_constituents_of_type_0_are_constructable, typeToString(apparentType) ); } if (hasSignatures) { // Bail early if we already found a siganture, no chance of "No constituent of type is callable" break; } } } if (!hasSignatures) { errorInfo = chainDiagnosticMessages( /* detials */ undefined, isCall ? Diagnostics.No_constituent_of_type_0_is_callable : Diagnostics.No_constituent_of_type_0_is_constructable, typeToString(apparentType) ); } if (!errorInfo) { errorInfo = chainDiagnosticMessages( errorInfo, isCall ? Diagnostics.Each_member_of_the_union_type_0_has_signatures_but_none_of_those_signatures_are_compatible_with_each_other : Diagnostics.Each_member_of_the_union_type_0_has_construct_signatures_but_none_of_those_signatures_are_compatible_with_each_other, typeToString(apparentType) ); } } else { errorInfo = chainDiagnosticMessages( errorInfo, isCall ? Diagnostics.Type_0_has_no_call_signatures : Diagnostics.Type_0_has_no_construct_signatures, typeToString(apparentType) ); } let headMessage = isCall ? Diagnostics.This_expression_is_not_callable : Diagnostics.This_expression_is_not_constructable; // Diagnose get accessors incorrectly called as functions if (isCallExpression(errorTarget.parent) && errorTarget.parent.arguments.length === 0) { const { resolvedSymbol } = getNodeLinks(errorTarget); if (resolvedSymbol && resolvedSymbol.flags & SymbolFlags.GetAccessor) { headMessage = Diagnostics.This_expression_is_not_callable_because_it_is_a_get_accessor_Did_you_mean_to_use_it_without; } } return { messageChain: chainDiagnosticMessages(errorInfo, headMessage), relatedMessage: maybeMissingAwait ? Diagnostics.Did_you_forget_to_use_await : undefined, }; } function invocationError(errorTarget: Node, apparentType: Type, kind: SignatureKind, relatedInformation?: DiagnosticRelatedInformation) { const { messageChain, relatedMessage: relatedInfo } = invocationErrorDetails(errorTarget, apparentType, kind); const diagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorTarget), errorTarget, messageChain); if (relatedInfo) { addRelatedInfo(diagnostic, createDiagnosticForNode(errorTarget, relatedInfo)); } if (isCallExpression(errorTarget.parent)) { const { start, length } = getDiagnosticSpanForCallNode(errorTarget.parent, /* doNotIncludeArguments */ true); diagnostic.start = start; diagnostic.length = length; } diagnostics.add(diagnostic); invocationErrorRecovery(apparentType, kind, relatedInformation ? addRelatedInfo(diagnostic, relatedInformation) : diagnostic); } function invocationErrorRecovery(apparentType: Type, kind: SignatureKind, diagnostic: Diagnostic) { if (!apparentType.symbol) { return; } const importNode = getSymbolLinks(apparentType.symbol).originatingImport; // Create a diagnostic on the originating import if possible onto which we can attach a quickfix // An import call expression cannot be rewritten into another form to correct the error - the only solution is to use `.default` at the use-site if (importNode && !isImportCall(importNode)) { const sigs = getSignaturesOfType(getTypeOfSymbol(getSymbolLinks(apparentType.symbol).target!), kind); if (!sigs || !sigs.length) return; addRelatedInfo(diagnostic, createDiagnosticForNode(importNode, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead) ); } } function resolveTaggedTemplateExpression(node: TaggedTemplateExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { const tagType = checkExpression(node.tag); const apparentType = getApparentType(tagType); if (isErrorType(apparentType)) { // Another error has already been reported return resolveErrorCall(node); } const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; if (isUntypedFunctionCall(tagType, apparentType, callSignatures.length, numConstructSignatures)) { return resolveUntypedCall(node); } if (!callSignatures.length) { if (isArrayLiteralExpression(node.parent)) { const diagnostic = createDiagnosticForNode(node.tag, Diagnostics.It_is_likely_that_you_are_missing_a_comma_to_separate_these_two_template_expressions_They_form_a_tagged_template_expression_which_cannot_be_invoked); diagnostics.add(diagnostic); return resolveErrorCall(node); } invocationError(node.tag, apparentType, SignatureKind.Call); return resolveErrorCall(node); } return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); } /** * Gets the localized diagnostic head message to use for errors when resolving a decorator as a call expression. */ function getDiagnosticHeadMessageForDecoratorResolution(node: Decorator) { switch (node.parent.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: return Diagnostics.Unable_to_resolve_signature_of_class_decorator_when_called_as_an_expression; case SyntaxKind.Parameter: return Diagnostics.Unable_to_resolve_signature_of_parameter_decorator_when_called_as_an_expression; case SyntaxKind.PropertyDeclaration: return Diagnostics.Unable_to_resolve_signature_of_property_decorator_when_called_as_an_expression; case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: return Diagnostics.Unable_to_resolve_signature_of_method_decorator_when_called_as_an_expression; default: return Debug.fail(); } } /** * Resolves a decorator as if it were a call expression. */ function resolveDecorator(node: Decorator, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { const funcType = checkExpression(node.expression); const apparentType = getApparentType(funcType); if (isErrorType(apparentType)) { return resolveErrorCall(node); } const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { return resolveUntypedCall(node); } if (isPotentiallyUncalledDecorator(node, callSignatures) && !isParenthesizedExpression(node.expression)) { const nodeStr = getTextOfNode(node.expression, /*includeTrivia*/ false); error(node, Diagnostics._0_accepts_too_few_arguments_to_be_used_as_a_decorator_here_Did_you_mean_to_call_it_first_and_write_0, nodeStr); return resolveErrorCall(node); } const headMessage = getDiagnosticHeadMessageForDecoratorResolution(node); if (!callSignatures.length) { const errorDetails = invocationErrorDetails(node.expression, apparentType, SignatureKind.Call); const messageChain = chainDiagnosticMessages(errorDetails.messageChain, headMessage); const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node.expression), node.expression, messageChain); if (errorDetails.relatedMessage) { addRelatedInfo(diag, createDiagnosticForNode(node.expression, errorDetails.relatedMessage)); } diagnostics.add(diag); invocationErrorRecovery(apparentType, SignatureKind.Call, diag); return resolveErrorCall(node); } return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None, headMessage); } function createSignatureForJSXIntrinsic(node: JsxOpeningLikeElement, result: Type): Signature { const namespace = getJsxNamespaceAt(node); const exports = namespace && getExportsOfSymbol(namespace); // We fake up a SFC signature for each intrinsic, however a more specific per-element signature drawn from the JSX declaration // file would probably be preferable. const typeSymbol = exports && getSymbol(exports, JsxNames.Element, SymbolFlags.Type); const returnNode = typeSymbol && nodeBuilder.symbolToEntityName(typeSymbol, SymbolFlags.Type, node); const declaration = factory.createFunctionTypeNode(/*typeParameters*/ undefined, [factory.createParameterDeclaration(/*modifiers*/ undefined, /*dotdotdot*/ undefined, "props", /*questionMark*/ undefined, nodeBuilder.typeToTypeNode(result, node))], returnNode ? factory.createTypeReferenceNode(returnNode, /*typeArguments*/ undefined) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword) ); const parameterSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "props" as __String); parameterSymbol.links.type = result; return createSignature( declaration, /*typeParameters*/ undefined, /*thisParameter*/ undefined, [parameterSymbol], typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType, /*returnTypePredicate*/ undefined, 1, SignatureFlags.None ); } function resolveJsxOpeningLikeElement(node: JsxOpeningLikeElement, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { if (isJsxIntrinsicIdentifier(node.tagName)) { const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node); const fakeSignature = createSignatureForJSXIntrinsic(node, result); checkTypeAssignableToAndOptionallyElaborate(checkExpressionWithContextualType(node.attributes, getEffectiveFirstArgumentForJsxSignature(fakeSignature, node), /*inferenceContext*/ undefined, CheckMode.Normal), result, node.tagName, node.attributes); if (length(node.typeArguments)) { forEach(node.typeArguments, checkSourceElement); diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), node.typeArguments!, Diagnostics.Expected_0_type_arguments_but_got_1, 0, length(node.typeArguments))); } return fakeSignature; } const exprTypes = checkExpression(node.tagName); const apparentType = getApparentType(exprTypes); if (isErrorType(apparentType)) { return resolveErrorCall(node); } const signatures = getUninstantiatedJsxSignaturesOfType(exprTypes, node); if (isUntypedFunctionCall(exprTypes, apparentType, signatures.length, /*constructSignatures*/ 0)) { return resolveUntypedCall(node); } if (signatures.length === 0) { // We found no signatures at all, which is an error error(node.tagName, Diagnostics.JSX_element_type_0_does_not_have_any_construct_or_call_signatures, getTextOfNode(node.tagName)); return resolveErrorCall(node); } return resolveCall(node, signatures, candidatesOutArray, checkMode, SignatureFlags.None); } /** * Sometimes, we have a decorator that could accept zero arguments, * but is receiving too many arguments as part of the decorator invocation. * In those cases, a user may have meant to *call* the expression before using it as a decorator. */ function isPotentiallyUncalledDecorator(decorator: Decorator, signatures: readonly Signature[]) { return signatures.length && every(signatures, signature => signature.minArgumentCount === 0 && !signatureHasRestParameter(signature) && signature.parameters.length < getDecoratorArgumentCount(decorator, signature)); } function resolveSignature(node: CallLikeExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { switch (node.kind) { case SyntaxKind.CallExpression: return resolveCallExpression(node, candidatesOutArray, checkMode); case SyntaxKind.NewExpression: return resolveNewExpression(node, candidatesOutArray, checkMode); case SyntaxKind.TaggedTemplateExpression: return resolveTaggedTemplateExpression(node, candidatesOutArray, checkMode); case SyntaxKind.Decorator: return resolveDecorator(node, candidatesOutArray, checkMode); case SyntaxKind.JsxOpeningElement: case SyntaxKind.JsxSelfClosingElement: return resolveJsxOpeningLikeElement(node, candidatesOutArray, checkMode); } throw Debug.assertNever(node, "Branch in 'resolveSignature' should be unreachable."); } /** * Resolve a signature of a given call-like expression. * @param node a call-like expression to try resolve a signature for * @param candidatesOutArray an array of signature to be filled in by the function. It is passed by signature help in the language service; * the function will fill it up with appropriate candidate signatures * @return a signature of the call-like expression or undefined if one can't be found */ function getResolvedSignature(node: CallLikeExpression, candidatesOutArray?: Signature[] | undefined, checkMode?: CheckMode): Signature { const links = getNodeLinks(node); // If getResolvedSignature has already been called, we will have cached the resolvedSignature. // However, it is possible that either candidatesOutArray was not passed in the first time, // or that a different candidatesOutArray was passed in. Therefore, we need to redo the work // to correctly fill the candidatesOutArray. const cached = links.resolvedSignature; if (cached && cached !== resolvingSignature && !candidatesOutArray) { return cached; } links.resolvedSignature = resolvingSignature; const result = resolveSignature(node, candidatesOutArray, checkMode || CheckMode.Normal); // When CheckMode.SkipGenericFunctions is set we use resolvingSignature to indicate that call // resolution should be deferred. if (result !== resolvingSignature) { // If signature resolution originated in control flow type analysis (for example to compute the // assigned type in a flow assignment) we don't cache the result as it may be based on temporary // types from the control flow analysis. links.resolvedSignature = flowLoopStart === flowLoopCount ? result : cached; } return result; } /** * Indicates whether a declaration can be treated as a constructor in a JavaScript * file. */ function isJSConstructor(node: Node | undefined): node is FunctionDeclaration | FunctionExpression { if (!node || !isInJSFile(node)) { return false; } const func = isFunctionDeclaration(node) || isFunctionExpression(node) ? node : (isVariableDeclaration(node) || isPropertyAssignment(node)) && node.initializer && isFunctionExpression(node.initializer) ? node.initializer : undefined; if (func) { // If the node has a @class or @constructor tag, treat it like a constructor. if (getJSDocClassTag(node)) return true; // If the node is a property of an object literal. if (isPropertyAssignment(walkUpParenthesizedExpressions(func.parent))) return false; // If the symbol of the node has members, treat it like a constructor. const symbol = getSymbolOfDeclaration(func); return !!symbol?.members?.size; } return false; } function mergeJSSymbols(target: Symbol, source: Symbol | undefined) { if (source) { const links = getSymbolLinks(source); if (!links.inferredClassSymbol || !links.inferredClassSymbol.has(getSymbolId(target))) { const inferred = isTransientSymbol(target) ? target : cloneSymbol(target); inferred.exports = inferred.exports || createSymbolTable(); inferred.members = inferred.members || createSymbolTable(); inferred.flags |= source.flags & SymbolFlags.Class; if (source.exports?.size) { mergeSymbolTable(inferred.exports, source.exports); } if (source.members?.size) { mergeSymbolTable(inferred.members, source.members); } (links.inferredClassSymbol || (links.inferredClassSymbol = new Map())).set(getSymbolId(inferred), inferred); return inferred; } return links.inferredClassSymbol.get(getSymbolId(target)); } } function getAssignedClassSymbol(decl: Declaration): Symbol | undefined { const assignmentSymbol = decl && getSymbolOfExpando(decl, /*allowDeclaration*/ true); const prototype = assignmentSymbol?.exports?.get("prototype" as __String); const init = prototype?.valueDeclaration && getAssignedJSPrototype(prototype.valueDeclaration); return init ? getSymbolOfDeclaration(init) : undefined; } function getSymbolOfExpando(node: Node, allowDeclaration: boolean): Symbol | undefined { if (!node.parent) { return undefined; } let name: Expression | BindingName | undefined; let decl: Node | undefined; if (isVariableDeclaration(node.parent) && node.parent.initializer === node) { if (!isInJSFile(node) && !(isVarConst(node.parent) && isFunctionLikeDeclaration(node))) { return undefined; } name = node.parent.name; decl = node.parent; } else if (isBinaryExpression(node.parent)) { const parentNode = node.parent; const parentNodeOperator = node.parent.operatorToken.kind; if (parentNodeOperator === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.right === node)) { name = parentNode.left; decl = name; } else if (parentNodeOperator === SyntaxKind.BarBarToken || parentNodeOperator === SyntaxKind.QuestionQuestionToken) { if (isVariableDeclaration(parentNode.parent) && parentNode.parent.initializer === parentNode) { name = parentNode.parent.name; decl = parentNode.parent; } else if (isBinaryExpression(parentNode.parent) && parentNode.parent.operatorToken.kind === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.parent.right === parentNode)) { name = parentNode.parent.left; decl = name; } if (!name || !isBindableStaticNameExpression(name) || !isSameEntityName(name, parentNode.left)) { return undefined; } } } else if (allowDeclaration && isFunctionDeclaration(node)) { name = node.name; decl = node; } if (!decl || !name || (!allowDeclaration && !getExpandoInitializer(node, isPrototypeAccess(name)))) { return undefined; } return getSymbolOfNode(decl); } function getAssignedJSPrototype(node: Node) { if (!node.parent) { return false; } let parent: Node = node.parent; while (parent && parent.kind === SyntaxKind.PropertyAccessExpression) { parent = parent.parent; } if (parent && isBinaryExpression(parent) && isPrototypeAccess(parent.left) && parent.operatorToken.kind === SyntaxKind.EqualsToken) { const right = getInitializerOfBinaryExpression(parent); return isObjectLiteralExpression(right) && right; } } /** * Syntactically and semantically checks a call or new expression. * @param node The call/new expression to be checked. * @returns On success, the expression's signature's return type. On failure, anyType. */ function checkCallExpression(node: CallExpression | NewExpression, checkMode?: CheckMode): Type { checkGrammarTypeArguments(node, node.typeArguments); const signature = getResolvedSignature(node, /*candidatesOutArray*/ undefined, checkMode); if (signature === resolvingSignature) { // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that // returns a function type. We defer checking and return silentNeverType. return silentNeverType; } checkDeprecatedSignature(signature, node); if (node.expression.kind === SyntaxKind.SuperKeyword) { return voidType; } if (node.kind === SyntaxKind.NewExpression) { const declaration = signature.declaration; if (declaration && declaration.kind !== SyntaxKind.Constructor && declaration.kind !== SyntaxKind.ConstructSignature && declaration.kind !== SyntaxKind.ConstructorType && !(isJSDocSignature(declaration) && getJSDocRoot(declaration)?.parent?.kind === SyntaxKind.Constructor) && !isJSDocConstructSignature(declaration) && !isJSConstructor(declaration)) { // When resolved signature is a call signature (and not a construct signature) the result type is any if (noImplicitAny) { error(node, Diagnostics.new_expression_whose_target_lacks_a_construct_signature_implicitly_has_an_any_type); } return anyType; } } // In JavaScript files, calls to any identifier 'require' are treated as external module imports if (isInJSFile(node) && shouldResolveJsRequire(compilerOptions) && isCommonJsRequire(node)) { return resolveExternalModuleTypeByLiteral(node.arguments![0] as StringLiteral); } const returnType = getReturnTypeOfSignature(signature); // Treat any call to the global 'Symbol' function that is part of a const variable or readonly property // as a fresh unique symbol literal type. if (returnType.flags & TypeFlags.ESSymbolLike && isSymbolOrSymbolForCall(node)) { return getESSymbolLikeTypeForNode(walkUpParenthesizedExpressions(node.parent)); } if (node.kind === SyntaxKind.CallExpression && !node.questionDotToken && node.parent.kind === SyntaxKind.ExpressionStatement && returnType.flags & TypeFlags.Void && getTypePredicateOfSignature(signature)) { if (!isDottedName(node.expression)) { error(node.expression, Diagnostics.Assertions_require_the_call_target_to_be_an_identifier_or_qualified_name); } else if (!getEffectsSignature(node)) { const diagnostic = error(node.expression, Diagnostics.Assertions_require_every_name_in_the_call_target_to_be_declared_with_an_explicit_type_annotation); getTypeOfDottedName(node.expression, diagnostic); } } if (isInJSFile(node)) { const jsSymbol = getSymbolOfExpando(node, /*allowDeclaration*/ false); if (jsSymbol?.exports?.size) { const jsAssignmentType = createAnonymousType(jsSymbol, jsSymbol.exports, emptyArray, emptyArray, emptyArray); jsAssignmentType.objectFlags |= ObjectFlags.JSLiteral; return getIntersectionType([returnType, jsAssignmentType]); } } return returnType; } function checkDeprecatedSignature(signature: Signature, node: CallLikeExpression) { if (signature.declaration && signature.declaration.flags & NodeFlags.Deprecated) { const suggestionNode = getDeprecatedSuggestionNode(node); const name = tryGetPropertyAccessOrIdentifierToString(getInvokedExpression(node)); addDeprecatedSuggestionWithSignature(suggestionNode, signature.declaration, name, signatureToString(signature)); } } function getDeprecatedSuggestionNode(node: Node): Node { node = skipParentheses(node); switch (node.kind) { case SyntaxKind.CallExpression: case SyntaxKind.Decorator: case SyntaxKind.NewExpression: return getDeprecatedSuggestionNode((node as Decorator | CallExpression | NewExpression).expression); case SyntaxKind.TaggedTemplateExpression: return getDeprecatedSuggestionNode((node as TaggedTemplateExpression).tag); case SyntaxKind.JsxOpeningElement: case SyntaxKind.JsxSelfClosingElement: return getDeprecatedSuggestionNode((node as JsxOpeningLikeElement).tagName); case SyntaxKind.ElementAccessExpression: return (node as ElementAccessExpression).argumentExpression; case SyntaxKind.PropertyAccessExpression: return (node as PropertyAccessExpression).name; case SyntaxKind.TypeReference: const typeReference = node as TypeReferenceNode; return isQualifiedName(typeReference.typeName) ? typeReference.typeName.right : typeReference; default: return node; } } function isSymbolOrSymbolForCall(node: Node) { if (!isCallExpression(node)) return false; let left = node.expression; if (isPropertyAccessExpression(left) && left.name.escapedText === "for") { left = left.expression; } if (!isIdentifier(left) || left.escapedText !== "Symbol") { return false; } // make sure `Symbol` is the global symbol const globalESSymbol = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); if (!globalESSymbol) { return false; } return globalESSymbol === resolveName(left, "Symbol" as __String, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ false); } function checkImportCallExpression(node: ImportCall): Type { // Check grammar of dynamic import checkGrammarImportCallExpression(node); if (node.arguments.length === 0) { return createPromiseReturnType(node, anyType); } const specifier = node.arguments[0]; const specifierType = checkExpressionCached(specifier); const optionsType = node.arguments.length > 1 ? checkExpressionCached(node.arguments[1]) : undefined; // Even though multiple arguments is grammatically incorrect, type-check extra arguments for completion for (let i = 2; i < node.arguments.length; ++i) { checkExpressionCached(node.arguments[i]); } if (specifierType.flags & TypeFlags.Undefined || specifierType.flags & TypeFlags.Null || !isTypeAssignableTo(specifierType, stringType)) { error(specifier, Diagnostics.Dynamic_import_s_specifier_must_be_of_type_string_but_here_has_type_0, typeToString(specifierType)); } if (optionsType) { const importCallOptionsType = getGlobalImportCallOptionsType(/*reportErrors*/ true); if (importCallOptionsType !== emptyObjectType) { checkTypeAssignableTo(optionsType, getNullableType(importCallOptionsType, TypeFlags.Undefined), node.arguments[1]); } } // resolveExternalModuleName will return undefined if the moduleReferenceExpression is not a string literal const moduleSymbol = resolveExternalModuleName(node, specifier); if (moduleSymbol) { const esModuleSymbol = resolveESModuleSymbol(moduleSymbol, specifier, /*dontRecursivelyResolve*/ true, /*suppressUsageError*/ false); if (esModuleSymbol) { return createPromiseReturnType(node, getTypeWithSyntheticDefaultOnly(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier) || getTypeWithSyntheticDefaultImportType(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier) ); } } return createPromiseReturnType(node, anyType); } function createDefaultPropertyWrapperForModule(symbol: Symbol, originalSymbol: Symbol, anonymousSymbol?: Symbol | undefined) { const memberTable = createSymbolTable(); const newSymbol = createSymbol(SymbolFlags.Alias, InternalSymbolName.Default); newSymbol.parent = originalSymbol; newSymbol.links.nameType = getStringLiteralType("default"); newSymbol.links.aliasTarget = resolveSymbol(symbol); memberTable.set(InternalSymbolName.Default, newSymbol); return createAnonymousType(anonymousSymbol, memberTable, emptyArray, emptyArray, emptyArray); } function getTypeWithSyntheticDefaultOnly(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression) { const hasDefaultOnly = isOnlyImportedAsDefault(moduleSpecifier); if (hasDefaultOnly && type && !isErrorType(type)) { const synthType = type as SyntheticDefaultModuleType; if (!synthType.defaultOnlyType) { const type = createDefaultPropertyWrapperForModule(symbol, originalSymbol); synthType.defaultOnlyType = type; } return synthType.defaultOnlyType; } return undefined; } function getTypeWithSyntheticDefaultImportType(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression): Type { if (allowSyntheticDefaultImports && type && !isErrorType(type)) { const synthType = type as SyntheticDefaultModuleType; if (!synthType.syntheticType) { const file = originalSymbol.declarations?.find(isSourceFile); const hasSyntheticDefault = canHaveSyntheticDefault(file, originalSymbol, /*dontResolveAlias*/ false, moduleSpecifier); if (hasSyntheticDefault) { const anonymousSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); const defaultContainingObject = createDefaultPropertyWrapperForModule(symbol, originalSymbol, anonymousSymbol); anonymousSymbol.links.type = defaultContainingObject; synthType.syntheticType = isValidSpreadType(type) ? getSpreadType(type, defaultContainingObject, anonymousSymbol, /*objectFlags*/ 0, /*readonly*/ false) : defaultContainingObject; } else { synthType.syntheticType = type; } } return synthType.syntheticType; } return type; } function isCommonJsRequire(node: Node): boolean { if (!isRequireCall(node, /*checkArgumentIsStringLiteralLike*/ true)) { return false; } // Make sure require is not a local function if (!isIdentifier(node.expression)) return Debug.fail(); const resolvedRequire = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ true)!; // TODO: GH#18217 if (resolvedRequire === requireSymbol) { return true; } // project includes symbol named 'require' - make sure that it is ambient and local non-alias if (resolvedRequire.flags & SymbolFlags.Alias) { return false; } const targetDeclarationKind = resolvedRequire.flags & SymbolFlags.Function ? SyntaxKind.FunctionDeclaration : resolvedRequire.flags & SymbolFlags.Variable ? SyntaxKind.VariableDeclaration : SyntaxKind.Unknown; if (targetDeclarationKind !== SyntaxKind.Unknown) { const decl = getDeclarationOfKind(resolvedRequire, targetDeclarationKind)!; // function/variable declaration should be ambient return !!decl && !!(decl.flags & NodeFlags.Ambient); } return false; } function checkTaggedTemplateExpression(node: TaggedTemplateExpression): Type { if (!checkGrammarTaggedTemplateChain(node)) checkGrammarTypeArguments(node, node.typeArguments); if (languageVersion < ScriptTarget.ES2015) { checkExternalEmitHelpers(node, ExternalEmitHelpers.MakeTemplateObject); } const signature = getResolvedSignature(node); checkDeprecatedSignature(signature, node); return getReturnTypeOfSignature(signature); } function checkAssertion(node: AssertionExpression) { if (node.kind === SyntaxKind.TypeAssertionExpression) { const file = getSourceFileOfNode(node); if (file && fileExtensionIsOneOf(file.fileName, [Extension.Cts, Extension.Mts])) { grammarErrorOnNode(node, Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Use_an_as_expression_instead); } } return checkAssertionWorker(node, node.type, node.expression); } function isValidConstAssertionArgument(node: Node): boolean { switch (node.kind) { case SyntaxKind.StringLiteral: case SyntaxKind.NoSubstitutionTemplateLiteral: case SyntaxKind.NumericLiteral: case SyntaxKind.BigIntLiteral: case SyntaxKind.TrueKeyword: case SyntaxKind.FalseKeyword: case SyntaxKind.ArrayLiteralExpression: case SyntaxKind.ObjectLiteralExpression: case SyntaxKind.TemplateExpression: return true; case SyntaxKind.ParenthesizedExpression: return isValidConstAssertionArgument((node as ParenthesizedExpression).expression); case SyntaxKind.PrefixUnaryExpression: const op = (node as PrefixUnaryExpression).operator; const arg = (node as PrefixUnaryExpression).operand; return op === SyntaxKind.MinusToken && (arg.kind === SyntaxKind.NumericLiteral || arg.kind === SyntaxKind.BigIntLiteral) || op === SyntaxKind.PlusToken && arg.kind === SyntaxKind.NumericLiteral; case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: const expr = skipParentheses((node as PropertyAccessExpression | ElementAccessExpression).expression); const symbol = isEntityNameExpression(expr) ? resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true) : undefined; return !!(symbol && symbol.flags & SymbolFlags.Enum); } return false; } function checkAssertionWorker(errNode: Node, type: TypeNode, expression: UnaryExpression | Expression, checkMode?: CheckMode) { let exprType = checkExpression(expression, checkMode); if (isConstTypeReference(type)) { if (!isValidConstAssertionArgument(expression)) { error(expression, Diagnostics.A_const_assertions_can_only_be_applied_to_references_to_enum_members_or_string_number_boolean_array_or_object_literals); } return getRegularTypeOfLiteralType(exprType); } checkSourceElement(type); exprType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(exprType)); const targetType = getTypeFromTypeNode(type); if (!isErrorType(targetType)) { addLazyDiagnostic(() => { const widenedType = getWidenedType(exprType); if (!isTypeComparableTo(targetType, widenedType)) { checkTypeComparableTo(exprType, targetType, errNode, Diagnostics.Conversion_of_type_0_to_type_1_may_be_a_mistake_because_neither_type_sufficiently_overlaps_with_the_other_If_this_was_intentional_convert_the_expression_to_unknown_first); } }); } return targetType; } function checkNonNullChain(node: NonNullChain) { const leftType = checkExpression(node.expression); const nonOptionalType = getOptionalExpressionType(leftType, node.expression); return propagateOptionalTypeMarker(getNonNullableType(nonOptionalType), node, nonOptionalType !== leftType); } function checkNonNullAssertion(node: NonNullExpression) { return node.flags & NodeFlags.OptionalChain ? checkNonNullChain(node as NonNullChain) : getNonNullableType(checkExpression(node.expression)); } function checkExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { checkGrammarExpressionWithTypeArguments(node); forEach(node.typeArguments, checkSourceElement); const exprType = node.kind === SyntaxKind.ExpressionWithTypeArguments ? checkExpression(node.expression) : isThisIdentifier(node.exprName) ? checkThisExpression(node.exprName) : checkExpression(node.exprName); return getInstantiationExpressionType(exprType, node); } function getInstantiationExpressionType(exprType: Type, node: NodeWithTypeArguments) { const typeArguments = node.typeArguments; if (exprType === silentNeverType || isErrorType(exprType) || !some(typeArguments)) { return exprType; } let hasSomeApplicableSignature = false; let nonApplicableType: Type | undefined; const result = getInstantiatedType(exprType); const errorType = hasSomeApplicableSignature ? nonApplicableType : exprType; if (errorType) { diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Type_0_has_no_signatures_for_which_the_type_argument_list_is_applicable, typeToString(errorType))); } return result; function getInstantiatedType(type: Type): Type { let hasSignatures = false; let hasApplicableSignature = false; const result = getInstantiatedTypePart(type); hasSomeApplicableSignature ||= hasApplicableSignature; if (hasSignatures && !hasApplicableSignature) { nonApplicableType ??= type; } return result; function getInstantiatedTypePart(type: Type): Type { if (type.flags & TypeFlags.Object) { const resolved = resolveStructuredTypeMembers(type as ObjectType); const callSignatures = getInstantiatedSignatures(resolved.callSignatures); const constructSignatures = getInstantiatedSignatures(resolved.constructSignatures); hasSignatures ||= resolved.callSignatures.length !== 0 || resolved.constructSignatures.length !== 0; hasApplicableSignature ||= callSignatures.length !== 0 || constructSignatures.length !== 0; if (callSignatures !== resolved.callSignatures || constructSignatures !== resolved.constructSignatures) { const result = createAnonymousType(undefined, resolved.members, callSignatures, constructSignatures, resolved.indexInfos) as ResolvedType & InstantiationExpressionType; result.objectFlags |= ObjectFlags.InstantiationExpressionType; result.node = node; return result; } } else if (type.flags & TypeFlags.InstantiableNonPrimitive) { const constraint = getBaseConstraintOfType(type); if (constraint) { const instantiated = getInstantiatedTypePart(constraint); if (instantiated !== constraint) { return instantiated; } } } else if (type.flags & TypeFlags.Union) { return mapType(type, getInstantiatedType); } else if (type.flags & TypeFlags.Intersection) { return getIntersectionType(sameMap((type as IntersectionType).types, getInstantiatedTypePart)); } return type; } } function getInstantiatedSignatures(signatures: readonly Signature[]) { const applicableSignatures = filter(signatures, sig => !!sig.typeParameters && hasCorrectTypeArgumentArity(sig, typeArguments)); return sameMap(applicableSignatures, sig => { const typeArgumentTypes = checkTypeArguments(sig, typeArguments!, /*reportErrors*/ true); return typeArgumentTypes ? getSignatureInstantiation(sig, typeArgumentTypes, isInJSFile(sig.declaration)) : sig; }); } } function checkSatisfiesExpression(node: SatisfiesExpression) { checkSourceElement(node.type); return checkSatisfiesExpressionWorker(node.expression, node.type); } function checkSatisfiesExpressionWorker(expression: Expression, target: TypeNode, checkMode?: CheckMode) { const exprType = checkExpression(expression, checkMode); const targetType = getTypeFromTypeNode(target); if (isErrorType(targetType)) { return targetType; } checkTypeAssignableToAndOptionallyElaborate(exprType, targetType, target, expression, Diagnostics.Type_0_does_not_satisfy_the_expected_type_1); return exprType; } function checkMetaProperty(node: MetaProperty): Type { checkGrammarMetaProperty(node); if (node.keywordToken === SyntaxKind.NewKeyword) { return checkNewTargetMetaProperty(node); } if (node.keywordToken === SyntaxKind.ImportKeyword) { return checkImportMetaProperty(node); } return Debug.assertNever(node.keywordToken); } function checkMetaPropertyKeyword(node: MetaProperty): Type { switch (node.keywordToken) { case SyntaxKind.ImportKeyword: return getGlobalImportMetaExpressionType(); case SyntaxKind.NewKeyword: const type = checkNewTargetMetaProperty(node); return isErrorType(type) ? errorType : createNewTargetExpressionType(type); default: Debug.assertNever(node.keywordToken); } } function checkNewTargetMetaProperty(node: MetaProperty) { const container = getNewTargetContainer(node); if (!container) { error(node, Diagnostics.Meta_property_0_is_only_allowed_in_the_body_of_a_function_declaration_function_expression_or_constructor, "new.target"); return errorType; } else if (container.kind === SyntaxKind.Constructor) { const symbol = getSymbolOfDeclaration(container.parent); return getTypeOfSymbol(symbol); } else { const symbol = getSymbolOfDeclaration(container)!; return getTypeOfSymbol(symbol); } } function checkImportMetaProperty(node: MetaProperty) { if (moduleKind === ModuleKind.Node16 || moduleKind === ModuleKind.NodeNext) { if (getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.ESNext) { error(node, Diagnostics.The_import_meta_meta_property_is_not_allowed_in_files_which_will_build_into_CommonJS_output); } } else if (moduleKind < ModuleKind.ES2020 && moduleKind !== ModuleKind.System) { error(node, Diagnostics.The_import_meta_meta_property_is_only_allowed_when_the_module_option_is_es2020_es2022_esnext_system_node16_or_nodenext); } const file = getSourceFileOfNode(node); Debug.assert(!!(file.flags & NodeFlags.PossiblyContainsImportMeta), "Containing file is missing import meta node flag."); return node.name.escapedText === "meta" ? getGlobalImportMetaType() : errorType; } function getTypeOfParameter(symbol: Symbol) { const type = getTypeOfSymbol(symbol); if (strictNullChecks) { const declaration = symbol.valueDeclaration; if (declaration && hasInitializer(declaration)) { return getOptionalType(type); } } return type; } function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember) { Debug.assert(isIdentifier(d.name)); // Parameter declarations could be binding patterns, but we only allow identifier names return d.name.escapedText; } function getParameterNameAtPosition(signature: Signature, pos: number, overrideRestType?: Type) { const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); if (pos < paramCount) { return signature.parameters[pos].escapedName; } const restParameter = signature.parameters[paramCount] || unknownSymbol; const restType = overrideRestType || getTypeOfSymbol(restParameter); if (isTupleType(restType)) { const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; const index = pos - paramCount; return associatedNames && getTupleElementLabel(associatedNames[index]) || restParameter.escapedName + "_" + index as __String; } return restParameter.escapedName; } function getParameterIdentifierNameAtPosition(signature: Signature, pos: number): [parameterName: __String, isRestParameter: boolean] | undefined { if (signature.declaration?.kind === SyntaxKind.JSDocFunctionType) { return undefined; } const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); if (pos < paramCount) { const param = signature.parameters[pos]; return isParameterDeclarationWithIdentifierName(param) ? [param.escapedName, false] : undefined; } const restParameter = signature.parameters[paramCount] || unknownSymbol; if (!isParameterDeclarationWithIdentifierName(restParameter)) { return undefined; } const restType = getTypeOfSymbol(restParameter); if (isTupleType(restType)) { const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; const index = pos - paramCount; const associatedName = associatedNames?.[index]; const isRestTupleElement = !!associatedName?.dotDotDotToken; return associatedName ? [ getTupleElementLabel(associatedName), isRestTupleElement ] : undefined; } if (pos === paramCount) { return [restParameter.escapedName, true]; } return undefined; } function isParameterDeclarationWithIdentifierName(symbol: Symbol) { return symbol.valueDeclaration && isParameter(symbol.valueDeclaration) && isIdentifier(symbol.valueDeclaration.name); } function isValidDeclarationForTupleLabel(d: Declaration): d is NamedTupleMember | (ParameterDeclaration & { name: Identifier }) { return d.kind === SyntaxKind.NamedTupleMember || (isParameter(d) && d.name && isIdentifier(d.name)); } function getNameableDeclarationAtPosition(signature: Signature, pos: number) { const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); if (pos < paramCount) { const decl = signature.parameters[pos].valueDeclaration; return decl && isValidDeclarationForTupleLabel(decl) ? decl : undefined; } const restParameter = signature.parameters[paramCount] || unknownSymbol; const restType = getTypeOfSymbol(restParameter); if (isTupleType(restType)) { const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; const index = pos - paramCount; return associatedNames && associatedNames[index]; } return restParameter.valueDeclaration && isValidDeclarationForTupleLabel(restParameter.valueDeclaration) ? restParameter.valueDeclaration : undefined; } function getTypeAtPosition(signature: Signature, pos: number): Type { return tryGetTypeAtPosition(signature, pos) || anyType; } function tryGetTypeAtPosition(signature: Signature, pos: number): Type | undefined { const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); if (pos < paramCount) { return getTypeOfParameter(signature.parameters[pos]); } if (signatureHasRestParameter(signature)) { // We want to return the value undefined for an out of bounds parameter position, // so we need to check bounds here before calling getIndexedAccessType (which // otherwise would return the type 'undefined'). const restType = getTypeOfSymbol(signature.parameters[paramCount]); const index = pos - paramCount; if (!isTupleType(restType) || restType.target.hasRestElement || index < restType.target.fixedLength) { return getIndexedAccessType(restType, getNumberLiteralType(index)); } } return undefined; } function getRestTypeAtPosition(source: Signature, pos: number): Type { const parameterCount = getParameterCount(source); const minArgumentCount = getMinArgumentCount(source); const restType = getEffectiveRestType(source); if (restType && pos >= parameterCount - 1) { return pos === parameterCount - 1 ? restType : createArrayType(getIndexedAccessType(restType, numberType)); } const types = []; const flags = []; const names = []; for (let i = pos; i < parameterCount; i++) { if (!restType || i < parameterCount - 1) { types.push(getTypeAtPosition(source, i)); flags.push(i < minArgumentCount ? ElementFlags.Required : ElementFlags.Optional); } else { types.push(restType); flags.push(ElementFlags.Variadic); } const name = getNameableDeclarationAtPosition(source, i); if (name) { names.push(name); } } return createTupleType(types, flags, /*readonly*/ false, length(names) === length(types) ? names : undefined); } // Return the number of parameters in a signature. The rest parameter, if present, counts as one // parameter. For example, the parameter count of (x: number, y: number, ...z: string[]) is 3 and // the parameter count of (x: number, ...args: [number, ...string[], boolean])) is also 3. In the // latter example, the effective rest type is [...string[], boolean]. function getParameterCount(signature: Signature) { const length = signature.parameters.length; if (signatureHasRestParameter(signature)) { const restType = getTypeOfSymbol(signature.parameters[length - 1]); if (isTupleType(restType)) { return length + restType.target.fixedLength - (restType.target.hasRestElement ? 0 : 1); } } return length; } function getMinArgumentCount(signature: Signature, flags?: MinArgumentCountFlags) { const strongArityForUntypedJS = flags! & MinArgumentCountFlags.StrongArityForUntypedJS; const voidIsNonOptional = flags! & MinArgumentCountFlags.VoidIsNonOptional; if (voidIsNonOptional || signature.resolvedMinArgumentCount === undefined) { let minArgumentCount: number | undefined; if (signatureHasRestParameter(signature)) { const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); if (isTupleType(restType)) { const firstOptionalIndex = findIndex(restType.target.elementFlags, f => !(f & ElementFlags.Required)); const requiredCount = firstOptionalIndex < 0 ? restType.target.fixedLength : firstOptionalIndex; if (requiredCount > 0) { minArgumentCount = signature.parameters.length - 1 + requiredCount; } } } if (minArgumentCount === undefined) { if (!strongArityForUntypedJS && signature.flags & SignatureFlags.IsUntypedSignatureInJSFile) { return 0; } minArgumentCount = signature.minArgumentCount; } if (voidIsNonOptional) { return minArgumentCount; } for (let i = minArgumentCount - 1; i >= 0; i--) { const type = getTypeAtPosition(signature, i); if (filterType(type, acceptsVoid).flags & TypeFlags.Never) { break; } minArgumentCount = i; } signature.resolvedMinArgumentCount = minArgumentCount; } return signature.resolvedMinArgumentCount; } function hasEffectiveRestParameter(signature: Signature) { if (signatureHasRestParameter(signature)) { const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); return !isTupleType(restType) || restType.target.hasRestElement; } return false; } function getEffectiveRestType(signature: Signature) { if (signatureHasRestParameter(signature)) { const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); if (!isTupleType(restType)) { return restType; } if (restType.target.hasRestElement) { return sliceTupleType(restType, restType.target.fixedLength); } } return undefined; } function getNonArrayRestType(signature: Signature) { const restType = getEffectiveRestType(signature); return restType && !isArrayType(restType) && !isTypeAny(restType) && (getReducedType(restType).flags & TypeFlags.Never) === 0 ? restType : undefined; } function getTypeOfFirstParameterOfSignature(signature: Signature) { return getTypeOfFirstParameterOfSignatureWithFallback(signature, neverType); } function getTypeOfFirstParameterOfSignatureWithFallback(signature: Signature, fallbackType: Type) { return signature.parameters.length > 0 ? getTypeAtPosition(signature, 0) : fallbackType; } function inferFromAnnotatedParameters(signature: Signature, context: Signature, inferenceContext: InferenceContext) { const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); for (let i = 0; i < len; i++) { const declaration = signature.parameters[i].valueDeclaration as ParameterDeclaration; if (declaration.type) { const typeNode = getEffectiveTypeAnnotationNode(declaration); if (typeNode) { inferTypes(inferenceContext.inferences, getTypeFromTypeNode(typeNode), getTypeAtPosition(context, i)); } } } } function assignContextualParameterTypes(signature: Signature, context: Signature) { if (context.typeParameters) { if (!signature.typeParameters) { signature.typeParameters = context.typeParameters; } else { return; // This signature has already has a contextual inference performed and cached on it! } } if (context.thisParameter) { const parameter = signature.thisParameter; if (!parameter || parameter.valueDeclaration && !(parameter.valueDeclaration as ParameterDeclaration).type) { if (!parameter) { signature.thisParameter = createSymbolWithType(context.thisParameter, /*type*/ undefined); } assignParameterType(signature.thisParameter!, getTypeOfSymbol(context.thisParameter)); } } const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); for (let i = 0; i < len; i++) { const parameter = signature.parameters[i]; if (!getEffectiveTypeAnnotationNode(parameter.valueDeclaration as ParameterDeclaration)) { const contextualParameterType = tryGetTypeAtPosition(context, i); assignParameterType(parameter, contextualParameterType); } } if (signatureHasRestParameter(signature)) { // parameter might be a transient symbol generated by use of `arguments` in the function body. const parameter = last(signature.parameters); if (parameter.valueDeclaration ? !getEffectiveTypeAnnotationNode(parameter.valueDeclaration as ParameterDeclaration) // a declarationless parameter may still have a `.type` already set by its construction logic // (which may pull a type from a jsdoc) - only allow fixing on `DeferredType` parameters with a fallback type : !!(getCheckFlags(parameter) & CheckFlags.DeferredType) ) { const contextualParameterType = getRestTypeAtPosition(context, len); assignParameterType(parameter, contextualParameterType); } } } function assignNonContextualParameterTypes(signature: Signature) { if (signature.thisParameter) { assignParameterType(signature.thisParameter); } for (const parameter of signature.parameters) { assignParameterType(parameter); } } function assignParameterType(parameter: Symbol, type?: Type) { const links = getSymbolLinks(parameter); if (!links.type) { const declaration = parameter.valueDeclaration as ParameterDeclaration | undefined; links.type = type || (declaration ? getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true) : getTypeOfSymbol(parameter)); if (declaration && declaration.name.kind !== SyntaxKind.Identifier) { // if inference didn't come up with anything but unknown, fall back to the binding pattern if present. if (links.type === unknownType) { links.type = getTypeFromBindingPattern(declaration.name); } assignBindingElementTypes(declaration.name, links.type); } } else if (type) { Debug.assertEqual(links.type, type, "Parameter symbol already has a cached type which differs from newly assigned type"); } } // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push // the destructured type into the contained binding elements. function assignBindingElementTypes(pattern: BindingPattern, parentType: Type) { for (const element of pattern.elements) { if (!isOmittedExpression(element)) { const type = getBindingElementTypeFromParentType(element, parentType); if (element.name.kind === SyntaxKind.Identifier) { getSymbolLinks(getSymbolOfDeclaration(element)).type = type; } else { assignBindingElementTypes(element.name, type); } } } } function createClassDecoratorContextType(classType: Type) { return tryCreateTypeReference(getGlobalClassDecoratorContextType(/*reportErrors*/ true), [classType]); } function createClassMethodDecoratorContextType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassMethodDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); } function createClassGetterDecoratorContextType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassGetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); } function createClassSetterDecoratorContextType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassSetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); } function createClassAccessorDecoratorContextType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassAccessorDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); } function createClassFieldDecoratorContextType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassFieldDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); } /** * Gets a type like `{ name: "foo", private: false, static: true }` that is used to provided member-specific * details that will be intersected with a decorator context type. */ function getClassMemberDecoratorContextOverrideType(nameType: Type, isPrivate: boolean, isStatic: boolean) { const key = `${isPrivate ? "p" : "P"}${isStatic ? "s" : "S"}${nameType.id}` as const; let overrideType = decoratorContextOverrideTypeCache.get(key); if (!overrideType) { const members = createSymbolTable(); members.set("name" as __String, createProperty("name" as __String, nameType)); members.set("private" as __String, createProperty("private" as __String, isPrivate ? trueType : falseType)); members.set("static" as __String, createProperty("static" as __String, isStatic ? trueType : falseType)); overrideType = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, emptyArray); decoratorContextOverrideTypeCache.set(key, overrideType); } return overrideType; } function createClassMemberDecoratorContextTypeForNode(node: MethodDeclaration | AccessorDeclaration | PropertyDeclaration, thisType: Type, valueType: Type) { const isStatic = hasStaticModifier(node); const isPrivate = isPrivateIdentifier(node.name); const nameType = isPrivate ? getStringLiteralType(idText(node.name)) : getLiteralTypeFromPropertyName(node.name); const contextType = isMethodDeclaration(node) ? createClassMethodDecoratorContextType(thisType, valueType) : isGetAccessorDeclaration(node) ? createClassGetterDecoratorContextType(thisType, valueType) : isSetAccessorDeclaration(node) ? createClassSetterDecoratorContextType(thisType, valueType) : isAutoAccessorPropertyDeclaration(node) ? createClassAccessorDecoratorContextType(thisType, valueType) : isPropertyDeclaration(node) ? createClassFieldDecoratorContextType(thisType, valueType) : Debug.failBadSyntaxKind(node); const overrideType = getClassMemberDecoratorContextOverrideType(nameType, isPrivate, isStatic); return getIntersectionType([contextType, overrideType]); } function createClassAccessorDecoratorTargetType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassAccessorDecoratorTargetType(/*reportError*/ true), [thisType, valueType]); } function createClassAccessorDecoratorResultType(thisType: Type, valueType: Type) { return tryCreateTypeReference(getGlobalClassAccessorDecoratorResultType(/*reportError*/ true), [thisType, valueType]); } function createClassFieldDecoratorInitializerMutatorType(thisType: Type, valueType: Type) { const thisParam = createParameter("this" as __String, thisType); const valueParam = createParameter("value" as __String, valueType); return createFunctionType(/*typeParameters*/ undefined, thisParam, [valueParam], valueType, /*typePredicate*/ undefined, 1); } /** * Creates a call signature for an ES Decorator. This method is used by the semantics of * `getESDecoratorCallSignature`, which you should probably be using instead. */ function createESDecoratorCallSignature(targetType: Type, contextType: Type, nonOptionalReturnType: Type) { const targetParam = createParameter("target" as __String, targetType); const contextParam = createParameter("context" as __String, contextType); const returnType = getUnionType([nonOptionalReturnType, voidType]); return createCallSignature(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, contextParam], returnType); } /** * Gets a call signature that should be used when resolving `decorator` as a call. This does not use the value * of the decorator itself, but instead uses the declaration on which it is placed along with its relative * position amongst other decorators on the same declaration to determine the applicable signature. The * resulting signature can be used for call resolution, inference, and contextual typing. */ function getESDecoratorCallSignature(decorator: Decorator) { // We are considering a future change that would allow the type of a decorator to affect the type of the // class and its members, such as a `@Stringify` decorator changing the type of a `number` field to `string`, or // a `@Callable` decorator adding a call signature to a `class`. The type arguments for the various context // types may eventually change to reflect such mutations. // // In some cases we describe such potential mutations as coming from a "prior decorator application". It is // important to note that, while decorators are *evaluated* left to right, they are *applied* right to left // to preserve f ৹ g -> f(g(x)) application order. In these cases, a "prior" decorator usually means the // next decorator following this one in document order. // // The "original type" of a class or member is the type it was declared as, or the type we infer from // initializers, before _any_ decorators are applied. // // The type of a class or member that is a result of a prior decorator application represents the // "current type", i.e., the type for the declaration at the time the decorator is _applied_. // // The type of a class or member that is the result of the application of *all* relevant decorators is the // "final type". // // Any decorator that allows mutation or replacement will also refer to an "input type" and an // "output type". The "input type" corresponds to the "current type" of the declaration, while the // "output type" will become either the "input type/current type" for a subsequent decorator application, // or the "final type" for the decorated declaration. // // It is important to understand decorator application order as it relates to how the "current", "input", // "output", and "final" types will be determined: // // @E2 @E1 class SomeClass { // @A2 @A1 static f() {} // @B2 @B1 g() {} // @C2 @C1 static x; // @D2 @D1 y; // } // // Per [the specification][1], decorators are applied in the following order: // // 1. For each static method (incl. get/set methods and `accessor` fields), in document order: // a. Apply each decorator for that method, in reverse order (`A1`, `A2`). // 2. For each instance method (incl. get/set methods and `accessor` fields), in document order: // a. Apply each decorator for that method, in reverse order (`B1`, `B2`). // 3. For each static field (excl. auto-accessors), in document order: // a. Apply each decorator for that field, in reverse order (`C1`, `C2`). // 4. For each instance field (excl. auto-accessors), in document order: // a. Apply each decorator for that field, in reverse order (`D1`, `D2`). // 5. Apply each decorator for the class, in reverse order (`E1`, `E2`). // // As a result, "current" types at each decorator application are as follows: // - For `A1`, the "current" types of the class and method are their "original" types. // - For `A2`, the "current type" of the method is the "output type" of `A1`, and the "current type" of the // class is the type of `SomeClass` where `f` is the "output type" of `A1`. This becomes the "final type" // of `f`. // - For `B1`, the "current type" of the method is its "original type", and the "current type" of the class // is the type of `SomeClass` where `f` now has its "final type". // - etc. // // [1]: https://arai-a.github.io/ecma262-compare/?pr=2417&id=sec-runtime-semantics-classdefinitionevaluation // // This seems complicated at first glance, but is not unlike our existing inference for functions: // // declare function pipe( // original: Original, // a1: (input: Original, context: Context) => A1, // a2: (input: A1, context: Context) => A2, // b1: (input: A2, context: Context) => B1, // b2: (input: B1, context: Context) => B2, // c1: (input: B2, context: Context) => C1, // c2: (input: C1, context: Context) => C2, // d1: (input: C2, context: Context) => D1, // d2: (input: D1, context: Context) => D2, // e1: (input: D2, context: Context) => E1, // e2: (input: E1, context: Context) => E2, // ): E2; // When a decorator is applied, it is passed two arguments: "target", which is a value representing the // thing being decorated (constructors for classes, functions for methods/accessors, `undefined` for fields, // and a `{ get, set }` object for auto-accessors), and "context", which is an object that provides // reflection information about the decorated element, as well as the ability to add additional "extra" // initializers. In most cases, the "target" argument corresponds to the "input type" in some way, and the // return value similarly corresponds to the "output type" (though if the "output type" is `void` or // `undefined` then the "output type" is the "input type"). const { parent } = decorator; const links = getNodeLinks(parent); if (!links.decoratorSignature) { links.decoratorSignature = anySignature; switch (parent.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: { // Class decorators have a `context` of `ClassDecoratorContext`, where the `Class` type // argument will be the "final type" of the class after all decorators are applied. const node = parent as ClassDeclaration | ClassExpression; const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); const contextType = createClassDecoratorContextType(targetType); links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, targetType); break; } case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: { const node = parent as MethodDeclaration | GetAccessorDeclaration | SetAccessorDeclaration; if (!isClassLike(node.parent)) break; // Method decorators have a `context` of `ClassMethodDecoratorContext`, where the // `Value` type argument corresponds to the "final type" of the method. // // Getter decorators have a `context` of `ClassGetterDecoratorContext`, where the // `Value` type argument corresponds to the "final type" of the value returned by the getter. // // Setter decorators have a `context` of `ClassSetterDecoratorContext`, where the // `Value` type argument corresponds to the "final type" of the parameter of the setter. // // In all three cases, the `This` type argument is the "final type" of either the class or // instance, depending on whether the member was `static`. const valueType = isMethodDeclaration(node) ? getOrCreateTypeFromSignature(getSignatureFromDeclaration(node)) : getTypeOfNode(node); const thisType = hasStaticModifier(node) ? getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); // We wrap the "input type", if necessary, to match the decoration target. For getters this is // something like `() => inputType`, for setters it's `(value: inputType) => void` and for // methods it is just the input type. const targetType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : valueType; const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); // We also wrap the "output type", as needed. const returnType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : valueType; links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); break; } case SyntaxKind.PropertyDeclaration: { const node = parent as PropertyDeclaration; if (!isClassLike(node.parent)) break; // Field decorators have a `context` of `ClassFieldDecoratorContext` and // auto-accessor decorators have a `context` of `ClassAccessorDecoratorContext. In // both cases, the `This` type argument is the "final type" of either the class or instance, // depending on whether the member was `static`, and the `Value` type argument corresponds to // the "final type" of the value stored in the field. const valueType = getTypeOfNode(node); const thisType = hasStaticModifier(node) ? getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); // The `target` of an auto-accessor decorator is a `{ get, set }` object, representing the // runtime-generated getter and setter that are added to the class/prototype. The `target` of a // regular field decorator is always `undefined` as it isn't installed until it is initialized. const targetType = hasAccessorModifier(node) ? createClassAccessorDecoratorTargetType(thisType, valueType) : undefinedType; const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); // We wrap the "output type" depending on the declaration. For auto-accessors, we wrap the // "output type" in a `ClassAccessorDecoratorResult` type, which allows for // mutation of the runtime-generated getter and setter, as well as the injection of an // initializer mutator. For regular fields, we wrap the "output type" in an initializer mutator. const returnType = hasAccessorModifier(node) ? createClassAccessorDecoratorResultType(thisType, valueType) : createClassFieldDecoratorInitializerMutatorType(thisType, valueType); links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); break; } } } return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; } function getLegacyDecoratorCallSignature(decorator: Decorator) { const { parent } = decorator; const links = getNodeLinks(parent); if (!links.decoratorSignature) { links.decoratorSignature = anySignature; switch (parent.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: { const node = parent as ClassDeclaration | ClassExpression; // For a class decorator, the `target` is the type of the class (e.g. the // "static" or "constructor" side of the class). const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); const targetParam = createParameter("target" as __String, targetType); links.decoratorSignature = createCallSignature( /*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam], getUnionType([targetType, voidType]) ); break; } case SyntaxKind.Parameter: { const node = parent as ParameterDeclaration; if (!isConstructorDeclaration(node.parent) && !((isMethodDeclaration(node.parent) || isSetAccessorDeclaration(node.parent) && isClassLike(node.parent.parent)))) { break; } if (getThisParameter(node.parent) === node) { break; } const index = getThisParameter(node.parent) ? node.parent.parameters.indexOf(node) - 1 : node.parent.parameters.indexOf(node); Debug.assert(index >= 0); // A parameter declaration decorator will have three arguments (see `ParameterDecorator` in // core.d.ts). const targetType = isConstructorDeclaration(node.parent) ? getTypeOfSymbol(getSymbolOfDeclaration(node.parent.parent)) : getParentTypeOfClassElement(node.parent); const keyType = isConstructorDeclaration(node.parent) ? undefinedType : getClassElementPropertyKeyType(node.parent); const indexType = getNumberLiteralType(index); const targetParam = createParameter("target" as __String, targetType); const keyParam = createParameter("propertyKey" as __String, keyType); const indexParam = createParameter("parameterIndex" as __String, indexType); links.decoratorSignature = createCallSignature( /*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, keyParam, indexParam], voidType ); break; } case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.PropertyDeclaration: { const node = parent as MethodDeclaration | AccessorDeclaration | PropertyDeclaration; if (!isClassLike(node.parent)) break; // A method or accessor declaration decorator will have either two or three arguments (see // `PropertyDecorator` and `MethodDecorator` in core.d.ts). If we are emitting decorators for // ES3, we will only pass two arguments. const targetType = getParentTypeOfClassElement(node); const targetParam = createParameter("target" as __String, targetType); const keyType = getClassElementPropertyKeyType(node); const keyParam = createParameter("propertyKey" as __String, keyType); const returnType = isPropertyDeclaration(node) ? voidType : createTypedPropertyDescriptorType(getTypeOfNode(node)); const hasPropDesc = languageVersion !== ScriptTarget.ES3 && (!isPropertyDeclaration(parent) || hasAccessorModifier(parent)); if (hasPropDesc) { const descriptorType = createTypedPropertyDescriptorType(getTypeOfNode(node)); const descriptorParam = createParameter("descriptor" as __String, descriptorType); links.decoratorSignature = createCallSignature( /*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, keyParam, descriptorParam], getUnionType([returnType, voidType]) ); } else { links.decoratorSignature = createCallSignature( /*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, keyParam], getUnionType([returnType, voidType]) ); } break; } } } return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; } function getDecoratorCallSignature(decorator: Decorator) { return legacyDecorators ? getLegacyDecoratorCallSignature(decorator) : getESDecoratorCallSignature(decorator); } function createPromiseType(promisedType: Type): Type { // creates a `Promise` type where `T` is the promisedType argument const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); if (globalPromiseType !== emptyGenericType) { // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type // Unwrap an `Awaited` to `T` to improve inference. promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; return createTypeReference(globalPromiseType, [promisedType]); } return unknownType; } function createPromiseLikeType(promisedType: Type): Type { // creates a `PromiseLike` type where `T` is the promisedType argument const globalPromiseLikeType = getGlobalPromiseLikeType(/*reportErrors*/ true); if (globalPromiseLikeType !== emptyGenericType) { // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type // Unwrap an `Awaited` to `T` to improve inference. promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; return createTypeReference(globalPromiseLikeType, [promisedType]); } return unknownType; } function createPromiseReturnType(func: FunctionLikeDeclaration | ImportCall, promisedType: Type) { const promiseType = createPromiseType(promisedType); if (promiseType === unknownType) { error(func, isImportCall(func) ? Diagnostics.A_dynamic_import_call_returns_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option : Diagnostics.An_async_function_or_method_must_return_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option); return errorType; } else if (!getGlobalPromiseConstructorSymbol(/*reportErrors*/ true)) { error(func, isImportCall(func) ? Diagnostics.A_dynamic_import_call_in_ES5_SlashES3_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option : Diagnostics.An_async_function_or_method_in_ES5_SlashES3_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option); } return promiseType; } function createNewTargetExpressionType(targetType: Type): Type { // Create a synthetic type `NewTargetExpression { target: TargetType; }` const symbol = createSymbol(SymbolFlags.None, "NewTargetExpression" as __String); const targetPropertySymbol = createSymbol(SymbolFlags.Property, "target" as __String, CheckFlags.Readonly); targetPropertySymbol.parent = symbol; targetPropertySymbol.links.type = targetType; const members = createSymbolTable([targetPropertySymbol]); symbol.members = members; return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); } function getReturnTypeFromBody(func: FunctionLikeDeclaration, checkMode?: CheckMode): Type { if (!func.body) { return errorType; } const functionFlags = getFunctionFlags(func); const isAsync = (functionFlags & FunctionFlags.Async) !== 0; const isGenerator = (functionFlags & FunctionFlags.Generator) !== 0; let returnType: Type | undefined; let yieldType: Type | undefined; let nextType: Type | undefined; let fallbackReturnType: Type = voidType; if (func.body.kind !== SyntaxKind.Block) { // Async or normal arrow function returnType = checkExpressionCached(func.body, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); if (isAsync) { // From within an async function you can return either a non-promise value or a promise. Any // Promise/A+ compatible implementation will always assimilate any foreign promise, so the // return type of the body should be unwrapped to its awaited type, which we will wrap in // the native Promise type later in this function. returnType = unwrapAwaitedType(checkAwaitedType(returnType, /*withAlias*/ false, /*errorNode*/ func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); } } else if (isGenerator) { // Generator or AsyncGenerator function const returnTypes = checkAndAggregateReturnExpressionTypes(func, checkMode); if (!returnTypes) { fallbackReturnType = neverType; } else if (returnTypes.length > 0) { returnType = getUnionType(returnTypes, UnionReduction.Subtype); } const { yieldTypes, nextTypes } = checkAndAggregateYieldOperandTypes(func, checkMode); yieldType = some(yieldTypes) ? getUnionType(yieldTypes, UnionReduction.Subtype) : undefined; nextType = some(nextTypes) ? getIntersectionType(nextTypes) : undefined; } else { // Async or normal function const types = checkAndAggregateReturnExpressionTypes(func, checkMode); if (!types) { // For an async function, the return type will not be never, but rather a Promise for never. return functionFlags & FunctionFlags.Async ? createPromiseReturnType(func, neverType) // Async function : neverType; // Normal function } if (types.length === 0) { // For an async function, the return type will not be void, but rather a Promise for void. return functionFlags & FunctionFlags.Async ? createPromiseReturnType(func, voidType) // Async function : voidType; // Normal function } // Return a union of the return expression types. returnType = getUnionType(types, UnionReduction.Subtype); } if (returnType || yieldType || nextType) { if (yieldType) reportErrorsFromWidening(func, yieldType, WideningKind.GeneratorYield); if (returnType) reportErrorsFromWidening(func, returnType, WideningKind.FunctionReturn); if (nextType) reportErrorsFromWidening(func, nextType, WideningKind.GeneratorNext); if (returnType && isUnitType(returnType) || yieldType && isUnitType(yieldType) || nextType && isUnitType(nextType)) { const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func); const contextualType = !contextualSignature ? undefined : contextualSignature === getSignatureFromDeclaration(func) ? isGenerator ? undefined : returnType : instantiateContextualType(getReturnTypeOfSignature(contextualSignature), func, /*contextFlags*/ undefined); if (isGenerator) { yieldType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(yieldType, contextualType, IterationTypeKind.Yield, isAsync); returnType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(returnType, contextualType, IterationTypeKind.Return, isAsync); nextType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(nextType, contextualType, IterationTypeKind.Next, isAsync); } else { returnType = getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(returnType, contextualType, isAsync); } } if (yieldType) yieldType = getWidenedType(yieldType); if (returnType) returnType = getWidenedType(returnType); if (nextType) nextType = getWidenedType(nextType); } if (isGenerator) { return createGeneratorReturnType( yieldType || neverType, returnType || fallbackReturnType, nextType || getContextualIterationType(IterationTypeKind.Next, func) || unknownType, isAsync); } else { // From within an async function you can return either a non-promise value or a promise. Any // Promise/A+ compatible implementation will always assimilate any foreign promise, so the // return type of the body is awaited type of the body, wrapped in a native Promise type. return isAsync ? createPromiseType(returnType || fallbackReturnType) : returnType || fallbackReturnType; } } function createGeneratorReturnType(yieldType: Type, returnType: Type, nextType: Type, isAsyncGenerator: boolean) { const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); yieldType = resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || unknownType; returnType = resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || unknownType; nextType = resolver.resolveIterationType(nextType, /*errorNode*/ undefined) || unknownType; if (globalGeneratorType === emptyGenericType) { // Fall back to the global IterableIterator if returnType is assignable to the expected return iteration // type of IterableIterator, and the expected next iteration type of IterableIterator is assignable to // nextType. const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); const iterationTypes = globalType !== emptyGenericType ? getIterationTypesOfGlobalIterableType(globalType, resolver) : undefined; const iterableIteratorReturnType = iterationTypes ? iterationTypes.returnType : anyType; const iterableIteratorNextType = iterationTypes ? iterationTypes.nextType : undefinedType; if (isTypeAssignableTo(returnType, iterableIteratorReturnType) && isTypeAssignableTo(iterableIteratorNextType, nextType)) { if (globalType !== emptyGenericType) { return createTypeFromGenericGlobalType(globalType, [yieldType]); } // The global IterableIterator type doesn't exist, so report an error resolver.getGlobalIterableIteratorType(/*reportErrors*/ true); return emptyObjectType; } // The global Generator type doesn't exist, so report an error resolver.getGlobalGeneratorType(/*reportErrors*/ true); return emptyObjectType; } return createTypeFromGenericGlobalType(globalGeneratorType, [yieldType, returnType, nextType]); } function checkAndAggregateYieldOperandTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined) { const yieldTypes: Type[] = []; const nextTypes: Type[] = []; const isAsync = (getFunctionFlags(func) & FunctionFlags.Async) !== 0; forEachYieldExpression(func.body as Block, yieldExpression => { const yieldExpressionType = yieldExpression.expression ? checkExpression(yieldExpression.expression, checkMode) : undefinedWideningType; pushIfUnique(yieldTypes, getYieldedTypeOfYieldExpression(yieldExpression, yieldExpressionType, anyType, isAsync)); let nextType: Type | undefined; if (yieldExpression.asteriskToken) { const iterationTypes = getIterationTypesOfIterable( yieldExpressionType, isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, yieldExpression.expression); nextType = iterationTypes && iterationTypes.nextType; } else { nextType = getContextualType(yieldExpression, /*contextFlags*/ undefined); } if (nextType) pushIfUnique(nextTypes, nextType); }); return { yieldTypes, nextTypes }; } function getYieldedTypeOfYieldExpression(node: YieldExpression, expressionType: Type, sentType: Type, isAsync: boolean): Type | undefined { const errorNode = node.expression || node; // A `yield*` expression effectively yields everything that its operand yields const yieldedType = node.asteriskToken ? checkIteratedTypeOrElementType(isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, expressionType, sentType, errorNode) : expressionType; return !isAsync ? yieldedType : getAwaitedType(yieldedType, errorNode, node.asteriskToken ? Diagnostics.Type_of_iterated_elements_of_a_yield_Asterisk_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member : Diagnostics.Type_of_yield_operand_in_an_async_generator_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); } // Return the combined not-equal type facts for all cases except those between the start and end indices. function getNotEqualFactsFromTypeofSwitch(start: number, end: number, witnesses: (string | undefined)[]): TypeFacts { let facts: TypeFacts = TypeFacts.None; for (let i = 0; i < witnesses.length; i++) { const witness = i < start || i >= end ? witnesses[i] : undefined; facts |= witness !== undefined ? typeofNEFacts.get(witness) || TypeFacts.TypeofNEHostObject : 0; } return facts; } function isExhaustiveSwitchStatement(node: SwitchStatement): boolean { const links = getNodeLinks(node); if (links.isExhaustive === undefined) { links.isExhaustive = 0; // Indicate resolution is in process const exhaustive = computeExhaustiveSwitchStatement(node); if (links.isExhaustive === 0) { links.isExhaustive = exhaustive; } } else if (links.isExhaustive === 0) { links.isExhaustive = false; // Resolve circularity to false } return links.isExhaustive; } function computeExhaustiveSwitchStatement(node: SwitchStatement): boolean { if (node.expression.kind === SyntaxKind.TypeOfExpression) { const witnesses = getSwitchClauseTypeOfWitnesses(node); if (!witnesses) { return false; } const operandConstraint = getBaseConstraintOrType(checkExpressionCached((node.expression as TypeOfExpression).expression)); // Get the not-equal flags for all handled cases. const notEqualFacts = getNotEqualFactsFromTypeofSwitch(0, 0, witnesses); if (operandConstraint.flags & TypeFlags.AnyOrUnknown) { // We special case the top types to be exhaustive when all cases are handled. return (TypeFacts.AllTypeofNE & notEqualFacts) === TypeFacts.AllTypeofNE; } // A missing not-equal flag indicates that the type wasn't handled by some case. return !someType(operandConstraint, t => (getTypeFacts(t) & notEqualFacts) === notEqualFacts); } const type = checkExpressionCached(node.expression); if (!isLiteralType(type)) { return false; } const switchTypes = getSwitchClauseTypes(node); if (!switchTypes.length || some(switchTypes, isNeitherUnitTypeNorNever)) { return false; } return eachTypeContainedIn(mapType(type, getRegularTypeOfLiteralType), switchTypes); } function functionHasImplicitReturn(func: FunctionLikeDeclaration) { return func.endFlowNode && isReachableFlowNode(func.endFlowNode); } /** NOTE: Return value of `[]` means a different thing than `undefined`. `[]` means func returns `void`, `undefined` means it returns `never`. */ function checkAndAggregateReturnExpressionTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined): Type[] | undefined { const functionFlags = getFunctionFlags(func); const aggregatedTypes: Type[] = []; let hasReturnWithNoExpression = functionHasImplicitReturn(func); let hasReturnOfTypeNever = false; forEachReturnStatement(func.body as Block, returnStatement => { const expr = returnStatement.expression; if (expr) { let type = checkExpressionCached(expr, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); if (functionFlags & FunctionFlags.Async) { // From within an async function you can return either a non-promise value or a promise. Any // Promise/A+ compatible implementation will always assimilate any foreign promise, so the // return type of the body should be unwrapped to its awaited type, which should be wrapped in // the native Promise type by the caller. type = unwrapAwaitedType(checkAwaitedType(type, /*withAlias*/ false, func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); } if (type.flags & TypeFlags.Never) { hasReturnOfTypeNever = true; } pushIfUnique(aggregatedTypes, type); } else { hasReturnWithNoExpression = true; } }); if (aggregatedTypes.length === 0 && !hasReturnWithNoExpression && (hasReturnOfTypeNever || mayReturnNever(func))) { return undefined; } if (strictNullChecks && aggregatedTypes.length && hasReturnWithNoExpression && !(isJSConstructor(func) && aggregatedTypes.some(t => t.symbol === func.symbol))) { // Javascript "callable constructors", containing eg `if (!(this instanceof A)) return new A()` should not add undefined pushIfUnique(aggregatedTypes, undefinedType); } return aggregatedTypes; } function mayReturnNever(func: FunctionLikeDeclaration): boolean { switch (func.kind) { case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: return true; case SyntaxKind.MethodDeclaration: return func.parent.kind === SyntaxKind.ObjectLiteralExpression; default: return false; } } /** * TypeScript Specification 1.0 (6.3) - July 2014 * An explicitly typed function whose return type isn't the Void type, * the Any type, or a union type containing the Void or Any type as a constituent * must have at least one return statement somewhere in its body. * An exception to this rule is if the function implementation consists of a single 'throw' statement. * * @param returnType - return type of the function, can be undefined if return type is not explicitly specified */ function checkAllCodePathsInNonVoidFunctionReturnOrThrow(func: FunctionLikeDeclaration | MethodSignature, returnType: Type | undefined) { addLazyDiagnostic(checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics); return; function checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics(): void { const functionFlags = getFunctionFlags(func); const type = returnType && unwrapReturnType(returnType, functionFlags); // Functions with with an explicitly specified 'void' or 'any' return type don't need any return expressions. if (type && maybeTypeOfKind(type, TypeFlags.Any | TypeFlags.Void)) { return; } // If all we have is a function signature, or an arrow function with an expression body, then there is nothing to check. // also if HasImplicitReturn flag is not set this means that all codepaths in function body end with return or throw if (func.kind === SyntaxKind.MethodSignature || nodeIsMissing(func.body) || func.body!.kind !== SyntaxKind.Block || !functionHasImplicitReturn(func)) { return; } const hasExplicitReturn = func.flags & NodeFlags.HasExplicitReturn; const errorNode = getEffectiveReturnTypeNode(func) || func; if (type && type.flags & TypeFlags.Never) { error(errorNode, Diagnostics.A_function_returning_never_cannot_have_a_reachable_end_point); } else if (type && !hasExplicitReturn) { // minimal check: function has syntactic return type annotation and no explicit return statements in the body // this function does not conform to the specification. error(errorNode, Diagnostics.A_function_whose_declared_type_is_neither_void_nor_any_must_return_a_value); } else if (type && strictNullChecks && !isTypeAssignableTo(undefinedType, type)) { error(errorNode, Diagnostics.Function_lacks_ending_return_statement_and_return_type_does_not_include_undefined); } else if (compilerOptions.noImplicitReturns) { if (!type) { // If return type annotation is omitted check if function has any explicit return statements. // If it does not have any - its inferred return type is void - don't do any checks. // Otherwise get inferred return type from function body and report error only if it is not void / anytype if (!hasExplicitReturn) { return; } const inferredReturnType = getReturnTypeOfSignature(getSignatureFromDeclaration(func)); if (isUnwrappedReturnTypeVoidOrAny(func, inferredReturnType)) { return; } } error(errorNode, Diagnostics.Not_all_code_paths_return_a_value); } } } function checkFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode): Type { Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); checkNodeDeferred(node); if (isFunctionExpression(node)) { checkCollisionsForDeclarationName(node, node.name); } // The identityMapper object is used to indicate that function expressions are wildcards if (checkMode && checkMode & CheckMode.SkipContextSensitive && isContextSensitive(node)) { // Skip parameters, return signature with return type that retains noncontextual parts so inferences can still be drawn in an early stage if (!getEffectiveReturnTypeNode(node) && !hasContextSensitiveParameters(node)) { // Return plain anyFunctionType if there is no possibility we'll make inferences from the return type const contextualSignature = getContextualSignature(node); if (contextualSignature && couldContainTypeVariables(getReturnTypeOfSignature(contextualSignature))) { const links = getNodeLinks(node); if (links.contextFreeType) { return links.contextFreeType; } const returnType = getReturnTypeFromBody(node, checkMode); const returnOnlySignature = createSignature(undefined, undefined, undefined, emptyArray, returnType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); const returnOnlyType = createAnonymousType(node.symbol, emptySymbols, [returnOnlySignature], emptyArray, emptyArray); returnOnlyType.objectFlags |= ObjectFlags.NonInferrableType; return links.contextFreeType = returnOnlyType; } } return anyFunctionType; } // Grammar checking const hasGrammarError = checkGrammarFunctionLikeDeclaration(node); if (!hasGrammarError && node.kind === SyntaxKind.FunctionExpression) { checkGrammarForGenerator(node); } contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node, checkMode); return getTypeOfSymbol(getSymbolOfDeclaration(node)); } function contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode) { const links = getNodeLinks(node); // Check if function expression is contextually typed and assign parameter types if so. if (!(links.flags & NodeCheckFlags.ContextChecked)) { const contextualSignature = getContextualSignature(node); // If a type check is started at a function expression that is an argument of a function call, obtaining the // contextual type may recursively get back to here during overload resolution of the call. If so, we will have // already assigned contextual types. if (!(links.flags & NodeCheckFlags.ContextChecked)) { links.flags |= NodeCheckFlags.ContextChecked; const signature = firstOrUndefined(getSignaturesOfType(getTypeOfSymbol(getSymbolOfDeclaration(node)), SignatureKind.Call)); if (!signature) { return; } if (isContextSensitive(node)) { if (contextualSignature) { const inferenceContext = getInferenceContext(node); let instantiatedContextualSignature: Signature | undefined; if (checkMode && checkMode & CheckMode.Inferential) { inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); const restType = getEffectiveRestType(contextualSignature); if (restType && restType.flags & TypeFlags.TypeParameter) { instantiatedContextualSignature = instantiateSignature(contextualSignature, inferenceContext!.nonFixingMapper); } } instantiatedContextualSignature ||= inferenceContext ? instantiateSignature(contextualSignature, inferenceContext.mapper) : contextualSignature; assignContextualParameterTypes(signature, instantiatedContextualSignature); } else { // Force resolution of all parameter types such that the absence of a contextual type is consistently reflected. assignNonContextualParameterTypes(signature); } } if (contextualSignature && !getReturnTypeFromAnnotation(node) && !signature.resolvedReturnType) { const returnType = getReturnTypeFromBody(node, checkMode); if (!signature.resolvedReturnType) { signature.resolvedReturnType = returnType; } } checkSignatureDeclaration(node); } } } function checkFunctionExpressionOrObjectLiteralMethodDeferred(node: ArrowFunction | FunctionExpression | MethodDeclaration) { Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); const functionFlags = getFunctionFlags(node); const returnType = getReturnTypeFromAnnotation(node); checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); if (node.body) { if (!getEffectiveReturnTypeNode(node)) { // There are some checks that are only performed in getReturnTypeFromBody, that may produce errors // we need. An example is the noImplicitAny errors resulting from widening the return expression // of a function. Because checking of function expression bodies is deferred, there was never an // appropriate time to do this during the main walk of the file (see the comment at the top of // checkFunctionExpressionBodies). So it must be done now. getReturnTypeOfSignature(getSignatureFromDeclaration(node)); } if (node.body.kind === SyntaxKind.Block) { checkSourceElement(node.body); } else { // From within an async function you can return either a non-promise value or a promise. Any // Promise/A+ compatible implementation will always assimilate any foreign promise, so we // should not be checking assignability of a promise to the return type. Instead, we need to // check assignability of the awaited type of the expression body against the promised type of // its return type annotation. const exprType = checkExpression(node.body); const returnOrPromisedType = returnType && unwrapReturnType(returnType, functionFlags); if (returnOrPromisedType) { if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { // Async function const awaitedType = checkAwaitedType(exprType, /*withAlias*/ false, node.body, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); checkTypeAssignableToAndOptionallyElaborate(awaitedType, returnOrPromisedType, node.body, node.body); } else { // Normal function checkTypeAssignableToAndOptionallyElaborate(exprType, returnOrPromisedType, node.body, node.body); } } } } } function checkArithmeticOperandType(operand: Node, type: Type, diagnostic: DiagnosticMessage, isAwaitValid = false): boolean { if (!isTypeAssignableTo(type, numberOrBigIntType)) { const awaitedType = isAwaitValid && getAwaitedTypeOfPromise(type); errorAndMaybeSuggestAwait( operand, !!awaitedType && isTypeAssignableTo(awaitedType, numberOrBigIntType), diagnostic); return false; } return true; } function isReadonlyAssignmentDeclaration(d: Declaration) { if (!isCallExpression(d)) { return false; } if (!isBindableObjectDefinePropertyCall(d)) { return false; } const objectLitType = checkExpressionCached(d.arguments[2]); const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); if (valueType) { const writableProp = getPropertyOfType(objectLitType, "writable" as __String); const writableType = writableProp && getTypeOfSymbol(writableProp); if (!writableType || writableType === falseType || writableType === regularFalseType) { return true; } // We include this definition whereupon we walk back and check the type at the declaration because // The usual definition of `Object.defineProperty` will _not_ cause literal types to be preserved in the // argument types, should the type be contextualized by the call itself. if (writableProp && writableProp.valueDeclaration && isPropertyAssignment(writableProp.valueDeclaration)) { const initializer = writableProp.valueDeclaration.initializer; const rawOriginalType = checkExpression(initializer); if (rawOriginalType === falseType || rawOriginalType === regularFalseType) { return true; } } return false; } const setProp = getPropertyOfType(objectLitType, "set" as __String); return !setProp; } function isReadonlySymbol(symbol: Symbol): boolean { // The following symbols are considered read-only: // Properties with a 'readonly' modifier // Variables declared with 'const' // Get accessors without matching set accessors // Enum members // Object.defineProperty assignments with writable false or no setter // Unions and intersections of the above (unions and intersections eagerly set isReadonly on creation) return !!(getCheckFlags(symbol) & CheckFlags.Readonly || symbol.flags & SymbolFlags.Property && getDeclarationModifierFlagsFromSymbol(symbol) & ModifierFlags.Readonly || symbol.flags & SymbolFlags.Variable && getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Const || symbol.flags & SymbolFlags.Accessor && !(symbol.flags & SymbolFlags.SetAccessor) || symbol.flags & SymbolFlags.EnumMember || some(symbol.declarations, isReadonlyAssignmentDeclaration) ); } function isAssignmentToReadonlyEntity(expr: Expression, symbol: Symbol, assignmentKind: AssignmentKind) { if (assignmentKind === AssignmentKind.None) { // no assigment means it doesn't matter whether the entity is readonly return false; } if (isReadonlySymbol(symbol)) { // Allow assignments to readonly properties within constructors of the same class declaration. if (symbol.flags & SymbolFlags.Property && isAccessExpression(expr) && expr.expression.kind === SyntaxKind.ThisKeyword) { // Look for if this is the constructor for the class that `symbol` is a property of. const ctor = getContainingFunction(expr); if (!(ctor && (ctor.kind === SyntaxKind.Constructor || isJSConstructor(ctor)))) { return true; } if (symbol.valueDeclaration) { const isAssignmentDeclaration = isBinaryExpression(symbol.valueDeclaration); const isLocalPropertyDeclaration = ctor.parent === symbol.valueDeclaration.parent; const isLocalParameterProperty = ctor === symbol.valueDeclaration.parent; const isLocalThisPropertyAssignment = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor.parent; const isLocalThisPropertyAssignmentConstructorFunction = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor; const isWriteableSymbol = isLocalPropertyDeclaration || isLocalParameterProperty || isLocalThisPropertyAssignment || isLocalThisPropertyAssignmentConstructorFunction; return !isWriteableSymbol; } } return true; } if (isAccessExpression(expr)) { // references through namespace import should be readonly const node = skipParentheses(expr.expression); if (node.kind === SyntaxKind.Identifier) { const symbol = getNodeLinks(node).resolvedSymbol!; if (symbol.flags & SymbolFlags.Alias) { const declaration = getDeclarationOfAliasSymbol(symbol); return !!declaration && declaration.kind === SyntaxKind.NamespaceImport; } } } return false; } function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage, invalidOptionalChainMessage: DiagnosticMessage): boolean { // References are combinations of identifiers, parentheses, and property accesses. const node = skipOuterExpressions(expr, OuterExpressionKinds.Assertions | OuterExpressionKinds.Parentheses); if (node.kind !== SyntaxKind.Identifier && !isAccessExpression(node)) { error(expr, invalidReferenceMessage); return false; } if (node.flags & NodeFlags.OptionalChain) { error(expr, invalidOptionalChainMessage); return false; } return true; } function checkDeleteExpression(node: DeleteExpression): Type { checkExpression(node.expression); const expr = skipParentheses(node.expression); if (!isAccessExpression(expr)) { error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_a_property_reference); return booleanType; } if (isPropertyAccessExpression(expr) && isPrivateIdentifier(expr.name)) { error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_private_identifier); } const links = getNodeLinks(expr); const symbol = getExportSymbolOfValueSymbolIfExported(links.resolvedSymbol); if (symbol) { if (isReadonlySymbol(symbol)) { error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_read_only_property); } checkDeleteExpressionMustBeOptional(expr, symbol); } return booleanType; } function checkDeleteExpressionMustBeOptional(expr: AccessExpression, symbol: Symbol) { const type = getTypeOfSymbol(symbol); if (strictNullChecks && !(type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Never)) && !(exactOptionalPropertyTypes ? symbol.flags & SymbolFlags.Optional : getTypeFacts(type) & TypeFacts.IsUndefined)) { error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_optional); } } function checkTypeOfExpression(node: TypeOfExpression): Type { checkExpression(node.expression); return typeofType; } function checkVoidExpression(node: VoidExpression): Type { checkExpression(node.expression); return undefinedWideningType; } function checkAwaitExpressionGrammar(node: AwaitExpression): void { // Grammar checking const container = getContainingFunctionOrClassStaticBlock(node); if (container && isClassStaticBlockDeclaration(container)) { error(node, Diagnostics.Await_expression_cannot_be_used_inside_a_class_static_block); } else if (!(node.flags & NodeFlags.AwaitContext)) { if (isInTopLevelContext(node)) { const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { let span: TextSpan | undefined; if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.await_expressions_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module); diagnostics.add(diagnostic); } switch (moduleKind) { case ModuleKind.Node16: case ModuleKind.NodeNext: if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); diagnostics.add( createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level) ); break; } // fallthrough case ModuleKind.ES2022: case ModuleKind.ESNext: case ModuleKind.System: if (languageVersion >= ScriptTarget.ES2017) { break; } // fallthrough default: span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); diagnostics.add( createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.Top_level_await_expressions_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_or_nodenext_and_the_target_option_is_set_to_es2017_or_higher ) ); break; } } } else { // use of 'await' in non-async function const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { const span = getSpanOfTokenAtPosition(sourceFile, node.pos); const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.await_expressions_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules); if (container && container.kind !== SyntaxKind.Constructor && (getFunctionFlags(container) & FunctionFlags.Async) === 0) { const relatedInfo = createDiagnosticForNode(container, Diagnostics.Did_you_mean_to_mark_this_function_as_async); addRelatedInfo(diagnostic, relatedInfo); } diagnostics.add(diagnostic); } } } if (isInParameterInitializerBeforeContainingFunction(node)) { error(node, Diagnostics.await_expressions_cannot_be_used_in_a_parameter_initializer); } } function checkAwaitExpression(node: AwaitExpression): Type { addLazyDiagnostic(() => checkAwaitExpressionGrammar(node)); const operandType = checkExpression(node.expression); const awaitedType = checkAwaitedType(operandType, /*withAlias*/ true, node, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); if (awaitedType === operandType && !isErrorType(awaitedType) && !(operandType.flags & TypeFlags.AnyOrUnknown)) { addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.await_has_no_effect_on_the_type_of_this_expression)); } return awaitedType; } function checkPrefixUnaryExpression(node: PrefixUnaryExpression): Type { const operandType = checkExpression(node.operand); if (operandType === silentNeverType) { return silentNeverType; } switch (node.operand.kind) { case SyntaxKind.NumericLiteral: switch (node.operator) { case SyntaxKind.MinusToken: return getFreshTypeOfLiteralType(getNumberLiteralType(-(node.operand as NumericLiteral).text)); case SyntaxKind.PlusToken: return getFreshTypeOfLiteralType(getNumberLiteralType(+(node.operand as NumericLiteral).text)); } break; case SyntaxKind.BigIntLiteral: if (node.operator === SyntaxKind.MinusToken) { return getFreshTypeOfLiteralType(getBigIntLiteralType({ negative: true, base10Value: parsePseudoBigInt((node.operand as BigIntLiteral).text) })); } } switch (node.operator) { case SyntaxKind.PlusToken: case SyntaxKind.MinusToken: case SyntaxKind.TildeToken: checkNonNullType(operandType, node.operand); if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.ESSymbolLike)) { error(node.operand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(node.operator)); } if (node.operator === SyntaxKind.PlusToken) { if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.BigIntLike)) { error(node.operand, Diagnostics.Operator_0_cannot_be_applied_to_type_1, tokenToString(node.operator), typeToString(getBaseTypeOfLiteralType(operandType))); } return numberType; } return getUnaryResultType(operandType); case SyntaxKind.ExclamationToken: checkTruthinessExpression(node.operand); const facts = getTypeFacts(operandType) & (TypeFacts.Truthy | TypeFacts.Falsy); return facts === TypeFacts.Truthy ? falseType : facts === TypeFacts.Falsy ? trueType : booleanType; case SyntaxKind.PlusPlusToken: case SyntaxKind.MinusMinusToken: const ok = checkArithmeticOperandType(node.operand, checkNonNullType(operandType, node.operand), Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type); if (ok) { // run check only if former checks succeeded to avoid reporting cascading errors checkReferenceExpression( node.operand, Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access); } return getUnaryResultType(operandType); } return errorType; } function checkPostfixUnaryExpression(node: PostfixUnaryExpression): Type { const operandType = checkExpression(node.operand); if (operandType === silentNeverType) { return silentNeverType; } const ok = checkArithmeticOperandType( node.operand, checkNonNullType(operandType, node.operand), Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type); if (ok) { // run check only if former checks succeeded to avoid reporting cascading errors checkReferenceExpression( node.operand, Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access); } return getUnaryResultType(operandType); } function getUnaryResultType(operandType: Type): Type { if (maybeTypeOfKind(operandType, TypeFlags.BigIntLike)) { return isTypeAssignableToKind(operandType, TypeFlags.AnyOrUnknown) || maybeTypeOfKind(operandType, TypeFlags.NumberLike) ? numberOrBigIntType : bigintType; } // If it's not a bigint type, implicit coercion will result in a number return numberType; } function maybeTypeOfKindConsideringBaseConstraint(type: Type, kind: TypeFlags): boolean { if (maybeTypeOfKind(type, kind)) { return true; } const baseConstraint = getBaseConstraintOrType(type); return !!baseConstraint && maybeTypeOfKind(baseConstraint, kind); } // Return true if type might be of the given kind. A union or intersection type might be of a given // kind if at least one constituent type is of the given kind. function maybeTypeOfKind(type: Type, kind: TypeFlags): boolean { if (type.flags & kind) { return true; } if (type.flags & TypeFlags.UnionOrIntersection) { const types = (type as UnionOrIntersectionType).types; for (const t of types) { if (maybeTypeOfKind(t, kind)) { return true; } } } return false; } function isTypeAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { if (source.flags & kind) { return true; } if (strict && source.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null)) { return false; } return !!(kind & TypeFlags.NumberLike) && isTypeAssignableTo(source, numberType) || !!(kind & TypeFlags.BigIntLike) && isTypeAssignableTo(source, bigintType) || !!(kind & TypeFlags.StringLike) && isTypeAssignableTo(source, stringType) || !!(kind & TypeFlags.BooleanLike) && isTypeAssignableTo(source, booleanType) || !!(kind & TypeFlags.Void) && isTypeAssignableTo(source, voidType) || !!(kind & TypeFlags.Never) && isTypeAssignableTo(source, neverType) || !!(kind & TypeFlags.Null) && isTypeAssignableTo(source, nullType) || !!(kind & TypeFlags.Undefined) && isTypeAssignableTo(source, undefinedType) || !!(kind & TypeFlags.ESSymbol) && isTypeAssignableTo(source, esSymbolType) || !!(kind & TypeFlags.NonPrimitive) && isTypeAssignableTo(source, nonPrimitiveType); } function allTypesAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { return source.flags & TypeFlags.Union ? every((source as UnionType).types, subType => allTypesAssignableToKind(subType, kind, strict)) : isTypeAssignableToKind(source, kind, strict); } function isConstEnumObjectType(type: Type): boolean { return !!(getObjectFlags(type) & ObjectFlags.Anonymous) && !!type.symbol && isConstEnumSymbol(type.symbol); } function isConstEnumSymbol(symbol: Symbol): boolean { return (symbol.flags & SymbolFlags.ConstEnum) !== 0; } function checkInstanceOfExpression(left: Expression, right: Expression, leftType: Type, rightType: Type): Type { if (leftType === silentNeverType || rightType === silentNeverType) { return silentNeverType; } // TypeScript 1.0 spec (April 2014): 4.15.4 // The instanceof operator requires the left operand to be of type Any, an object type, or a type parameter type, // and the right operand to be of type Any, a subtype of the 'Function' interface type, or have a call or construct signature. // The result is always of the Boolean primitive type. // NOTE: do not raise error if leftType is unknown as related error was already reported if (!isTypeAny(leftType) && allTypesAssignableToKind(leftType, TypeFlags.Primitive)) { error(left, Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_of_type_any_an_object_type_or_a_type_parameter); } // NOTE: do not raise error if right is unknown as related error was already reported if (!(isTypeAny(rightType) || typeHasCallOrConstructSignatures(rightType) || isTypeSubtypeOf(rightType, globalFunctionType))) { error(right, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_be_of_type_any_or_of_a_type_assignable_to_the_Function_interface_type); } return booleanType; } function hasEmptyObjectIntersection(type: Type): boolean { return someType(type, t => t === unknownEmptyObjectType || !!(t.flags & TypeFlags.Intersection) && isEmptyAnonymousObjectType(getBaseConstraintOrType(t))); } function checkInExpression(left: Expression, right: Expression, leftType: Type, rightType: Type): Type { if (leftType === silentNeverType || rightType === silentNeverType) { return silentNeverType; } if (isPrivateIdentifier(left)) { if (languageVersion < ScriptTarget.ESNext) { checkExternalEmitHelpers(left, ExternalEmitHelpers.ClassPrivateFieldIn); } // Unlike in 'checkPrivateIdentifierExpression' we now have access to the RHS type // which provides us with the opportunity to emit more detailed errors if (!getNodeLinks(left).resolvedSymbol && getContainingClass(left)) { const isUncheckedJS = isUncheckedJSSuggestion(left, rightType.symbol, /*excludeClasses*/ true); reportNonexistentProperty(left, rightType, isUncheckedJS); } } else { // The type of the lef operand must be assignable to string, number, or symbol. checkTypeAssignableTo(checkNonNullType(leftType, left), stringNumberSymbolType, left); } // The type of the right operand must be assignable to 'object'. if (checkTypeAssignableTo(checkNonNullType(rightType, right), nonPrimitiveType, right)) { // The {} type is assignable to the object type, yet {} might represent a primitive type. Here we // detect and error on {} that results from narrowing the unknown type, as well as intersections // that include {} (we know that the other types in such intersections are assignable to object // since we already checked for that). if (hasEmptyObjectIntersection(rightType)) { error(right, Diagnostics.Type_0_may_represent_a_primitive_value_which_is_not_permitted_as_the_right_operand_of_the_in_operator, typeToString(rightType)); } } // The result is always of the Boolean primitive type. return booleanType; } function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type, rightIsThis?: boolean): Type { const properties = node.properties; if (strictNullChecks && properties.length === 0) { return checkNonNullType(sourceType, node); } for (let i = 0; i < properties.length; i++) { checkObjectLiteralDestructuringPropertyAssignment(node, sourceType, i, properties, rightIsThis); } return sourceType; } /** Note: If property cannot be a SpreadAssignment, then allProperties does not need to be provided */ function checkObjectLiteralDestructuringPropertyAssignment(node: ObjectLiteralExpression, objectLiteralType: Type, propertyIndex: number, allProperties?: NodeArray, rightIsThis = false) { const properties = node.properties; const property = properties[propertyIndex]; if (property.kind === SyntaxKind.PropertyAssignment || property.kind === SyntaxKind.ShorthandPropertyAssignment) { const name = property.name; const exprType = getLiteralTypeFromPropertyName(name); if (isTypeUsableAsPropertyName(exprType)) { const text = getPropertyNameFromType(exprType); const prop = getPropertyOfType(objectLiteralType, text); if (prop) { markPropertyAsReferenced(prop, property, rightIsThis); checkPropertyAccessibility(property, /*isSuper*/ false, /*writing*/ true, objectLiteralType, prop); } } const elementType = getIndexedAccessType(objectLiteralType, exprType, AccessFlags.ExpressionPosition, name); const type = getFlowTypeOfDestructuring(property, elementType); return checkDestructuringAssignment(property.kind === SyntaxKind.ShorthandPropertyAssignment ? property : property.initializer, type); } else if (property.kind === SyntaxKind.SpreadAssignment) { if (propertyIndex < properties.length - 1) { error(property, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); } else { if (languageVersion < ScriptTarget.ESNext) { checkExternalEmitHelpers(property, ExternalEmitHelpers.Rest); } const nonRestNames: PropertyName[] = []; if (allProperties) { for (const otherProperty of allProperties) { if (!isSpreadAssignment(otherProperty)) { nonRestNames.push(otherProperty.name); } } } const type = getRestType(objectLiteralType, nonRestNames, objectLiteralType.symbol); checkGrammarForDisallowedTrailingComma(allProperties, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); return checkDestructuringAssignment(property.expression, type); } } else { error(property, Diagnostics.Property_assignment_expected); } } function checkArrayLiteralAssignment(node: ArrayLiteralExpression, sourceType: Type, checkMode?: CheckMode): Type { const elements = node.elements; if (languageVersion < ScriptTarget.ES2015 && compilerOptions.downlevelIteration) { checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); } // This elementType will be used if the specific property corresponding to this index is not // present (aka the tuple element property). This call also checks that the parentType is in // fact an iterable or array (depending on target language). const possiblyOutOfBoundsType = checkIteratedTypeOrElementType(IterationUse.Destructuring | IterationUse.PossiblyOutOfBounds, sourceType, undefinedType, node) || errorType; let inBoundsType: Type | undefined = compilerOptions.noUncheckedIndexedAccess ? undefined: possiblyOutOfBoundsType; for (let i = 0; i < elements.length; i++) { let type = possiblyOutOfBoundsType; if (node.elements[i].kind === SyntaxKind.SpreadElement) { type = inBoundsType = inBoundsType ?? (checkIteratedTypeOrElementType(IterationUse.Destructuring, sourceType, undefinedType, node) || errorType); } checkArrayLiteralDestructuringElementAssignment(node, sourceType, i, type, checkMode); } return sourceType; } function checkArrayLiteralDestructuringElementAssignment(node: ArrayLiteralExpression, sourceType: Type, elementIndex: number, elementType: Type, checkMode?: CheckMode) { const elements = node.elements; const element = elements[elementIndex]; if (element.kind !== SyntaxKind.OmittedExpression) { if (element.kind !== SyntaxKind.SpreadElement) { const indexType = getNumberLiteralType(elementIndex); if (isArrayLikeType(sourceType)) { // We create a synthetic expression so that getIndexedAccessType doesn't get confused // when the element is a SyntaxKind.ElementAccessExpression. const accessFlags = AccessFlags.ExpressionPosition | (hasDefaultValue(element) ? AccessFlags.NoTupleBoundsCheck : 0); const elementType = getIndexedAccessTypeOrUndefined(sourceType, indexType, accessFlags, createSyntheticExpression(element, indexType)) || errorType; const assignedType = hasDefaultValue(element) ? getTypeWithFacts(elementType, TypeFacts.NEUndefined) : elementType; const type = getFlowTypeOfDestructuring(element, assignedType); return checkDestructuringAssignment(element, type, checkMode); } return checkDestructuringAssignment(element, elementType, checkMode); } if (elementIndex < elements.length - 1) { error(element, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); } else { const restExpression = (element as SpreadElement).expression; if (restExpression.kind === SyntaxKind.BinaryExpression && (restExpression as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { error((restExpression as BinaryExpression).operatorToken, Diagnostics.A_rest_element_cannot_have_an_initializer); } else { checkGrammarForDisallowedTrailingComma(node.elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); const type = everyType(sourceType, isTupleType) ? mapType(sourceType, t => sliceTupleType(t as TupleTypeReference, elementIndex)) : createArrayType(elementType); return checkDestructuringAssignment(restExpression, type, checkMode); } } } return undefined; } function checkDestructuringAssignment(exprOrAssignment: Expression | ShorthandPropertyAssignment, sourceType: Type, checkMode?: CheckMode, rightIsThis?: boolean): Type { let target: Expression; if (exprOrAssignment.kind === SyntaxKind.ShorthandPropertyAssignment) { const prop = exprOrAssignment as ShorthandPropertyAssignment; if (prop.objectAssignmentInitializer) { // In strict null checking mode, if a default value of a non-undefined type is specified, remove // undefined from the final type. if (strictNullChecks && !(getTypeFacts(checkExpression(prop.objectAssignmentInitializer)) & TypeFacts.IsUndefined)) { sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); } checkBinaryLikeExpression(prop.name, prop.equalsToken!, prop.objectAssignmentInitializer, checkMode); } target = (exprOrAssignment as ShorthandPropertyAssignment).name; } else { target = exprOrAssignment; } if (target.kind === SyntaxKind.BinaryExpression && (target as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { checkBinaryExpression(target as BinaryExpression, checkMode); target = (target as BinaryExpression).left; // A default value is specified, so remove undefined from the final type. if (strictNullChecks) { sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); } } if (target.kind === SyntaxKind.ObjectLiteralExpression) { return checkObjectLiteralAssignment(target as ObjectLiteralExpression, sourceType, rightIsThis); } if (target.kind === SyntaxKind.ArrayLiteralExpression) { return checkArrayLiteralAssignment(target as ArrayLiteralExpression, sourceType, checkMode); } return checkReferenceAssignment(target, sourceType, checkMode); } function checkReferenceAssignment(target: Expression, sourceType: Type, checkMode?: CheckMode): Type { const targetType = checkExpression(target, checkMode); const error = target.parent.kind === SyntaxKind.SpreadAssignment ? Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access : Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access; const optionalError = target.parent.kind === SyntaxKind.SpreadAssignment ? Diagnostics.The_target_of_an_object_rest_assignment_may_not_be_an_optional_property_access : Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access; if (checkReferenceExpression(target, error, optionalError)) { checkTypeAssignableToAndOptionallyElaborate(sourceType, targetType, target, target); } if (isPrivateIdentifierPropertyAccessExpression(target)) { checkExternalEmitHelpers(target.parent, ExternalEmitHelpers.ClassPrivateFieldSet); } return sourceType; } /** * This is a *shallow* check: An expression is side-effect-free if the * evaluation of the expression *itself* cannot produce side effects. * For example, x++ / 3 is side-effect free because the / operator * does not have side effects. * The intent is to "smell test" an expression for correctness in positions where * its value is discarded (e.g. the left side of the comma operator). */ function isSideEffectFree(node: Node): boolean { node = skipParentheses(node); switch (node.kind) { case SyntaxKind.Identifier: case SyntaxKind.StringLiteral: case SyntaxKind.RegularExpressionLiteral: case SyntaxKind.TaggedTemplateExpression: case SyntaxKind.TemplateExpression: case SyntaxKind.NoSubstitutionTemplateLiteral: case SyntaxKind.NumericLiteral: case SyntaxKind.BigIntLiteral: case SyntaxKind.TrueKeyword: case SyntaxKind.FalseKeyword: case SyntaxKind.NullKeyword: case SyntaxKind.UndefinedKeyword: case SyntaxKind.FunctionExpression: case SyntaxKind.ClassExpression: case SyntaxKind.ArrowFunction: case SyntaxKind.ArrayLiteralExpression: case SyntaxKind.ObjectLiteralExpression: case SyntaxKind.TypeOfExpression: case SyntaxKind.NonNullExpression: case SyntaxKind.JsxSelfClosingElement: case SyntaxKind.JsxElement: return true; case SyntaxKind.ConditionalExpression: return isSideEffectFree((node as ConditionalExpression).whenTrue) && isSideEffectFree((node as ConditionalExpression).whenFalse); case SyntaxKind.BinaryExpression: if (isAssignmentOperator((node as BinaryExpression).operatorToken.kind)) { return false; } return isSideEffectFree((node as BinaryExpression).left) && isSideEffectFree((node as BinaryExpression).right); case SyntaxKind.PrefixUnaryExpression: case SyntaxKind.PostfixUnaryExpression: // Unary operators ~, !, +, and - have no side effects. // The rest do. switch ((node as PrefixUnaryExpression).operator) { case SyntaxKind.ExclamationToken: case SyntaxKind.PlusToken: case SyntaxKind.MinusToken: case SyntaxKind.TildeToken: return true; } return false; // Some forms listed here for clarity case SyntaxKind.VoidExpression: // Explicit opt-out case SyntaxKind.TypeAssertionExpression: // Not SEF, but can produce useful type warnings case SyntaxKind.AsExpression: // Not SEF, but can produce useful type warnings default: return false; } } function isTypeEqualityComparableTo(source: Type, target: Type) { return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target); } function createCheckBinaryExpression() { interface WorkArea { readonly checkMode: CheckMode | undefined; skip: boolean; stackIndex: number; /** * Holds the types from the left-side of an expression from [0..stackIndex]. * Holds the type of the result at stackIndex+1. This allows us to reuse existing stack entries * and avoid storing an extra property on the object (i.e., `lastResult`). */ typeStack: (Type | undefined)[]; } const trampoline = createBinaryExpressionTrampoline(onEnter, onLeft, onOperator, onRight, onExit, foldState); return (node: BinaryExpression, checkMode: CheckMode | undefined) => { const result = trampoline(node, checkMode); Debug.assertIsDefined(result); return result; }; function onEnter(node: BinaryExpression, state: WorkArea | undefined, checkMode: CheckMode | undefined) { if (state) { state.stackIndex++; state.skip = false; setLeftType(state, /*type*/ undefined); setLastResult(state, /*type*/ undefined); } else { state = { checkMode, skip: false, stackIndex: 0, typeStack: [undefined, undefined], }; } if (isInJSFile(node) && getAssignedExpandoInitializer(node)) { state.skip = true; setLastResult(state, checkExpression(node.right, checkMode)); return state; } checkGrammarNullishCoalesceWithLogicalExpression(node); const operator = node.operatorToken.kind; if (operator === SyntaxKind.EqualsToken && (node.left.kind === SyntaxKind.ObjectLiteralExpression || node.left.kind === SyntaxKind.ArrayLiteralExpression)) { state.skip = true; setLastResult(state, checkDestructuringAssignment(node.left, checkExpression(node.right, checkMode), checkMode, node.right.kind === SyntaxKind.ThisKeyword)); return state; } return state; } function onLeft(left: Expression, state: WorkArea, _node: BinaryExpression) { if (!state.skip) { return maybeCheckExpression(state, left); } } function onOperator(operatorToken: BinaryOperatorToken, state: WorkArea, node: BinaryExpression) { if (!state.skip) { const leftType = getLastResult(state); Debug.assertIsDefined(leftType); setLeftType(state, leftType); setLastResult(state, /*type*/ undefined); const operator = operatorToken.kind; if (isLogicalOrCoalescingBinaryOperator(operator)) { let parent = node.parent; while (parent.kind === SyntaxKind.ParenthesizedExpression || isLogicalOrCoalescingBinaryExpression(parent)) { parent = parent.parent; } if (operator === SyntaxKind.AmpersandAmpersandToken || isIfStatement(parent)) { checkTestingKnownTruthyCallableOrAwaitableType(node.left, leftType, isIfStatement(parent) ? parent.thenStatement : undefined); } checkTruthinessOfType(leftType, node.left); } } } function onRight(right: Expression, state: WorkArea, _node: BinaryExpression) { if (!state.skip) { return maybeCheckExpression(state, right); } } function onExit(node: BinaryExpression, state: WorkArea): Type | undefined { let result: Type | undefined; if (state.skip) { result = getLastResult(state); } else { const leftType = getLeftType(state); Debug.assertIsDefined(leftType); const rightType = getLastResult(state); Debug.assertIsDefined(rightType); result = checkBinaryLikeExpressionWorker(node.left, node.operatorToken, node.right, leftType, rightType, node); } state.skip = false; setLeftType(state, /*type*/ undefined); setLastResult(state, /*type*/ undefined); state.stackIndex--; return result; } function foldState(state: WorkArea, result: Type | undefined, _side: "left" | "right") { setLastResult(state, result); return state; } function maybeCheckExpression(state: WorkArea, node: Expression): BinaryExpression | undefined { if (isBinaryExpression(node)) { return node; } setLastResult(state, checkExpression(node, state.checkMode)); } function getLeftType(state: WorkArea) { return state.typeStack[state.stackIndex]; } function setLeftType(state: WorkArea, type: Type | undefined) { state.typeStack[state.stackIndex] = type; } function getLastResult(state: WorkArea) { return state.typeStack[state.stackIndex + 1]; } function setLastResult(state: WorkArea, type: Type | undefined) { // To reduce overhead, reuse the next stack entry to store the // last result. This avoids the overhead of an additional property // on `WorkArea` and reuses empty stack entries as we walk back up // the stack. state.typeStack[state.stackIndex + 1] = type; } } function checkGrammarNullishCoalesceWithLogicalExpression(node: BinaryExpression) { const { left, operatorToken, right } = node; if (operatorToken.kind === SyntaxKind.QuestionQuestionToken) { if (isBinaryExpression(left) && (left.operatorToken.kind === SyntaxKind.BarBarToken || left.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { grammarErrorOnNode(left, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(left.operatorToken.kind), tokenToString(operatorToken.kind)); } if (isBinaryExpression(right) && (right.operatorToken.kind === SyntaxKind.BarBarToken || right.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { grammarErrorOnNode(right, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(right.operatorToken.kind), tokenToString(operatorToken.kind)); } } } // Note that this and `checkBinaryExpression` above should behave mostly the same, except this elides some // expression-wide checks and does not use a work stack to fold nested binary expressions into the same callstack frame function checkBinaryLikeExpression(left: Expression, operatorToken: Node, right: Expression, checkMode?: CheckMode, errorNode?: Node): Type { const operator = operatorToken.kind; if (operator === SyntaxKind.EqualsToken && (left.kind === SyntaxKind.ObjectLiteralExpression || left.kind === SyntaxKind.ArrayLiteralExpression)) { return checkDestructuringAssignment(left, checkExpression(right, checkMode), checkMode, right.kind === SyntaxKind.ThisKeyword); } let leftType: Type; if (isLogicalOrCoalescingBinaryOperator(operator)) { leftType = checkTruthinessExpression(left, checkMode); } else { leftType = checkExpression(left, checkMode); } const rightType = checkExpression(right, checkMode); return checkBinaryLikeExpressionWorker(left, operatorToken, right, leftType, rightType, errorNode); } function checkBinaryLikeExpressionWorker( left: Expression, operatorToken: Node, right: Expression, leftType: Type, rightType: Type, errorNode?: Node ): Type { const operator = operatorToken.kind; switch (operator) { case SyntaxKind.AsteriskToken: case SyntaxKind.AsteriskAsteriskToken: case SyntaxKind.AsteriskEqualsToken: case SyntaxKind.AsteriskAsteriskEqualsToken: case SyntaxKind.SlashToken: case SyntaxKind.SlashEqualsToken: case SyntaxKind.PercentToken: case SyntaxKind.PercentEqualsToken: case SyntaxKind.MinusToken: case SyntaxKind.MinusEqualsToken: case SyntaxKind.LessThanLessThanToken: case SyntaxKind.LessThanLessThanEqualsToken: case SyntaxKind.GreaterThanGreaterThanToken: case SyntaxKind.GreaterThanGreaterThanEqualsToken: case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: case SyntaxKind.BarToken: case SyntaxKind.BarEqualsToken: case SyntaxKind.CaretToken: case SyntaxKind.CaretEqualsToken: case SyntaxKind.AmpersandToken: case SyntaxKind.AmpersandEqualsToken: if (leftType === silentNeverType || rightType === silentNeverType) { return silentNeverType; } leftType = checkNonNullType(leftType, left); rightType = checkNonNullType(rightType, right); let suggestedOperator: SyntaxKind | undefined; // if a user tries to apply a bitwise operator to 2 boolean operands // try and return them a helpful suggestion if ((leftType.flags & TypeFlags.BooleanLike) && (rightType.flags & TypeFlags.BooleanLike) && (suggestedOperator = getSuggestedBooleanOperator(operatorToken.kind)) !== undefined) { error(errorNode || operatorToken, Diagnostics.The_0_operator_is_not_allowed_for_boolean_types_Consider_using_1_instead, tokenToString(operatorToken.kind), tokenToString(suggestedOperator)); return numberType; } else { // otherwise just check each operand separately and report errors as normal const leftOk = checkArithmeticOperandType(left, leftType, Diagnostics.The_left_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); const rightOk = checkArithmeticOperandType(right, rightType, Diagnostics.The_right_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); let resultType: Type; // If both are any or unknown, allow operation; assume it will resolve to number if ((isTypeAssignableToKind(leftType, TypeFlags.AnyOrUnknown) && isTypeAssignableToKind(rightType, TypeFlags.AnyOrUnknown)) || // Or, if neither could be bigint, implicit coercion results in a number result !(maybeTypeOfKind(leftType, TypeFlags.BigIntLike) || maybeTypeOfKind(rightType, TypeFlags.BigIntLike)) ) { resultType = numberType; } // At least one is assignable to bigint, so check that both are else if (bothAreBigIntLike(leftType, rightType)) { switch (operator) { case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: reportOperatorError(); break; case SyntaxKind.AsteriskAsteriskToken: case SyntaxKind.AsteriskAsteriskEqualsToken: if (languageVersion < ScriptTarget.ES2016) { error(errorNode, Diagnostics.Exponentiation_cannot_be_performed_on_bigint_values_unless_the_target_option_is_set_to_es2016_or_later); } } resultType = bigintType; } // Exactly one of leftType/rightType is assignable to bigint else { reportOperatorError(bothAreBigIntLike); resultType = errorType; } if (leftOk && rightOk) { checkAssignmentOperator(resultType); } return resultType; } case SyntaxKind.PlusToken: case SyntaxKind.PlusEqualsToken: if (leftType === silentNeverType || rightType === silentNeverType) { return silentNeverType; } if (!isTypeAssignableToKind(leftType, TypeFlags.StringLike) && !isTypeAssignableToKind(rightType, TypeFlags.StringLike)) { leftType = checkNonNullType(leftType, left); rightType = checkNonNullType(rightType, right); } let resultType: Type | undefined; if (isTypeAssignableToKind(leftType, TypeFlags.NumberLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.NumberLike, /*strict*/ true)) { // Operands of an enum type are treated as having the primitive type Number. // If both operands are of the Number primitive type, the result is of the Number primitive type. resultType = numberType; } else if (isTypeAssignableToKind(leftType, TypeFlags.BigIntLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.BigIntLike, /*strict*/ true)) { // If both operands are of the BigInt primitive type, the result is of the BigInt primitive type. resultType = bigintType; } else if (isTypeAssignableToKind(leftType, TypeFlags.StringLike, /*strict*/ true) || isTypeAssignableToKind(rightType, TypeFlags.StringLike, /*strict*/ true)) { // If one or both operands are of the String primitive type, the result is of the String primitive type. resultType = stringType; } else if (isTypeAny(leftType) || isTypeAny(rightType)) { // Otherwise, the result is of type Any. // NOTE: unknown type here denotes error type. Old compiler treated this case as any type so do we. resultType = isErrorType(leftType) || isErrorType(rightType) ? errorType : anyType; } // Symbols are not allowed at all in arithmetic expressions if (resultType && !checkForDisallowedESSymbolOperand(operator)) { return resultType; } if (!resultType) { // Types that have a reasonably good chance of being a valid operand type. // If both types have an awaited type of one of these, we'll assume the user // might be missing an await without doing an exhaustive check that inserting // await(s) will actually be a completely valid binary expression. const closeEnoughKind = TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.AnyOrUnknown; reportOperatorError((left, right) => isTypeAssignableToKind(left, closeEnoughKind) && isTypeAssignableToKind(right, closeEnoughKind)); return anyType; } if (operator === SyntaxKind.PlusEqualsToken) { checkAssignmentOperator(resultType); } return resultType; case SyntaxKind.LessThanToken: case SyntaxKind.GreaterThanToken: case SyntaxKind.LessThanEqualsToken: case SyntaxKind.GreaterThanEqualsToken: if (checkForDisallowedESSymbolOperand(operator)) { leftType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(leftType, left)); rightType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(rightType, right)); reportOperatorErrorUnless((left, right) => { if (isTypeAny(left) || isTypeAny(right)) { return true; } const leftAssignableToNumber = isTypeAssignableTo(left, numberOrBigIntType); const rightAssignableToNumber = isTypeAssignableTo(right, numberOrBigIntType); return leftAssignableToNumber && rightAssignableToNumber || !leftAssignableToNumber && !rightAssignableToNumber && areTypesComparable(left, right); }); } return booleanType; case SyntaxKind.EqualsEqualsToken: case SyntaxKind.ExclamationEqualsToken: case SyntaxKind.EqualsEqualsEqualsToken: case SyntaxKind.ExclamationEqualsEqualsToken: if (isLiteralExpressionOfObject(left) || isLiteralExpressionOfObject(right)) { const eqType = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; error(errorNode, Diagnostics.This_condition_will_always_return_0_since_JavaScript_compares_objects_by_reference_not_value, eqType ? "false" : "true"); } checkNaNEquality(errorNode, operator, left, right); reportOperatorErrorUnless((left, right) => isTypeEqualityComparableTo(left, right) || isTypeEqualityComparableTo(right, left)); return booleanType; case SyntaxKind.InstanceOfKeyword: return checkInstanceOfExpression(left, right, leftType, rightType); case SyntaxKind.InKeyword: return checkInExpression(left, right, leftType, rightType); case SyntaxKind.AmpersandAmpersandToken: case SyntaxKind.AmpersandAmpersandEqualsToken: { const resultType = getTypeFacts(leftType) & TypeFacts.Truthy ? getUnionType([extractDefinitelyFalsyTypes(strictNullChecks ? leftType : getBaseTypeOfLiteralType(rightType)), rightType]) : leftType; if (operator === SyntaxKind.AmpersandAmpersandEqualsToken) { checkAssignmentOperator(rightType); } return resultType; } case SyntaxKind.BarBarToken: case SyntaxKind.BarBarEqualsToken: { const resultType = getTypeFacts(leftType) & TypeFacts.Falsy ? getUnionType([getNonNullableType(removeDefinitelyFalsyTypes(leftType)), rightType], UnionReduction.Subtype) : leftType; if (operator === SyntaxKind.BarBarEqualsToken) { checkAssignmentOperator(rightType); } return resultType; } case SyntaxKind.QuestionQuestionToken: case SyntaxKind.QuestionQuestionEqualsToken: { const resultType = getTypeFacts(leftType) & TypeFacts.EQUndefinedOrNull ? getUnionType([getNonNullableType(leftType), rightType], UnionReduction.Subtype) : leftType; if (operator === SyntaxKind.QuestionQuestionEqualsToken) { checkAssignmentOperator(rightType); } return resultType; } case SyntaxKind.EqualsToken: const declKind = isBinaryExpression(left.parent) ? getAssignmentDeclarationKind(left.parent) : AssignmentDeclarationKind.None; checkAssignmentDeclaration(declKind, rightType); if (isAssignmentDeclaration(declKind)) { if (!(rightType.flags & TypeFlags.Object) || declKind !== AssignmentDeclarationKind.ModuleExports && declKind !== AssignmentDeclarationKind.Prototype && !isEmptyObjectType(rightType) && !isFunctionObjectType(rightType as ObjectType) && !(getObjectFlags(rightType) & ObjectFlags.Class)) { // don't check assignability of module.exports=, C.prototype=, or expando types because they will necessarily be incomplete checkAssignmentOperator(rightType); } return leftType; } else { checkAssignmentOperator(rightType); return rightType; } case SyntaxKind.CommaToken: if (!compilerOptions.allowUnreachableCode && isSideEffectFree(left) && !isIndirectCall(left.parent as BinaryExpression)) { const sf = getSourceFileOfNode(left); const sourceText = sf.text; const start = skipTrivia(sourceText, left.pos); const isInDiag2657 = sf.parseDiagnostics.some(diag => { if (diag.code !== Diagnostics.JSX_expressions_must_have_one_parent_element.code) return false; return textSpanContainsPosition(diag, start); }); if (!isInDiag2657) error(left, Diagnostics.Left_side_of_comma_operator_is_unused_and_has_no_side_effects); } return rightType; default: return Debug.fail(); } function bothAreBigIntLike(left: Type, right: Type): boolean { return isTypeAssignableToKind(left, TypeFlags.BigIntLike) && isTypeAssignableToKind(right, TypeFlags.BigIntLike); } function checkAssignmentDeclaration(kind: AssignmentDeclarationKind, rightType: Type) { if (kind === AssignmentDeclarationKind.ModuleExports) { for (const prop of getPropertiesOfObjectType(rightType)) { const propType = getTypeOfSymbol(prop); if (propType.symbol && propType.symbol.flags & SymbolFlags.Class) { const name = prop.escapedName; const symbol = resolveName(prop.valueDeclaration, name, SymbolFlags.Type, undefined, name, /*isUse*/ false); if (symbol?.declarations && symbol.declarations.some(isJSDocTypedefTag)) { addDuplicateDeclarationErrorsForSymbols(symbol, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), prop); addDuplicateDeclarationErrorsForSymbols(prop, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), symbol); } } } } } // Return true for "indirect calls", (i.e. `(0, x.f)(...)` or `(0, eval)(...)`), which prevents passing `this`. function isIndirectCall(node: BinaryExpression): boolean { return node.parent.kind === SyntaxKind.ParenthesizedExpression && isNumericLiteral(node.left) && node.left.text === "0" && (isCallExpression(node.parent.parent) && node.parent.parent.expression === node.parent || node.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) && // special-case for "eval" because it's the only non-access case where an indirect call actually affects behavior. (isAccessExpression(node.right) || isIdentifier(node.right) && node.right.escapedText === "eval"); } // Return true if there was no error, false if there was an error. function checkForDisallowedESSymbolOperand(operator: SyntaxKind): boolean { const offendingSymbolOperand = maybeTypeOfKindConsideringBaseConstraint(leftType, TypeFlags.ESSymbolLike) ? left : maybeTypeOfKindConsideringBaseConstraint(rightType, TypeFlags.ESSymbolLike) ? right : undefined; if (offendingSymbolOperand) { error(offendingSymbolOperand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(operator)); return false; } return true; } function getSuggestedBooleanOperator(operator: SyntaxKind): SyntaxKind | undefined { switch (operator) { case SyntaxKind.BarToken: case SyntaxKind.BarEqualsToken: return SyntaxKind.BarBarToken; case SyntaxKind.CaretToken: case SyntaxKind.CaretEqualsToken: return SyntaxKind.ExclamationEqualsEqualsToken; case SyntaxKind.AmpersandToken: case SyntaxKind.AmpersandEqualsToken: return SyntaxKind.AmpersandAmpersandToken; default: return undefined; } } function checkAssignmentOperator(valueType: Type): void { if (isAssignmentOperator(operator)) { addLazyDiagnostic(checkAssignmentOperatorWorker); } function checkAssignmentOperatorWorker() { // TypeScript 1.0 spec (April 2014): 4.17 // An assignment of the form // VarExpr = ValueExpr // requires VarExpr to be classified as a reference // A compound assignment furthermore requires VarExpr to be classified as a reference (section 4.1) // and the type of the non-compound operation to be assignable to the type of VarExpr. if (checkReferenceExpression(left, Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access, Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access) ) { let headMessage: DiagnosticMessage | undefined; if (exactOptionalPropertyTypes && isPropertyAccessExpression(left) && maybeTypeOfKind(valueType, TypeFlags.Undefined)) { const target = getTypeOfPropertyOfType(getTypeOfExpression(left.expression), left.name.escapedText); if (isExactOptionalPropertyMismatch(valueType, target)) { headMessage = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target; } } // to avoid cascading errors check assignability only if 'isReference' check succeeded and no errors were reported checkTypeAssignableToAndOptionallyElaborate(valueType, leftType, left, right, headMessage); } } } function isAssignmentDeclaration(kind: AssignmentDeclarationKind) { switch (kind) { case AssignmentDeclarationKind.ModuleExports: return true; case AssignmentDeclarationKind.ExportsProperty: case AssignmentDeclarationKind.Property: case AssignmentDeclarationKind.Prototype: case AssignmentDeclarationKind.PrototypeProperty: case AssignmentDeclarationKind.ThisProperty: const symbol = getSymbolOfNode(left); const init = getAssignedExpandoInitializer(right); return !!init && isObjectLiteralExpression(init) && !!symbol?.exports?.size; default: return false; } } /** * Returns true if an error is reported */ function reportOperatorErrorUnless(typesAreCompatible: (left: Type, right: Type) => boolean): boolean { if (!typesAreCompatible(leftType, rightType)) { reportOperatorError(typesAreCompatible); return true; } return false; } function reportOperatorError(isRelated?: (left: Type, right: Type) => boolean) { let wouldWorkWithAwait = false; const errNode = errorNode || operatorToken; if (isRelated) { const awaitedLeftType = getAwaitedTypeNoAlias(leftType); const awaitedRightType = getAwaitedTypeNoAlias(rightType); wouldWorkWithAwait = !(awaitedLeftType === leftType && awaitedRightType === rightType) && !!(awaitedLeftType && awaitedRightType) && isRelated(awaitedLeftType, awaitedRightType); } let effectiveLeft = leftType; let effectiveRight = rightType; if (!wouldWorkWithAwait && isRelated) { [effectiveLeft, effectiveRight] = getBaseTypesIfUnrelated(leftType, rightType, isRelated); } const [leftStr, rightStr] = getTypeNamesForErrorDisplay(effectiveLeft, effectiveRight); if (!tryGiveBetterPrimaryError(errNode, wouldWorkWithAwait, leftStr, rightStr)) { errorAndMaybeSuggestAwait( errNode, wouldWorkWithAwait, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2, tokenToString(operatorToken.kind), leftStr, rightStr, ); } } function tryGiveBetterPrimaryError(errNode: Node, maybeMissingAwait: boolean, leftStr: string, rightStr: string) { switch (operatorToken.kind) { case SyntaxKind.EqualsEqualsEqualsToken: case SyntaxKind.EqualsEqualsToken: case SyntaxKind.ExclamationEqualsEqualsToken: case SyntaxKind.ExclamationEqualsToken: return errorAndMaybeSuggestAwait( errNode, maybeMissingAwait, Diagnostics.This_comparison_appears_to_be_unintentional_because_the_types_0_and_1_have_no_overlap, leftStr, rightStr); default: return undefined; } } function checkNaNEquality(errorNode: Node | undefined, operator: SyntaxKind, left: Expression, right: Expression) { const isLeftNaN = isGlobalNaN(skipParentheses(left)); const isRightNaN = isGlobalNaN(skipParentheses(right)); if (isLeftNaN || isRightNaN) { const err = error(errorNode, Diagnostics.This_condition_will_always_return_0, tokenToString(operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.EqualsEqualsToken ? SyntaxKind.FalseKeyword : SyntaxKind.TrueKeyword)); if (isLeftNaN && isRightNaN) return; const operatorString = operator === SyntaxKind.ExclamationEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? tokenToString(SyntaxKind.ExclamationToken) : ""; const location = isLeftNaN ? right : left; const expression = skipParentheses(location); addRelatedInfo(err, createDiagnosticForNode(location, Diagnostics.Did_you_mean_0, `${operatorString}Number.isNaN(${isEntityNameExpression(expression) ? entityNameToString(expression) : "..."})`)); } } function isGlobalNaN(expr: Expression): boolean { if (isIdentifier(expr) && expr.escapedText === "NaN") { const globalNaNSymbol = getGlobalNaNSymbol(); return !!globalNaNSymbol && globalNaNSymbol === getResolvedSymbol(expr); } return false; } } function getBaseTypesIfUnrelated(leftType: Type, rightType: Type, isRelated: (left: Type, right: Type) => boolean): [Type, Type] { let effectiveLeft = leftType; let effectiveRight = rightType; const leftBase = getBaseTypeOfLiteralType(leftType); const rightBase = getBaseTypeOfLiteralType(rightType); if (!isRelated(leftBase, rightBase)) { effectiveLeft = leftBase; effectiveRight = rightBase; } return [ effectiveLeft, effectiveRight ]; } function checkYieldExpression(node: YieldExpression): Type { addLazyDiagnostic(checkYieldExpressionGrammar); const func = getContainingFunction(node); if (!func) return anyType; const functionFlags = getFunctionFlags(func); if (!(functionFlags & FunctionFlags.Generator)) { // If the user's code is syntactically correct, the func should always have a star. After all, we are in a yield context. return anyType; } const isAsync = (functionFlags & FunctionFlags.Async) !== 0; if (node.asteriskToken) { // Async generator functions prior to ESNext require the __await, __asyncDelegator, // and __asyncValues helpers if (isAsync && languageVersion < ScriptTarget.ESNext) { checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncDelegatorIncludes); } // Generator functions prior to ES2015 require the __values helper if (!isAsync && languageVersion < ScriptTarget.ES2015 && compilerOptions.downlevelIteration) { checkExternalEmitHelpers(node, ExternalEmitHelpers.Values); } } // There is no point in doing an assignability check if the function // has no explicit return type because the return type is directly computed // from the yield expressions. const returnType = getReturnTypeFromAnnotation(func); const iterationTypes = returnType && getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsync); const signatureYieldType = iterationTypes && iterationTypes.yieldType || anyType; const signatureNextType = iterationTypes && iterationTypes.nextType || anyType; const resolvedSignatureNextType = isAsync ? getAwaitedType(signatureNextType) || anyType : signatureNextType; const yieldExpressionType = node.expression ? checkExpression(node.expression) : undefinedWideningType; const yieldedType = getYieldedTypeOfYieldExpression(node, yieldExpressionType, resolvedSignatureNextType, isAsync); if (returnType && yieldedType) { checkTypeAssignableToAndOptionallyElaborate(yieldedType, signatureYieldType, node.expression || node, node.expression); } if (node.asteriskToken) { const use = isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar; return getIterationTypeOfIterable(use, IterationTypeKind.Return, yieldExpressionType, node.expression) || anyType; } else if (returnType) { return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, isAsync) || anyType; } let type = getContextualIterationType(IterationTypeKind.Next, func); if (!type) { type = anyType; addLazyDiagnostic(() => { if (noImplicitAny && !expressionResultIsUnused(node)) { const contextualType = getContextualType(node, /*contextFlags*/ undefined); if (!contextualType || isTypeAny(contextualType)) { error(node, Diagnostics.yield_expression_implicitly_results_in_an_any_type_because_its_containing_generator_lacks_a_return_type_annotation); } } }); } return type; function checkYieldExpressionGrammar() { if (!(node.flags & NodeFlags.YieldContext)) { grammarErrorOnFirstToken(node, Diagnostics.A_yield_expression_is_only_allowed_in_a_generator_body); } if (isInParameterInitializerBeforeContainingFunction(node)) { error(node, Diagnostics.yield_expressions_cannot_be_used_in_a_parameter_initializer); } } } function checkConditionalExpression(node: ConditionalExpression, checkMode?: CheckMode): Type { const type = checkTruthinessExpression(node.condition); checkTestingKnownTruthyCallableOrAwaitableType(node.condition, type, node.whenTrue); const type1 = checkExpression(node.whenTrue, checkMode); const type2 = checkExpression(node.whenFalse, checkMode); return getUnionType([type1, type2], UnionReduction.Subtype); } function isTemplateLiteralContext(node: Node): boolean { const parent = node.parent; return isParenthesizedExpression(parent) && isTemplateLiteralContext(parent) || isElementAccessExpression(parent) && parent.argumentExpression === node; } function checkTemplateExpression(node: TemplateExpression): Type { const texts = [node.head.text]; const types = []; for (const span of node.templateSpans) { const type = checkExpression(span.expression); if (maybeTypeOfKindConsideringBaseConstraint(type, TypeFlags.ESSymbolLike)) { error(span.expression, Diagnostics.Implicit_conversion_of_a_symbol_to_a_string_will_fail_at_runtime_Consider_wrapping_this_expression_in_String); } texts.push(span.literal.text); types.push(isTypeAssignableTo(type, templateConstraintType) ? type : stringType); } return isConstContext(node) || isTemplateLiteralContext(node) || someType(getContextualType(node, /*contextFlags*/ undefined) || unknownType, isTemplateLiteralContextualType) ? getTemplateLiteralType(texts, types) : stringType; } function isTemplateLiteralContextualType(type: Type): boolean { return !!(type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral) || type.flags & TypeFlags.InstantiableNonPrimitive && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.StringLike)); } function getContextNode(node: Expression): Expression { if (isJsxAttributes(node) && !isJsxSelfClosingElement(node.parent)) { return node.parent.parent; // Needs to be the root JsxElement, so it encompasses the attributes _and_ the children (which are essentially part of the attributes) } return node; } function checkExpressionWithContextualType(node: Expression, contextualType: Type, inferenceContext: InferenceContext | undefined, checkMode: CheckMode): Type { const contextNode = getContextNode(node); pushContextualType(contextNode, contextualType, /*isCache*/ false); pushInferenceContext(contextNode, inferenceContext); const type = checkExpression(node, checkMode | CheckMode.Contextual | (inferenceContext ? CheckMode.Inferential : 0)); // In CheckMode.Inferential we collect intra-expression inference sites to process before fixing any type // parameters. This information is no longer needed after the call to checkExpression. if (inferenceContext && inferenceContext.intraExpressionInferenceSites) { inferenceContext.intraExpressionInferenceSites = undefined; } // We strip literal freshness when an appropriate contextual type is present such that contextually typed // literals always preserve their literal types (otherwise they might widen during type inference). An alternative // here would be to not mark contextually typed literals as fresh in the first place. const result = maybeTypeOfKind(type, TypeFlags.Literal) && isLiteralOfContextualType(type, instantiateContextualType(contextualType, node, /*contextFlags*/ undefined)) ? getRegularTypeOfLiteralType(type) : type; popInferenceContext(); popContextualType(); return result; } function checkExpressionCached(node: Expression | QualifiedName, checkMode?: CheckMode): Type { if (checkMode) { return checkExpression(node, checkMode); } const links = getNodeLinks(node); if (!links.resolvedType) { // When computing a type that we're going to cache, we need to ignore any ongoing control flow // analysis because variables may have transient types in indeterminable states. Moving flowLoopStart // to the top of the stack ensures all transient types are computed from a known point. const saveFlowLoopStart = flowLoopStart; const saveFlowTypeCache = flowTypeCache; flowLoopStart = flowLoopCount; flowTypeCache = undefined; links.resolvedType = checkExpression(node, checkMode); flowTypeCache = saveFlowTypeCache; flowLoopStart = saveFlowLoopStart; } return links.resolvedType; } function isTypeAssertion(node: Expression) { node = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); return node.kind === SyntaxKind.TypeAssertionExpression || node.kind === SyntaxKind.AsExpression || isJSDocTypeAssertion(node); } function checkDeclarationInitializer( declaration: HasExpressionInitializer, checkMode: CheckMode, contextualType?: Type | undefined ) { const initializer = getEffectiveInitializer(declaration)!; if (isInJSFile(declaration)) { const typeNode = tryGetJSDocSatisfiesTypeNode(declaration); if (typeNode) { return checkSatisfiesExpressionWorker(initializer, typeNode, checkMode); } } const type = getQuickTypeOfExpression(initializer) || (contextualType ? checkExpressionWithContextualType(initializer, contextualType, /*inferenceContext*/ undefined, checkMode || CheckMode.Normal) : checkExpressionCached(initializer, checkMode)); return isParameter(declaration) && declaration.name.kind === SyntaxKind.ArrayBindingPattern && isTupleType(type) && !type.target.hasRestElement && getTypeReferenceArity(type) < declaration.name.elements.length ? padTupleType(type, declaration.name) : type; } function padTupleType(type: TupleTypeReference, pattern: ArrayBindingPattern) { const patternElements = pattern.elements; const elementTypes = getTypeArguments(type).slice(); const elementFlags = type.target.elementFlags.slice(); for (let i = getTypeReferenceArity(type); i < patternElements.length; i++) { const e = patternElements[i]; if (i < patternElements.length - 1 || !(e.kind === SyntaxKind.BindingElement && e.dotDotDotToken)) { elementTypes.push(!isOmittedExpression(e) && hasDefaultValue(e) ? getTypeFromBindingElement(e, /*includePatternInType*/ false, /*reportErrors*/ false) : anyType); elementFlags.push(ElementFlags.Optional); if (!isOmittedExpression(e) && !hasDefaultValue(e)) { reportImplicitAny(e, anyType); } } } return createTupleType(elementTypes, elementFlags, type.target.readonly); } function widenTypeInferredFromInitializer(declaration: HasExpressionInitializer, type: Type) { const widened = getCombinedNodeFlags(declaration) & NodeFlags.Const || isDeclarationReadonly(declaration) ? type : getWidenedLiteralType(type); if (isInJSFile(declaration)) { if (isEmptyLiteralType(widened)) { reportImplicitAny(declaration, anyType); return anyType; } else if (isEmptyArrayLiteralType(widened)) { reportImplicitAny(declaration, anyArrayType); return anyArrayType; } } return widened; } function isLiteralOfContextualType(candidateType: Type, contextualType: Type | undefined): boolean { if (contextualType) { if (contextualType.flags & TypeFlags.UnionOrIntersection) { const types = (contextualType as UnionType).types; return some(types, t => isLiteralOfContextualType(candidateType, t)); } if (contextualType.flags & TypeFlags.InstantiableNonPrimitive) { // If the contextual type is a type variable constrained to a primitive type, consider // this a literal context for literals of that primitive type. For example, given a // type parameter 'T extends string', infer string literal types for T. const constraint = getBaseConstraintOfType(contextualType) || unknownType; return maybeTypeOfKind(constraint, TypeFlags.String) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || maybeTypeOfKind(constraint, TypeFlags.Number) && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || maybeTypeOfKind(constraint, TypeFlags.BigInt) && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || maybeTypeOfKind(constraint, TypeFlags.ESSymbol) && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol) || isLiteralOfContextualType(candidateType, constraint); } // If the contextual type is a literal of a particular primitive type, we consider this a // literal context for all literals of that primitive type. return !!(contextualType.flags & (TypeFlags.StringLiteral | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || contextualType.flags & TypeFlags.NumberLiteral && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || contextualType.flags & TypeFlags.BigIntLiteral && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || contextualType.flags & TypeFlags.BooleanLiteral && maybeTypeOfKind(candidateType, TypeFlags.BooleanLiteral) || contextualType.flags & TypeFlags.UniqueESSymbol && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol)); } return false; } function isConstContext(node: Expression): boolean { const parent = node.parent; return isAssertionExpression(parent) && isConstTypeReference(parent.type) || isJSDocTypeAssertion(parent) && isConstTypeReference(getJSDocTypeAssertionType(parent)) || isValidConstAssertionArgument(node) && isConstTypeParameterContext(node) || (isParenthesizedExpression(parent) || isArrayLiteralExpression(parent) || isSpreadElement(parent)) && isConstContext(parent) || (isPropertyAssignment(parent) || isShorthandPropertyAssignment(parent) || isTemplateSpan(parent)) && isConstContext(parent.parent); } function isConstTypeParameterContext(node: Expression) { const contextualType = getContextualType(node, ContextFlags.None); return !!contextualType && someType(contextualType, isConstTypeVariable); } function checkExpressionForMutableLocation(node: Expression, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { const type = checkExpression(node, checkMode, forceTuple); return isConstContext(node) || isCommonJsExportedExpression(node) ? getRegularTypeOfLiteralType(type) : isTypeAssertion(node) ? type : getWidenedLiteralLikeTypeForContextualType(type, instantiateContextualType(getContextualType(node, /*contextFlags*/ undefined), node, /*contextFlags*/ undefined)); } function checkPropertyAssignment(node: PropertyAssignment, checkMode?: CheckMode): Type { // Do not use hasDynamicName here, because that returns false for well known symbols. // We want to perform checkComputedPropertyName for all computed properties, including // well known symbols. if (node.name.kind === SyntaxKind.ComputedPropertyName) { checkComputedPropertyName(node.name); } return checkExpressionForMutableLocation(node.initializer, checkMode); } function checkObjectLiteralMethod(node: MethodDeclaration, checkMode?: CheckMode): Type { // Grammar checking checkGrammarMethod(node); // Do not use hasDynamicName here, because that returns false for well known symbols. // We want to perform checkComputedPropertyName for all computed properties, including // well known symbols. if (node.name.kind === SyntaxKind.ComputedPropertyName) { checkComputedPropertyName(node.name); } const uninstantiatedType = checkFunctionExpressionOrObjectLiteralMethod(node, checkMode); return instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); } function instantiateTypeWithSingleGenericCallSignature(node: Expression | MethodDeclaration | QualifiedName, type: Type, checkMode?: CheckMode) { if (checkMode && checkMode & (CheckMode.Inferential | CheckMode.SkipGenericFunctions)) { const callSignature = getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ true); const constructSignature = getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ true); const signature = callSignature || constructSignature; if (signature && signature.typeParameters) { const contextualType = getApparentTypeOfContextualType(node as Expression, ContextFlags.NoConstraints); if (contextualType) { const contextualSignature = getSingleSignature(getNonNullableType(contextualType), callSignature ? SignatureKind.Call : SignatureKind.Construct, /*allowMembers*/ false); if (contextualSignature && !contextualSignature.typeParameters) { if (checkMode & CheckMode.SkipGenericFunctions) { skippedGenericFunction(node, checkMode); return anyFunctionType; } const context = getInferenceContext(node)!; // We have an expression that is an argument of a generic function for which we are performing // type argument inference. The expression is of a function type with a single generic call // signature and a contextual function type with a single non-generic call signature. Now check // if the outer function returns a function type with a single non-generic call signature and // if some of the outer function type parameters have no inferences so far. If so, we can // potentially add inferred type parameters to the outer function return type. const returnType = context.signature && getReturnTypeOfSignature(context.signature); const returnSignature = returnType && getSingleCallOrConstructSignature(returnType); if (returnSignature && !returnSignature.typeParameters && !every(context.inferences, hasInferenceCandidates)) { // Instantiate the signature with its own type parameters as type arguments, possibly // renaming the type parameters to ensure they have unique names. const uniqueTypeParameters = getUniqueTypeParameters(context, signature.typeParameters); const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, uniqueTypeParameters); // Infer from the parameters of the instantiated signature to the parameters of the // contextual signature starting with an empty set of inference candidates. const inferences = map(context.inferences, info => createInferenceInfo(info.typeParameter)); applyToParameterTypes(instantiatedSignature, contextualSignature, (source, target) => { inferTypes(inferences, source, target, /*priority*/ 0, /*contravariant*/ true); }); if (some(inferences, hasInferenceCandidates)) { // We have inference candidates, indicating that one or more type parameters are referenced // in the parameter types of the contextual signature. Now also infer from the return type. applyToReturnTypes(instantiatedSignature, contextualSignature, (source, target) => { inferTypes(inferences, source, target); }); // If the type parameters for which we produced candidates do not have any inferences yet, // we adopt the new inference candidates and add the type parameters of the expression type // to the set of inferred type parameters for the outer function return type. if (!hasOverlappingInferences(context.inferences, inferences)) { mergeInferences(context.inferences, inferences); context.inferredTypeParameters = concatenate(context.inferredTypeParameters, uniqueTypeParameters); return getOrCreateTypeFromSignature(instantiatedSignature); } } } return getOrCreateTypeFromSignature(instantiateSignatureInContextOf(signature, contextualSignature, context)); } } } } return type; } function skippedGenericFunction(node: Node, checkMode: CheckMode) { if (checkMode & CheckMode.Inferential) { // We have skipped a generic function during inferential typing. Obtain the inference context and // indicate this has occurred such that we know a second pass of inference is be needed. const context = getInferenceContext(node)!; context.flags |= InferenceFlags.SkippedGenericFunction; } } function hasInferenceCandidates(info: InferenceInfo) { return !!(info.candidates || info.contraCandidates); } function hasInferenceCandidatesOrDefault(info: InferenceInfo) { return !!(info.candidates || info.contraCandidates || hasTypeParameterDefault(info.typeParameter)); } function hasOverlappingInferences(a: InferenceInfo[], b: InferenceInfo[]) { for (let i = 0; i < a.length; i++) { if (hasInferenceCandidates(a[i]) && hasInferenceCandidates(b[i])) { return true; } } return false; } function mergeInferences(target: InferenceInfo[], source: InferenceInfo[]) { for (let i = 0; i < target.length; i++) { if (!hasInferenceCandidates(target[i]) && hasInferenceCandidates(source[i])) { target[i] = source[i]; } } } function getUniqueTypeParameters(context: InferenceContext, typeParameters: readonly TypeParameter[]): readonly TypeParameter[] { const result: TypeParameter[] = []; let oldTypeParameters: TypeParameter[] | undefined; let newTypeParameters: TypeParameter[] | undefined; for (const tp of typeParameters) { const name = tp.symbol.escapedName; if (hasTypeParameterByName(context.inferredTypeParameters, name) || hasTypeParameterByName(result, name)) { const newName = getUniqueTypeParameterName(concatenate(context.inferredTypeParameters, result), name); const symbol = createSymbol(SymbolFlags.TypeParameter, newName); const newTypeParameter = createTypeParameter(symbol); newTypeParameter.target = tp; oldTypeParameters = append(oldTypeParameters, tp); newTypeParameters = append(newTypeParameters, newTypeParameter); result.push(newTypeParameter); } else { result.push(tp); } } if (newTypeParameters) { const mapper = createTypeMapper(oldTypeParameters!, newTypeParameters); for (const tp of newTypeParameters) { tp.mapper = mapper; } } return result; } function hasTypeParameterByName(typeParameters: readonly TypeParameter[] | undefined, name: __String) { return some(typeParameters, tp => tp.symbol.escapedName === name); } function getUniqueTypeParameterName(typeParameters: readonly TypeParameter[], baseName: __String) { let len = (baseName as string).length; while (len > 1 && (baseName as string).charCodeAt(len - 1) >= CharacterCodes._0 && (baseName as string).charCodeAt(len - 1) <= CharacterCodes._9) len--; const s = (baseName as string).slice(0, len); for (let index = 1; true; index++) { const augmentedName = (s + index as __String); if (!hasTypeParameterByName(typeParameters, augmentedName)) { return augmentedName; } } } function getReturnTypeOfSingleNonGenericCallSignature(funcType: Type) { const signature = getSingleCallSignature(funcType); if (signature && !signature.typeParameters) { return getReturnTypeOfSignature(signature); } } function getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr: CallChain) { const funcType = checkExpression(expr.expression); const nonOptionalType = getOptionalExpressionType(funcType, expr.expression); const returnType = getReturnTypeOfSingleNonGenericCallSignature(funcType); return returnType && propagateOptionalTypeMarker(returnType, expr, nonOptionalType !== funcType); } /** * Returns the type of an expression. Unlike checkExpression, this function is simply concerned * with computing the type and may not fully check all contained sub-expressions for errors. */ function getTypeOfExpression(node: Expression) { // Don't bother caching types that require no flow analysis and are quick to compute. const quickType = getQuickTypeOfExpression(node); if (quickType) { return quickType; } // If a type has been cached for the node, return it. if (node.flags & NodeFlags.TypeCached && flowTypeCache) { const cachedType = flowTypeCache[getNodeId(node)]; if (cachedType) { return cachedType; } } const startInvocationCount = flowInvocationCount; const type = checkExpression(node); // If control flow analysis was required to determine the type, it is worth caching. if (flowInvocationCount !== startInvocationCount) { const cache = flowTypeCache || (flowTypeCache = []); cache[getNodeId(node)] = type; setNodeFlags(node, node.flags | NodeFlags.TypeCached); } return type; } function getQuickTypeOfExpression(node: Expression): Type | undefined { let expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); if (isJSDocTypeAssertion(expr)) { const type = getJSDocTypeAssertionType(expr); if (!isConstTypeReference(type)) { return getTypeFromTypeNode(type); } } expr = skipParentheses(node); if (isAwaitExpression(expr)) { const type = getQuickTypeOfExpression(expr.expression); return type ? getAwaitedType(type) : undefined; } // Optimize for the common case of a call to a function with a single non-generic call // signature where we can just fetch the return type without checking the arguments. if (isCallExpression(expr) && expr.expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*checkArgumentIsStringLiteralLike*/ true) && !isSymbolOrSymbolForCall(expr)) { return isCallChain(expr) ? getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr) : getReturnTypeOfSingleNonGenericCallSignature(checkNonNullExpression(expr.expression)); } else if (isAssertionExpression(expr) && !isConstTypeReference(expr.type)) { return getTypeFromTypeNode((expr as TypeAssertion).type); } else if (isLiteralExpression(node) || isBooleanLiteral(node)) { return checkExpression(node); } return undefined; } /** * Returns the type of an expression. Unlike checkExpression, this function is simply concerned * with computing the type and may not fully check all contained sub-expressions for errors. * It is intended for uses where you know there is no contextual type, * and requesting the contextual type might cause a circularity or other bad behaviour. * It sets the contextual type of the node to any before calling getTypeOfExpression. */ function getContextFreeTypeOfExpression(node: Expression) { const links = getNodeLinks(node); if (links.contextFreeType) { return links.contextFreeType; } pushContextualType(node, anyType, /*isCache*/ false); const type = links.contextFreeType = checkExpression(node, CheckMode.SkipContextSensitive); popContextualType(); return type; } function checkExpression(node: Expression | QualifiedName, checkMode?: CheckMode, forceTuple?: boolean): Type { tracing?.push(tracing.Phase.Check, "checkExpression", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); const saveCurrentNode = currentNode; currentNode = node; instantiationCount = 0; const uninstantiatedType = checkExpressionWorker(node, checkMode, forceTuple); const type = instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); if (isConstEnumObjectType(type)) { checkConstEnumAccess(node, type); } currentNode = saveCurrentNode; tracing?.pop(); return type; } function checkConstEnumAccess(node: Expression | QualifiedName, type: Type) { // enum object type for const enums are only permitted in: // - 'left' in property access // - 'object' in indexed access // - target in rhs of import statement const ok = (node.parent.kind === SyntaxKind.PropertyAccessExpression && (node.parent as PropertyAccessExpression).expression === node) || (node.parent.kind === SyntaxKind.ElementAccessExpression && (node.parent as ElementAccessExpression).expression === node) || ((node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.QualifiedName) && isInRightSideOfImportOrExportAssignment(node as Identifier) || (node.parent.kind === SyntaxKind.TypeQuery && (node.parent as TypeQueryNode).exprName === node)) || (node.parent.kind === SyntaxKind.ExportSpecifier); // We allow reexporting const enums if (!ok) { error(node, Diagnostics.const_enums_can_only_be_used_in_property_or_index_access_expressions_or_the_right_hand_side_of_an_import_declaration_or_export_assignment_or_type_query); } if (getIsolatedModules(compilerOptions)) { Debug.assert(!!(type.symbol.flags & SymbolFlags.ConstEnum)); const constEnumDeclaration = type.symbol.valueDeclaration as EnumDeclaration; if (constEnumDeclaration.flags & NodeFlags.Ambient) { error(node, Diagnostics.Cannot_access_ambient_const_enums_when_0_is_enabled, isolatedModulesLikeFlagName); } } } function checkParenthesizedExpression(node: ParenthesizedExpression, checkMode?: CheckMode): Type { if (hasJSDocNodes(node)) { if (isJSDocSatisfiesExpression(node)) { return checkSatisfiesExpressionWorker(node.expression, getJSDocSatisfiesExpressionType(node), checkMode); } if (isJSDocTypeAssertion(node)) { const type = getJSDocTypeAssertionType(node); return checkAssertionWorker(type, type, node.expression, checkMode); } } return checkExpression(node.expression, checkMode); } function checkExpressionWorker(node: Expression | QualifiedName, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { const kind = node.kind; if (cancellationToken) { // Only bother checking on a few construct kinds. We don't want to be excessively // hitting the cancellation token on every node we check. switch (kind) { case SyntaxKind.ClassExpression: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: cancellationToken.throwIfCancellationRequested(); } } switch (kind) { case SyntaxKind.Identifier: return checkIdentifier(node as Identifier, checkMode); case SyntaxKind.PrivateIdentifier: return checkPrivateIdentifierExpression(node as PrivateIdentifier); case SyntaxKind.ThisKeyword: return checkThisExpression(node); case SyntaxKind.SuperKeyword: return checkSuperExpression(node); case SyntaxKind.NullKeyword: return nullWideningType; case SyntaxKind.NoSubstitutionTemplateLiteral: case SyntaxKind.StringLiteral: return getFreshTypeOfLiteralType(getStringLiteralType((node as StringLiteralLike).text)); case SyntaxKind.NumericLiteral: checkGrammarNumericLiteral(node as NumericLiteral); return getFreshTypeOfLiteralType(getNumberLiteralType(+(node as NumericLiteral).text)); case SyntaxKind.BigIntLiteral: checkGrammarBigIntLiteral(node as BigIntLiteral); return getFreshTypeOfLiteralType(getBigIntLiteralType({ negative: false, base10Value: parsePseudoBigInt((node as BigIntLiteral).text) })); case SyntaxKind.TrueKeyword: return trueType; case SyntaxKind.FalseKeyword: return falseType; case SyntaxKind.TemplateExpression: return checkTemplateExpression(node as TemplateExpression); case SyntaxKind.RegularExpressionLiteral: return globalRegExpType; case SyntaxKind.ArrayLiteralExpression: return checkArrayLiteral(node as ArrayLiteralExpression, checkMode, forceTuple); case SyntaxKind.ObjectLiteralExpression: return checkObjectLiteral(node as ObjectLiteralExpression, checkMode); case SyntaxKind.PropertyAccessExpression: return checkPropertyAccessExpression(node as PropertyAccessExpression, checkMode); case SyntaxKind.QualifiedName: return checkQualifiedName(node as QualifiedName, checkMode); case SyntaxKind.ElementAccessExpression: return checkIndexedAccess(node as ElementAccessExpression, checkMode); case SyntaxKind.CallExpression: if ((node as CallExpression).expression.kind === SyntaxKind.ImportKeyword) { return checkImportCallExpression(node as ImportCall); } // falls through case SyntaxKind.NewExpression: return checkCallExpression(node as CallExpression, checkMode); case SyntaxKind.TaggedTemplateExpression: return checkTaggedTemplateExpression(node as TaggedTemplateExpression); case SyntaxKind.ParenthesizedExpression: return checkParenthesizedExpression(node as ParenthesizedExpression, checkMode); case SyntaxKind.ClassExpression: return checkClassExpression(node as ClassExpression); case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: return checkFunctionExpressionOrObjectLiteralMethod(node as FunctionExpression | ArrowFunction, checkMode); case SyntaxKind.TypeOfExpression: return checkTypeOfExpression(node as TypeOfExpression); case SyntaxKind.TypeAssertionExpression: case SyntaxKind.AsExpression: return checkAssertion(node as AssertionExpression); case SyntaxKind.NonNullExpression: return checkNonNullAssertion(node as NonNullExpression); case SyntaxKind.ExpressionWithTypeArguments: return checkExpressionWithTypeArguments(node as ExpressionWithTypeArguments); case SyntaxKind.SatisfiesExpression: return checkSatisfiesExpression(node as SatisfiesExpression); case SyntaxKind.MetaProperty: return checkMetaProperty(node as MetaProperty); case SyntaxKind.DeleteExpression: return checkDeleteExpression(node as DeleteExpression); case SyntaxKind.VoidExpression: return checkVoidExpression(node as VoidExpression); case SyntaxKind.AwaitExpression: return checkAwaitExpression(node as AwaitExpression); case SyntaxKind.PrefixUnaryExpression: return checkPrefixUnaryExpression(node as PrefixUnaryExpression); case SyntaxKind.PostfixUnaryExpression: return checkPostfixUnaryExpression(node as PostfixUnaryExpression); case SyntaxKind.BinaryExpression: return checkBinaryExpression(node as BinaryExpression, checkMode); case SyntaxKind.ConditionalExpression: return checkConditionalExpression(node as ConditionalExpression, checkMode); case SyntaxKind.SpreadElement: return checkSpreadExpression(node as SpreadElement, checkMode); case SyntaxKind.OmittedExpression: return undefinedWideningType; case SyntaxKind.YieldExpression: return checkYieldExpression(node as YieldExpression); case SyntaxKind.SyntheticExpression: return checkSyntheticExpression(node as SyntheticExpression); case SyntaxKind.JsxExpression: return checkJsxExpression(node as JsxExpression, checkMode); case SyntaxKind.JsxElement: return checkJsxElement(node as JsxElement, checkMode); case SyntaxKind.JsxSelfClosingElement: return checkJsxSelfClosingElement(node as JsxSelfClosingElement, checkMode); case SyntaxKind.JsxFragment: return checkJsxFragment(node as JsxFragment); case SyntaxKind.JsxAttributes: return checkJsxAttributes(node as JsxAttributes, checkMode); case SyntaxKind.JsxOpeningElement: Debug.fail("Shouldn't ever directly check a JsxOpeningElement"); } return errorType; } // DECLARATION AND STATEMENT TYPE CHECKING function checkTypeParameter(node: TypeParameterDeclaration) { // Grammar Checking checkGrammarModifiers(node); if (node.expression) { grammarErrorOnFirstToken(node.expression, Diagnostics.Type_expected); } checkSourceElement(node.constraint); checkSourceElement(node.default); const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); // Resolve base constraint to reveal circularity errors getBaseConstraintOfType(typeParameter); if (!hasNonCircularTypeParameterDefault(typeParameter)) { error(node.default, Diagnostics.Type_parameter_0_has_a_circular_default, typeToString(typeParameter)); } const constraintType = getConstraintOfTypeParameter(typeParameter); const defaultType = getDefaultFromTypeParameter(typeParameter); if (constraintType && defaultType) { checkTypeAssignableTo(defaultType, getTypeWithThisArgument(instantiateType(constraintType, makeUnaryTypeMapper(typeParameter, defaultType)), defaultType), node.default, Diagnostics.Type_0_does_not_satisfy_the_constraint_1); } checkNodeDeferred(node); addLazyDiagnostic(() => checkTypeNameIsReserved(node.name, Diagnostics.Type_parameter_name_cannot_be_0)); } function checkTypeParameterDeferred(node: TypeParameterDeclaration) { if (isInterfaceDeclaration(node.parent) || isClassLike(node.parent) || isTypeAliasDeclaration(node.parent)) { const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); const modifiers = getTypeParameterModifiers(typeParameter) & (ModifierFlags.In | ModifierFlags.Out); if (modifiers) { const symbol = getSymbolOfDeclaration(node.parent); if (isTypeAliasDeclaration(node.parent) && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Anonymous | ObjectFlags.Mapped))) { error(node, Diagnostics.Variance_annotations_are_only_supported_in_type_aliases_for_object_function_constructor_and_mapped_types); } else if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) { tracing?.push(tracing.Phase.CheckTypes, "checkTypeParameterDeferred", { parent: getTypeId(getDeclaredTypeOfSymbol(symbol)), id: getTypeId(typeParameter) }); const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubTypeForCheck : markerSuperTypeForCheck); const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperTypeForCheck : markerSubTypeForCheck); const saveVarianceTypeParameter = typeParameter; varianceTypeParameter = typeParameter; checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation); varianceTypeParameter = saveVarianceTypeParameter; tracing?.pop(); } } } } function checkParameter(node: ParameterDeclaration) { // Grammar checking // It is a SyntaxError if the Identifier "eval" or the Identifier "arguments" occurs as the // Identifier in a PropertySetParameterList of a PropertyAssignment that is contained in strict code // or if its FunctionBody is strict code(11.1.5). checkGrammarModifiers(node); checkVariableLikeDeclaration(node); const func = getContainingFunction(node)!; if (hasSyntacticModifier(node, ModifierFlags.ParameterPropertyModifier)) { if (!(func.kind === SyntaxKind.Constructor && nodeIsPresent(func.body))) { error(node, Diagnostics.A_parameter_property_is_only_allowed_in_a_constructor_implementation); } if (func.kind === SyntaxKind.Constructor && isIdentifier(node.name) && node.name.escapedText === "constructor") { error(node.name, Diagnostics.constructor_cannot_be_used_as_a_parameter_property_name); } } if (!node.initializer && isOptionalDeclaration(node) && isBindingPattern(node.name) && (func as FunctionLikeDeclaration).body) { error(node, Diagnostics.A_binding_pattern_parameter_cannot_be_optional_in_an_implementation_signature); } if (node.name && isIdentifier(node.name) && (node.name.escapedText === "this" || node.name.escapedText === "new")) { if (func.parameters.indexOf(node) !== 0) { error(node, Diagnostics.A_0_parameter_must_be_the_first_parameter, node.name.escapedText as string); } if (func.kind === SyntaxKind.Constructor || func.kind === SyntaxKind.ConstructSignature || func.kind === SyntaxKind.ConstructorType) { error(node, Diagnostics.A_constructor_cannot_have_a_this_parameter); } if (func.kind === SyntaxKind.ArrowFunction) { error(node, Diagnostics.An_arrow_function_cannot_have_a_this_parameter); } if (func.kind === SyntaxKind.GetAccessor || func.kind === SyntaxKind.SetAccessor) { error(node, Diagnostics.get_and_set_accessors_cannot_declare_this_parameters); } } // Only check rest parameter type if it's not a binding pattern. Since binding patterns are // not allowed in a rest parameter, we already have an error from checkGrammarParameterList. if (node.dotDotDotToken && !isBindingPattern(node.name) && !isTypeAssignableTo(getReducedType(getTypeOfSymbol(node.symbol)), anyReadonlyArrayType)) { error(node, Diagnostics.A_rest_parameter_must_be_of_an_array_type); } } function checkTypePredicate(node: TypePredicateNode): void { const parent = getTypePredicateParent(node); if (!parent) { // The parent must not be valid. error(node, Diagnostics.A_type_predicate_is_only_allowed_in_return_type_position_for_functions_and_methods); return; } const signature = getSignatureFromDeclaration(parent); const typePredicate = getTypePredicateOfSignature(signature); if (!typePredicate) { return; } checkSourceElement(node.type); const { parameterName } = node; if (typePredicate.kind === TypePredicateKind.This || typePredicate.kind === TypePredicateKind.AssertsThis) { getTypeFromThisTypeNode(parameterName as ThisTypeNode); } else { if (typePredicate.parameterIndex >= 0) { if (signatureHasRestParameter(signature) && typePredicate.parameterIndex === signature.parameters.length - 1) { error(parameterName, Diagnostics.A_type_predicate_cannot_reference_a_rest_parameter); } else { if (typePredicate.type) { const leadingError = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.A_type_predicate_s_type_must_be_assignable_to_its_parameter_s_type); checkTypeAssignableTo(typePredicate.type, getTypeOfSymbol(signature.parameters[typePredicate.parameterIndex]), node.type, /*headMessage*/ undefined, leadingError); } } } else if (parameterName) { let hasReportedError = false; for (const { name } of parent.parameters) { if (isBindingPattern(name) && checkIfTypePredicateVariableIsDeclaredInBindingPattern(name, parameterName, typePredicate.parameterName)) { hasReportedError = true; break; } } if (!hasReportedError) { error(node.parameterName, Diagnostics.Cannot_find_parameter_0, typePredicate.parameterName); } } } } function getTypePredicateParent(node: Node): SignatureDeclaration | undefined { switch (node.parent.kind) { case SyntaxKind.ArrowFunction: case SyntaxKind.CallSignature: case SyntaxKind.FunctionDeclaration: case SyntaxKind.FunctionExpression: case SyntaxKind.FunctionType: case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: const parent = node.parent as SignatureDeclaration; if (node === parent.type) { return parent; } } } function checkIfTypePredicateVariableIsDeclaredInBindingPattern( pattern: BindingPattern, predicateVariableNode: Node, predicateVariableName: string) { for (const element of pattern.elements) { if (isOmittedExpression(element)) { continue; } const name = element.name; if (name.kind === SyntaxKind.Identifier && name.escapedText === predicateVariableName) { error(predicateVariableNode, Diagnostics.A_type_predicate_cannot_reference_element_0_in_a_binding_pattern, predicateVariableName); return true; } else if (name.kind === SyntaxKind.ArrayBindingPattern || name.kind === SyntaxKind.ObjectBindingPattern) { if (checkIfTypePredicateVariableIsDeclaredInBindingPattern( name, predicateVariableNode, predicateVariableName)) { return true; } } } } function checkSignatureDeclaration(node: SignatureDeclaration) { // Grammar checking if (node.kind === SyntaxKind.IndexSignature) { checkGrammarIndexSignature(node); } // TODO (yuisu): Remove this check in else-if when SyntaxKind.Construct is moved and ambient context is handled else if (node.kind === SyntaxKind.FunctionType || node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.ConstructorType || node.kind === SyntaxKind.CallSignature || node.kind === SyntaxKind.Constructor || node.kind === SyntaxKind.ConstructSignature) { checkGrammarFunctionLikeDeclaration(node as FunctionLikeDeclaration); } const functionFlags = getFunctionFlags(node as FunctionLikeDeclaration); if (!(functionFlags & FunctionFlags.Invalid)) { // Async generators prior to ESNext require the __await and __asyncGenerator helpers if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.AsyncGenerator && languageVersion < ScriptTarget.ESNext) { checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncGeneratorIncludes); } // Async functions prior to ES2017 require the __awaiter helper if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async && languageVersion < ScriptTarget.ES2017) { checkExternalEmitHelpers(node, ExternalEmitHelpers.Awaiter); } // Generator functions, Async functions, and Async Generator functions prior to // ES2015 require the __generator helper if ((functionFlags & FunctionFlags.AsyncGenerator) !== FunctionFlags.Normal && languageVersion < ScriptTarget.ES2015) { checkExternalEmitHelpers(node, ExternalEmitHelpers.Generator); } } checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); checkUnmatchedJSDocParameters(node); forEach(node.parameters, checkParameter); // TODO(rbuckton): Should we start checking JSDoc types? if (node.type) { checkSourceElement(node.type); } addLazyDiagnostic(checkSignatureDeclarationDiagnostics); function checkSignatureDeclarationDiagnostics() { checkCollisionWithArgumentsInGeneratedCode(node); const returnTypeNode = getEffectiveReturnTypeNode(node); if (noImplicitAny && !returnTypeNode) { switch (node.kind) { case SyntaxKind.ConstructSignature: error(node, Diagnostics.Construct_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); break; case SyntaxKind.CallSignature: error(node, Diagnostics.Call_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); break; } } if (returnTypeNode) { const functionFlags = getFunctionFlags(node as FunctionDeclaration); if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Generator)) === FunctionFlags.Generator) { const returnType = getTypeFromTypeNode(returnTypeNode); if (returnType === voidType) { error(returnTypeNode, Diagnostics.A_generator_cannot_have_a_void_type_annotation); } else { // Naively, one could check that Generator is assignable to the return type annotation. // However, that would not catch the error in the following case. // // interface BadGenerator extends Iterable, Iterator { } // function* g(): BadGenerator { } // Iterable and Iterator have different types! // const generatorYieldType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, returnType, (functionFlags & FunctionFlags.Async) !== 0) || anyType; const generatorReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, (functionFlags & FunctionFlags.Async) !== 0) || generatorYieldType; const generatorNextType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, (functionFlags & FunctionFlags.Async) !== 0) || unknownType; const generatorInstantiation = createGeneratorReturnType(generatorYieldType, generatorReturnType, generatorNextType, !!(functionFlags & FunctionFlags.Async)); checkTypeAssignableTo(generatorInstantiation, returnType, returnTypeNode); } } else if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { checkAsyncFunctionReturnType(node as FunctionLikeDeclaration, returnTypeNode); } } if (node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.JSDocFunctionType) { registerForUnusedIdentifiersCheck(node); } } } function checkClassForDuplicateDeclarations(node: ClassLikeDeclaration) { const instanceNames = new Map<__String, DeclarationMeaning>(); const staticNames = new Map<__String, DeclarationMeaning>(); // instance and static private identifiers share the same scope const privateIdentifiers = new Map<__String, DeclarationMeaning>(); for (const member of node.members) { if (member.kind === SyntaxKind.Constructor) { for (const param of (member as ConstructorDeclaration).parameters) { if (isParameterPropertyDeclaration(param, member) && !isBindingPattern(param.name)) { addName(instanceNames, param.name, param.name.escapedText, DeclarationMeaning.GetOrSetAccessor); } } } else { const isStaticMember = isStatic(member); const name = member.name; if (!name) { continue; } const isPrivate = isPrivateIdentifier(name); const privateStaticFlags = isPrivate && isStaticMember ? DeclarationMeaning.PrivateStatic : 0; const names = isPrivate ? privateIdentifiers : isStaticMember ? staticNames : instanceNames; const memberName = name && getPropertyNameForPropertyNameNode(name); if (memberName) { switch (member.kind) { case SyntaxKind.GetAccessor: addName(names, name, memberName, DeclarationMeaning.GetAccessor | privateStaticFlags); break; case SyntaxKind.SetAccessor: addName(names, name, memberName, DeclarationMeaning.SetAccessor | privateStaticFlags); break; case SyntaxKind.PropertyDeclaration: addName(names, name, memberName, DeclarationMeaning.GetOrSetAccessor | privateStaticFlags); break; case SyntaxKind.MethodDeclaration: addName(names, name, memberName, DeclarationMeaning.Method | privateStaticFlags); break; } } } } function addName(names: UnderscoreEscapedMap, location: Node, name: __String, meaning: DeclarationMeaning) { const prev = names.get(name); if (prev) { // For private identifiers, do not allow mixing of static and instance members with the same name if ((prev & DeclarationMeaning.PrivateStatic) !== (meaning & DeclarationMeaning.PrivateStatic)) { error(location, Diagnostics.Duplicate_identifier_0_Static_and_instance_elements_cannot_share_the_same_private_name, getTextOfNode(location)); } else { const prevIsMethod = !!(prev & DeclarationMeaning.Method); const isMethod = !!(meaning & DeclarationMeaning.Method); if (prevIsMethod || isMethod) { if (prevIsMethod !== isMethod) { error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); } // If this is a method/method duplication is might be an overload, so this will be handled when overloads are considered } else if (prev & meaning & ~DeclarationMeaning.PrivateStatic) { error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); } else { names.set(name, prev | meaning); } } } else { names.set(name, meaning); } } } /** * Static members being set on a constructor function may conflict with built-in properties * of Function. Esp. in ECMAScript 5 there are non-configurable and non-writable * built-in properties. This check issues a transpile error when a class has a static * member with the same name as a non-writable built-in property. * * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.3 * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.5 * @see http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-function-constructor * @see http://www.ecma-international.org/ecma-262/6.0/#sec-function-instances */ function checkClassForStaticPropertyNameConflicts(node: ClassLikeDeclaration) { for (const member of node.members) { const memberNameNode = member.name; const isStaticMember = isStatic(member); if (isStaticMember && memberNameNode) { const memberName = getPropertyNameForPropertyNameNode(memberNameNode); switch (memberName) { case "name": case "length": case "caller": case "arguments": case "prototype": const message = Diagnostics.Static_property_0_conflicts_with_built_in_property_Function_0_of_constructor_function_1; const className = getNameOfSymbolAsWritten(getSymbolOfDeclaration(node)); error(memberNameNode, message, memberName, className); break; } } } } function checkObjectTypeForDuplicateDeclarations(node: TypeLiteralNode | InterfaceDeclaration) { const names = new Map(); for (const member of node.members) { if (member.kind === SyntaxKind.PropertySignature) { let memberName: string; const name = member.name!; switch (name.kind) { case SyntaxKind.StringLiteral: case SyntaxKind.NumericLiteral: memberName = name.text; break; case SyntaxKind.Identifier: memberName = idText(name); break; default: continue; } if (names.get(memberName)) { error(getNameOfDeclaration(member.symbol.valueDeclaration), Diagnostics.Duplicate_identifier_0, memberName); error(member.name, Diagnostics.Duplicate_identifier_0, memberName); } else { names.set(memberName, true); } } } } function checkTypeForDuplicateIndexSignatures(node: ClassLikeDeclaration | InterfaceDeclaration | TypeLiteralNode) { if (node.kind === SyntaxKind.InterfaceDeclaration) { const nodeSymbol = getSymbolOfDeclaration(node); // in case of merging interface declaration it is possible that we'll enter this check procedure several times for every declaration // to prevent this run check only for the first declaration of a given kind if (nodeSymbol.declarations && nodeSymbol.declarations.length > 0 && nodeSymbol.declarations[0] !== node) { return; } } // TypeScript 1.0 spec (April 2014) // 3.7.4: An object type can contain at most one string index signature and one numeric index signature. // 8.5: A class declaration can have at most one string index member declaration and one numeric index member declaration const indexSymbol = getIndexSymbol(getSymbolOfDeclaration(node)!); if (indexSymbol?.declarations) { const indexSignatureMap = new Map(); for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { if (declaration.parameters.length === 1 && declaration.parameters[0].type) { forEachType(getTypeFromTypeNode(declaration.parameters[0].type), type => { const entry = indexSignatureMap.get(getTypeId(type)); if (entry) { entry.declarations.push(declaration); } else { indexSignatureMap.set(getTypeId(type), { type, declarations: [declaration] }); } }); } } indexSignatureMap.forEach(entry => { if (entry.declarations.length > 1) { for (const declaration of entry.declarations) { error(declaration, Diagnostics.Duplicate_index_signature_for_type_0, typeToString(entry.type)); } } }); } } function checkPropertyDeclaration(node: PropertyDeclaration | PropertySignature) { // Grammar checking if (!checkGrammarModifiers(node) && !checkGrammarProperty(node)) checkGrammarComputedPropertyName(node.name); checkVariableLikeDeclaration(node); setNodeLinksForPrivateIdentifierScope(node); // property signatures already report "initializer not allowed in ambient context" elsewhere if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.PropertyDeclaration && node.initializer) { error(node, Diagnostics.Property_0_cannot_have_an_initializer_because_it_is_marked_abstract, declarationNameToString(node.name)); } } function checkPropertySignature(node: PropertySignature) { if (isPrivateIdentifier(node.name)) { error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); } return checkPropertyDeclaration(node); } function checkMethodDeclaration(node: MethodDeclaration | MethodSignature) { // Grammar checking if (!checkGrammarMethod(node)) checkGrammarComputedPropertyName(node.name); if (isMethodDeclaration(node) && node.asteriskToken && isIdentifier(node.name) && idText(node.name) === "constructor") { error(node.name, Diagnostics.Class_constructor_may_not_be_a_generator); } // Grammar checking for modifiers is done inside the function checkGrammarFunctionLikeDeclaration checkFunctionOrMethodDeclaration(node); // method signatures already report "implementation not allowed in ambient context" elsewhere if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.MethodDeclaration && node.body) { error(node, Diagnostics.Method_0_cannot_have_an_implementation_because_it_is_marked_abstract, declarationNameToString(node.name)); } // Private named methods are only allowed in class declarations if (isPrivateIdentifier(node.name) && !getContainingClass(node)) { error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); } setNodeLinksForPrivateIdentifierScope(node); } function setNodeLinksForPrivateIdentifierScope(node: PropertyDeclaration | PropertySignature | MethodDeclaration | MethodSignature | AccessorDeclaration) { if (isPrivateIdentifier(node.name) && languageVersion < ScriptTarget.ESNext) { for (let lexicalScope = getEnclosingBlockScopeContainer(node); !!lexicalScope; lexicalScope = getEnclosingBlockScopeContainer(lexicalScope)) { getNodeLinks(lexicalScope).flags |= NodeCheckFlags.ContainsClassWithPrivateIdentifiers; } // If this is a private element in a class expression inside the body of a loop, // then we must use a block-scoped binding to store the additional variables required // to transform private elements. if (isClassExpression(node.parent)) { const enclosingIterationStatement = getEnclosingIterationStatement(node.parent); if (enclosingIterationStatement) { getNodeLinks(node.name).flags |= NodeCheckFlags.BlockScopedBindingInLoop; getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; } } } } function checkClassStaticBlockDeclaration(node: ClassStaticBlockDeclaration) { checkGrammarModifiers(node); forEachChild(node, checkSourceElement); } function checkConstructorDeclaration(node: ConstructorDeclaration) { // Grammar check on signature of constructor and modifier of the constructor is done in checkSignatureDeclaration function. checkSignatureDeclaration(node); // Grammar check for checking only related to constructorDeclaration if (!checkGrammarConstructorTypeParameters(node)) checkGrammarConstructorTypeAnnotation(node); checkSourceElement(node.body); const symbol = getSymbolOfDeclaration(node); const firstDeclaration = getDeclarationOfKind(symbol, node.kind); // Only type check the symbol once if (node === firstDeclaration) { checkFunctionOrConstructorSymbol(symbol); } // exit early in the case of signature - super checks are not relevant to them if (nodeIsMissing(node.body)) { return; } addLazyDiagnostic(checkConstructorDeclarationDiagnostics); return; function isInstancePropertyWithInitializerOrPrivateIdentifierProperty(n: Node): boolean { if (isPrivateIdentifierClassElementDeclaration(n)) { return true; } return n.kind === SyntaxKind.PropertyDeclaration && !isStatic(n) && !!(n as PropertyDeclaration).initializer; } function checkConstructorDeclarationDiagnostics() { // TS 1.0 spec (April 2014): 8.3.2 // Constructors of classes with no extends clause may not contain super calls, whereas // constructors of derived classes must contain at least one super call somewhere in their function body. const containingClassDecl = node.parent as ClassDeclaration; if (getClassExtendsHeritageElement(containingClassDecl)) { captureLexicalThis(node.parent, containingClassDecl); const classExtendsNull = classDeclarationExtendsNull(containingClassDecl); const superCall = findFirstSuperCall(node.body!); if (superCall) { if (classExtendsNull) { error(superCall, Diagnostics.A_constructor_cannot_contain_a_super_call_when_its_class_extends_null); } // A super call must be root-level in a constructor if both of the following are true: // - The containing class is a derived class. // - The constructor declares parameter properties // or the containing class declares instance member variables with initializers. const superCallShouldBeRootLevel = (getEmitScriptTarget(compilerOptions) !== ScriptTarget.ESNext || !useDefineForClassFields) && (some((node.parent as ClassDeclaration).members, isInstancePropertyWithInitializerOrPrivateIdentifierProperty) || some(node.parameters, p => hasSyntacticModifier(p, ModifierFlags.ParameterPropertyModifier))); if (superCallShouldBeRootLevel) { // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional // See GH #8277 if (!superCallIsRootLevelInConstructor(superCall, node.body!)) { error(superCall, Diagnostics.A_super_call_must_be_a_root_level_statement_within_a_constructor_of_a_derived_class_that_contains_initialized_properties_parameter_properties_or_private_identifiers); } // Skip past any prologue directives to check statements for referring to 'super' or 'this' before a super call else { let superCallStatement: ExpressionStatement | undefined; for (const statement of node.body!.statements) { if (isExpressionStatement(statement) && isSuperCall(skipOuterExpressions(statement.expression))) { superCallStatement = statement; break; } if (nodeImmediatelyReferencesSuperOrThis(statement)) { break; } } // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional // See GH #8277 if (superCallStatement === undefined) { error(node, Diagnostics.A_super_call_must_be_the_first_statement_in_the_constructor_to_refer_to_super_or_this_when_a_derived_class_contains_initialized_properties_parameter_properties_or_private_identifiers); } } } } else if (!classExtendsNull) { error(node, Diagnostics.Constructors_for_derived_classes_must_contain_a_super_call); } } } } function superCallIsRootLevelInConstructor(superCall: Node, body: Block) { const superCallParent = walkUpParenthesizedExpressions(superCall.parent); return isExpressionStatement(superCallParent) && superCallParent.parent === body; } function nodeImmediatelyReferencesSuperOrThis(node: Node): boolean { if (node.kind === SyntaxKind.SuperKeyword || node.kind === SyntaxKind.ThisKeyword) { return true; } if (isThisContainerOrFunctionBlock(node)) { return false; } return !!forEachChild(node, nodeImmediatelyReferencesSuperOrThis); } function checkAccessorDeclaration(node: AccessorDeclaration) { if (isIdentifier(node.name) && idText(node.name) === "constructor") { error(node.name, Diagnostics.Class_constructor_may_not_be_an_accessor); } addLazyDiagnostic(checkAccessorDeclarationDiagnostics); checkSourceElement(node.body); setNodeLinksForPrivateIdentifierScope(node); function checkAccessorDeclarationDiagnostics() { // Grammar checking accessors if (!checkGrammarFunctionLikeDeclaration(node) && !checkGrammarAccessor(node)) checkGrammarComputedPropertyName(node.name); checkDecorators(node); checkSignatureDeclaration(node); if (node.kind === SyntaxKind.GetAccessor) { if (!(node.flags & NodeFlags.Ambient) && nodeIsPresent(node.body) && (node.flags & NodeFlags.HasImplicitReturn)) { if (!(node.flags & NodeFlags.HasExplicitReturn)) { error(node.name, Diagnostics.A_get_accessor_must_return_a_value); } } } // Do not use hasDynamicName here, because that returns false for well known symbols. // We want to perform checkComputedPropertyName for all computed properties, including // well known symbols. if (node.name.kind === SyntaxKind.ComputedPropertyName) { checkComputedPropertyName(node.name); } if (hasBindableName(node)) { // TypeScript 1.0 spec (April 2014): 8.4.3 // Accessors for the same member name must specify the same accessibility. const symbol = getSymbolOfDeclaration(node); const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); if (getter && setter && !(getNodeCheckFlags(getter) & NodeCheckFlags.TypeChecked)) { getNodeLinks(getter).flags |= NodeCheckFlags.TypeChecked; const getterFlags = getEffectiveModifierFlags(getter); const setterFlags = getEffectiveModifierFlags(setter); if ((getterFlags & ModifierFlags.Abstract) !== (setterFlags & ModifierFlags.Abstract)) { error(getter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); error(setter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); } if (((getterFlags & ModifierFlags.Protected) && !(setterFlags & (ModifierFlags.Protected | ModifierFlags.Private))) || ((getterFlags & ModifierFlags.Private) && !(setterFlags & ModifierFlags.Private))) { error(getter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); error(setter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); } const getterType = getAnnotatedAccessorType(getter); const setterType = getAnnotatedAccessorType(setter); if (getterType && setterType) { checkTypeAssignableTo(getterType, setterType, getter, Diagnostics.The_return_type_of_a_get_accessor_must_be_assignable_to_its_set_accessor_type); } } } const returnType = getTypeOfAccessors(getSymbolOfDeclaration(node)); if (node.kind === SyntaxKind.GetAccessor) { checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); } } } function checkMissingDeclaration(node: Node) { checkDecorators(node); } function getEffectiveTypeArgumentAtIndex(node: TypeReferenceNode | ExpressionWithTypeArguments, typeParameters: readonly TypeParameter[], index: number): Type { if (node.typeArguments && index < node.typeArguments.length) { return getTypeFromTypeNode(node.typeArguments[index]); } return getEffectiveTypeArguments(node, typeParameters)[index]; } function getEffectiveTypeArguments(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): Type[] { return fillMissingTypeArguments(map(node.typeArguments!, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(node)); } function checkTypeArgumentConstraints(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): boolean { let typeArguments: Type[] | undefined; let mapper: TypeMapper | undefined; let result = true; for (let i = 0; i < typeParameters.length; i++) { const constraint = getConstraintOfTypeParameter(typeParameters[i]); if (constraint) { if (!typeArguments) { typeArguments = getEffectiveTypeArguments(node, typeParameters); mapper = createTypeMapper(typeParameters, typeArguments); } result = result && checkTypeAssignableTo( typeArguments[i], instantiateType(constraint, mapper), node.typeArguments![i], Diagnostics.Type_0_does_not_satisfy_the_constraint_1); } } return result; } function getTypeParametersForTypeAndSymbol(type: Type, symbol: Symbol) { if (!isErrorType(type)) { return symbol.flags & SymbolFlags.TypeAlias && getSymbolLinks(symbol).typeParameters || (getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target.localTypeParameters : undefined); } return undefined; } function getTypeParametersForTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { const type = getTypeFromTypeNode(node); if (!isErrorType(type)) { const symbol = getNodeLinks(node).resolvedSymbol; if (symbol) { return getTypeParametersForTypeAndSymbol(type, symbol); } } return undefined; } function checkTypeReferenceNode(node: TypeReferenceNode | ExpressionWithTypeArguments) { checkGrammarTypeArguments(node, node.typeArguments); if (node.kind === SyntaxKind.TypeReference && !isInJSFile(node) && !isInJSDoc(node) && node.typeArguments && node.typeName.end !== node.typeArguments.pos) { // If there was a token between the type name and the type arguments, check if it was a DotToken const sourceFile = getSourceFileOfNode(node); if (scanTokenAtPosition(sourceFile, node.typeName.end) === SyntaxKind.DotToken) { grammarErrorAtPos(node, skipTrivia(sourceFile.text, node.typeName.end), 1, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); } } forEach(node.typeArguments, checkSourceElement); checkTypeReferenceOrImport(node); } function checkTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { const type = getTypeFromTypeNode(node); if (!isErrorType(type)) { if (node.typeArguments) { addLazyDiagnostic(() => { const typeParameters = getTypeParametersForTypeReferenceOrImport(node); if (typeParameters) { checkTypeArgumentConstraints(node, typeParameters); } }); } const symbol = getNodeLinks(node).resolvedSymbol; if (symbol) { if (some(symbol.declarations, d => isTypeDeclaration(d) && !!(d.flags & NodeFlags.Deprecated))) { addDeprecatedSuggestion( getDeprecatedSuggestionNode(node), symbol.declarations!, symbol.escapedName as string ); } } } } function getTypeArgumentConstraint(node: TypeNode): Type | undefined { const typeReferenceNode = tryCast(node.parent, isTypeReferenceType); if (!typeReferenceNode) return undefined; const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReferenceNode); if (!typeParameters) return undefined; const constraint = getConstraintOfTypeParameter(typeParameters[typeReferenceNode.typeArguments!.indexOf(node)]); return constraint && instantiateType(constraint, createTypeMapper(typeParameters, getEffectiveTypeArguments(typeReferenceNode, typeParameters))); } function checkTypeQuery(node: TypeQueryNode) { getTypeFromTypeQueryNode(node); } function checkTypeLiteral(node: TypeLiteralNode) { forEach(node.members, checkSourceElement); addLazyDiagnostic(checkTypeLiteralDiagnostics); function checkTypeLiteralDiagnostics() { const type = getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node); checkIndexConstraints(type, type.symbol); checkTypeForDuplicateIndexSignatures(node); checkObjectTypeForDuplicateDeclarations(node); } } function checkArrayType(node: ArrayTypeNode) { checkSourceElement(node.elementType); } function checkTupleType(node: TupleTypeNode) { const elementTypes = node.elements; let seenOptionalElement = false; let seenRestElement = false; const hasNamedElement = some(elementTypes, isNamedTupleMember); for (const e of elementTypes) { if (e.kind !== SyntaxKind.NamedTupleMember && hasNamedElement) { grammarErrorOnNode(e, Diagnostics.Tuple_members_must_all_have_names_or_all_not_have_names); break; } const flags = getTupleElementFlags(e); if (flags & ElementFlags.Variadic) { const type = getTypeFromTypeNode((e as RestTypeNode | NamedTupleMember).type); if (!isArrayLikeType(type)) { error(e, Diagnostics.A_rest_element_type_must_be_an_array_type); break; } if (isArrayType(type) || isTupleType(type) && type.target.combinedFlags & ElementFlags.Rest) { seenRestElement = true; } } else if (flags & ElementFlags.Rest) { if (seenRestElement) { grammarErrorOnNode(e, Diagnostics.A_rest_element_cannot_follow_another_rest_element); break; } seenRestElement = true; } else if (flags & ElementFlags.Optional) { if (seenRestElement) { grammarErrorOnNode(e, Diagnostics.An_optional_element_cannot_follow_a_rest_element); break; } seenOptionalElement = true; } else if (seenOptionalElement) { grammarErrorOnNode(e, Diagnostics.A_required_element_cannot_follow_an_optional_element); break; } } forEach(node.elements, checkSourceElement); getTypeFromTypeNode(node); } function checkUnionOrIntersectionType(node: UnionOrIntersectionTypeNode) { forEach(node.types, checkSourceElement); getTypeFromTypeNode(node); } function checkIndexedAccessIndexType(type: Type, accessNode: IndexedAccessTypeNode | ElementAccessExpression) { if (!(type.flags & TypeFlags.IndexedAccess)) { return type; } // Check if the index type is assignable to 'keyof T' for the object type. const objectType = (type as IndexedAccessType).objectType; const indexType = (type as IndexedAccessType).indexType; if (isTypeAssignableTo(indexType, getIndexType(objectType, /*stringsOnly*/ false))) { if (accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) && getObjectFlags(objectType) & ObjectFlags.Mapped && getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.IncludeReadonly) { error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); } return type; } // Check if we're indexing with a numeric type and if either object or index types // is a generic type with a constraint that has a numeric index signature. const apparentObjectType = getApparentType(objectType); if (getIndexInfoOfType(apparentObjectType, numberType) && isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) { return type; } if (isGenericObjectType(objectType)) { const propertyName = getPropertyNameFromIndex(indexType, accessNode); if (propertyName) { const propertySymbol = forEachType(apparentObjectType, t => getPropertyOfType(t, propertyName)); if (propertySymbol && getDeclarationModifierFlagsFromSymbol(propertySymbol) & ModifierFlags.NonPublicAccessibilityModifier) { error(accessNode, Diagnostics.Private_or_protected_member_0_cannot_be_accessed_on_a_type_parameter, unescapeLeadingUnderscores(propertyName)); return errorType; } } } error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(objectType)); return errorType; } function checkIndexedAccessType(node: IndexedAccessTypeNode) { checkSourceElement(node.objectType); checkSourceElement(node.indexType); checkIndexedAccessIndexType(getTypeFromIndexedAccessTypeNode(node), node); } function checkMappedType(node: MappedTypeNode) { checkGrammarMappedType(node); checkSourceElement(node.typeParameter); checkSourceElement(node.nameType); checkSourceElement(node.type); if (!node.type) { reportImplicitAny(node, anyType); } const type = getTypeFromMappedTypeNode(node) as MappedType; const nameType = getNameTypeFromMappedType(type); if (nameType) { checkTypeAssignableTo(nameType, keyofConstraintType, node.nameType); } else { const constraintType = getConstraintTypeFromMappedType(type); checkTypeAssignableTo(constraintType, keyofConstraintType, getEffectiveConstraintOfTypeParameter(node.typeParameter)); } } function checkGrammarMappedType(node: MappedTypeNode) { if (node.members?.length) { return grammarErrorOnNode(node.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); } } function checkThisType(node: ThisTypeNode) { getTypeFromThisTypeNode(node); } function checkTypeOperator(node: TypeOperatorNode) { checkGrammarTypeOperatorNode(node); checkSourceElement(node.type); } function checkConditionalType(node: ConditionalTypeNode) { forEachChild(node, checkSourceElement); } function checkInferType(node: InferTypeNode) { if (!findAncestor(node, n => n.parent && n.parent.kind === SyntaxKind.ConditionalType && (n.parent as ConditionalTypeNode).extendsType === n)) { grammarErrorOnNode(node, Diagnostics.infer_declarations_are_only_permitted_in_the_extends_clause_of_a_conditional_type); } checkSourceElement(node.typeParameter); const symbol = getSymbolOfDeclaration(node.typeParameter); if (symbol.declarations && symbol.declarations.length > 1) { const links = getSymbolLinks(symbol); if (!links.typeParametersChecked) { links.typeParametersChecked = true; const typeParameter = getDeclaredTypeOfTypeParameter(symbol); const declarations: TypeParameterDeclaration[] = getDeclarationsOfKind(symbol, SyntaxKind.TypeParameter); if (!areTypeParametersIdentical(declarations, [typeParameter], decl => [decl])) { // Report an error on every conflicting declaration. const name = symbolToString(symbol); for (const declaration of declarations) { error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_constraints, name); } } } } registerForUnusedIdentifiersCheck(node); } function checkTemplateLiteralType(node: TemplateLiteralTypeNode) { for (const span of node.templateSpans) { checkSourceElement(span.type); const type = getTypeFromTypeNode(span.type); checkTypeAssignableTo(type, templateConstraintType, span.type); } getTypeFromTypeNode(node); } function checkImportType(node: ImportTypeNode) { checkSourceElement(node.argument); if (node.assertions) { const override = getResolutionModeOverrideForClause(node.assertions.assertClause, grammarErrorOnNode); if (override) { if (!isNightly()) { grammarErrorOnNode(node.assertions.assertClause, Diagnostics.resolution_mode_assertions_are_unstable_Use_nightly_TypeScript_to_silence_this_error_Try_updating_with_npm_install_D_typescript_next); } if (getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Node16 && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.NodeNext) { grammarErrorOnNode(node.assertions.assertClause, Diagnostics.resolution_mode_assertions_are_only_supported_when_moduleResolution_is_node16_or_nodenext); } } } checkTypeReferenceOrImport(node); } function checkNamedTupleMember(node: NamedTupleMember) { if (node.dotDotDotToken && node.questionToken) { grammarErrorOnNode(node, Diagnostics.A_tuple_member_cannot_be_both_optional_and_rest); } if (node.type.kind === SyntaxKind.OptionalType) { grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_optional_with_a_question_mark_after_the_name_and_before_the_colon_rather_than_after_the_type); } if (node.type.kind === SyntaxKind.RestType) { grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_rest_with_a_before_the_name_rather_than_before_the_type); } checkSourceElement(node.type); getTypeFromTypeNode(node); } function isPrivateWithinAmbient(node: Node): boolean { return (hasEffectiveModifier(node, ModifierFlags.Private) || isPrivateIdentifierClassElementDeclaration(node)) && !!(node.flags & NodeFlags.Ambient); } function getEffectiveDeclarationFlags(n: Declaration, flagsToCheck: ModifierFlags): ModifierFlags { let flags = getCombinedModifierFlags(n); // children of classes (even ambient classes) should not be marked as ambient or export // because those flags have no useful semantics there. if (n.parent.kind !== SyntaxKind.InterfaceDeclaration && n.parent.kind !== SyntaxKind.ClassDeclaration && n.parent.kind !== SyntaxKind.ClassExpression && n.flags & NodeFlags.Ambient) { if (!(flags & ModifierFlags.Ambient) && !(isModuleBlock(n.parent) && isModuleDeclaration(n.parent.parent) && isGlobalScopeAugmentation(n.parent.parent))) { // It is nested in an ambient context, which means it is automatically exported flags |= ModifierFlags.Export; } flags |= ModifierFlags.Ambient; } return flags & flagsToCheck; } function checkFunctionOrConstructorSymbol(symbol: Symbol): void { addLazyDiagnostic(() => checkFunctionOrConstructorSymbolWorker(symbol)); } function checkFunctionOrConstructorSymbolWorker(symbol: Symbol): void { function getCanonicalOverload(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined): Declaration { // Consider the canonical set of flags to be the flags of the bodyDeclaration or the first declaration // Error on all deviations from this canonical set of flags // The caveat is that if some overloads are defined in lib.d.ts, we don't want to // report the errors on those. To achieve this, we will say that the implementation is // the canonical signature only if it is in the same container as the first overload const implementationSharesContainerWithFirstOverload = implementation !== undefined && implementation.parent === overloads[0].parent; return implementationSharesContainerWithFirstOverload ? implementation : overloads[0]; } function checkFlagAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, flagsToCheck: ModifierFlags, someOverloadFlags: ModifierFlags, allOverloadFlags: ModifierFlags): void { // Error if some overloads have a flag that is not shared by all overloads. To find the // deviations, we XOR someOverloadFlags with allOverloadFlags const someButNotAllOverloadFlags = someOverloadFlags ^ allOverloadFlags; if (someButNotAllOverloadFlags !== 0) { const canonicalFlags = getEffectiveDeclarationFlags(getCanonicalOverload(overloads, implementation), flagsToCheck); forEach(overloads, o => { const deviation = getEffectiveDeclarationFlags(o, flagsToCheck) ^ canonicalFlags; if (deviation & ModifierFlags.Export) { error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_exported_or_non_exported); } else if (deviation & ModifierFlags.Ambient) { error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_ambient_or_non_ambient); } else if (deviation & (ModifierFlags.Private | ModifierFlags.Protected)) { error(getNameOfDeclaration(o) || o, Diagnostics.Overload_signatures_must_all_be_public_private_or_protected); } else if (deviation & ModifierFlags.Abstract) { error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_abstract_or_non_abstract); } }); } } function checkQuestionTokenAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, someHaveQuestionToken: boolean, allHaveQuestionToken: boolean): void { if (someHaveQuestionToken !== allHaveQuestionToken) { const canonicalHasQuestionToken = hasQuestionToken(getCanonicalOverload(overloads, implementation)); forEach(overloads, o => { const deviation = hasQuestionToken(o) !== canonicalHasQuestionToken; if (deviation) { error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_optional_or_required); } }); } } const flagsToCheck: ModifierFlags = ModifierFlags.Export | ModifierFlags.Ambient | ModifierFlags.Private | ModifierFlags.Protected | ModifierFlags.Abstract; let someNodeFlags: ModifierFlags = ModifierFlags.None; let allNodeFlags = flagsToCheck; let someHaveQuestionToken = false; let allHaveQuestionToken = true; let hasOverloads = false; let bodyDeclaration: FunctionLikeDeclaration | undefined; let lastSeenNonAmbientDeclaration: FunctionLikeDeclaration | undefined; let previousDeclaration: SignatureDeclaration | undefined; const declarations = symbol.declarations; const isConstructor = (symbol.flags & SymbolFlags.Constructor) !== 0; function reportImplementationExpectedError(node: SignatureDeclaration): void { if (node.name && nodeIsMissing(node.name)) { return; } let seen = false; const subsequentNode = forEachChild(node.parent, c => { if (seen) { return c; } else { seen = c === node; } }); // We may be here because of some extra nodes between overloads that could not be parsed into a valid node. // In this case the subsequent node is not really consecutive (.pos !== node.end), and we must ignore it here. if (subsequentNode && subsequentNode.pos === node.end) { if (subsequentNode.kind === node.kind) { const errorNode: Node = (subsequentNode as FunctionLikeDeclaration).name || subsequentNode; const subsequentName = (subsequentNode as FunctionLikeDeclaration).name; if (node.name && subsequentName && ( // both are private identifiers isPrivateIdentifier(node.name) && isPrivateIdentifier(subsequentName) && node.name.escapedText === subsequentName.escapedText || // Both are computed property names // TODO: GH#17345: These are methods, so handle computed name case. (`Always allowing computed property names is *not* the correct behavior!) isComputedPropertyName(node.name) && isComputedPropertyName(subsequentName) || // Both are literal property names that are the same. isPropertyNameLiteral(node.name) && isPropertyNameLiteral(subsequentName) && getEscapedTextOfIdentifierOrLiteral(node.name) === getEscapedTextOfIdentifierOrLiteral(subsequentName) )) { const reportError = (node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature) && isStatic(node) !== isStatic(subsequentNode); // we can get here in two cases // 1. mixed static and instance class members // 2. something with the same name was defined before the set of overloads that prevents them from merging // here we'll report error only for the first case since for second we should already report error in binder if (reportError) { const diagnostic = isStatic(node) ? Diagnostics.Function_overload_must_be_static : Diagnostics.Function_overload_must_not_be_static; error(errorNode, diagnostic); } return; } if (nodeIsPresent((subsequentNode as FunctionLikeDeclaration).body)) { error(errorNode, Diagnostics.Function_implementation_name_must_be_0, declarationNameToString(node.name)); return; } } } const errorNode: Node = node.name || node; if (isConstructor) { error(errorNode, Diagnostics.Constructor_implementation_is_missing); } else { // Report different errors regarding non-consecutive blocks of declarations depending on whether // the node in question is abstract. if (hasSyntacticModifier(node, ModifierFlags.Abstract)) { error(errorNode, Diagnostics.All_declarations_of_an_abstract_method_must_be_consecutive); } else { error(errorNode, Diagnostics.Function_implementation_is_missing_or_not_immediately_following_the_declaration); } } } let duplicateFunctionDeclaration = false; let multipleConstructorImplementation = false; let hasNonAmbientClass = false; const functionDeclarations = [] as Declaration[]; if (declarations) { for (const current of declarations) { const node = current as SignatureDeclaration | ClassDeclaration | ClassExpression; const inAmbientContext = node.flags & NodeFlags.Ambient; const inAmbientContextOrInterface = node.parent && (node.parent.kind === SyntaxKind.InterfaceDeclaration || node.parent.kind === SyntaxKind.TypeLiteral) || inAmbientContext; if (inAmbientContextOrInterface) { // check if declarations are consecutive only if they are non-ambient // 1. ambient declarations can be interleaved // i.e. this is legal // declare function foo(); // declare function bar(); // declare function foo(); // 2. mixing ambient and non-ambient declarations is a separate error that will be reported - do not want to report an extra one previousDeclaration = undefined; } if ((node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression) && !inAmbientContext) { hasNonAmbientClass = true; } if (node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature || node.kind === SyntaxKind.Constructor) { functionDeclarations.push(node); const currentNodeFlags = getEffectiveDeclarationFlags(node, flagsToCheck); someNodeFlags |= currentNodeFlags; allNodeFlags &= currentNodeFlags; someHaveQuestionToken = someHaveQuestionToken || hasQuestionToken(node); allHaveQuestionToken = allHaveQuestionToken && hasQuestionToken(node); const bodyIsPresent = nodeIsPresent((node as FunctionLikeDeclaration).body); if (bodyIsPresent && bodyDeclaration) { if (isConstructor) { multipleConstructorImplementation = true; } else { duplicateFunctionDeclaration = true; } } else if (previousDeclaration?.parent === node.parent && previousDeclaration.end !== node.pos) { reportImplementationExpectedError(previousDeclaration); } if (bodyIsPresent) { if (!bodyDeclaration) { bodyDeclaration = node as FunctionLikeDeclaration; } } else { hasOverloads = true; } previousDeclaration = node; if (!inAmbientContextOrInterface) { lastSeenNonAmbientDeclaration = node as FunctionLikeDeclaration; } } if (isInJSFile(current) && isFunctionLike(current) && current.jsDoc) { for (const node of current.jsDoc) { if (node.tags) { for (const tag of node.tags) { if (isJSDocOverloadTag(tag)) { hasOverloads = true; } } } } } } } if (multipleConstructorImplementation) { forEach(functionDeclarations, declaration => { error(declaration, Diagnostics.Multiple_constructor_implementations_are_not_allowed); }); } if (duplicateFunctionDeclaration) { forEach(functionDeclarations, declaration => { error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Duplicate_function_implementation); }); } if (hasNonAmbientClass && !isConstructor && symbol.flags & SymbolFlags.Function && declarations) { const relatedDiagnostics = filter(declarations, d => d.kind === SyntaxKind.ClassDeclaration) .map(d => createDiagnosticForNode(d, Diagnostics.Consider_adding_a_declare_modifier_to_this_class)); forEach(declarations, declaration => { const diagnostic = declaration.kind === SyntaxKind.ClassDeclaration ? Diagnostics.Class_declaration_cannot_implement_overload_list_for_0 : declaration.kind === SyntaxKind.FunctionDeclaration ? Diagnostics.Function_with_bodies_can_only_merge_with_classes_that_are_ambient : undefined; if (diagnostic) { addRelatedInfo( error(getNameOfDeclaration(declaration) || declaration, diagnostic, symbolName(symbol)), ...relatedDiagnostics ); } }); } // Abstract methods can't have an implementation -- in particular, they don't need one. if (lastSeenNonAmbientDeclaration && !lastSeenNonAmbientDeclaration.body && !hasSyntacticModifier(lastSeenNonAmbientDeclaration, ModifierFlags.Abstract) && !lastSeenNonAmbientDeclaration.questionToken) { reportImplementationExpectedError(lastSeenNonAmbientDeclaration); } if (hasOverloads) { if (declarations) { checkFlagAgreementBetweenOverloads(declarations, bodyDeclaration, flagsToCheck, someNodeFlags, allNodeFlags); checkQuestionTokenAgreementBetweenOverloads(declarations, bodyDeclaration, someHaveQuestionToken, allHaveQuestionToken); } if (bodyDeclaration) { const signatures = getSignaturesOfSymbol(symbol); const bodySignature = getSignatureFromDeclaration(bodyDeclaration); for (const signature of signatures) { if (!isImplementationCompatibleWithOverload(bodySignature, signature)) { const errorNode = signature.declaration && isJSDocSignature(signature.declaration) ? (signature.declaration.parent as JSDocOverloadTag | JSDocCallbackTag).tagName : signature.declaration; addRelatedInfo( error(errorNode, Diagnostics.This_overload_signature_is_not_compatible_with_its_implementation_signature), createDiagnosticForNode(bodyDeclaration, Diagnostics.The_implementation_signature_is_declared_here) ); break; } } } } } function checkExportsOnMergedDeclarations(node: Declaration): void { addLazyDiagnostic(() => checkExportsOnMergedDeclarationsWorker(node)); } function checkExportsOnMergedDeclarationsWorker(node: Declaration): void { // if localSymbol is defined on node then node itself is exported - check is required let symbol = node.localSymbol; if (!symbol) { // local symbol is undefined => this declaration is non-exported. // however symbol might contain other declarations that are exported symbol = getSymbolOfDeclaration(node)!; if (!symbol.exportSymbol) { // this is a pure local symbol (all declarations are non-exported) - no need to check anything return; } } // run the check only for the first declaration in the list if (getDeclarationOfKind(symbol, node.kind) !== node) { return; } let exportedDeclarationSpaces = DeclarationSpaces.None; let nonExportedDeclarationSpaces = DeclarationSpaces.None; let defaultExportedDeclarationSpaces = DeclarationSpaces.None; for (const d of symbol.declarations!) { const declarationSpaces = getDeclarationSpaces(d); const effectiveDeclarationFlags = getEffectiveDeclarationFlags(d, ModifierFlags.Export | ModifierFlags.Default); if (effectiveDeclarationFlags & ModifierFlags.Export) { if (effectiveDeclarationFlags & ModifierFlags.Default) { defaultExportedDeclarationSpaces |= declarationSpaces; } else { exportedDeclarationSpaces |= declarationSpaces; } } else { nonExportedDeclarationSpaces |= declarationSpaces; } } // Spaces for anything not declared a 'default export'. const nonDefaultExportedDeclarationSpaces = exportedDeclarationSpaces | nonExportedDeclarationSpaces; const commonDeclarationSpacesForExportsAndLocals = exportedDeclarationSpaces & nonExportedDeclarationSpaces; const commonDeclarationSpacesForDefaultAndNonDefault = defaultExportedDeclarationSpaces & nonDefaultExportedDeclarationSpaces; if (commonDeclarationSpacesForExportsAndLocals || commonDeclarationSpacesForDefaultAndNonDefault) { // declaration spaces for exported and non-exported declarations intersect for (const d of symbol.declarations!) { const declarationSpaces = getDeclarationSpaces(d); const name = getNameOfDeclaration(d); // Only error on the declarations that contributed to the intersecting spaces. if (declarationSpaces & commonDeclarationSpacesForDefaultAndNonDefault) { error(name, Diagnostics.Merged_declaration_0_cannot_include_a_default_export_declaration_Consider_adding_a_separate_export_default_0_declaration_instead, declarationNameToString(name)); } else if (declarationSpaces & commonDeclarationSpacesForExportsAndLocals) { error(name, Diagnostics.Individual_declarations_in_merged_declaration_0_must_be_all_exported_or_all_local, declarationNameToString(name)); } } } function getDeclarationSpaces(decl: Declaration): DeclarationSpaces { let d = decl as Node; switch (d.kind) { case SyntaxKind.InterfaceDeclaration: case SyntaxKind.TypeAliasDeclaration: // A jsdoc typedef and callback are, by definition, type aliases. // falls through case SyntaxKind.JSDocTypedefTag: case SyntaxKind.JSDocCallbackTag: case SyntaxKind.JSDocEnumTag: return DeclarationSpaces.ExportType; case SyntaxKind.ModuleDeclaration: return isAmbientModule(d as ModuleDeclaration) || getModuleInstanceState(d as ModuleDeclaration) !== ModuleInstanceState.NonInstantiated ? DeclarationSpaces.ExportNamespace | DeclarationSpaces.ExportValue : DeclarationSpaces.ExportNamespace; case SyntaxKind.ClassDeclaration: case SyntaxKind.EnumDeclaration: case SyntaxKind.EnumMember: return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue; case SyntaxKind.SourceFile: return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue | DeclarationSpaces.ExportNamespace; case SyntaxKind.ExportAssignment: case SyntaxKind.BinaryExpression: const node = d as ExportAssignment | BinaryExpression; const expression = isExportAssignment(node) ? node.expression : node.right; // Export assigned entity name expressions act as aliases and should fall through, otherwise they export values if (!isEntityNameExpression(expression)) { return DeclarationSpaces.ExportValue; } d = expression; // The below options all declare an Alias, which is allowed to merge with other values within the importing module. // falls through case SyntaxKind.ImportEqualsDeclaration: case SyntaxKind.NamespaceImport: case SyntaxKind.ImportClause: let result = DeclarationSpaces.None; const target = resolveAlias(getSymbolOfDeclaration(d as ImportEqualsDeclaration | NamespaceImport | ImportClause | ExportAssignment | BinaryExpression)!); forEach(target.declarations, d => { result |= getDeclarationSpaces(d); }); return result; case SyntaxKind.VariableDeclaration: case SyntaxKind.BindingElement: case SyntaxKind.FunctionDeclaration: case SyntaxKind.ImportSpecifier: // https://github.com/Microsoft/TypeScript/pull/7591 case SyntaxKind.Identifier: // https://github.com/microsoft/TypeScript/issues/36098 // Identifiers are used as declarations of assignment declarations whose parents may be // SyntaxKind.CallExpression - `Object.defineProperty(thing, "aField", {value: 42});` // SyntaxKind.ElementAccessExpression - `thing["aField"] = 42;` or `thing["aField"];` (with a doc comment on it) // or SyntaxKind.PropertyAccessExpression - `thing.aField = 42;` // all of which are pretty much always values, or at least imply a value meaning. // It may be apprpriate to treat these as aliases in the future. return DeclarationSpaces.ExportValue; case SyntaxKind.MethodSignature: case SyntaxKind.PropertySignature: return DeclarationSpaces.ExportType; default: return Debug.failBadSyntaxKind(d); } } } function getAwaitedTypeOfPromise(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, arg0?: string | number): Type | undefined { const promisedType = getPromisedTypeOfPromise(type, errorNode); return promisedType && getAwaitedType(promisedType, errorNode, diagnosticMessage, arg0); } /** * Gets the "promised type" of a promise. * @param type The type of the promise. * @remarks The "promised type" of a type is the type of the "value" parameter of the "onfulfilled" callback. */ function getPromisedTypeOfPromise(type: Type, errorNode?: Node, thisTypeForErrorOut?: { value?: Type }): Type | undefined { // // { // type // then( // thenFunction // onfulfilled: ( // onfulfilledParameterType // value: T // valueParameterType // ) => any // ): any; // } // if (isTypeAny(type)) { return undefined; } const typeAsPromise = type as PromiseOrAwaitableType; if (typeAsPromise.promisedTypeOfPromise) { return typeAsPromise.promisedTypeOfPromise; } if (isReferenceToType(type, getGlobalPromiseType(/*reportErrors*/ false))) { return typeAsPromise.promisedTypeOfPromise = getTypeArguments(type as GenericType)[0]; } // primitives with a `{ then() }` won't be unwrapped/adopted. if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) { return undefined; } const thenFunction = getTypeOfPropertyOfType(type, "then" as __String)!; // TODO: GH#18217 if (isTypeAny(thenFunction)) { return undefined; } const thenSignatures = thenFunction ? getSignaturesOfType(thenFunction, SignatureKind.Call) : emptyArray; if (thenSignatures.length === 0) { if (errorNode) { error(errorNode, Diagnostics.A_promise_must_have_a_then_method); } return undefined; } let thisTypeForError: Type | undefined; let candidates: Signature[] | undefined; for (const thenSignature of thenSignatures) { const thisType = getThisTypeOfSignature(thenSignature); if (thisType && thisType !== voidType && !isTypeRelatedTo(type, thisType, subtypeRelation)) { thisTypeForError = thisType; } else { candidates = append(candidates, thenSignature); } } if (!candidates) { Debug.assertIsDefined(thisTypeForError); if (thisTypeForErrorOut) { thisTypeForErrorOut.value = thisTypeForError; } if (errorNode) { error(errorNode, Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1, typeToString(type), typeToString(thisTypeForError)); } return undefined; } const onfulfilledParameterType = getTypeWithFacts(getUnionType(map(candidates, getTypeOfFirstParameterOfSignature)), TypeFacts.NEUndefinedOrNull); if (isTypeAny(onfulfilledParameterType)) { return undefined; } const onfulfilledParameterSignatures = getSignaturesOfType(onfulfilledParameterType, SignatureKind.Call); if (onfulfilledParameterSignatures.length === 0) { if (errorNode) { error(errorNode, Diagnostics.The_first_parameter_of_the_then_method_of_a_promise_must_be_a_callback); } return undefined; } return typeAsPromise.promisedTypeOfPromise = getUnionType(map(onfulfilledParameterSignatures, getTypeOfFirstParameterOfSignature), UnionReduction.Subtype); } /** * Gets the "awaited type" of a type. * @param type The type to await. * @param withAlias When `true`, wraps the "awaited type" in `Awaited` if needed. * @remarks The "awaited type" of an expression is its "promised type" if the expression is a * Promise-like type; otherwise, it is the type of the expression. This is used to reflect * The runtime behavior of the `await` keyword. */ function checkAwaitedType(type: Type, withAlias: boolean, errorNode: Node, diagnosticMessage: DiagnosticMessage, arg0?: string | number): Type { const awaitedType = withAlias ? getAwaitedType(type, errorNode, diagnosticMessage, arg0) : getAwaitedTypeNoAlias(type, errorNode, diagnosticMessage, arg0); return awaitedType || errorType; } /** * Determines whether a type is an object with a callable `then` member. */ function isThenableType(type: Type): boolean { if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) { // primitive types cannot be considered "thenable" since they are not objects. return false; } const thenFunction = getTypeOfPropertyOfType(type, "then" as __String); return !!thenFunction && getSignaturesOfType(getTypeWithFacts(thenFunction, TypeFacts.NEUndefinedOrNull), SignatureKind.Call).length > 0; } interface AwaitedTypeInstantiation extends Type { _awaitedTypeBrand: never; aliasSymbol: Symbol; aliasTypeArguments: readonly Type[]; } function isAwaitedTypeInstantiation(type: Type): type is AwaitedTypeInstantiation { if (type.flags & TypeFlags.Conditional) { const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ false); return !!awaitedSymbol && type.aliasSymbol === awaitedSymbol && type.aliasTypeArguments?.length === 1; } return false; } /** * For a generic `Awaited`, gets `T`. */ function unwrapAwaitedType(type: Type) { return type.flags & TypeFlags.Union ? mapType(type, unwrapAwaitedType) : isAwaitedTypeInstantiation(type) ? type.aliasTypeArguments[0] : type; } function isAwaitedTypeNeeded(type: Type) { // If this is already an `Awaited`, we shouldn't wrap it. This helps to avoid `Awaited>` in higher-order. if (isTypeAny(type) || isAwaitedTypeInstantiation(type)) { return false; } // We only need `Awaited` if `T` contains possibly non-primitive types. if (isGenericObjectType(type)) { const baseConstraint = getBaseConstraintOfType(type); // We only need `Awaited` if `T` is a type variable that has no base constraint, or the base constraint of `T` is `any`, `unknown`, `{}`, `object`, // or is promise-like. if (baseConstraint ? baseConstraint.flags & TypeFlags.AnyOrUnknown || isEmptyObjectType(baseConstraint) || someType(baseConstraint, isThenableType) : maybeTypeOfKind(type, TypeFlags.TypeVariable)) { return true; } } return false; } function tryCreateAwaitedType(type: Type): Type | undefined { // Nothing to do if `Awaited` doesn't exist const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ true); if (awaitedSymbol) { // Unwrap unions that may contain `Awaited`, otherwise its possible to manufacture an `Awaited | U>` where // an `Awaited` would suffice. return getTypeAliasInstantiation(awaitedSymbol, [unwrapAwaitedType(type)]); } return undefined; } function createAwaitedTypeIfNeeded(type: Type): Type { // We wrap type `T` in `Awaited` based on the following conditions: // - `T` is not already an `Awaited`, and // - `T` is generic, and // - One of the following applies: // - `T` has no base constraint, or // - The base constraint of `T` is `any`, `unknown`, `object`, or `{}`, or // - The base constraint of `T` is an object type with a callable `then` method. if (isAwaitedTypeNeeded(type)) { const awaitedType = tryCreateAwaitedType(type); if (awaitedType) { return awaitedType; } } Debug.assert(isAwaitedTypeInstantiation(type) || getPromisedTypeOfPromise(type) === undefined, "type provided should not be a non-generic 'promise'-like."); return type; } /** * Gets the "awaited type" of a type. * * The "awaited type" of an expression is its "promised type" if the expression is a * Promise-like type; otherwise, it is the type of the expression. If the "promised * type" is itself a Promise-like, the "promised type" is recursively unwrapped until a * non-promise type is found. * * This is used to reflect the runtime behavior of the `await` keyword. */ function getAwaitedType(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, arg0?: string | number): Type | undefined { const awaitedType = getAwaitedTypeNoAlias(type, errorNode, diagnosticMessage, arg0); return awaitedType && createAwaitedTypeIfNeeded(awaitedType); } /** * Gets the "awaited type" of a type without introducing an `Awaited` wrapper. * * @see {@link getAwaitedType} */ function getAwaitedTypeNoAlias(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, arg0?: string | number): Type | undefined { if (isTypeAny(type)) { return type; } // If this is already an `Awaited`, just return it. This avoids `Awaited>` in higher-order if (isAwaitedTypeInstantiation(type)) { return type; } // If we've already cached an awaited type, return a possible `Awaited` for it. const typeAsAwaitable = type as PromiseOrAwaitableType; if (typeAsAwaitable.awaitedTypeOfType) { return typeAsAwaitable.awaitedTypeOfType; } // For a union, get a union of the awaited types of each constituent. if (type.flags & TypeFlags.Union) { if (awaitedTypeStack.lastIndexOf(type.id) >= 0) { if (errorNode) { error(errorNode, Diagnostics.Type_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method); } return undefined; } const mapper = errorNode ? (constituentType: Type) => getAwaitedTypeNoAlias(constituentType, errorNode, diagnosticMessage, arg0) : getAwaitedTypeNoAlias; awaitedTypeStack.push(type.id); const mapped = mapType(type, mapper); awaitedTypeStack.pop(); return typeAsAwaitable.awaitedTypeOfType = mapped; } // If `type` is generic and should be wrapped in `Awaited`, return it. if (isAwaitedTypeNeeded(type)) { return typeAsAwaitable.awaitedTypeOfType = type; } const thisTypeForErrorOut: { value: Type | undefined } = { value: undefined }; const promisedType = getPromisedTypeOfPromise(type, /*errorNode*/ undefined, thisTypeForErrorOut); if (promisedType) { if (type.id === promisedType.id || awaitedTypeStack.lastIndexOf(promisedType.id) >= 0) { // Verify that we don't have a bad actor in the form of a promise whose // promised type is the same as the promise type, or a mutually recursive // promise. If so, we return undefined as we cannot guess the shape. If this // were the actual case in the JavaScript, this Promise would never resolve. // // An example of a bad actor with a singly-recursive promise type might // be: // // interface BadPromise { // then( // onfulfilled: (value: BadPromise) => any, // onrejected: (error: any) => any): BadPromise; // } // // The above interface will pass the PromiseLike check, and return a // promised type of `BadPromise`. Since this is a self reference, we // don't want to keep recursing ad infinitum. // // An example of a bad actor in the form of a mutually-recursive // promise type might be: // // interface BadPromiseA { // then( // onfulfilled: (value: BadPromiseB) => any, // onrejected: (error: any) => any): BadPromiseB; // } // // interface BadPromiseB { // then( // onfulfilled: (value: BadPromiseA) => any, // onrejected: (error: any) => any): BadPromiseA; // } // if (errorNode) { error(errorNode, Diagnostics.Type_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method); } return undefined; } // Keep track of the type we're about to unwrap to avoid bad recursive promise types. // See the comments above for more information. awaitedTypeStack.push(type.id); const awaitedType = getAwaitedTypeNoAlias(promisedType, errorNode, diagnosticMessage, arg0); awaitedTypeStack.pop(); if (!awaitedType) { return undefined; } return typeAsAwaitable.awaitedTypeOfType = awaitedType; } // The type was not a promise, so it could not be unwrapped any further. // As long as the type does not have a callable "then" property, it is // safe to return the type; otherwise, an error is reported and we return // undefined. // // An example of a non-promise "thenable" might be: // // await { then(): void {} } // // The "thenable" does not match the minimal definition for a promise. When // a Promise/A+-compatible or ES6 promise tries to adopt this value, the promise // will never settle. We treat this as an error to help flag an early indicator // of a runtime problem. If the user wants to return this value from an async // function, they would need to wrap it in some other value. If they want it to // be treated as a promise, they can cast to . if (isThenableType(type)) { if (errorNode) { Debug.assertIsDefined(diagnosticMessage); let chain: DiagnosticMessageChain | undefined; if (thisTypeForErrorOut.value) { chain = chainDiagnosticMessages(chain, Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1, typeToString(type), typeToString(thisTypeForErrorOut.value)); } chain = chainDiagnosticMessages(chain, diagnosticMessage, arg0); diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode), errorNode, chain)); } return undefined; } return typeAsAwaitable.awaitedTypeOfType = type; } /** * Checks the return type of an async function to ensure it is a compatible * Promise implementation. * * This checks that an async function has a valid Promise-compatible return type. * An async function has a valid Promise-compatible return type if the resolved value * of the return type has a construct signature that takes in an `initializer` function * that in turn supplies a `resolve` function as one of its arguments and results in an * object with a callable `then` signature. * * @param node The signature to check */ function checkAsyncFunctionReturnType(node: FunctionLikeDeclaration | MethodSignature, returnTypeNode: TypeNode) { // As part of our emit for an async function, we will need to emit the entity name of // the return type annotation as an expression. To meet the necessary runtime semantics // for __awaiter, we must also check that the type of the declaration (e.g. the static // side or "constructor" of the promise type) is compatible `PromiseConstructorLike`. // // An example might be (from lib.es6.d.ts): // // interface Promise { ... } // interface PromiseConstructor { // new (...): Promise; // } // declare var Promise: PromiseConstructor; // // When an async function declares a return type annotation of `Promise`, we // need to get the type of the `Promise` variable declaration above, which would // be `PromiseConstructor`. // // The same case applies to a class: // // declare class Promise { // constructor(...); // then(...): Promise; // } // const returnType = getTypeFromTypeNode(returnTypeNode); if (languageVersion >= ScriptTarget.ES2015) { if (isErrorType(returnType)) { return; } const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); if (globalPromiseType !== emptyGenericType && !isReferenceToType(returnType, globalPromiseType)) { // The promise type was not a valid type reference to the global promise type, so we // report an error and return the unknown type. error(returnTypeNode, Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type_Did_you_mean_to_write_Promise_0, typeToString(getAwaitedTypeNoAlias(returnType) || voidType)); return; } } else { // Always mark the type node as referenced if it points to a value markTypeNodeAsReferenced(returnTypeNode); if (isErrorType(returnType)) { return; } const promiseConstructorName = getEntityNameFromTypeNode(returnTypeNode); if (promiseConstructorName === undefined) { error(returnTypeNode, Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_SlashES3_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, typeToString(returnType)); return; } const promiseConstructorSymbol = resolveEntityName(promiseConstructorName, SymbolFlags.Value, /*ignoreErrors*/ true); const promiseConstructorType = promiseConstructorSymbol ? getTypeOfSymbol(promiseConstructorSymbol) : errorType; if (isErrorType(promiseConstructorType)) { if (promiseConstructorName.kind === SyntaxKind.Identifier && promiseConstructorName.escapedText === "Promise" && getTargetType(returnType) === getGlobalPromiseType(/*reportErrors*/ false)) { error(returnTypeNode, Diagnostics.An_async_function_or_method_in_ES5_SlashES3_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option); } else { error(returnTypeNode, Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_SlashES3_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, entityNameToString(promiseConstructorName)); } return; } const globalPromiseConstructorLikeType = getGlobalPromiseConstructorLikeType(/*reportErrors*/ true); if (globalPromiseConstructorLikeType === emptyObjectType) { // If we couldn't resolve the global PromiseConstructorLike type we cannot verify // compatibility with __awaiter. error(returnTypeNode, Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_SlashES3_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, entityNameToString(promiseConstructorName)); return; } if (!checkTypeAssignableTo(promiseConstructorType, globalPromiseConstructorLikeType, returnTypeNode, Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_SlashES3_because_it_does_not_refer_to_a_Promise_compatible_constructor_value)) { return; } // Verify there is no local declaration that could collide with the promise constructor. const rootName = promiseConstructorName && getFirstIdentifier(promiseConstructorName); const collidingSymbol = getSymbol(node.locals!, rootName.escapedText, SymbolFlags.Value); if (collidingSymbol) { error(collidingSymbol.valueDeclaration, Diagnostics.Duplicate_identifier_0_Compiler_uses_declaration_1_to_support_async_functions, idText(rootName), entityNameToString(promiseConstructorName)); return; } } checkAwaitedType(returnType, /*withAlias*/ false, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); } /** Check a decorator */ function checkDecorator(node: Decorator): void { const signature = getResolvedSignature(node); checkDeprecatedSignature(signature, node); const returnType = getReturnTypeOfSignature(signature); if (returnType.flags & TypeFlags.Any) { return; } // if we fail to get a signature and return type here, we will have already reported a grammar error in `checkDecorators`. const decoratorSignature = getDecoratorCallSignature(node); if (!decoratorSignature?.resolvedReturnType) return; let headMessage: DiagnosticMessage; const expectedReturnType = decoratorSignature.resolvedReturnType; switch (node.parent.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; break; case SyntaxKind.PropertyDeclaration: if (!legacyDecorators) { headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; break; } // falls through case SyntaxKind.Parameter: headMessage = Diagnostics.Decorator_function_return_type_is_0_but_is_expected_to_be_void_or_any; break; case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; break; default: return Debug.failBadSyntaxKind(node.parent); } checkTypeAssignableTo(returnType, expectedReturnType, node.expression, headMessage); } /** * Creates a synthetic `Signature` corresponding to a call signature. */ function createCallSignature( typeParameters: readonly TypeParameter[] | undefined, thisParameter: Symbol | undefined, parameters: readonly Symbol[], returnType: Type, typePredicate?: TypePredicate, minArgumentCount: number = parameters.length, flags: SignatureFlags = SignatureFlags.None ) { const decl = factory.createFunctionTypeNode(/*typeParameters*/ undefined, emptyArray, factory.createKeywordTypeNode(SyntaxKind.AnyKeyword)); return createSignature(decl, typeParameters, thisParameter, parameters, returnType, typePredicate, minArgumentCount, flags); } /** * Creates a synthetic `FunctionType` */ function createFunctionType( typeParameters: readonly TypeParameter[] | undefined, thisParameter: Symbol | undefined, parameters: readonly Symbol[], returnType: Type, typePredicate?: TypePredicate, minArgumentCount?: number, flags?: SignatureFlags ) { const signature = createCallSignature(typeParameters, thisParameter, parameters, returnType, typePredicate, minArgumentCount, flags); return getOrCreateTypeFromSignature(signature); } function createGetterFunctionType(type: Type) { return createFunctionType(/*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, type); } function createSetterFunctionType(type: Type) { const valueParam = createParameter("value" as __String, type); return createFunctionType(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [valueParam], voidType); } /** * If a TypeNode can be resolved to a value symbol imported from an external module, it is * marked as referenced to prevent import elision. */ function markTypeNodeAsReferenced(node: TypeNode) { markEntityNameOrEntityExpressionAsReference(node && getEntityNameFromTypeNode(node), /*forDecoratorMetadata*/ false); } function markEntityNameOrEntityExpressionAsReference(typeName: EntityNameOrEntityNameExpression | undefined, forDecoratorMetadata: boolean) { if (!typeName) return; const rootName = getFirstIdentifier(typeName); const meaning = (typeName.kind === SyntaxKind.Identifier ? SymbolFlags.Type : SymbolFlags.Namespace) | SymbolFlags.Alias; const rootSymbol = resolveName(rootName, rootName.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isReference*/ true); if (rootSymbol && rootSymbol.flags & SymbolFlags.Alias) { if (!compilerOptions.verbatimModuleSyntax && symbolIsValue(rootSymbol) && !isConstEnumOrConstEnumOnlyModule(resolveAlias(rootSymbol)) && !getTypeOnlyAliasDeclaration(rootSymbol)) { markAliasSymbolAsReferenced(rootSymbol); } else if (forDecoratorMetadata && getIsolatedModules(compilerOptions) && getEmitModuleKind(compilerOptions) >= ModuleKind.ES2015 && !symbolIsValue(rootSymbol) && !some(rootSymbol.declarations, isTypeOnlyImportOrExportDeclaration)) { const diag = error(typeName, Diagnostics.A_type_referenced_in_a_decorated_signature_must_be_imported_with_import_type_or_a_namespace_import_when_isolatedModules_and_emitDecoratorMetadata_are_enabled); const aliasDeclaration = find(rootSymbol.declarations || emptyArray, isAliasSymbolDeclaration); if (aliasDeclaration) { addRelatedInfo(diag, createDiagnosticForNode(aliasDeclaration, Diagnostics._0_was_imported_here, idText(rootName))); } } } } /** * This function marks the type used for metadata decorator as referenced if it is import * from external module. * This is different from markTypeNodeAsReferenced because it tries to simplify type nodes in * union and intersection type * @param node */ function markDecoratorMedataDataTypeNodeAsReferenced(node: TypeNode | undefined): void { const entityName = getEntityNameForDecoratorMetadata(node); if (entityName && isEntityName(entityName)) { markEntityNameOrEntityExpressionAsReference(entityName, /*forDecoratorMetadata*/ true); } } function getEntityNameForDecoratorMetadata(node: TypeNode | undefined): EntityName | undefined { if (node) { switch (node.kind) { case SyntaxKind.IntersectionType: case SyntaxKind.UnionType: return getEntityNameForDecoratorMetadataFromTypeList((node as UnionOrIntersectionTypeNode).types); case SyntaxKind.ConditionalType: return getEntityNameForDecoratorMetadataFromTypeList([(node as ConditionalTypeNode).trueType, (node as ConditionalTypeNode).falseType]); case SyntaxKind.ParenthesizedType: case SyntaxKind.NamedTupleMember: return getEntityNameForDecoratorMetadata((node as ParenthesizedTypeNode).type); case SyntaxKind.TypeReference: return (node as TypeReferenceNode).typeName; } } } function getEntityNameForDecoratorMetadataFromTypeList(types: readonly TypeNode[]): EntityName | undefined { let commonEntityName: EntityName | undefined; for (let typeNode of types) { while (typeNode.kind === SyntaxKind.ParenthesizedType || typeNode.kind === SyntaxKind.NamedTupleMember) { typeNode = (typeNode as ParenthesizedTypeNode | NamedTupleMember).type; // Skip parens if need be } if (typeNode.kind === SyntaxKind.NeverKeyword) { continue; // Always elide `never` from the union/intersection if possible } if (!strictNullChecks && (typeNode.kind === SyntaxKind.LiteralType && (typeNode as LiteralTypeNode).literal.kind === SyntaxKind.NullKeyword || typeNode.kind === SyntaxKind.UndefinedKeyword)) { continue; // Elide null and undefined from unions for metadata, just like what we did prior to the implementation of strict null checks } const individualEntityName = getEntityNameForDecoratorMetadata(typeNode); if (!individualEntityName) { // Individual is something like string number // So it would be serialized to either that type or object // Safe to return here return undefined; } if (commonEntityName) { // Note this is in sync with the transformation that happens for type node. // Keep this in sync with serializeUnionOrIntersectionType // Verify if they refer to same entity and is identifier // return undefined if they dont match because we would emit object if (!isIdentifier(commonEntityName) || !isIdentifier(individualEntityName) || commonEntityName.escapedText !== individualEntityName.escapedText) { return undefined; } } else { commonEntityName = individualEntityName; } } return commonEntityName; } function getParameterTypeNodeForDecoratorCheck(node: ParameterDeclaration): TypeNode | undefined { const typeNode = getEffectiveTypeAnnotationNode(node); return isRestParameter(node) ? getRestParameterElementType(typeNode) : typeNode; } /** Check the decorators of a node */ function checkDecorators(node: Node): void { // skip this check for nodes that cannot have decorators. These should have already had an error reported by // checkGrammarModifiers. if (!canHaveDecorators(node) || !hasDecorators(node) || !node.modifiers || !nodeCanBeDecorated(legacyDecorators, node, node.parent, node.parent.parent)) { return; } const firstDecorator = find(node.modifiers, isDecorator); if (!firstDecorator) { return; } if (legacyDecorators) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Decorate); if (node.kind === SyntaxKind.Parameter) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Param); } } else if (languageVersion < ScriptTarget.ESNext) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.ESDecorateAndRunInitializers); if (isClassDeclaration(node)) { if (!node.name) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); } else { const member = getFirstTransformableStaticClassElement(node); if (member) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); } } } else if (!isClassExpression(node)) { if (isPrivateIdentifier(node.name) && (isMethodDeclaration(node) || isAccessor(node) || isAutoAccessorPropertyDeclaration(node))) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); } if (isComputedPropertyName(node.name)) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.PropKey); } } } if (compilerOptions.emitDecoratorMetadata) { checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Metadata); // we only need to perform these checks if we are emitting serialized type metadata for the target of a decorator. switch (node.kind) { case SyntaxKind.ClassDeclaration: const constructor = getFirstConstructorWithBody(node); if (constructor) { for (const parameter of constructor.parameters) { markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); } } break; case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: const otherKind = node.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(node), otherKind); markDecoratorMedataDataTypeNodeAsReferenced(getAnnotatedAccessorTypeNode(node) || otherAccessor && getAnnotatedAccessorTypeNode(otherAccessor)); break; case SyntaxKind.MethodDeclaration: for (const parameter of node.parameters) { markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); } markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(node)); break; case SyntaxKind.PropertyDeclaration: markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveTypeAnnotationNode(node)); break; case SyntaxKind.Parameter: markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(node)); const containingSignature = node.parent; for (const parameter of containingSignature.parameters) { markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); } break; } } for (const modifier of node.modifiers) { if (isDecorator(modifier)) { checkDecorator(modifier); } } } function checkFunctionDeclaration(node: FunctionDeclaration): void { addLazyDiagnostic(checkFunctionDeclarationDiagnostics); function checkFunctionDeclarationDiagnostics() { checkFunctionOrMethodDeclaration(node); checkGrammarForGenerator(node); checkCollisionsForDeclarationName(node, node.name); } } function checkJSDocTypeAliasTag(node: JSDocTypedefTag | JSDocCallbackTag) { if (!node.typeExpression) { // If the node had `@property` tags, `typeExpression` would have been set to the first property tag. error(node.name, Diagnostics.JSDoc_typedef_tag_should_either_have_a_type_annotation_or_be_followed_by_property_or_member_tags); } if (node.name) { checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0); } checkSourceElement(node.typeExpression); checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); } function checkJSDocTemplateTag(node: JSDocTemplateTag): void { checkSourceElement(node.constraint); for (const tp of node.typeParameters) { checkSourceElement(tp); } } function checkJSDocTypeTag(node: JSDocTypeTag) { checkSourceElement(node.typeExpression); } function checkJSDocSatisfiesTag(node: JSDocSatisfiesTag) { checkSourceElement(node.typeExpression); const host = getEffectiveJSDocHost(node); if (host) { const tags = getAllJSDocTags(host, isJSDocSatisfiesTag); if (length(tags) > 1) { for (let i = 1; i < length(tags); i++) { const tagName = tags[i].tagName; error(tagName, Diagnostics._0_tag_already_specified, idText(tagName)); } } } } function checkJSDocLinkLikeTag(node: JSDocLink | JSDocLinkCode | JSDocLinkPlain) { if (node.name) { resolveJSDocMemberName(node.name, /*ignoreErrors*/ true); } } function checkJSDocParameterTag(node: JSDocParameterTag) { checkSourceElement(node.typeExpression); } function checkJSDocPropertyTag(node: JSDocPropertyTag) { checkSourceElement(node.typeExpression); } function checkJSDocFunctionType(node: JSDocFunctionType): void { addLazyDiagnostic(checkJSDocFunctionTypeImplicitAny); checkSignatureDeclaration(node); function checkJSDocFunctionTypeImplicitAny() { if (!node.type && !isJSDocConstructSignature(node)) { reportImplicitAny(node, anyType); } } } function checkJSDocImplementsTag(node: JSDocImplementsTag): void { const classLike = getEffectiveJSDocHost(node); if (!classLike || !isClassDeclaration(classLike) && !isClassExpression(classLike)) { error(classLike, Diagnostics.JSDoc_0_is_not_attached_to_a_class, idText(node.tagName)); } } function checkJSDocAugmentsTag(node: JSDocAugmentsTag): void { const classLike = getEffectiveJSDocHost(node); if (!classLike || !isClassDeclaration(classLike) && !isClassExpression(classLike)) { error(classLike, Diagnostics.JSDoc_0_is_not_attached_to_a_class, idText(node.tagName)); return; } const augmentsTags = getJSDocTags(classLike).filter(isJSDocAugmentsTag); Debug.assert(augmentsTags.length > 0); if (augmentsTags.length > 1) { error(augmentsTags[1], Diagnostics.Class_declarations_cannot_have_more_than_one_augments_or_extends_tag); } const name = getIdentifierFromEntityNameExpression(node.class.expression); const extend = getClassExtendsHeritageElement(classLike); if (extend) { const className = getIdentifierFromEntityNameExpression(extend.expression); if (className && name.escapedText !== className.escapedText) { error(name, Diagnostics.JSDoc_0_1_does_not_match_the_extends_2_clause, idText(node.tagName), idText(name), idText(className)); } } } function checkJSDocAccessibilityModifiers(node: JSDocPublicTag | JSDocProtectedTag | JSDocPrivateTag): void { const host = getJSDocHost(node); if (host && isPrivateIdentifierClassElementDeclaration(host)) { error(node, Diagnostics.An_accessibility_modifier_cannot_be_used_with_a_private_identifier); } } function getIdentifierFromEntityNameExpression(node: Identifier | PropertyAccessExpression): Identifier | PrivateIdentifier; function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateIdentifier | undefined; function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateIdentifier | undefined { switch (node.kind) { case SyntaxKind.Identifier: return node as Identifier; case SyntaxKind.PropertyAccessExpression: return (node as PropertyAccessExpression).name; default: return undefined; } } function checkFunctionOrMethodDeclaration(node: FunctionDeclaration | MethodDeclaration | MethodSignature): void { checkDecorators(node); checkSignatureDeclaration(node); const functionFlags = getFunctionFlags(node); // Do not use hasDynamicName here, because that returns false for well known symbols. // We want to perform checkComputedPropertyName for all computed properties, including // well known symbols. if (node.name && node.name.kind === SyntaxKind.ComputedPropertyName) { // This check will account for methods in class/interface declarations, // as well as accessors in classes/object literals checkComputedPropertyName(node.name); } if (hasBindableName(node)) { // first we want to check the local symbol that contain this declaration // - if node.localSymbol !== undefined - this is current declaration is exported and localSymbol points to the local symbol // - if node.localSymbol === undefined - this node is non-exported so we can just pick the result of getSymbolOfNode const symbol = getSymbolOfDeclaration(node); const localSymbol = node.localSymbol || symbol; // Since the javascript won't do semantic analysis like typescript, // if the javascript file comes before the typescript file and both contain same name functions, // checkFunctionOrConstructorSymbol wouldn't be called if we didnt ignore javascript function. const firstDeclaration = localSymbol.declarations?.find( // Get first non javascript function declaration declaration => declaration.kind === node.kind && !(declaration.flags & NodeFlags.JavaScriptFile)); // Only type check the symbol once if (node === firstDeclaration) { checkFunctionOrConstructorSymbol(localSymbol); } if (symbol.parent) { // run check on export symbol to check that modifiers agree across all exported declarations checkFunctionOrConstructorSymbol(symbol); } } const body = node.kind === SyntaxKind.MethodSignature ? undefined : node.body; checkSourceElement(body); checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, getReturnTypeFromAnnotation(node)); addLazyDiagnostic(checkFunctionOrMethodDeclarationDiagnostics); // A js function declaration can have a @type tag instead of a return type node, but that type must have a call signature if (isInJSFile(node)) { const typeTag = getJSDocTypeTag(node); if (typeTag && typeTag.typeExpression && !getContextualCallSignature(getTypeFromTypeNode(typeTag.typeExpression), node)) { error(typeTag.typeExpression.type, Diagnostics.The_type_of_a_function_declaration_must_match_the_function_s_signature); } } function checkFunctionOrMethodDeclarationDiagnostics() { if (!getEffectiveReturnTypeNode(node)) { // Report an implicit any error if there is no body, no explicit return type, and node is not a private method // in an ambient context if (nodeIsMissing(body) && !isPrivateWithinAmbient(node)) { reportImplicitAny(node, anyType); } if (functionFlags & FunctionFlags.Generator && nodeIsPresent(body)) { // A generator with a body and no type annotation can still cause errors. It can error if the // yielded values have no common supertype, or it can give an implicit any error if it has no // yielded values. The only way to trigger these errors is to try checking its return type. getReturnTypeOfSignature(getSignatureFromDeclaration(node)); } } } } function registerForUnusedIdentifiersCheck(node: PotentiallyUnusedIdentifier): void { addLazyDiagnostic(registerForUnusedIdentifiersCheckDiagnostics); function registerForUnusedIdentifiersCheckDiagnostics() { // May be in a call such as getTypeOfNode that happened to call this. But potentiallyUnusedIdentifiers is only defined in the scope of `checkSourceFile`. const sourceFile = getSourceFileOfNode(node); let potentiallyUnusedIdentifiers = allPotentiallyUnusedIdentifiers.get(sourceFile.path); if (!potentiallyUnusedIdentifiers) { potentiallyUnusedIdentifiers = []; allPotentiallyUnusedIdentifiers.set(sourceFile.path, potentiallyUnusedIdentifiers); } // TODO: GH#22580 // Debug.assert(addToSeen(seenPotentiallyUnusedIdentifiers, getNodeId(node)), "Adding potentially-unused identifier twice"); potentiallyUnusedIdentifiers.push(node); } } type PotentiallyUnusedIdentifier = | SourceFile | ModuleDeclaration | ClassLikeDeclaration | InterfaceDeclaration | Block | CaseBlock | ForStatement | ForInStatement | ForOfStatement | Exclude | TypeAliasDeclaration | InferTypeNode; function checkUnusedIdentifiers(potentiallyUnusedIdentifiers: readonly PotentiallyUnusedIdentifier[], addDiagnostic: AddUnusedDiagnostic) { for (const node of potentiallyUnusedIdentifiers) { switch (node.kind) { case SyntaxKind.ClassDeclaration: case SyntaxKind.ClassExpression: checkUnusedClassMembers(node, addDiagnostic); checkUnusedTypeParameters(node, addDiagnostic); break; case SyntaxKind.SourceFile: case SyntaxKind.ModuleDeclaration: case SyntaxKind.Block: case SyntaxKind.CaseBlock: case SyntaxKind.ForStatement: case SyntaxKind.ForInStatement: case SyntaxKind.ForOfStatement: checkUnusedLocalsAndParameters(node, addDiagnostic); break; case SyntaxKind.Constructor: case SyntaxKind.FunctionExpression: case SyntaxKind.FunctionDeclaration: case SyntaxKind.ArrowFunction: case SyntaxKind.MethodDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: if (node.body) { // Don't report unused parameters in overloads checkUnusedLocalsAndParameters(node, addDiagnostic); } checkUnusedTypeParameters(node, addDiagnostic); break; case SyntaxKind.MethodSignature: case SyntaxKind.CallSignature: case SyntaxKind.ConstructSignature: case SyntaxKind.FunctionType: case SyntaxKind.ConstructorType: case SyntaxKind.TypeAliasDeclaration: case SyntaxKind.InterfaceDeclaration: checkUnusedTypeParameters(node, addDiagnostic); break; case SyntaxKind.InferType: checkUnusedInferTypeParameter(node, addDiagnostic); break; default: Debug.assertNever(node, "Node should not have been registered for unused identifiers check"); } } } function errorUnusedLocal(declaration: Declaration, name: string, addDiagnostic: AddUnusedDiagnostic) { const node = getNameOfDeclaration(declaration) || declaration; const message = isTypeDeclaration(declaration) ? Diagnostics._0_is_declared_but_never_used : Diagnostics._0_is_declared_but_its_value_is_never_read; addDiagnostic(declaration, UnusedKind.Local, createDiagnosticForNode(node, message, name)); } function isIdentifierThatStartsWithUnderscore(node: Node) { return isIdentifier(node) && idText(node).charCodeAt(0) === CharacterCodes._; } function checkUnusedClassMembers(node: ClassDeclaration | ClassExpression, addDiagnostic: AddUnusedDiagnostic): void { for (const member of node.members) { switch (member.kind) { case SyntaxKind.MethodDeclaration: case SyntaxKind.PropertyDeclaration: case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: if (member.kind === SyntaxKind.SetAccessor && member.symbol.flags & SymbolFlags.GetAccessor) { // Already would have reported an error on the getter. break; } const symbol = getSymbolOfDeclaration(member); if (!symbol.isReferenced && (hasEffectiveModifier(member, ModifierFlags.Private) || isNamedDeclaration(member) && isPrivateIdentifier(member.name)) && !(member.flags & NodeFlags.Ambient)) { addDiagnostic(member, UnusedKind.Local, createDiagnosticForNode(member.name!, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolToString(symbol))); } break; case SyntaxKind.Constructor: for (const parameter of (member as ConstructorDeclaration).parameters) { if (!parameter.symbol.isReferenced && hasSyntacticModifier(parameter, ModifierFlags.Private)) { addDiagnostic(parameter, UnusedKind.Local, createDiagnosticForNode(parameter.name, Diagnostics.Property_0_is_declared_but_its_value_is_never_read, symbolName(parameter.symbol))); } } break; case SyntaxKind.IndexSignature: case SyntaxKind.SemicolonClassElement: case SyntaxKind.ClassStaticBlockDeclaration: // Can't be private break; default: Debug.fail("Unexpected class member"); } } } function checkUnusedInferTypeParameter(node: InferTypeNode, addDiagnostic: AddUnusedDiagnostic): void { const { typeParameter } = node; if (isTypeParameterUnused(typeParameter)) { addDiagnostic(node, UnusedKind.Parameter, createDiagnosticForNode(node, Diagnostics._0_is_declared_but_its_value_is_never_read, idText(typeParameter.name))); } } function checkUnusedTypeParameters(node: ClassLikeDeclaration | SignatureDeclaration | InterfaceDeclaration | TypeAliasDeclaration, addDiagnostic: AddUnusedDiagnostic): void { // Only report errors on the last declaration for the type parameter container; // this ensures that all uses have been accounted for. const declarations = getSymbolOfDeclaration(node).declarations; if (!declarations || last(declarations) !== node) return; const typeParameters = getEffectiveTypeParameterDeclarations(node); const seenParentsWithEveryUnused = new Set(); for (const typeParameter of typeParameters) { if (!isTypeParameterUnused(typeParameter)) continue; const name = idText(typeParameter.name); const { parent } = typeParameter; if (parent.kind !== SyntaxKind.InferType && parent.typeParameters!.every(isTypeParameterUnused)) { if (tryAddToSet(seenParentsWithEveryUnused, parent)) { const sourceFile = getSourceFileOfNode(parent); const range = isJSDocTemplateTag(parent) // Whole @template tag ? rangeOfNode(parent) // Include the `<>` in the error message : rangeOfTypeParameters(sourceFile, parent.typeParameters!); const only = parent.typeParameters!.length === 1; //TODO: following line is possible reason for bug #41974, unusedTypeParameters_TemplateTag const message = only ? Diagnostics._0_is_declared_but_its_value_is_never_read : Diagnostics.All_type_parameters_are_unused; const arg0 = only ? name : undefined; addDiagnostic(typeParameter, UnusedKind.Parameter, createFileDiagnostic(sourceFile, range.pos, range.end - range.pos, message, arg0)); } } else { //TODO: following line is possible reason for bug #41974, unusedTypeParameters_TemplateTag addDiagnostic(typeParameter, UnusedKind.Parameter, createDiagnosticForNode(typeParameter, Diagnostics._0_is_declared_but_its_value_is_never_read, name)); } } } function isTypeParameterUnused(typeParameter: TypeParameterDeclaration): boolean { return !(getMergedSymbol(typeParameter.symbol).isReferenced! & SymbolFlags.TypeParameter) && !isIdentifierThatStartsWithUnderscore(typeParameter.name); } function addToGroup(map: Map, key: K, value: V, getKey: (key: K) => number | string): void { const keyString = String(getKey(key)); const group = map.get(keyString); if (group) { group[1].push(value); } else { map.set(keyString, [key, [value]]); } } function tryGetRootParameterDeclaration(node: Node): ParameterDeclaration | undefined { return tryCast(getRootDeclaration(node), isParameter); } function isValidUnusedLocalDeclaration(declaration: Declaration): boolean { if (isBindingElement(declaration)) { if (isObjectBindingPattern(declaration.parent)) { /** * ignore starts with underscore names _ * const { a: _a } = { a: 1 } */ return !!(declaration.propertyName && isIdentifierThatStartsWithUnderscore(declaration.name)); } return isIdentifierThatStartsWithUnderscore(declaration.name); } return isAmbientModule(declaration) || (isVariableDeclaration(declaration) && isForInOrOfStatement(declaration.parent.parent) || isImportedDeclaration(declaration)) && isIdentifierThatStartsWithUnderscore(declaration.name!); } function checkUnusedLocalsAndParameters(nodeWithLocals: HasLocals, addDiagnostic: AddUnusedDiagnostic): void { // Ideally we could use the ImportClause directly as a key, but must wait until we have full ES6 maps. So must store key along with value. const unusedImports = new Map(); const unusedDestructures = new Map(); const unusedVariables = new Map(); nodeWithLocals.locals!.forEach(local => { // If it's purely a type parameter, ignore, will be checked in `checkUnusedTypeParameters`. // If it's a type parameter merged with a parameter, check if the parameter-side is used. if (local.flags & SymbolFlags.TypeParameter ? !(local.flags & SymbolFlags.Variable && !(local.isReferenced! & SymbolFlags.Variable)) : local.isReferenced || local.exportSymbol) { return; } if (local.declarations) { for (const declaration of local.declarations) { if (isValidUnusedLocalDeclaration(declaration)) { continue; } if (isImportedDeclaration(declaration)) { addToGroup(unusedImports, importClauseFromImported(declaration), declaration, getNodeId); } else if (isBindingElement(declaration) && isObjectBindingPattern(declaration.parent)) { // In `{ a, ...b }, `a` is considered used since it removes a property from `b`. `b` may still be unused though. const lastElement = last(declaration.parent.elements); if (declaration === lastElement || !last(declaration.parent.elements).dotDotDotToken) { addToGroup(unusedDestructures, declaration.parent, declaration, getNodeId); } } else if (isVariableDeclaration(declaration)) { addToGroup(unusedVariables, declaration.parent, declaration, getNodeId); } else { const parameter = local.valueDeclaration && tryGetRootParameterDeclaration(local.valueDeclaration); const name = local.valueDeclaration && getNameOfDeclaration(local.valueDeclaration); if (parameter && name) { if (!isParameterPropertyDeclaration(parameter, parameter.parent) && !parameterIsThisKeyword(parameter) && !isIdentifierThatStartsWithUnderscore(name)) { if (isBindingElement(declaration) && isArrayBindingPattern(declaration.parent)) { addToGroup(unusedDestructures, declaration.parent, declaration, getNodeId); } else { addDiagnostic(parameter, UnusedKind.Parameter, createDiagnosticForNode(name, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolName(local))); } } } else { errorUnusedLocal(declaration, symbolName(local), addDiagnostic); } } } } }); unusedImports.forEach(([importClause, unuseds]) => { const importDecl = importClause.parent; const nDeclarations = (importClause.name ? 1 : 0) + (importClause.namedBindings ? (importClause.namedBindings.kind === SyntaxKind.NamespaceImport ? 1 : importClause.namedBindings.elements.length) : 0); if (nDeclarations === unuseds.length) { addDiagnostic(importDecl, UnusedKind.Local, unuseds.length === 1 ? createDiagnosticForNode(importDecl, Diagnostics._0_is_declared_but_its_value_is_never_read, idText(first(unuseds).name!)) : createDiagnosticForNode(importDecl, Diagnostics.All_imports_in_import_declaration_are_unused)); } else { for (const unused of unuseds) errorUnusedLocal(unused, idText(unused.name!), addDiagnostic); } }); unusedDestructures.forEach(([bindingPattern, bindingElements]) => { const kind = tryGetRootParameterDeclaration(bindingPattern.parent) ? UnusedKind.Parameter : UnusedKind.Local; if (bindingPattern.elements.length === bindingElements.length) { if (bindingElements.length === 1 && bindingPattern.parent.kind === SyntaxKind.VariableDeclaration && bindingPattern.parent.parent.kind === SyntaxKind.VariableDeclarationList) { addToGroup(unusedVariables, bindingPattern.parent.parent, bindingPattern.parent, getNodeId); } else { addDiagnostic(bindingPattern, kind, bindingElements.length === 1 ? createDiagnosticForNode(bindingPattern, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(first(bindingElements).name)) : createDiagnosticForNode(bindingPattern, Diagnostics.All_destructured_elements_are_unused)); } } else { for (const e of bindingElements) { addDiagnostic(e, kind, createDiagnosticForNode(e, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(e.name))); } } }); unusedVariables.forEach(([declarationList, declarations]) => { if (declarationList.declarations.length === declarations.length) { addDiagnostic(declarationList, UnusedKind.Local, declarations.length === 1 ? createDiagnosticForNode(first(declarations).name, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(first(declarations).name)) : createDiagnosticForNode(declarationList.parent.kind === SyntaxKind.VariableStatement ? declarationList.parent : declarationList, Diagnostics.All_variables_are_unused)); } else { for (const decl of declarations) { addDiagnostic(decl, UnusedKind.Local, createDiagnosticForNode(decl, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(decl.name))); } } }); } function checkPotentialUncheckedRenamedBindingElementsInTypes() { for (const node of potentialUnusedRenamedBindingElementsInTypes) { if (!getSymbolOfDeclaration(node)?.isReferenced) { const wrappingDeclaration = walkUpBindingElementsAndPatterns(node); Debug.assert(isParameterDeclaration(wrappingDeclaration), "Only parameter declaration should be checked here"); const diagnostic = createDiagnosticForNode(node.name, Diagnostics._0_is_an_unused_renaming_of_1_Did_you_intend_to_use_it_as_a_type_annotation, declarationNameToString(node.name), declarationNameToString(node.propertyName)); if (!wrappingDeclaration.type) { // entire parameter does not have type annotation, suggest adding an annotation addRelatedInfo( diagnostic, createFileDiagnostic(getSourceFileOfNode(wrappingDeclaration), wrappingDeclaration.end, 1, Diagnostics.We_can_only_write_a_type_for_0_by_adding_a_type_for_the_entire_parameter_here, declarationNameToString(node.propertyName)) ); } diagnostics.add(diagnostic); } } } function bindingNameText(name: BindingName): string { switch (name.kind) { case SyntaxKind.Identifier: return idText(name); case SyntaxKind.ArrayBindingPattern: case SyntaxKind.ObjectBindingPattern: return bindingNameText(cast(first(name.elements), isBindingElement).name); default: return Debug.assertNever(name); } } type ImportedDeclaration = ImportClause | ImportSpecifier | NamespaceImport; function isImportedDeclaration(node: Node): node is ImportedDeclaration { return node.kind === SyntaxKind.ImportClause || node.kind === SyntaxKind.ImportSpecifier || node.kind === SyntaxKind.NamespaceImport; } function importClauseFromImported(decl: ImportedDeclaration): ImportClause { return decl.kind === SyntaxKind.ImportClause ? decl : decl.kind === SyntaxKind.NamespaceImport ? decl.parent : decl.parent.parent; } function checkBlock(node: Block) { // Grammar checking for SyntaxKind.Block if (node.kind === SyntaxKind.Block) { checkGrammarStatementInAmbientContext(node); } if (isFunctionOrModuleBlock(node)) { const saveFlowAnalysisDisabled = flowAnalysisDisabled; forEach(node.statements, checkSourceElement); flowAnalysisDisabled = saveFlowAnalysisDisabled; } else { forEach(node.statements, checkSourceElement); } if (node.locals) { registerForUnusedIdentifiersCheck(node); } } function checkCollisionWithArgumentsInGeneratedCode(node: SignatureDeclaration) { // no rest parameters \ declaration context \ overload - no codegen impact if (languageVersion >= ScriptTarget.ES2015 || !hasRestParameter(node) || node.flags & NodeFlags.Ambient || nodeIsMissing((node as FunctionLikeDeclaration).body)) { return; } forEach(node.parameters, p => { if (p.name && !isBindingPattern(p.name) && p.name.escapedText === argumentsSymbol.escapedName) { errorSkippedOn("noEmit", p, Diagnostics.Duplicate_identifier_arguments_Compiler_uses_arguments_to_initialize_rest_parameters); } }); } /** * Checks whether an {@link Identifier}, in the context of another {@link Node}, would collide with a runtime value * of {@link name} in an outer scope. This is used to check for collisions for downlevel transformations that * require names like `Object`, `Promise`, `Reflect`, `require`, `exports`, etc. */ function needCollisionCheckForIdentifier(node: Node, identifier: Identifier | undefined, name: string): boolean { if (identifier?.escapedText !== name) { return false; } if (node.kind === SyntaxKind.PropertyDeclaration || node.kind === SyntaxKind.PropertySignature || node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature || node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor || node.kind === SyntaxKind.PropertyAssignment) { // it is ok to have member named '_super', '_this', `Promise`, etc. - member access is always qualified return false; } if (node.flags & NodeFlags.Ambient) { // ambient context - no codegen impact return false; } if (isImportClause(node) || isImportEqualsDeclaration(node) || isImportSpecifier(node)) { // type-only imports do not require collision checks against runtime values. if (isTypeOnlyImportOrExportDeclaration(node)) { return false; } } const root = getRootDeclaration(node); if (isParameter(root) && nodeIsMissing((root.parent as FunctionLikeDeclaration).body)) { // just an overload - no codegen impact return false; } return true; } // this function will run after checking the source file so 'CaptureThis' is correct for all nodes function checkIfThisIsCapturedInEnclosingScope(node: Node): void { findAncestor(node, current => { if (getNodeCheckFlags(current) & NodeCheckFlags.CaptureThis) { const isDeclaration = node.kind !== SyntaxKind.Identifier; if (isDeclaration) { error(getNameOfDeclaration(node as Declaration), Diagnostics.Duplicate_identifier_this_Compiler_uses_variable_declaration_this_to_capture_this_reference); } else { error(node, Diagnostics.Expression_resolves_to_variable_declaration_this_that_compiler_uses_to_capture_this_reference); } return true; } return false; }); } function checkIfNewTargetIsCapturedInEnclosingScope(node: Node): void { findAncestor(node, current => { if (getNodeCheckFlags(current) & NodeCheckFlags.CaptureNewTarget) { const isDeclaration = node.kind !== SyntaxKind.Identifier; if (isDeclaration) { error(getNameOfDeclaration(node as Declaration), Diagnostics.Duplicate_identifier_newTarget_Compiler_uses_variable_declaration_newTarget_to_capture_new_target_meta_property_reference); } else { error(node, Diagnostics.Expression_resolves_to_variable_declaration_newTarget_that_compiler_uses_to_capture_new_target_meta_property_reference); } return true; } return false; }); } function checkCollisionWithRequireExportsInGeneratedCode(node: Node, name: Identifier | undefined) { // No need to check for require or exports for ES6 modules and later if (moduleKind >= ModuleKind.ES2015 && !(moduleKind >= ModuleKind.Node16 && getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { return; } if (!name || !needCollisionCheckForIdentifier(node, name, "require") && !needCollisionCheckForIdentifier(node, name, "exports")) { return; } // Uninstantiated modules shouldnt do this check if (isModuleDeclaration(node) && getModuleInstanceState(node) !== ModuleInstanceState.Instantiated) { return; } // In case of variable declaration, node.parent is variable statement so look at the variable statement's parent const parent = getDeclarationContainer(node); if (parent.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(parent as SourceFile)) { // If the declaration happens to be in external module, report error that require and exports are reserved keywords errorSkippedOn("noEmit", name, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_in_top_level_scope_of_a_module, declarationNameToString(name), declarationNameToString(name)); } } function checkCollisionWithGlobalPromiseInGeneratedCode(node: Node, name: Identifier | undefined): void { if (!name || languageVersion >= ScriptTarget.ES2017 || !needCollisionCheckForIdentifier(node, name, "Promise")) { return; } // Uninstantiated modules shouldnt do this check if (isModuleDeclaration(node) && getModuleInstanceState(node) !== ModuleInstanceState.Instantiated) { return; } // In case of variable declaration, node.parent is variable statement so look at the variable statement's parent const parent = getDeclarationContainer(node); if (parent.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(parent as SourceFile) && parent.flags & NodeFlags.HasAsyncFunctions) { // If the declaration happens to be in external module, report error that Promise is a reserved identifier. errorSkippedOn("noEmit", name, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_in_top_level_scope_of_a_module_containing_async_functions, declarationNameToString(name), declarationNameToString(name)); } } function recordPotentialCollisionWithWeakMapSetInGeneratedCode(node: Node, name: Identifier): void { if (languageVersion <= ScriptTarget.ES2021 && (needCollisionCheckForIdentifier(node, name, "WeakMap") || needCollisionCheckForIdentifier(node, name, "WeakSet"))) { potentialWeakMapSetCollisions.push(node); } } function checkWeakMapSetCollision(node: Node) { const enclosingBlockScope = getEnclosingBlockScopeContainer(node); if (getNodeCheckFlags(enclosingBlockScope) & NodeCheckFlags.ContainsClassWithPrivateIdentifiers) { Debug.assert(isNamedDeclaration(node) && isIdentifier(node.name) && typeof node.name.escapedText === "string", "The target of a WeakMap/WeakSet collision check should be an identifier"); errorSkippedOn("noEmit", node, Diagnostics.Compiler_reserves_name_0_when_emitting_private_identifier_downlevel, node.name.escapedText); } } function recordPotentialCollisionWithReflectInGeneratedCode(node: Node, name: Identifier | undefined): void { if (name && languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 && needCollisionCheckForIdentifier(node, name, "Reflect")) { potentialReflectCollisions.push(node); } } function checkReflectCollision(node: Node) { let hasCollision = false; if (isClassExpression(node)) { // ClassExpression names don't contribute to their containers, but do matter for any of their block-scoped members. for (const member of node.members) { if (getNodeCheckFlags(member) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { hasCollision = true; break; } } } else if (isFunctionExpression(node)) { // FunctionExpression names don't contribute to their containers, but do matter for their contents if (getNodeCheckFlags(node) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { hasCollision = true; } } else { const container = getEnclosingBlockScopeContainer(node); if (container && getNodeCheckFlags(container) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { hasCollision = true; } } if (hasCollision) { Debug.assert(isNamedDeclaration(node) && isIdentifier(node.name), "The target of a Reflect collision check should be an identifier"); errorSkippedOn("noEmit", node, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_when_emitting_super_references_in_static_initializers, declarationNameToString(node.name), "Reflect"); } } function checkCollisionsForDeclarationName(node: Node, name: Identifier | undefined) { if (!name) return; checkCollisionWithRequireExportsInGeneratedCode(node, name); checkCollisionWithGlobalPromiseInGeneratedCode(node, name); recordPotentialCollisionWithWeakMapSetInGeneratedCode(node, name); recordPotentialCollisionWithReflectInGeneratedCode(node, name); if (isClassLike(node)) { checkTypeNameIsReserved(name, Diagnostics.Class_name_cannot_be_0); if (!(node.flags & NodeFlags.Ambient)) { checkClassNameCollisionWithObject(name); } } else if (isEnumDeclaration(node)) { checkTypeNameIsReserved(name, Diagnostics.Enum_name_cannot_be_0); } } function checkVarDeclaredNamesNotShadowed(node: VariableDeclaration | BindingElement) { // - ScriptBody : StatementList // It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList // also occurs in the VarDeclaredNames of StatementList. // - Block : { StatementList } // It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList // also occurs in the VarDeclaredNames of StatementList. // Variable declarations are hoisted to the top of their function scope. They can shadow // block scoped declarations, which bind tighter. this will not be flagged as duplicate definition // by the binder as the declaration scope is different. // A non-initialized declaration is a no-op as the block declaration will resolve before the var // declaration. the problem is if the declaration has an initializer. this will act as a write to the // block declared value. this is fine for let, but not const. // Only consider declarations with initializers, uninitialized const declarations will not // step on a let/const variable. // Do not consider const and const declarations, as duplicate block-scoped declarations // are handled by the binder. // We are only looking for const declarations that step on let\const declarations from a // different scope. e.g.: // { // const x = 0; // localDeclarationSymbol obtained after name resolution will correspond to this declaration // const x = 0; // symbol for this declaration will be 'symbol' // } // skip block-scoped variables and parameters if ((getCombinedNodeFlags(node) & NodeFlags.BlockScoped) !== 0 || isParameterDeclaration(node)) { return; } // skip variable declarations that don't have initializers // NOTE: in ES6 spec initializer is required in variable declarations where name is binding pattern // so we'll always treat binding elements as initialized if (node.kind === SyntaxKind.VariableDeclaration && !node.initializer) { return; } const symbol = getSymbolOfDeclaration(node); if (symbol.flags & SymbolFlags.FunctionScopedVariable) { if (!isIdentifier(node.name)) return Debug.fail(); const localDeclarationSymbol = resolveName(node, node.name.escapedText, SymbolFlags.Variable, /*nodeNotFoundErrorMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ false); if (localDeclarationSymbol && localDeclarationSymbol !== symbol && localDeclarationSymbol.flags & SymbolFlags.BlockScopedVariable) { if (getDeclarationNodeFlagsFromSymbol(localDeclarationSymbol) & NodeFlags.BlockScoped) { const varDeclList = getAncestor(localDeclarationSymbol.valueDeclaration, SyntaxKind.VariableDeclarationList)!; const container = varDeclList.parent.kind === SyntaxKind.VariableStatement && varDeclList.parent.parent ? varDeclList.parent.parent : undefined; // names of block-scoped and function scoped variables can collide only // if block scoped variable is defined in the function\module\source file scope (because of variable hoisting) const namesShareScope = container && (container.kind === SyntaxKind.Block && isFunctionLike(container.parent) || container.kind === SyntaxKind.ModuleBlock || container.kind === SyntaxKind.ModuleDeclaration || container.kind === SyntaxKind.SourceFile); // here we know that function scoped variable is shadowed by block scoped one // if they are defined in the same scope - binder has already reported redeclaration error // otherwise if variable has an initializer - show error that initialization will fail // since LHS will be block scoped name instead of function scoped if (!namesShareScope) { const name = symbolToString(localDeclarationSymbol); error(node, Diagnostics.Cannot_initialize_outer_scoped_variable_0_in_the_same_scope_as_block_scoped_declaration_1, name, name); } } } } } function convertAutoToAny(type: Type) { return type === autoType ? anyType : type === autoArrayType ? anyArrayType : type; } // Check variable, parameter, or property declaration function checkVariableLikeDeclaration(node: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement) { checkDecorators(node); if (!isBindingElement(node)) { checkSourceElement(node.type); } // JSDoc `function(string, string): string` syntax results in parameters with no name if (!node.name) { return; } // For a computed property, just check the initializer and exit // Do not use hasDynamicName here, because that returns false for well known symbols. // We want to perform checkComputedPropertyName for all computed properties, including // well known symbols. if (node.name.kind === SyntaxKind.ComputedPropertyName) { checkComputedPropertyName(node.name); if (hasOnlyExpressionInitializer(node) && node.initializer) { checkExpressionCached(node.initializer); } } if (isBindingElement(node)) { if ( node.propertyName && isIdentifier(node.name) && isParameterDeclaration(node) && nodeIsMissing((getContainingFunction(node) as FunctionLikeDeclaration).body)) { // type F = ({a: string}) => void; // ^^^^^^ // variable renaming in function type notation is confusing, // so we forbid it even if noUnusedLocals is not enabled potentialUnusedRenamedBindingElementsInTypes.push(node); return; } if (isObjectBindingPattern(node.parent) && node.dotDotDotToken && languageVersion < ScriptTarget.ES2018) { checkExternalEmitHelpers(node, ExternalEmitHelpers.Rest); } // check computed properties inside property names of binding elements if (node.propertyName && node.propertyName.kind === SyntaxKind.ComputedPropertyName) { checkComputedPropertyName(node.propertyName); } // check private/protected variable access const parent = node.parent.parent; const parentCheckMode = node.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; const parentType = getTypeForBindingElementParent(parent, parentCheckMode); const name = node.propertyName || node.name; if (parentType && !isBindingPattern(name)) { const exprType = getLiteralTypeFromPropertyName(name); if (isTypeUsableAsPropertyName(exprType)) { const nameText = getPropertyNameFromType(exprType); const property = getPropertyOfType(parentType, nameText); if (property) { markPropertyAsReferenced(property, /*nodeForCheckWriteOnly*/ undefined, /*isSelfTypeAccess*/ false); // A destructuring is never a write-only reference. checkPropertyAccessibility(node, !!parent.initializer && parent.initializer.kind === SyntaxKind.SuperKeyword, /*writing*/ false, parentType, property); } } } } // For a binding pattern, check contained binding elements if (isBindingPattern(node.name)) { if (node.name.kind === SyntaxKind.ArrayBindingPattern && languageVersion < ScriptTarget.ES2015 && compilerOptions.downlevelIteration) { checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); } forEach(node.name.elements, checkSourceElement); } // For a parameter declaration with an initializer, error and exit if the containing function doesn't have a body if (isParameter(node) && node.initializer && nodeIsMissing((getContainingFunction(node) as FunctionLikeDeclaration).body)) { error(node, Diagnostics.A_parameter_initializer_is_only_allowed_in_a_function_or_constructor_implementation); return; } // For a binding pattern, validate the initializer and exit if (isBindingPattern(node.name)) { const needCheckInitializer = hasOnlyExpressionInitializer(node) && node.initializer && node.parent.parent.kind !== SyntaxKind.ForInStatement; const needCheckWidenedType = !some(node.name.elements, not(isOmittedExpression)); if (needCheckInitializer || needCheckWidenedType) { // Don't validate for-in initializer as it is already an error const widenedType = getWidenedTypeForVariableLikeDeclaration(node); if (needCheckInitializer) { const initializerType = checkExpressionCached(node.initializer); if (strictNullChecks && needCheckWidenedType) { checkNonNullNonVoidType(initializerType, node); } else { checkTypeAssignableToAndOptionallyElaborate(initializerType, getWidenedTypeForVariableLikeDeclaration(node), node, node.initializer); } } // check the binding pattern with empty elements if (needCheckWidenedType) { if (isArrayBindingPattern(node.name)) { checkIteratedTypeOrElementType(IterationUse.Destructuring, widenedType, undefinedType, node); } else if (strictNullChecks) { checkNonNullNonVoidType(widenedType, node); } } } return; } // For a commonjs `const x = require`, validate the alias and exit const symbol = getSymbolOfDeclaration(node); if (symbol.flags & SymbolFlags.Alias && (isVariableDeclarationInitializedToBareOrAccessedRequire(node) || isBindingElementOfBareOrAccessedRequire(node))) { checkAliasSymbol(node); return; } const type = convertAutoToAny(getTypeOfSymbol(symbol)); if (node === symbol.valueDeclaration) { // Node is the primary declaration of the symbol, just validate the initializer // Don't validate for-in initializer as it is already an error const initializer = hasOnlyExpressionInitializer(node) && getEffectiveInitializer(node); if (initializer) { const isJSObjectLiteralInitializer = isInJSFile(node) && isObjectLiteralExpression(initializer) && (initializer.properties.length === 0 || isPrototypeAccess(node.name)) && !!symbol.exports?.size; if (!isJSObjectLiteralInitializer && node.parent.parent.kind !== SyntaxKind.ForInStatement) { checkTypeAssignableToAndOptionallyElaborate(checkExpressionCached(initializer), type, node, initializer, /*headMessage*/ undefined); } } if (symbol.declarations && symbol.declarations.length > 1) { if (some(symbol.declarations, d => d !== node && isVariableLike(d) && !areDeclarationFlagsIdentical(d, node))) { error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_modifiers, declarationNameToString(node.name)); } } } else { // Node is a secondary declaration, check that type is identical to primary declaration and check that // initializer is consistent with type associated with the node const declarationType = convertAutoToAny(getWidenedTypeForVariableLikeDeclaration(node)); if (!isErrorType(type) && !isErrorType(declarationType) && !isTypeIdenticalTo(type, declarationType) && !(symbol.flags & SymbolFlags.Assignment)) { errorNextVariableOrPropertyDeclarationMustHaveSameType(symbol.valueDeclaration, type, node, declarationType); } if (hasOnlyExpressionInitializer(node) && node.initializer) { checkTypeAssignableToAndOptionallyElaborate(checkExpressionCached(node.initializer), declarationType, node, node.initializer, /*headMessage*/ undefined); } if (symbol.valueDeclaration && !areDeclarationFlagsIdentical(node, symbol.valueDeclaration)) { error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_modifiers, declarationNameToString(node.name)); } } if (node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.PropertySignature) { // We know we don't have a binding pattern or computed name here checkExportsOnMergedDeclarations(node); if (node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement) { checkVarDeclaredNamesNotShadowed(node); } checkCollisionsForDeclarationName(node, node.name); } } function errorNextVariableOrPropertyDeclarationMustHaveSameType(firstDeclaration: Declaration | undefined, firstType: Type, nextDeclaration: Declaration, nextType: Type): void { const nextDeclarationName = getNameOfDeclaration(nextDeclaration); const message = nextDeclaration.kind === SyntaxKind.PropertyDeclaration || nextDeclaration.kind === SyntaxKind.PropertySignature ? Diagnostics.Subsequent_property_declarations_must_have_the_same_type_Property_0_must_be_of_type_1_but_here_has_type_2 : Diagnostics.Subsequent_variable_declarations_must_have_the_same_type_Variable_0_must_be_of_type_1_but_here_has_type_2; const declName = declarationNameToString(nextDeclarationName); const err = error( nextDeclarationName, message, declName, typeToString(firstType), typeToString(nextType) ); if (firstDeclaration) { addRelatedInfo(err, createDiagnosticForNode(firstDeclaration, Diagnostics._0_was_also_declared_here, declName) ); } } function areDeclarationFlagsIdentical(left: Declaration, right: Declaration) { if ((left.kind === SyntaxKind.Parameter && right.kind === SyntaxKind.VariableDeclaration) || (left.kind === SyntaxKind.VariableDeclaration && right.kind === SyntaxKind.Parameter)) { // Differences in optionality between parameters and variables are allowed. return true; } if (hasQuestionToken(left) !== hasQuestionToken(right)) { return false; } const interestingFlags = ModifierFlags.Private | ModifierFlags.Protected | ModifierFlags.Async | ModifierFlags.Abstract | ModifierFlags.Readonly | ModifierFlags.Static; return getSelectedEffectiveModifierFlags(left, interestingFlags) === getSelectedEffectiveModifierFlags(right, interestingFlags); } function checkVariableDeclaration(node: VariableDeclaration) { tracing?.push(tracing.Phase.Check, "checkVariableDeclaration", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); checkGrammarVariableDeclaration(node); checkVariableLikeDeclaration(node); tracing?.pop(); } function checkBindingElement(node: BindingElement) { checkGrammarBindingElement(node); return checkVariableLikeDeclaration(node); } function checkVariableStatement(node: VariableStatement) { // Grammar checking if (!checkGrammarModifiers(node) && !checkGrammarVariableDeclarationList(node.declarationList)) checkGrammarForDisallowedLetOrConstStatement(node); forEach(node.declarationList.declarations, checkSourceElement); } function checkExpressionStatement(node: ExpressionStatement) { // Grammar checking checkGrammarStatementInAmbientContext(node); checkExpression(node.expression); } function checkIfStatement(node: IfStatement) { // Grammar checking checkGrammarStatementInAmbientContext(node); const type = checkTruthinessExpression(node.expression); checkTestingKnownTruthyCallableOrAwaitableType(node.expression, type, node.thenStatement); checkSourceElement(node.thenStatement); if (node.thenStatement.kind === SyntaxKind.EmptyStatement) { error(node.thenStatement, Diagnostics.The_body_of_an_if_statement_cannot_be_the_empty_statement); } checkSourceElement(node.elseStatement); } function checkTestingKnownTruthyCallableOrAwaitableType(condExpr: Expression, condType: Type, body?: Statement | Expression) { if (!strictNullChecks) return; bothHelper(condExpr, body); function bothHelper(condExpr: Expression, body: Expression | Statement | undefined) { condExpr = skipParentheses(condExpr); helper(condExpr, body); while (isBinaryExpression(condExpr) && (condExpr.operatorToken.kind === SyntaxKind.BarBarToken || condExpr.operatorToken.kind === SyntaxKind.QuestionQuestionToken)) { condExpr = skipParentheses(condExpr.left); helper(condExpr, body); } } function helper(condExpr: Expression, body: Expression | Statement | undefined) { const location = isLogicalOrCoalescingBinaryExpression(condExpr) ? skipParentheses(condExpr.right) : condExpr; if (isModuleExportsAccessExpression(location)) { return; } if (isLogicalOrCoalescingBinaryExpression(location)) { bothHelper(location, body); return; } const type = location === condExpr ? condType : checkTruthinessExpression(location); const isPropertyExpressionCast = isPropertyAccessExpression(location) && isTypeAssertion(location.expression); if (!(getTypeFacts(type) & TypeFacts.Truthy) || isPropertyExpressionCast) return; // While it technically should be invalid for any known-truthy value // to be tested, we de-scope to functions and Promises unreferenced in // the block as a heuristic to identify the most common bugs. There // are too many false positives for values sourced from type // definitions without strictNullChecks otherwise. const callSignatures = getSignaturesOfType(type, SignatureKind.Call); const isPromise = !!getAwaitedTypeOfPromise(type); if (callSignatures.length === 0 && !isPromise) { return; } const testedNode = isIdentifier(location) ? location : isPropertyAccessExpression(location) ? location.name : undefined; const testedSymbol = testedNode && getSymbolAtLocation(testedNode); if (!testedSymbol && !isPromise) { return; } const isUsed = testedSymbol && isBinaryExpression(condExpr.parent) && isSymbolUsedInBinaryExpressionChain(condExpr.parent, testedSymbol) || testedSymbol && body && isSymbolUsedInConditionBody(condExpr, body, testedNode, testedSymbol); if (!isUsed) { if (isPromise) { errorAndMaybeSuggestAwait( location, /*maybeMissingAwait*/ true, Diagnostics.This_condition_will_always_return_true_since_this_0_is_always_defined, getTypeNameForErrorDisplay(type)); } else { error(location, Diagnostics.This_condition_will_always_return_true_since_this_function_is_always_defined_Did_you_mean_to_call_it_instead); } } } } function isSymbolUsedInConditionBody(expr: Expression, body: Statement | Expression, testedNode: Node, testedSymbol: Symbol): boolean { return !!forEachChild(body, function check(childNode): boolean | undefined { if (isIdentifier(childNode)) { const childSymbol = getSymbolAtLocation(childNode); if (childSymbol && childSymbol === testedSymbol) { // If the test was a simple identifier, the above check is sufficient if (isIdentifier(expr) || isIdentifier(testedNode) && isBinaryExpression(testedNode.parent)) { return true; } // Otherwise we need to ensure the symbol is called on the same target let testedExpression = testedNode.parent; let childExpression = childNode.parent; while (testedExpression && childExpression) { if (isIdentifier(testedExpression) && isIdentifier(childExpression) || testedExpression.kind === SyntaxKind.ThisKeyword && childExpression.kind === SyntaxKind.ThisKeyword) { return getSymbolAtLocation(testedExpression) === getSymbolAtLocation(childExpression); } else if (isPropertyAccessExpression(testedExpression) && isPropertyAccessExpression(childExpression)) { if (getSymbolAtLocation(testedExpression.name) !== getSymbolAtLocation(childExpression.name)) { return false; } childExpression = childExpression.expression; testedExpression = testedExpression.expression; } else if (isCallExpression(testedExpression) && isCallExpression(childExpression)) { childExpression = childExpression.expression; testedExpression = testedExpression.expression; } else { return false; } } } } return forEachChild(childNode, check); }); } function isSymbolUsedInBinaryExpressionChain(node: Node, testedSymbol: Symbol): boolean { while (isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { const isUsed = forEachChild(node.right, function visit(child): boolean | undefined { if (isIdentifier(child)) { const symbol = getSymbolAtLocation(child); if (symbol && symbol === testedSymbol) { return true; } } return forEachChild(child, visit); }); if (isUsed) { return true; } node = node.parent; } return false; } function checkDoStatement(node: DoStatement) { // Grammar checking checkGrammarStatementInAmbientContext(node); checkSourceElement(node.statement); checkTruthinessExpression(node.expression); } function checkWhileStatement(node: WhileStatement) { // Grammar checking checkGrammarStatementInAmbientContext(node); checkTruthinessExpression(node.expression); checkSourceElement(node.statement); } function checkTruthinessOfType(type: Type, node: Node) { if (type.flags & TypeFlags.Void) { error(node, Diagnostics.An_expression_of_type_void_cannot_be_tested_for_truthiness); } return type; } function checkTruthinessExpression(node: Expression, checkMode?: CheckMode) { return checkTruthinessOfType(checkExpression(node, checkMode), node); } function checkForStatement(node: ForStatement) { // Grammar checking if (!checkGrammarStatementInAmbientContext(node)) { if (node.initializer && node.initializer.kind === SyntaxKind.VariableDeclarationList) { checkGrammarVariableDeclarationList(node.initializer as VariableDeclarationList); } } if (node.initializer) { if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { forEach((node.initializer as VariableDeclarationList).declarations, checkVariableDeclaration); } else { checkExpression(node.initializer); } } if (node.condition) checkTruthinessExpression(node.condition); if (node.incrementor) checkExpression(node.incrementor); checkSourceElement(node.statement); if (node.locals) { registerForUnusedIdentifiersCheck(node); } } function checkForOfStatement(node: ForOfStatement): void { checkGrammarForInOrForOfStatement(node); const container = getContainingFunctionOrClassStaticBlock(node); if (node.awaitModifier) { if (container && isClassStaticBlockDeclaration(container)) { grammarErrorOnNode(node.awaitModifier, Diagnostics.For_await_loops_cannot_be_used_inside_a_class_static_block); } else { const functionFlags = getFunctionFlags(container); if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Async)) === FunctionFlags.Async && languageVersion < ScriptTarget.ESNext) { // for..await..of in an async function or async generator function prior to ESNext requires the __asyncValues helper checkExternalEmitHelpers(node, ExternalEmitHelpers.ForAwaitOfIncludes); } } } else if (compilerOptions.downlevelIteration && languageVersion < ScriptTarget.ES2015) { // for..of prior to ES2015 requires the __values helper when downlevelIteration is enabled checkExternalEmitHelpers(node, ExternalEmitHelpers.ForOfIncludes); } // Check the LHS and RHS // If the LHS is a declaration, just check it as a variable declaration, which will in turn check the RHS // via checkRightHandSideOfForOf. // If the LHS is an expression, check the LHS, as a destructuring assignment or as a reference. // Then check that the RHS is assignable to it. if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { checkForInOrForOfVariableDeclaration(node); } else { const varExpr = node.initializer; const iteratedType = checkRightHandSideOfForOf(node); // There may be a destructuring assignment on the left side if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) { // iteratedType may be undefined. In this case, we still want to check the structure of // varExpr, in particular making sure it's a valid LeftHandSideExpression. But we'd like // to short circuit the type relation checking as much as possible, so we pass the unknownType. checkDestructuringAssignment(varExpr, iteratedType || errorType); } else { const leftType = checkExpression(varExpr); checkReferenceExpression( varExpr, Diagnostics.The_left_hand_side_of_a_for_of_statement_must_be_a_variable_or_a_property_access, Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access); // iteratedType will be undefined if the rightType was missing properties/signatures // required to get its iteratedType (like [Symbol.iterator] or next). This may be // because we accessed properties from anyType, or it may have led to an error inside // getElementTypeOfIterable. if (iteratedType) { checkTypeAssignableToAndOptionallyElaborate(iteratedType, leftType, varExpr, node.expression); } } } checkSourceElement(node.statement); if (node.locals) { registerForUnusedIdentifiersCheck(node); } } function checkForInStatement(node: ForInStatement) { // Grammar checking checkGrammarForInOrForOfStatement(node); const rightType = getNonNullableTypeIfNeeded(checkExpression(node.expression)); // TypeScript 1.0 spec (April 2014): 5.4 // In a 'for-in' statement of the form // for (let VarDecl in Expr) Statement // VarDecl must be a variable declaration without a type annotation that declares a variable of type Any, // and Expr must be an expression of type Any, an object type, or a type parameter type. if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { const variable = (node.initializer as VariableDeclarationList).declarations[0]; if (variable && isBindingPattern(variable.name)) { error(variable.name, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern); } checkForInOrForOfVariableDeclaration(node); } else { // In a 'for-in' statement of the form // for (Var in Expr) Statement // Var must be an expression classified as a reference of type Any or the String primitive type, // and Expr must be an expression of type Any, an object type, or a type parameter type. const varExpr = node.initializer; const leftType = checkExpression(varExpr); if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) { error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern); } else if (!isTypeAssignableTo(getIndexTypeOrString(rightType), leftType)) { error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_of_type_string_or_any); } else { // run check only former check succeeded to avoid cascading errors checkReferenceExpression( varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_a_variable_or_a_property_access, Diagnostics.The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access); } } // unknownType is returned i.e. if node.expression is identifier whose name cannot be resolved // in this case error about missing name is already reported - do not report extra one if (rightType === neverType || !isTypeAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.InstantiableNonPrimitive)) { error(node.expression, Diagnostics.The_right_hand_side_of_a_for_in_statement_must_be_of_type_any_an_object_type_or_a_type_parameter_but_here_has_type_0, typeToString(rightType)); } checkSourceElement(node.statement); if (node.locals) { registerForUnusedIdentifiersCheck(node); } } function checkForInOrForOfVariableDeclaration(iterationStatement: ForInOrOfStatement): void { const variableDeclarationList = iterationStatement.initializer as VariableDeclarationList; // checkGrammarForInOrForOfStatement will check that there is exactly one declaration. if (variableDeclarationList.declarations.length >= 1) { const decl = variableDeclarationList.declarations[0]; checkVariableDeclaration(decl); } } function checkRightHandSideOfForOf(statement: ForOfStatement): Type { const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; return checkIteratedTypeOrElementType(use, checkNonNullExpression(statement.expression), undefinedType, statement.expression); } function checkIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined): Type { if (isTypeAny(inputType)) { return inputType; } return getIteratedTypeOrElementType(use, inputType, sentType, errorNode, /*checkAssignability*/ true) || anyType; } /** * When consuming an iterable type in a for..of, spread, or iterator destructuring assignment * we want to get the iterated type of an iterable for ES2015 or later, or the iterated type * of a iterable (if defined globally) or element type of an array like for ES2015 or earlier. */ function getIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined, checkAssignability: boolean): Type | undefined { const allowAsyncIterables = (use & IterationUse.AllowsAsyncIterablesFlag) !== 0; if (inputType === neverType) { reportTypeNotIterableError(errorNode!, inputType, allowAsyncIterables); // TODO: GH#18217 return undefined; } const uplevelIteration = languageVersion >= ScriptTarget.ES2015; const downlevelIteration = !uplevelIteration && compilerOptions.downlevelIteration; const possibleOutOfBounds = compilerOptions.noUncheckedIndexedAccess && !!(use & IterationUse.PossiblyOutOfBounds); // Get the iterated type of an `Iterable` or `IterableIterator` only in ES2015 // or higher, when inside of an async generator or for-await-if, or when // downlevelIteration is requested. if (uplevelIteration || downlevelIteration || allowAsyncIterables) { // We only report errors for an invalid iterable type in ES2015 or higher. const iterationTypes = getIterationTypesOfIterable(inputType, use, uplevelIteration ? errorNode : undefined); if (checkAssignability) { if (iterationTypes) { const diagnostic = use & IterationUse.ForOfFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_for_of_will_always_send_0 : use & IterationUse.SpreadFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_array_spread_will_always_send_0 : use & IterationUse.DestructuringFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_array_destructuring_will_always_send_0 : use & IterationUse.YieldStarFlag ? Diagnostics.Cannot_delegate_iteration_to_value_because_the_next_method_of_its_iterator_expects_type_1_but_the_containing_generator_will_always_send_0 : undefined; if (diagnostic) { checkTypeAssignableTo(sentType, iterationTypes.nextType, errorNode, diagnostic); } } } if (iterationTypes || uplevelIteration) { return possibleOutOfBounds ? includeUndefinedInIndexSignature(iterationTypes && iterationTypes.yieldType) : (iterationTypes && iterationTypes.yieldType); } } let arrayType = inputType; let reportedError = false; let hasStringConstituent = false; // If strings are permitted, remove any string-like constituents from the array type. // This allows us to find other non-string element types from an array unioned with // a string. if (use & IterationUse.AllowsStringInputFlag) { if (arrayType.flags & TypeFlags.Union) { // After we remove all types that are StringLike, we will know if there was a string constituent // based on whether the result of filter is a new array. const arrayTypes = (inputType as UnionType).types; const filteredTypes = filter(arrayTypes, t => !(t.flags & TypeFlags.StringLike)); if (filteredTypes !== arrayTypes) { arrayType = getUnionType(filteredTypes, UnionReduction.Subtype); } } else if (arrayType.flags & TypeFlags.StringLike) { arrayType = neverType; } hasStringConstituent = arrayType !== inputType; if (hasStringConstituent) { if (languageVersion < ScriptTarget.ES5) { if (errorNode) { error(errorNode, Diagnostics.Using_a_string_in_a_for_of_statement_is_only_supported_in_ECMAScript_5_and_higher); reportedError = true; } } // Now that we've removed all the StringLike types, if no constituents remain, then the entire // arrayOrStringType was a string. if (arrayType.flags & TypeFlags.Never) { return possibleOutOfBounds ? includeUndefinedInIndexSignature(stringType) : stringType; } } } if (!isArrayLikeType(arrayType)) { if (errorNode && !reportedError) { // Which error we report depends on whether we allow strings or if there was a // string constituent. For example, if the input type is number | string, we // want to say that number is not an array type. But if the input was just // number and string input is allowed, we want to say that number is not an // array type or a string type. const allowsStrings = !!(use & IterationUse.AllowsStringInputFlag) && !hasStringConstituent; const [defaultDiagnostic, maybeMissingAwait] = getIterationDiagnosticDetails(allowsStrings, downlevelIteration); errorAndMaybeSuggestAwait( errorNode, maybeMissingAwait && !!getAwaitedTypeOfPromise(arrayType), defaultDiagnostic, typeToString(arrayType)); } return hasStringConstituent ? possibleOutOfBounds ? includeUndefinedInIndexSignature(stringType) : stringType : undefined; } const arrayElementType = getIndexTypeOfType(arrayType, numberType); if (hasStringConstituent && arrayElementType) { // This is just an optimization for the case where arrayOrStringType is string | string[] if (arrayElementType.flags & TypeFlags.StringLike && !compilerOptions.noUncheckedIndexedAccess) { return stringType; } return getUnionType(possibleOutOfBounds ? [arrayElementType, stringType, undefinedType] : [arrayElementType, stringType], UnionReduction.Subtype); } return (use & IterationUse.PossiblyOutOfBounds) ? includeUndefinedInIndexSignature(arrayElementType) : arrayElementType; function getIterationDiagnosticDetails(allowsStrings: boolean, downlevelIteration: boolean | undefined): [error: DiagnosticMessage, maybeMissingAwait: boolean] { if (downlevelIteration) { return allowsStrings ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true] : [Diagnostics.Type_0_is_not_an_array_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true]; } const yieldType = getIterationTypeOfIterable(use, IterationTypeKind.Yield, inputType, /*errorNode*/ undefined); if (yieldType) { return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, false]; } if (isES2015OrLaterIterable(inputType.symbol?.escapedName)) { return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, true]; } return allowsStrings ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type, true] : [Diagnostics.Type_0_is_not_an_array_type, true]; } } function isES2015OrLaterIterable(n: __String) { switch (n) { case "Float32Array": case "Float64Array": case "Int16Array": case "Int32Array": case "Int8Array": case "NodeList": case "Uint16Array": case "Uint32Array": case "Uint8Array": case "Uint8ClampedArray": return true; } return false; } /** * Gets the requested "iteration type" from an `Iterable`-like or `AsyncIterable`-like type. */ function getIterationTypeOfIterable(use: IterationUse, typeKind: IterationTypeKind, inputType: Type, errorNode: Node | undefined): Type | undefined { if (isTypeAny(inputType)) { return undefined; } const iterationTypes = getIterationTypesOfIterable(inputType, use, errorNode); return iterationTypes && iterationTypes[getIterationTypesKeyFromIterationTypeKind(typeKind)]; } function createIterationTypes(yieldType: Type = neverType, returnType: Type = neverType, nextType: Type = unknownType): IterationTypes { // `yieldType` and `returnType` are defaulted to `neverType` they each will be combined // via `getUnionType` when merging iteration types. `nextType` is defined as `unknownType` // as it is combined via `getIntersectionType` when merging iteration types. // Use the cache only for intrinsic types to keep it small as they are likely to be // more frequently created (i.e. `Iterator`). Iteration types // are also cached on the type they are requested for, so we shouldn't need to maintain // the cache for less-frequently used types. if (yieldType.flags & TypeFlags.Intrinsic && returnType.flags & (TypeFlags.Any | TypeFlags.Never | TypeFlags.Unknown | TypeFlags.Void | TypeFlags.Undefined) && nextType.flags & (TypeFlags.Any | TypeFlags.Never | TypeFlags.Unknown | TypeFlags.Void | TypeFlags.Undefined)) { const id = getTypeListId([yieldType, returnType, nextType]); let iterationTypes = iterationTypesCache.get(id); if (!iterationTypes) { iterationTypes = { yieldType, returnType, nextType }; iterationTypesCache.set(id, iterationTypes); } return iterationTypes; } return { yieldType, returnType, nextType }; } /** * Combines multiple `IterationTypes` records. * * If `array` is empty or all elements are missing or are references to `noIterationTypes`, * then `noIterationTypes` is returned. Otherwise, an `IterationTypes` record is returned * for the combined iteration types. */ function combineIterationTypes(array: (IterationTypes | undefined)[]) { let yieldTypes: Type[] | undefined; let returnTypes: Type[] | undefined; let nextTypes: Type[] | undefined; for (const iterationTypes of array) { if (iterationTypes === undefined || iterationTypes === noIterationTypes) { continue; } if (iterationTypes === anyIterationTypes) { return anyIterationTypes; } yieldTypes = append(yieldTypes, iterationTypes.yieldType); returnTypes = append(returnTypes, iterationTypes.returnType); nextTypes = append(nextTypes, iterationTypes.nextType); } if (yieldTypes || returnTypes || nextTypes) { return createIterationTypes( yieldTypes && getUnionType(yieldTypes), returnTypes && getUnionType(returnTypes), nextTypes && getIntersectionType(nextTypes)); } return noIterationTypes; } function getCachedIterationTypes(type: Type, cacheKey: MatchingKeys) { return (type as IterableOrIteratorType)[cacheKey]; } function setCachedIterationTypes(type: Type, cacheKey: MatchingKeys, cachedTypes: IterationTypes) { return (type as IterableOrIteratorType)[cacheKey] = cachedTypes; } /** * Gets the *yield*, *return*, and *next* types from an `Iterable`-like or `AsyncIterable`-like type. * * At every level that involves analyzing return types of signatures, we union the return types of all the signatures. * * Another thing to note is that at any step of this process, we could run into a dead end, * meaning either the property is missing, or we run into the anyType. If either of these things * happens, we return `undefined` to signal that we could not find the iteration type. If a property * is missing, and the previous step did not result in `any`, then we also give an error if the * caller requested it. Then the caller can decide what to do in the case where there is no iterated * type. * * For a **for-of** statement, `yield*` (in a normal generator), spread, array * destructuring, or normal generator we will only ever look for a `[Symbol.iterator]()` * method. * * For an async generator we will only ever look at the `[Symbol.asyncIterator]()` method. * * For a **for-await-of** statement or a `yield*` in an async generator we will look for * the `[Symbol.asyncIterator]()` method first, and then the `[Symbol.iterator]()` method. */ function getIterationTypesOfIterable(type: Type, use: IterationUse, errorNode: Node | undefined) { if (isTypeAny(type)) { return anyIterationTypes; } if (!(type.flags & TypeFlags.Union)) { const errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined = errorNode ? { errors: undefined } : undefined; const iterationTypes = getIterationTypesOfIterableWorker(type, use, errorNode, errorOutputContainer); if (iterationTypes === noIterationTypes) { if (errorNode) { const rootDiag = reportTypeNotIterableError(errorNode, type, !!(use & IterationUse.AllowsAsyncIterablesFlag)); if (errorOutputContainer?.errors) { addRelatedInfo(rootDiag, ...errorOutputContainer.errors); } } return undefined; } else if (errorOutputContainer?.errors?.length) { for (const diag of errorOutputContainer.errors) { diagnostics.add(diag); } } return iterationTypes; } const cacheKey = use & IterationUse.AllowsAsyncIterablesFlag ? "iterationTypesOfAsyncIterable" : "iterationTypesOfIterable"; const cachedTypes = getCachedIterationTypes(type, cacheKey); if (cachedTypes) return cachedTypes === noIterationTypes ? undefined : cachedTypes; let allIterationTypes: IterationTypes[] | undefined; for (const constituent of (type as UnionType).types) { const errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined = errorNode ? { errors: undefined } : undefined; const iterationTypes = getIterationTypesOfIterableWorker(constituent, use, errorNode, errorOutputContainer); if (iterationTypes === noIterationTypes) { if (errorNode) { const rootDiag = reportTypeNotIterableError(errorNode, type, !!(use & IterationUse.AllowsAsyncIterablesFlag)); if (errorOutputContainer?.errors) { addRelatedInfo(rootDiag, ...errorOutputContainer.errors); } } setCachedIterationTypes(type, cacheKey, noIterationTypes); return undefined; } else if (errorOutputContainer?.errors?.length) { for (const diag of errorOutputContainer.errors) { diagnostics.add(diag); } } allIterationTypes = append(allIterationTypes, iterationTypes); } const iterationTypes = allIterationTypes ? combineIterationTypes(allIterationTypes) : noIterationTypes; setCachedIterationTypes(type, cacheKey, iterationTypes); return iterationTypes === noIterationTypes ? undefined : iterationTypes; } function getAsyncFromSyncIterationTypes(iterationTypes: IterationTypes, errorNode: Node | undefined) { if (iterationTypes === noIterationTypes) return noIterationTypes; if (iterationTypes === anyIterationTypes) return anyIterationTypes; const { yieldType, returnType, nextType } = iterationTypes; // if we're requesting diagnostics, report errors for a missing `Awaited`. if (errorNode) { getGlobalAwaitedSymbol(/*reportErrors*/ true); } return createIterationTypes( getAwaitedType(yieldType, errorNode) || anyType, getAwaitedType(returnType, errorNode) || anyType, nextType); } /** * Gets the *yield*, *return*, and *next* types from a non-union type. * * If we are unable to find the *yield*, *return*, and *next* types, `noIterationTypes` is * returned to indicate to the caller that it should report an error. Otherwise, an * `IterationTypes` record is returned. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterable` instead. */ function getIterationTypesOfIterableWorker(type: Type, use: IterationUse, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined) { if (isTypeAny(type)) { return anyIterationTypes; } // If we are reporting errors and encounter a cached `noIterationTypes`, we should ignore the cached value and continue as if nothing was cached. // In addition, we should not cache any new results for this call. let noCache = false; if (use & IterationUse.AllowsAsyncIterablesFlag) { const iterationTypes = getIterationTypesOfIterableCached(type, asyncIterationTypesResolver) || getIterationTypesOfIterableFast(type, asyncIterationTypesResolver); if (iterationTypes) { if (iterationTypes === noIterationTypes && errorNode) { // ignore the cached value noCache = true; } else { return use & IterationUse.ForOfFlag ? getAsyncFromSyncIterationTypes(iterationTypes, errorNode) : iterationTypes; } } } if (use & IterationUse.AllowsSyncIterablesFlag) { let iterationTypes = getIterationTypesOfIterableCached(type, syncIterationTypesResolver) || getIterationTypesOfIterableFast(type, syncIterationTypesResolver); if (iterationTypes) { if (iterationTypes === noIterationTypes && errorNode) { // ignore the cached value noCache = true; } else { if (use & IterationUse.AllowsAsyncIterablesFlag) { // for a sync iterable in an async context, only use the cached types if they are valid. if (iterationTypes !== noIterationTypes) { iterationTypes = getAsyncFromSyncIterationTypes(iterationTypes, errorNode); return noCache ? iterationTypes : setCachedIterationTypes(type, "iterationTypesOfAsyncIterable", iterationTypes); } } else { return iterationTypes; } } } } if (use & IterationUse.AllowsAsyncIterablesFlag) { const iterationTypes = getIterationTypesOfIterableSlow(type, asyncIterationTypesResolver, errorNode, errorOutputContainer, noCache); if (iterationTypes !== noIterationTypes) { return iterationTypes; } } if (use & IterationUse.AllowsSyncIterablesFlag) { let iterationTypes = getIterationTypesOfIterableSlow(type, syncIterationTypesResolver, errorNode, errorOutputContainer, noCache); if (iterationTypes !== noIterationTypes) { if (use & IterationUse.AllowsAsyncIterablesFlag) { iterationTypes = getAsyncFromSyncIterationTypes(iterationTypes, errorNode); return noCache ? iterationTypes : setCachedIterationTypes(type, "iterationTypesOfAsyncIterable", iterationTypes); } else { return iterationTypes; } } } return noIterationTypes; } /** * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or * `AsyncIterable`-like type from the cache. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterable` instead. */ function getIterationTypesOfIterableCached(type: Type, resolver: IterationTypesResolver) { return getCachedIterationTypes(type, resolver.iterableCacheKey); } function getIterationTypesOfGlobalIterableType(globalType: Type, resolver: IterationTypesResolver) { const globalIterationTypes = getIterationTypesOfIterableCached(globalType, resolver) || getIterationTypesOfIterableSlow(globalType, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined, /*noCache*/ false); return globalIterationTypes === noIterationTypes ? defaultIterationTypes : globalIterationTypes; } /** * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or `AsyncIterable`-like * type from from common heuristics. * * If we previously analyzed this type and found no iteration types, `noIterationTypes` is * returned. If we found iteration types, an `IterationTypes` record is returned. * Otherwise, we return `undefined` to indicate to the caller it should perform a more * exhaustive analysis. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterable` instead. */ function getIterationTypesOfIterableFast(type: Type, resolver: IterationTypesResolver) { // As an optimization, if the type is an instantiation of one of the following global types, then // just grab its related type argument: // - `Iterable` or `AsyncIterable` // - `IterableIterator` or `AsyncIterableIterator` let globalType: Type; if (isReferenceToType(type, globalType = resolver.getGlobalIterableType(/*reportErrors*/ false)) || isReferenceToType(type, globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false))) { const [yieldType] = getTypeArguments(type as GenericType); // The "return" and "next" types of `Iterable` and `IterableIterator` are defined by the // iteration types of their `[Symbol.iterator]()` method. The same is true for their async cousins. // While we define these as `any` and `undefined` in our libs by default, a custom lib *could* use // different definitions. const { returnType, nextType } = getIterationTypesOfGlobalIterableType(globalType, resolver); return setCachedIterationTypes(type, resolver.iterableCacheKey, createIterationTypes(resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || yieldType, resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || returnType, nextType)); } // As an optimization, if the type is an instantiation of the following global type, then // just grab its related type arguments: // - `Generator` or `AsyncGenerator` if (isReferenceToType(type, resolver.getGlobalGeneratorType(/*reportErrors*/ false))) { const [yieldType, returnType, nextType] = getTypeArguments(type as GenericType); return setCachedIterationTypes(type, resolver.iterableCacheKey, createIterationTypes(resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || yieldType, resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || returnType, nextType)); } } function getPropertyNameForKnownSymbolName(symbolName: string): __String { const ctorType = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); const uniqueType = ctorType && getTypeOfPropertyOfType(getTypeOfSymbol(ctorType), escapeLeadingUnderscores(symbolName)); return uniqueType && isTypeUsableAsPropertyName(uniqueType) ? getPropertyNameFromType(uniqueType) : `__@${symbolName}` as __String; } /** * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or `AsyncIterable`-like * type from its members. * * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` * record is returned. Otherwise, `noIterationTypes` is returned. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterable` instead. */ function getIterationTypesOfIterableSlow(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined, noCache: boolean) { const method = getPropertyOfType(type, getPropertyNameForKnownSymbolName(resolver.iteratorSymbolName)); const methodType = method && !(method.flags & SymbolFlags.Optional) ? getTypeOfSymbol(method) : undefined; if (isTypeAny(methodType)) { return noCache ? anyIterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, anyIterationTypes); } const signatures = methodType ? getSignaturesOfType(methodType, SignatureKind.Call) : undefined; if (!some(signatures)) { return noCache ? noIterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, noIterationTypes); } const iteratorType = getIntersectionType(map(signatures, getReturnTypeOfSignature)); const iterationTypes = getIterationTypesOfIteratorWorker(iteratorType, resolver, errorNode, errorOutputContainer, noCache) ?? noIterationTypes; return noCache ? iterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, iterationTypes); } function reportTypeNotIterableError(errorNode: Node, type: Type, allowAsyncIterables: boolean): Diagnostic { const message = allowAsyncIterables ? Diagnostics.Type_0_must_have_a_Symbol_asyncIterator_method_that_returns_an_async_iterator : Diagnostics.Type_0_must_have_a_Symbol_iterator_method_that_returns_an_iterator; const suggestAwait = // for (const x of Promise<...>) or [...Promise<...>] !!getAwaitedTypeOfPromise(type) // for (const x of AsyncIterable<...>) || ( !allowAsyncIterables && isForOfStatement(errorNode.parent) && errorNode.parent.expression === errorNode && getGlobalAsyncIterableType(/** reportErrors */ false) !== emptyGenericType && isTypeAssignableTo(type, getGlobalAsyncIterableType(/** reportErrors */ false) )); return errorAndMaybeSuggestAwait(errorNode, suggestAwait, message, typeToString(type)); } /** * Gets the *yield*, *return*, and *next* types from an `Iterator`-like or `AsyncIterator`-like type. * * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` * record is returned. Otherwise, `undefined` is returned. */ function getIterationTypesOfIterator(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined) { return getIterationTypesOfIteratorWorker(type, resolver, errorNode, errorOutputContainer, /*noCache*/ false); } /** * Gets the *yield*, *return*, and *next* types from an `Iterator`-like or `AsyncIterator`-like type. * * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` * record is returned. Otherwise, `undefined` is returned. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterator` instead. */ function getIterationTypesOfIteratorWorker(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined, noCache: boolean) { if (isTypeAny(type)) { return anyIterationTypes; } let iterationTypes = getIterationTypesOfIteratorCached(type, resolver) || getIterationTypesOfIteratorFast(type, resolver); if (iterationTypes === noIterationTypes && errorNode) { iterationTypes = undefined; noCache = true; } iterationTypes ??= getIterationTypesOfIteratorSlow(type, resolver, errorNode, errorOutputContainer, noCache); return iterationTypes === noIterationTypes ? undefined : iterationTypes; } /** * Gets the iteration types of an `Iterator`-like or `AsyncIterator`-like type from the * cache. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterator` instead. */ function getIterationTypesOfIteratorCached(type: Type, resolver: IterationTypesResolver) { return getCachedIterationTypes(type, resolver.iteratorCacheKey); } /** * Gets the iteration types of an `Iterator`-like or `AsyncIterator`-like type from the * cache or from common heuristics. * * If we previously analyzed this type and found no iteration types, `noIterationTypes` is * returned. If we found iteration types, an `IterationTypes` record is returned. * Otherwise, we return `undefined` to indicate to the caller it should perform a more * exhaustive analysis. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterator` instead. */ function getIterationTypesOfIteratorFast(type: Type, resolver: IterationTypesResolver) { // As an optimization, if the type is an instantiation of one of the following global types, // then just grab its related type argument: // - `IterableIterator` or `AsyncIterableIterator` // - `Iterator` or `AsyncIterator` // - `Generator` or `AsyncGenerator` const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); if (isReferenceToType(type, globalType)) { const [yieldType] = getTypeArguments(type as GenericType); // The "return" and "next" types of `IterableIterator` and `AsyncIterableIterator` are defined by the // iteration types of their `next`, `return`, and `throw` methods. While we define these as `any` // and `undefined` in our libs by default, a custom lib *could* use different definitions. const globalIterationTypes = getIterationTypesOfIteratorCached(globalType, resolver) || getIterationTypesOfIteratorSlow(globalType, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined, /*noCache*/ false); const { returnType, nextType } = globalIterationTypes === noIterationTypes ? defaultIterationTypes : globalIterationTypes; return setCachedIterationTypes(type, resolver.iteratorCacheKey, createIterationTypes(yieldType, returnType, nextType)); } if (isReferenceToType(type, resolver.getGlobalIteratorType(/*reportErrors*/ false)) || isReferenceToType(type, resolver.getGlobalGeneratorType(/*reportErrors*/ false))) { const [yieldType, returnType, nextType] = getTypeArguments(type as GenericType); return setCachedIterationTypes(type, resolver.iteratorCacheKey, createIterationTypes(yieldType, returnType, nextType)); } } function isIteratorResult(type: Type, kind: IterationTypeKind.Yield | IterationTypeKind.Return) { // From https://tc39.github.io/ecma262/#sec-iteratorresult-interface: // > [done] is the result status of an iterator `next` method call. If the end of the iterator was reached `done` is `true`. // > If the end was not reached `done` is `false` and a value is available. // > If a `done` property (either own or inherited) does not exist, it is consider to have the value `false`. const doneType = getTypeOfPropertyOfType(type, "done" as __String) || falseType; return isTypeAssignableTo(kind === IterationTypeKind.Yield ? falseType : trueType, doneType); } function isYieldIteratorResult(type: Type) { return isIteratorResult(type, IterationTypeKind.Yield); } function isReturnIteratorResult(type: Type) { return isIteratorResult(type, IterationTypeKind.Return); } /** * Gets the *yield* and *return* types of an `IteratorResult`-like type. * * If we are unable to determine a *yield* or a *return* type, `noIterationTypes` is * returned to indicate to the caller that it should handle the error. Otherwise, an * `IterationTypes` record is returned. */ function getIterationTypesOfIteratorResult(type: Type) { if (isTypeAny(type)) { return anyIterationTypes; } const cachedTypes = getCachedIterationTypes(type, "iterationTypesOfIteratorResult"); if (cachedTypes) { return cachedTypes; } // As an optimization, if the type is an instantiation of one of the global `IteratorYieldResult` // or `IteratorReturnResult` types, then just grab its type argument. if (isReferenceToType(type, getGlobalIteratorYieldResultType(/*reportErrors*/ false))) { const yieldType = getTypeArguments(type as GenericType)[0]; return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(yieldType, /*returnType*/ undefined, /*nextType*/ undefined)); } if (isReferenceToType(type, getGlobalIteratorReturnResultType(/*reportErrors*/ false))) { const returnType = getTypeArguments(type as GenericType)[0]; return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(/*yieldType*/ undefined, returnType, /*nextType*/ undefined)); } // Choose any constituents that can produce the requested iteration type. const yieldIteratorResult = filterType(type, isYieldIteratorResult); const yieldType = yieldIteratorResult !== neverType ? getTypeOfPropertyOfType(yieldIteratorResult, "value" as __String) : undefined; const returnIteratorResult = filterType(type, isReturnIteratorResult); const returnType = returnIteratorResult !== neverType ? getTypeOfPropertyOfType(returnIteratorResult, "value" as __String) : undefined; if (!yieldType && !returnType) { return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", noIterationTypes); } // From https://tc39.github.io/ecma262/#sec-iteratorresult-interface // > ... If the iterator does not have a return value, `value` is `undefined`. In that case, the // > `value` property may be absent from the conforming object if it does not inherit an explicit // > `value` property. return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(yieldType, returnType || voidType, /*nextType*/ undefined)); } /** * Gets the *yield*, *return*, and *next* types of a the `next()`, `return()`, or * `throw()` method of an `Iterator`-like or `AsyncIterator`-like type. * * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` * record is returned. Otherwise, we return `undefined`. */ function getIterationTypesOfMethod(type: Type, resolver: IterationTypesResolver, methodName: "next" | "return" | "throw", errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined): IterationTypes | undefined { const method = getPropertyOfType(type, methodName as __String); // Ignore 'return' or 'throw' if they are missing. if (!method && methodName !== "next") { return undefined; } const methodType = method && !(methodName === "next" && (method.flags & SymbolFlags.Optional)) ? methodName === "next" ? getTypeOfSymbol(method) : getTypeWithFacts(getTypeOfSymbol(method), TypeFacts.NEUndefinedOrNull) : undefined; if (isTypeAny(methodType)) { // `return()` and `throw()` don't provide a *next* type. return methodName === "next" ? anyIterationTypes : anyIterationTypesExceptNext; } // Both async and non-async iterators *must* have a `next` method. const methodSignatures = methodType ? getSignaturesOfType(methodType, SignatureKind.Call) : emptyArray; if (methodSignatures.length === 0) { if (errorNode) { const diagnostic = methodName === "next" ? resolver.mustHaveANextMethodDiagnostic : resolver.mustBeAMethodDiagnostic; if (errorOutputContainer) { errorOutputContainer.errors ??= []; errorOutputContainer.errors.push(createDiagnosticForNode(errorNode, diagnostic, methodName)); } else { error(errorNode, diagnostic, methodName); } } return methodName === "next" ? noIterationTypes : undefined; } // If the method signature comes exclusively from the global iterator or generator type, // create iteration types from its type arguments like `getIterationTypesOfIteratorFast` // does (so as to remove `undefined` from the next and return types). We arrive here when // a contextual type for a generator was not a direct reference to one of those global types, // but looking up `methodType` referred to one of them (and nothing else). E.g., in // `interface SpecialIterator extends Iterator {}`, `SpecialIterator` is not a // reference to `Iterator`, but its `next` member derives exclusively from `Iterator`. if (methodType?.symbol && methodSignatures.length === 1) { const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); const globalIteratorType = resolver.getGlobalIteratorType(/*reportErrors*/ false); const isGeneratorMethod = globalGeneratorType.symbol?.members?.get(methodName as __String) === methodType.symbol; const isIteratorMethod = !isGeneratorMethod && globalIteratorType.symbol?.members?.get(methodName as __String) === methodType.symbol; if (isGeneratorMethod || isIteratorMethod) { const globalType = isGeneratorMethod ? globalGeneratorType : globalIteratorType; const { mapper } = methodType as AnonymousType; return createIterationTypes( getMappedType(globalType.typeParameters![0], mapper!), getMappedType(globalType.typeParameters![1], mapper!), methodName === "next" ? getMappedType(globalType.typeParameters![2], mapper!) : undefined); } } // Extract the first parameter and return type of each signature. let methodParameterTypes: Type[] | undefined; let methodReturnTypes: Type[] | undefined; for (const signature of methodSignatures) { if (methodName !== "throw" && some(signature.parameters)) { methodParameterTypes = append(methodParameterTypes, getTypeAtPosition(signature, 0)); } methodReturnTypes = append(methodReturnTypes, getReturnTypeOfSignature(signature)); } // Resolve the *next* or *return* type from the first parameter of a `next()` or // `return()` method, respectively. let returnTypes: Type[] | undefined; let nextType: Type | undefined; if (methodName !== "throw") { const methodParameterType = methodParameterTypes ? getUnionType(methodParameterTypes) : unknownType; if (methodName === "next") { // The value of `next(value)` is *not* awaited by async generators nextType = methodParameterType; } else if (methodName === "return") { // The value of `return(value)` *is* awaited by async generators const resolvedMethodParameterType = resolver.resolveIterationType(methodParameterType, errorNode) || anyType; returnTypes = append(returnTypes, resolvedMethodParameterType); } } // Resolve the *yield* and *return* types from the return type of the method (i.e. `IteratorResult`) let yieldType: Type; const methodReturnType = methodReturnTypes ? getIntersectionType(methodReturnTypes) : neverType; const resolvedMethodReturnType = resolver.resolveIterationType(methodReturnType, errorNode) || anyType; const iterationTypes = getIterationTypesOfIteratorResult(resolvedMethodReturnType); if (iterationTypes === noIterationTypes) { if (errorNode) { if (errorOutputContainer) { errorOutputContainer.errors ??= []; errorOutputContainer.errors.push(createDiagnosticForNode(errorNode, resolver.mustHaveAValueDiagnostic, methodName)); } else { error(errorNode, resolver.mustHaveAValueDiagnostic, methodName); } } yieldType = anyType; returnTypes = append(returnTypes, anyType); } else { yieldType = iterationTypes.yieldType; returnTypes = append(returnTypes, iterationTypes.returnType); } return createIterationTypes(yieldType, getUnionType(returnTypes), nextType); } /** * Gets the *yield*, *return*, and *next* types of an `Iterator`-like or `AsyncIterator`-like * type from its members. * * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` * record is returned. Otherwise, `noIterationTypes` is returned. * * NOTE: You probably don't want to call this directly and should be calling * `getIterationTypesOfIterator` instead. */ function getIterationTypesOfIteratorSlow(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined } | undefined, noCache: boolean) { const iterationTypes = combineIterationTypes([ getIterationTypesOfMethod(type, resolver, "next", errorNode, errorOutputContainer), getIterationTypesOfMethod(type, resolver, "return", errorNode, errorOutputContainer), getIterationTypesOfMethod(type, resolver, "throw", errorNode, errorOutputContainer), ]); return noCache ? iterationTypes : setCachedIterationTypes(type, resolver.iteratorCacheKey, iterationTypes); } /** * Gets the requested "iteration type" from a type that is either `Iterable`-like, `Iterator`-like, * `IterableIterator`-like, or `Generator`-like (for a non-async generator); or `AsyncIterable`-like, * `AsyncIterator`-like, `AsyncIterableIterator`-like, or `AsyncGenerator`-like (for an async generator). */ function getIterationTypeOfGeneratorFunctionReturnType(kind: IterationTypeKind, returnType: Type, isAsyncGenerator: boolean): Type | undefined { if (isTypeAny(returnType)) { return undefined; } const iterationTypes = getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsyncGenerator); return iterationTypes && iterationTypes[getIterationTypesKeyFromIterationTypeKind(kind)]; } function getIterationTypesOfGeneratorFunctionReturnType(type: Type, isAsyncGenerator: boolean) { if (isTypeAny(type)) { return anyIterationTypes; } const use = isAsyncGenerator ? IterationUse.AsyncGeneratorReturnType : IterationUse.GeneratorReturnType; const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; return getIterationTypesOfIterable(type, use, /*errorNode*/ undefined) || getIterationTypesOfIterator(type, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined); } function checkBreakOrContinueStatement(node: BreakOrContinueStatement) { // Grammar checking if (!checkGrammarStatementInAmbientContext(node)) checkGrammarBreakOrContinueStatement(node); // TODO: Check that target label is valid } function unwrapReturnType(returnType: Type, functionFlags: FunctionFlags) { const isGenerator = !!(functionFlags & FunctionFlags.Generator); const isAsync = !!(functionFlags & FunctionFlags.Async); if (isGenerator) { const returnIterationType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, isAsync); if (!returnIterationType) { return errorType; } return isAsync ? getAwaitedTypeNoAlias(unwrapAwaitedType(returnIterationType)) : returnIterationType; } return isAsync ? getAwaitedTypeNoAlias(returnType) || errorType : returnType; } function isUnwrappedReturnTypeVoidOrAny(func: SignatureDeclaration, returnType: Type): boolean { const unwrappedReturnType = unwrapReturnType(returnType, getFunctionFlags(func)); return !!unwrappedReturnType && maybeTypeOfKind(unwrappedReturnType, TypeFlags.Void | TypeFlags.AnyOrUnknown); } function checkReturnStatement(node: ReturnStatement) { // Grammar checking if (checkGrammarStatementInAmbientContext(node)) { return; } const container = getContainingFunctionOrClassStaticBlock(node); if(container && isClassStaticBlockDeclaration(container)) { grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_cannot_be_used_inside_a_class_static_block); return; } if (!container) { grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_can_only_be_used_within_a_function_body); return; } const signature = getSignatureFromDeclaration(container); const returnType = getReturnTypeOfSignature(signature); const functionFlags = getFunctionFlags(container); if (strictNullChecks || node.expression || returnType.flags & TypeFlags.Never) { const exprType = node.expression ? checkExpressionCached(node.expression) : undefinedType; if (container.kind === SyntaxKind.SetAccessor) { if (node.expression) { error(node, Diagnostics.Setters_cannot_return_a_value); } } else if (container.kind === SyntaxKind.Constructor) { if (node.expression && !checkTypeAssignableToAndOptionallyElaborate(exprType, returnType, node, node.expression)) { error(node, Diagnostics.Return_type_of_constructor_signature_must_be_assignable_to_the_instance_type_of_the_class); } } else if (getReturnTypeFromAnnotation(container)) { const unwrappedReturnType = unwrapReturnType(returnType, functionFlags) ?? returnType; const unwrappedExprType = functionFlags & FunctionFlags.Async ? checkAwaitedType(exprType, /*withAlias*/ false, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member) : exprType; if (unwrappedReturnType) { // If the function has a return type, but promisedType is // undefined, an error will be reported in checkAsyncFunctionReturnType // so we don't need to report one here. checkTypeAssignableToAndOptionallyElaborate(unwrappedExprType, unwrappedReturnType, node, node.expression); } } } else if (container.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeVoidOrAny(container, returnType)) { // The function has a return type, but the return statement doesn't have an expression. error(node, Diagnostics.Not_all_code_paths_return_a_value); } } function checkWithStatement(node: WithStatement) { // Grammar checking for withStatement if (!checkGrammarStatementInAmbientContext(node)) { if (node.flags & NodeFlags.AwaitContext) { grammarErrorOnFirstToken(node, Diagnostics.with_statements_are_not_allowed_in_an_async_function_block); } } checkExpression(node.expression); const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { const start = getSpanOfTokenAtPosition(sourceFile, node.pos).start; const end = node.statement.pos; grammarErrorAtPos(sourceFile, start, end - start, Diagnostics.The_with_statement_is_not_supported_All_symbols_in_a_with_block_will_have_type_any); } } function checkSwitchStatement(node: SwitchStatement) { // Grammar checking checkGrammarStatementInAmbientContext(node); let firstDefaultClause: CaseOrDefaultClause; let hasDuplicateDefaultClause = false; const expressionType = checkExpression(node.expression); forEach(node.caseBlock.clauses, clause => { // Grammar check for duplicate default clauses, skip if we already report duplicate default clause if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) { if (firstDefaultClause === undefined) { firstDefaultClause = clause; } else { grammarErrorOnNode(clause, Diagnostics.A_default_clause_cannot_appear_more_than_once_in_a_switch_statement); hasDuplicateDefaultClause = true; } } if (clause.kind === SyntaxKind.CaseClause) { addLazyDiagnostic(createLazyCaseClauseDiagnostics(clause)); } forEach(clause.statements, checkSourceElement); if (compilerOptions.noFallthroughCasesInSwitch && clause.fallthroughFlowNode && isReachableFlowNode(clause.fallthroughFlowNode)) { error(clause, Diagnostics.Fallthrough_case_in_switch); } function createLazyCaseClauseDiagnostics(clause: CaseClause) { return () => { // TypeScript 1.0 spec (April 2014): 5.9 // In a 'switch' statement, each 'case' expression must be of a type that is comparable // to or from the type of the 'switch' expression. const caseType = checkExpression(clause.expression); if (!isTypeEqualityComparableTo(expressionType, caseType)) { // expressionType is not comparable to caseType, try the reversed check and report errors if it fails checkTypeComparableTo(caseType, expressionType, clause.expression, /*headMessage*/ undefined); } }; } }); if (node.caseBlock.locals) { registerForUnusedIdentifiersCheck(node.caseBlock); } } function checkLabeledStatement(node: LabeledStatement) { // Grammar checking if (!checkGrammarStatementInAmbientContext(node)) { findAncestor(node.parent, current => { if (isFunctionLike(current)) { return "quit"; } if (current.kind === SyntaxKind.LabeledStatement && (current as LabeledStatement).label.escapedText === node.label.escapedText) { grammarErrorOnNode(node.label, Diagnostics.Duplicate_label_0, getTextOfNode(node.label)); return true; } return false; }); } // ensure that label is unique checkSourceElement(node.statement); } function checkThrowStatement(node: ThrowStatement) { // Grammar checking if (!checkGrammarStatementInAmbientContext(node)) { if (isIdentifier(node.expression) && !node.expression.escapedText) { grammarErrorAfterFirstToken(node, Diagnostics.Line_break_not_permitted_here); } } if (node.expression) { checkExpression(node.expression); } } function checkTryStatement(node: TryStatement) { // Grammar checking checkGrammarStatementInAmbientContext(node); checkBlock(node.tryBlock); const catchClause = node.catchClause; if (catchClause) { // Grammar checking if (catchClause.variableDeclaration) { const declaration = catchClause.variableDeclaration; checkVariableLikeDeclaration(declaration); const typeNode = getEffectiveTypeAnnotationNode(declaration); if (typeNode) { const type = getTypeFromTypeNode(typeNode); if (type && !(type.flags & TypeFlags.AnyOrUnknown)) { grammarErrorOnFirstToken(typeNode, Diagnostics.Catch_clause_variable_type_annotation_must_be_any_or_unknown_if_specified); } } else if (declaration.initializer) { grammarErrorOnFirstToken(declaration.initializer, Diagnostics.Catch_clause_variable_cannot_have_an_initializer); } else { const blockLocals = catchClause.block.locals; if (blockLocals) { forEachKey(catchClause.locals!, caughtName => { const blockLocal = blockLocals.get(caughtName); if (blockLocal?.valueDeclaration && (blockLocal.flags & SymbolFlags.BlockScopedVariable) !== 0) { grammarErrorOnNode(blockLocal.valueDeclaration, Diagnostics.Cannot_redeclare_identifier_0_in_catch_clause, caughtName); } }); } } } checkBlock(catchClause.block); } if (node.finallyBlock) { checkBlock(node.finallyBlock); } } function checkIndexConstraints(type: Type, symbol: Symbol, isStaticIndex?: boolean) { const indexInfos = getIndexInfosOfType(type); if (indexInfos.length === 0) { return; } for (const prop of getPropertiesOfObjectType(type)) { if (!(isStaticIndex && prop.flags & SymbolFlags.Prototype)) { checkIndexConstraintForProperty(type, prop, getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique, /*includeNonPublic*/ true), getNonMissingTypeOfSymbol(prop)); } } const typeDeclaration = symbol.valueDeclaration; if (typeDeclaration && isClassLike(typeDeclaration)) { for (const member of typeDeclaration.members) { // Only process instance properties with computed names here. Static properties cannot be in conflict with indexers, // and properties with literal names were already checked. if (!isStatic(member) && !hasBindableName(member)) { const symbol = getSymbolOfDeclaration(member); checkIndexConstraintForProperty(type, symbol, getTypeOfExpression((member as DynamicNamedDeclaration).name.expression), getNonMissingTypeOfSymbol(symbol)); } } } if (indexInfos.length > 1) { for (const info of indexInfos) { checkIndexConstraintForIndexSignature(type, info); } } } function checkIndexConstraintForProperty(type: Type, prop: Symbol, propNameType: Type, propType: Type) { const declaration = prop.valueDeclaration; const name = getNameOfDeclaration(declaration); if (name && isPrivateIdentifier(name)) { return; } const indexInfos = getApplicableIndexInfos(type, propNameType); const interfaceDeclaration = getObjectFlags(type) & ObjectFlags.Interface ? getDeclarationOfKind(type.symbol, SyntaxKind.InterfaceDeclaration) : undefined; const propDeclaration = declaration && declaration.kind === SyntaxKind.BinaryExpression || name && name.kind === SyntaxKind.ComputedPropertyName ? declaration : undefined; const localPropDeclaration = getParentOfSymbol(prop) === type.symbol ? declaration : undefined; for (const info of indexInfos) { const localIndexDeclaration = info.declaration && getParentOfSymbol(getSymbolOfDeclaration(info.declaration)) === type.symbol ? info.declaration : undefined; // We check only when (a) the property is declared in the containing type, or (b) the applicable index signature is declared // in the containing type, or (c) the containing type is an interface and no base interface contains both the property and // the index signature (i.e. property and index signature are declared in separate inherited interfaces). const errorNode = localPropDeclaration || localIndexDeclaration || (interfaceDeclaration && !some(getBaseTypes(type as InterfaceType), base => !!getPropertyOfObjectType(base, prop.escapedName) && !!getIndexTypeOfType(base, info.keyType)) ? interfaceDeclaration : undefined); if (errorNode && !isTypeAssignableTo(propType, info.type)) { const diagnostic = createError(errorNode, Diagnostics.Property_0_of_type_1_is_not_assignable_to_2_index_type_3, symbolToString(prop), typeToString(propType), typeToString(info.keyType), typeToString(info.type)); if (propDeclaration && errorNode !== propDeclaration) { addRelatedInfo(diagnostic, createDiagnosticForNode(propDeclaration, Diagnostics._0_is_declared_here, symbolToString(prop))); } diagnostics.add(diagnostic); } } } function checkIndexConstraintForIndexSignature(type: Type, checkInfo: IndexInfo) { const declaration = checkInfo.declaration; const indexInfos = getApplicableIndexInfos(type, checkInfo.keyType); const interfaceDeclaration = getObjectFlags(type) & ObjectFlags.Interface ? getDeclarationOfKind(type.symbol, SyntaxKind.InterfaceDeclaration) : undefined; const localCheckDeclaration = declaration && getParentOfSymbol(getSymbolOfDeclaration(declaration)) === type.symbol ? declaration : undefined; for (const info of indexInfos) { if (info === checkInfo) continue; const localIndexDeclaration = info.declaration && getParentOfSymbol(getSymbolOfDeclaration(info.declaration)) === type.symbol ? info.declaration : undefined; // We check only when (a) the check index signature is declared in the containing type, or (b) the applicable index // signature is declared in the containing type, or (c) the containing type is an interface and no base interface contains // both index signatures (i.e. the index signatures are declared in separate inherited interfaces). const errorNode = localCheckDeclaration || localIndexDeclaration || (interfaceDeclaration && !some(getBaseTypes(type as InterfaceType), base => !!getIndexInfoOfType(base, checkInfo.keyType) && !!getIndexTypeOfType(base, info.keyType)) ? interfaceDeclaration : undefined); if (errorNode && !isTypeAssignableTo(checkInfo.type, info.type)) { error(errorNode, Diagnostics._0_index_type_1_is_not_assignable_to_2_index_type_3, typeToString(checkInfo.keyType), typeToString(checkInfo.type), typeToString(info.keyType), typeToString(info.type)); } } } function checkTypeNameIsReserved(name: Identifier, message: DiagnosticMessage): void { // TS 1.0 spec (April 2014): 3.6.1 // The predefined type keywords are reserved and cannot be used as names of user defined types. switch (name.escapedText) { case "any": case "unknown": case "never": case "number": case "bigint": case "boolean": case "string": case "symbol": case "void": case "object": error(name, message, name.escapedText as string); } } /** * The name cannot be used as 'Object' of user defined types with special target. */ function checkClassNameCollisionWithObject(name: Identifier): void { if (languageVersion >= ScriptTarget.ES5 && name.escapedText === "Object" && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(name).impliedNodeFormat === ModuleKind.CommonJS)) { error(name, Diagnostics.Class_name_cannot_be_Object_when_targeting_ES5_with_module_0, ModuleKind[moduleKind]); // https://github.com/Microsoft/TypeScript/issues/17494 } } function checkUnmatchedJSDocParameters(node: SignatureDeclaration) { const jsdocParameters = filter(getJSDocTags(node), isJSDocParameterTag); if (!length(jsdocParameters)) return; const isJs = isInJSFile(node); const parameters = new Set<__String>(); const excludedParameters = new Set(); forEach(node.parameters, ({ name }, index) => { if (isIdentifier(name)) { parameters.add(name.escapedText); } if (isBindingPattern(name)) { excludedParameters.add(index); } }); const containsArguments = containsArgumentsReference(node); if (containsArguments) { const lastJSDocParamIndex = jsdocParameters.length - 1; const lastJSDocParam = jsdocParameters[lastJSDocParamIndex]; if (isJs && lastJSDocParam && isIdentifier(lastJSDocParam.name) && lastJSDocParam.typeExpression && lastJSDocParam.typeExpression.type && !parameters.has(lastJSDocParam.name.escapedText) && !excludedParameters.has(lastJSDocParamIndex) && !isArrayType(getTypeFromTypeNode(lastJSDocParam.typeExpression.type))) { error(lastJSDocParam.name, Diagnostics.JSDoc_param_tag_has_name_0_but_there_is_no_parameter_with_that_name_It_would_match_arguments_if_it_had_an_array_type, idText(lastJSDocParam.name)); } } else { forEach(jsdocParameters, ({ name, isNameFirst }, index) => { if (excludedParameters.has(index) || isIdentifier(name) && parameters.has(name.escapedText)) { return; } if (isQualifiedName(name)) { if (isJs) { error(name, Diagnostics.Qualified_name_0_is_not_allowed_without_a_leading_param_object_1, entityNameToString(name), entityNameToString(name.left)); } } else { if (!isNameFirst) { errorOrSuggestion(isJs, name, Diagnostics.JSDoc_param_tag_has_name_0_but_there_is_no_parameter_with_that_name, idText(name)); } } }); } } /** * Check each type parameter and check that type parameters have no duplicate type parameter declarations */ function checkTypeParameters(typeParameterDeclarations: readonly TypeParameterDeclaration[] | undefined) { let seenDefault = false; if (typeParameterDeclarations) { for (let i = 0; i < typeParameterDeclarations.length; i++) { const node = typeParameterDeclarations[i]; checkTypeParameter(node); addLazyDiagnostic(createCheckTypeParameterDiagnostic(node, i)); } } function createCheckTypeParameterDiagnostic(node: TypeParameterDeclaration, i: number) { return () => { if (node.default) { seenDefault = true; checkTypeParametersNotReferenced(node.default, typeParameterDeclarations!, i); } else if (seenDefault) { error(node, Diagnostics.Required_type_parameters_may_not_follow_optional_type_parameters); } for (let j = 0; j < i; j++) { if (typeParameterDeclarations![j].symbol === node.symbol) { error(node.name, Diagnostics.Duplicate_identifier_0, declarationNameToString(node.name)); } } }; } } /** Check that type parameter defaults only reference previously declared type parameters */ function checkTypeParametersNotReferenced(root: TypeNode, typeParameters: readonly TypeParameterDeclaration[], index: number) { visit(root); function visit(node: Node) { if (node.kind === SyntaxKind.TypeReference) { const type = getTypeFromTypeReference(node as TypeReferenceNode); if (type.flags & TypeFlags.TypeParameter) { for (let i = index; i < typeParameters.length; i++) { if (type.symbol === getSymbolOfDeclaration(typeParameters[i])) { error(node, Diagnostics.Type_parameter_defaults_can_only_reference_previously_declared_type_parameters); } } } } forEachChild(node, visit); } } /** Check that type parameter lists are identical across multiple declarations */ function checkTypeParameterListsIdentical(symbol: Symbol) { if (symbol.declarations && symbol.declarations.length === 1) { return; } const links = getSymbolLinks(symbol); if (!links.typeParametersChecked) { links.typeParametersChecked = true; const declarations = getClassOrInterfaceDeclarationsOfSymbol(symbol); if (!declarations || declarations.length <= 1) { return; } const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; if (!areTypeParametersIdentical(declarations, type.localTypeParameters!, getEffectiveTypeParameterDeclarations)) { // Report an error on every conflicting declaration. const name = symbolToString(symbol); for (const declaration of declarations) { error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_type_parameters, name); } } } } function areTypeParametersIdentical(declarations: readonly T[], targetParameters: TypeParameter[], getTypeParameterDeclarations: (node: T) => readonly TypeParameterDeclaration[]) { const maxTypeArgumentCount = length(targetParameters); const minTypeArgumentCount = getMinTypeArgumentCount(targetParameters); for (const declaration of declarations) { // If this declaration has too few or too many type parameters, we report an error const sourceParameters = getTypeParameterDeclarations(declaration); const numTypeParameters = sourceParameters.length; if (numTypeParameters < minTypeArgumentCount || numTypeParameters > maxTypeArgumentCount) { return false; } for (let i = 0; i < numTypeParameters; i++) { const source = sourceParameters[i]; const target = targetParameters[i]; // If the type parameter node does not have the same as the resolved type // parameter at this position, we report an error. if (source.name.escapedText !== target.symbol.escapedName) { return false; } // If the type parameter node does not have an identical constraint as the resolved // type parameter at this position, we report an error. const constraint = getEffectiveConstraintOfTypeParameter(source); const sourceConstraint = constraint && getTypeFromTypeNode(constraint); const targetConstraint = getConstraintOfTypeParameter(target); // relax check if later interface augmentation has no constraint, it's more broad and is OK to merge with // a more constrained interface (this could be generalized to a full hierarchy check, but that's maybe overkill) if (sourceConstraint && targetConstraint && !isTypeIdenticalTo(sourceConstraint, targetConstraint)) { return false; } // If the type parameter node has a default and it is not identical to the default // for the type parameter at this position, we report an error. const sourceDefault = source.default && getTypeFromTypeNode(source.default); const targetDefault = getDefaultFromTypeParameter(target); if (sourceDefault && targetDefault && !isTypeIdenticalTo(sourceDefault, targetDefault)) { return false; } } } return true; } function getFirstTransformableStaticClassElement(node: ClassLikeDeclaration) { const willTransformStaticElementsOfDecoratedClass = !legacyDecorators && languageVersion < ScriptTarget.ESNext && classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, node); const willTransformPrivateElementsOrClassStaticBlocks = languageVersion <= ScriptTarget.ES2022; const willTransformInitializers = !useDefineForClassFields || languageVersion < ScriptTarget.ES2022; if (willTransformStaticElementsOfDecoratedClass || willTransformPrivateElementsOrClassStaticBlocks) { for (const member of node.members) { if (willTransformStaticElementsOfDecoratedClass && classElementOrClassElementParameterIsDecorated(/*useLegacyDecorators*/ false, member, node)) { return firstOrUndefined(getDecorators(node)) ?? node; } else if (willTransformPrivateElementsOrClassStaticBlocks) { if (isClassStaticBlockDeclaration(member)) { return member; } else if (isStatic(member)) { if (isPrivateIdentifierClassElementDeclaration(member) || willTransformInitializers && isInitializedProperty(member)) { return member; } } } } } } function checkClassExpressionExternalHelpers(node: ClassExpression) { if (node.name) return; const parent = walkUpOuterExpressions(node); if (!isNamedEvaluationSource(parent)) return; const willTransformESDecorators = !legacyDecorators && languageVersion < ScriptTarget.ESNext; let location: Node | undefined; if (willTransformESDecorators && classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, node)) { location = firstOrUndefined(getDecorators(node)) ?? node; } else { location = getFirstTransformableStaticClassElement(node); } if (location) { checkExternalEmitHelpers(location, ExternalEmitHelpers.SetFunctionName); if ((isPropertyAssignment(parent) || isPropertyDeclaration(parent) || isBindingElement(parent)) && isComputedPropertyName(parent.name)) { checkExternalEmitHelpers(location, ExternalEmitHelpers.PropKey); } } } function checkClassExpression(node: ClassExpression): Type { checkClassLikeDeclaration(node); checkNodeDeferred(node); checkClassExpressionExternalHelpers(node); return getTypeOfSymbol(getSymbolOfDeclaration(node)); } function checkClassExpressionDeferred(node: ClassExpression) { forEach(node.members, checkSourceElement); registerForUnusedIdentifiersCheck(node); } function checkClassDeclaration(node: ClassDeclaration) { const firstDecorator = find(node.modifiers, isDecorator); if (legacyDecorators && firstDecorator && some(node.members, p => hasStaticModifier(p) && isPrivateIdentifierClassElementDeclaration(p))) { grammarErrorOnNode(firstDecorator, Diagnostics.Class_decorators_can_t_be_used_with_static_private_identifier_Consider_removing_the_experimental_decorator); } if (!node.name && !hasSyntacticModifier(node, ModifierFlags.Default)) { grammarErrorOnFirstToken(node, Diagnostics.A_class_declaration_without_the_default_modifier_must_have_a_name); } checkClassLikeDeclaration(node); forEach(node.members, checkSourceElement); registerForUnusedIdentifiersCheck(node); } function checkClassLikeDeclaration(node: ClassLikeDeclaration) { checkGrammarClassLikeDeclaration(node); checkDecorators(node); checkCollisionsForDeclarationName(node, node.name); checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); checkExportsOnMergedDeclarations(node); const symbol = getSymbolOfDeclaration(node); const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; const typeWithThis = getTypeWithThisArgument(type); const staticType = getTypeOfSymbol(symbol) as ObjectType; checkTypeParameterListsIdentical(symbol); checkFunctionOrConstructorSymbol(symbol); checkClassForDuplicateDeclarations(node); // Only check for reserved static identifiers on non-ambient context. const nodeInAmbientContext = !!(node.flags & NodeFlags.Ambient); if (!nodeInAmbientContext) { checkClassForStaticPropertyNameConflicts(node); } const baseTypeNode = getEffectiveBaseTypeNode(node); if (baseTypeNode) { forEach(baseTypeNode.typeArguments, checkSourceElement); if (languageVersion < ScriptTarget.ES2015) { checkExternalEmitHelpers(baseTypeNode.parent, ExternalEmitHelpers.Extends); } // check both @extends and extends if both are specified. const extendsNode = getClassExtendsHeritageElement(node); if (extendsNode && extendsNode !== baseTypeNode) { checkExpression(extendsNode.expression); } const baseTypes = getBaseTypes(type); if (baseTypes.length) { addLazyDiagnostic(() => { const baseType = baseTypes[0]; const baseConstructorType = getBaseConstructorTypeOfClass(type); const staticBaseType = getApparentType(baseConstructorType); checkBaseTypeAccessibility(staticBaseType, baseTypeNode); checkSourceElement(baseTypeNode.expression); if (some(baseTypeNode.typeArguments)) { forEach(baseTypeNode.typeArguments, checkSourceElement); for (const constructor of getConstructorsForTypeArguments(staticBaseType, baseTypeNode.typeArguments, baseTypeNode)) { if (!checkTypeArgumentConstraints(baseTypeNode, constructor.typeParameters!)) { break; } } } const baseWithThis = getTypeWithThisArgument(baseType, type.thisType); if (!checkTypeAssignableTo(typeWithThis, baseWithThis, /*errorNode*/ undefined)) { issueMemberSpecificError(node, typeWithThis, baseWithThis, Diagnostics.Class_0_incorrectly_extends_base_class_1); } else { // Report static side error only when instance type is assignable checkTypeAssignableTo(staticType, getTypeWithoutSignatures(staticBaseType), node.name || node, Diagnostics.Class_static_side_0_incorrectly_extends_base_class_static_side_1); } if (baseConstructorType.flags & TypeFlags.TypeVariable) { if (!isMixinConstructorType(staticType)) { error(node.name || node, Diagnostics.A_mixin_class_must_have_a_constructor_with_a_single_rest_parameter_of_type_any); } else { const constructSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); if (constructSignatures.some(signature => signature.flags & SignatureFlags.Abstract) && !hasSyntacticModifier(node, ModifierFlags.Abstract)) { error(node.name || node, Diagnostics.A_mixin_class_that_extends_from_a_type_variable_containing_an_abstract_construct_signature_must_also_be_declared_abstract); } } } if (!(staticBaseType.symbol && staticBaseType.symbol.flags & SymbolFlags.Class) && !(baseConstructorType.flags & TypeFlags.TypeVariable)) { // When the static base type is a "class-like" constructor function (but not actually a class), we verify // that all instantiated base constructor signatures return the same type. const constructors = getInstantiatedConstructorsForTypeArguments(staticBaseType, baseTypeNode.typeArguments, baseTypeNode); if (forEach(constructors, sig => !isJSConstructor(sig.declaration) && !isTypeIdenticalTo(getReturnTypeOfSignature(sig), baseType))) { error(baseTypeNode.expression, Diagnostics.Base_constructors_must_all_have_the_same_return_type); } } checkKindsOfPropertyMemberOverrides(type, baseType); }); } } checkMembersForOverrideModifier(node, type, typeWithThis, staticType); const implementedTypeNodes = getEffectiveImplementsTypeNodes(node); if (implementedTypeNodes) { for (const typeRefNode of implementedTypeNodes) { if (!isEntityNameExpression(typeRefNode.expression) || isOptionalChain(typeRefNode.expression)) { error(typeRefNode.expression, Diagnostics.A_class_can_only_implement_an_identifier_Slashqualified_name_with_optional_type_arguments); } checkTypeReferenceNode(typeRefNode); addLazyDiagnostic(createImplementsDiagnostics(typeRefNode)); } } addLazyDiagnostic(() => { checkIndexConstraints(type, symbol); checkIndexConstraints(staticType, symbol, /*isStaticIndex*/ true); checkTypeForDuplicateIndexSignatures(node); checkPropertyInitialization(node); }); function createImplementsDiagnostics(typeRefNode: ExpressionWithTypeArguments) { return () => { const t = getReducedType(getTypeFromTypeNode(typeRefNode)); if (!isErrorType(t)) { if (isValidBaseType(t)) { const genericDiag = t.symbol && t.symbol.flags & SymbolFlags.Class ? Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass : Diagnostics.Class_0_incorrectly_implements_interface_1; const baseWithThis = getTypeWithThisArgument(t, type.thisType); if (!checkTypeAssignableTo(typeWithThis, baseWithThis, /*errorNode*/ undefined)) { issueMemberSpecificError(node, typeWithThis, baseWithThis, genericDiag); } } else { error(typeRefNode, Diagnostics.A_class_can_only_implement_an_object_type_or_intersection_of_object_types_with_statically_known_members); } } }; } } function checkMembersForOverrideModifier(node: ClassLikeDeclaration, type: InterfaceType, typeWithThis: Type, staticType: ObjectType) { const baseTypeNode = getEffectiveBaseTypeNode(node); const baseTypes = baseTypeNode && getBaseTypes(type); const baseWithThis = baseTypes?.length ? getTypeWithThisArgument(first(baseTypes), type.thisType) : undefined; const baseStaticType = getBaseConstructorTypeOfClass(type); for (const member of node.members) { if (hasAmbientModifier(member)) { continue; } if (isConstructorDeclaration(member)) { forEach(member.parameters, param => { if (isParameterPropertyDeclaration(param, member)) { checkExistingMemberForOverrideModifier( node, staticType, baseStaticType, baseWithThis, type, typeWithThis, param, /* memberIsParameterProperty */ true ); } }); } checkExistingMemberForOverrideModifier( node, staticType, baseStaticType, baseWithThis, type, typeWithThis, member, /* memberIsParameterProperty */ false, ); } } /** * @param member Existing member node to be checked. * Note: `member` cannot be a synthetic node. */ function checkExistingMemberForOverrideModifier( node: ClassLikeDeclaration, staticType: ObjectType, baseStaticType: Type, baseWithThis: Type | undefined, type: InterfaceType, typeWithThis: Type, member: ClassElement | ParameterPropertyDeclaration, memberIsParameterProperty: boolean, reportErrors = true, ): MemberOverrideStatus { const declaredProp = member.name && getSymbolAtLocation(member.name) || getSymbolAtLocation(member); if (!declaredProp) { return MemberOverrideStatus.Ok; } return checkMemberForOverrideModifier( node, staticType, baseStaticType, baseWithThis, type, typeWithThis, hasOverrideModifier(member), hasAbstractModifier(member), isStatic(member), memberIsParameterProperty, symbolName(declaredProp), reportErrors ? member : undefined, ); } /** * Checks a class member declaration for either a missing or an invalid `override` modifier. * Note: this function can be used for speculative checking, * i.e. checking a member that does not yet exist in the program. * An example of that would be to call this function in a completions scenario, * when offering a method declaration as completion. * @param errorNode The node where we should report an error, or undefined if we should not report errors. */ function checkMemberForOverrideModifier( node: ClassLikeDeclaration, staticType: ObjectType, baseStaticType: Type, baseWithThis: Type | undefined, type: InterfaceType, typeWithThis: Type, memberHasOverrideModifier: boolean, memberHasAbstractModifier: boolean, memberIsStatic: boolean, memberIsParameterProperty: boolean, memberName: string, errorNode?: Node, ): MemberOverrideStatus { const isJs = isInJSFile(node); const nodeInAmbientContext = !!(node.flags & NodeFlags.Ambient); if (baseWithThis && (memberHasOverrideModifier || compilerOptions.noImplicitOverride)) { const memberEscapedName = escapeLeadingUnderscores(memberName); const thisType = memberIsStatic ? staticType : typeWithThis; const baseType = memberIsStatic ? baseStaticType : baseWithThis; const prop = getPropertyOfType(thisType, memberEscapedName); const baseProp = getPropertyOfType(baseType, memberEscapedName); const baseClassName = typeToString(baseWithThis); if (prop && !baseProp && memberHasOverrideModifier) { if (errorNode) { const suggestion = getSuggestedSymbolForNonexistentClassMember(memberName, baseType); // Again, using symbol name: note that's different from `symbol.escapedName` suggestion ? error( errorNode, isJs ? Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1 : Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1, baseClassName, symbolToString(suggestion)) : error( errorNode, isJs ? Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_it_is_not_declared_in_the_base_class_0 : Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0, baseClassName); } return MemberOverrideStatus.HasInvalidOverride; } else if (prop && baseProp?.declarations && compilerOptions.noImplicitOverride && !nodeInAmbientContext) { const baseHasAbstract = some(baseProp.declarations, hasAbstractModifier); if (memberHasOverrideModifier) { return MemberOverrideStatus.Ok; } if (!baseHasAbstract) { if (errorNode) { const diag = memberIsParameterProperty ? isJs ? Diagnostics.This_parameter_property_must_have_a_JSDoc_comment_with_an_override_tag_because_it_overrides_a_member_in_the_base_class_0 : Diagnostics.This_parameter_property_must_have_an_override_modifier_because_it_overrides_a_member_in_base_class_0 : isJs ? Diagnostics.This_member_must_have_a_JSDoc_comment_with_an_override_tag_because_it_overrides_a_member_in_the_base_class_0 : Diagnostics.This_member_must_have_an_override_modifier_because_it_overrides_a_member_in_the_base_class_0; error(errorNode, diag, baseClassName); } return MemberOverrideStatus.NeedsOverride; } else if (memberHasAbstractModifier && baseHasAbstract) { if (errorNode) { error(errorNode, Diagnostics.This_member_must_have_an_override_modifier_because_it_overrides_an_abstract_method_that_is_declared_in_the_base_class_0, baseClassName); } return MemberOverrideStatus.NeedsOverride; } } } else if (memberHasOverrideModifier) { if (errorNode) { const className = typeToString(type); error( errorNode, isJs ? Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_its_containing_class_0_does_not_extend_another_class : Diagnostics.This_member_cannot_have_an_override_modifier_because_its_containing_class_0_does_not_extend_another_class, className); } return MemberOverrideStatus.HasInvalidOverride; } return MemberOverrideStatus.Ok; } function issueMemberSpecificError(node: ClassLikeDeclaration, typeWithThis: Type, baseWithThis: Type, broadDiag: DiagnosticMessage) { // iterate over all implemented properties and issue errors on each one which isn't compatible, rather than the class as a whole, if possible let issuedMemberError = false; for (const member of node.members) { if (isStatic(member)) { continue; } const declaredProp = member.name && getSymbolAtLocation(member.name) || getSymbolAtLocation(member); if (declaredProp) { const prop = getPropertyOfType(typeWithThis, declaredProp.escapedName); const baseProp = getPropertyOfType(baseWithThis, declaredProp.escapedName); if (prop && baseProp) { const rootChain = () => chainDiagnosticMessages( /*details*/ undefined, Diagnostics.Property_0_in_type_1_is_not_assignable_to_the_same_property_in_base_type_2, symbolToString(declaredProp), typeToString(typeWithThis), typeToString(baseWithThis) ); if (!checkTypeAssignableTo(getTypeOfSymbol(prop), getTypeOfSymbol(baseProp), member.name || member, /*message*/ undefined, rootChain)) { issuedMemberError = true; } } } } if (!issuedMemberError) { // check again with diagnostics to generate a less-specific error checkTypeAssignableTo(typeWithThis, baseWithThis, node.name || node, broadDiag); } } function checkBaseTypeAccessibility(type: Type, node: ExpressionWithTypeArguments) { const signatures = getSignaturesOfType(type, SignatureKind.Construct); if (signatures.length) { const declaration = signatures[0].declaration; if (declaration && hasEffectiveModifier(declaration, ModifierFlags.Private)) { const typeClassDeclaration = getClassLikeDeclarationOfSymbol(type.symbol)!; if (!isNodeWithinClass(node, typeClassDeclaration)) { error(node, Diagnostics.Cannot_extend_a_class_0_Class_constructor_is_marked_as_private, getFullyQualifiedName(type.symbol)); } } } } /** * Checks a member declaration node to see if has a missing or invalid `override` modifier. * @param node Class-like node where the member is declared. * @param member Member declaration node. * @param memberSymbol Member symbol. * Note: `member` can be a synthetic node without a parent. */ function getMemberOverrideModifierStatus(node: ClassLikeDeclaration, member: ClassElement, memberSymbol: Symbol): MemberOverrideStatus { if (!member.name) { return MemberOverrideStatus.Ok; } const classSymbol = getSymbolOfDeclaration(node); const type = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; const typeWithThis = getTypeWithThisArgument(type); const staticType = getTypeOfSymbol(classSymbol) as ObjectType; const baseTypeNode = getEffectiveBaseTypeNode(node); const baseTypes = baseTypeNode && getBaseTypes(type); const baseWithThis = baseTypes?.length ? getTypeWithThisArgument(first(baseTypes), type.thisType) : undefined; const baseStaticType = getBaseConstructorTypeOfClass(type); const memberHasOverrideModifier = member.parent ? hasOverrideModifier(member) : hasSyntacticModifier(member, ModifierFlags.Override); return checkMemberForOverrideModifier( node, staticType, baseStaticType, baseWithThis, type, typeWithThis, memberHasOverrideModifier, hasAbstractModifier(member), isStatic(member), /* memberIsParameterProperty */ false, symbolName(memberSymbol), ); } function getTargetSymbol(s: Symbol) { // if symbol is instantiated its flags are not copied from the 'target' // so we'll need to get back original 'target' symbol to work with correct set of flags // NOTE: cast to TransientSymbol should be safe because only TransientSymbols have CheckFlags.Instantiated return getCheckFlags(s) & CheckFlags.Instantiated ? (s as TransientSymbol).links.target! : s; } function getClassOrInterfaceDeclarationsOfSymbol(symbol: Symbol) { return filter(symbol.declarations, (d: Declaration): d is ClassDeclaration | InterfaceDeclaration => d.kind === SyntaxKind.ClassDeclaration || d.kind === SyntaxKind.InterfaceDeclaration); } function checkKindsOfPropertyMemberOverrides(type: InterfaceType, baseType: BaseType): void { // TypeScript 1.0 spec (April 2014): 8.2.3 // A derived class inherits all members from its base class it doesn't override. // Inheritance means that a derived class implicitly contains all non - overridden members of the base class. // Both public and private property members are inherited, but only public property members can be overridden. // A property member in a derived class is said to override a property member in a base class // when the derived class property member has the same name and kind(instance or static) // as the base class property member. // The type of an overriding property member must be assignable(section 3.8.4) // to the type of the overridden property member, or otherwise a compile - time error occurs. // Base class instance member functions can be overridden by derived class instance member functions, // but not by other kinds of members. // Base class instance member variables and accessors can be overridden by // derived class instance member variables and accessors, but not by other kinds of members. // NOTE: assignability is checked in checkClassDeclaration const baseProperties = getPropertiesOfType(baseType); basePropertyCheck: for (const baseProperty of baseProperties) { const base = getTargetSymbol(baseProperty); if (base.flags & SymbolFlags.Prototype) { continue; } const baseSymbol = getPropertyOfObjectType(type, base.escapedName); if (!baseSymbol) { continue; } const derived = getTargetSymbol(baseSymbol); const baseDeclarationFlags = getDeclarationModifierFlagsFromSymbol(base); Debug.assert(!!derived, "derived should point to something, even if it is the base class' declaration."); // In order to resolve whether the inherited method was overridden in the base class or not, // we compare the Symbols obtained. Since getTargetSymbol returns the symbol on the *uninstantiated* // type declaration, derived and base resolve to the same symbol even in the case of generic classes. if (derived === base) { // derived class inherits base without override/redeclaration const derivedClassDecl = getClassLikeDeclarationOfSymbol(type.symbol)!; // It is an error to inherit an abstract member without implementing it or being declared abstract. // If there is no declaration for the derived class (as in the case of class expressions), // then the class cannot be declared abstract. if (baseDeclarationFlags & ModifierFlags.Abstract && (!derivedClassDecl || !hasSyntacticModifier(derivedClassDecl, ModifierFlags.Abstract))) { // Searches other base types for a declaration that would satisfy the inherited abstract member. // (The class may have more than one base type via declaration merging with an interface with the // same name.) for (const otherBaseType of getBaseTypes(type)) { if (otherBaseType === baseType) continue; const baseSymbol = getPropertyOfObjectType(otherBaseType, base.escapedName); const derivedElsewhere = baseSymbol && getTargetSymbol(baseSymbol); if (derivedElsewhere && derivedElsewhere !== base) { continue basePropertyCheck; } } if (derivedClassDecl.kind === SyntaxKind.ClassExpression) { error(derivedClassDecl, Diagnostics.Non_abstract_class_expression_does_not_implement_inherited_abstract_member_0_from_class_1, symbolToString(baseProperty), typeToString(baseType)); } else { error(derivedClassDecl, Diagnostics.Non_abstract_class_0_does_not_implement_inherited_abstract_member_1_from_class_2, typeToString(type), symbolToString(baseProperty), typeToString(baseType)); } } } else { // derived overrides base. const derivedDeclarationFlags = getDeclarationModifierFlagsFromSymbol(derived); if (baseDeclarationFlags & ModifierFlags.Private || derivedDeclarationFlags & ModifierFlags.Private) { // either base or derived property is private - not override, skip it continue; } let errorMessage: DiagnosticMessage; const basePropertyFlags = base.flags & SymbolFlags.PropertyOrAccessor; const derivedPropertyFlags = derived.flags & SymbolFlags.PropertyOrAccessor; if (basePropertyFlags && derivedPropertyFlags) { // property/accessor is overridden with property/accessor if ((getCheckFlags(base) & CheckFlags.Synthetic ? base.declarations?.some(d => isPropertyAbstractOrInterface(d, baseDeclarationFlags)) : base.declarations?.every(d => isPropertyAbstractOrInterface(d, baseDeclarationFlags))) || getCheckFlags(base) & CheckFlags.Mapped || derived.valueDeclaration && isBinaryExpression(derived.valueDeclaration)) { // when the base property is abstract or from an interface, base/derived flags don't need to match // for intersection properties, this must be true of *any* of the declarations, for others it must be true of *all* // same when the derived property is from an assignment continue; } const overriddenInstanceProperty = basePropertyFlags !== SymbolFlags.Property && derivedPropertyFlags === SymbolFlags.Property; const overriddenInstanceAccessor = basePropertyFlags === SymbolFlags.Property && derivedPropertyFlags !== SymbolFlags.Property; if (overriddenInstanceProperty || overriddenInstanceAccessor) { const errorMessage = overriddenInstanceProperty ? Diagnostics._0_is_defined_as_an_accessor_in_class_1_but_is_overridden_here_in_2_as_an_instance_property : Diagnostics._0_is_defined_as_a_property_in_class_1_but_is_overridden_here_in_2_as_an_accessor; error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType), typeToString(type)); } else if (useDefineForClassFields) { const uninitialized = derived.declarations?.find(d => d.kind === SyntaxKind.PropertyDeclaration && !(d as PropertyDeclaration).initializer); if (uninitialized && !(derived.flags & SymbolFlags.Transient) && !(baseDeclarationFlags & ModifierFlags.Abstract) && !(derivedDeclarationFlags & ModifierFlags.Abstract) && !derived.declarations?.some(d => !!(d.flags & NodeFlags.Ambient))) { const constructor = findConstructorDeclaration(getClassLikeDeclarationOfSymbol(type.symbol)!); const propName = (uninitialized as PropertyDeclaration).name; if ((uninitialized as PropertyDeclaration).exclamationToken || !constructor || !isIdentifier(propName) || !strictNullChecks || !isPropertyInitializedInConstructor(propName, type, constructor)) { const errorMessage = Diagnostics.Property_0_will_overwrite_the_base_property_in_1_If_this_is_intentional_add_an_initializer_Otherwise_add_a_declare_modifier_or_remove_the_redundant_declaration; error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType)); } } } // correct case continue; } else if (isPrototypeProperty(base)) { if (isPrototypeProperty(derived) || derived.flags & SymbolFlags.Property) { // method is overridden with method or property -- correct case continue; } else { Debug.assert(!!(derived.flags & SymbolFlags.Accessor)); errorMessage = Diagnostics.Class_0_defines_instance_member_function_1_but_extended_class_2_defines_it_as_instance_member_accessor; } } else if (base.flags & SymbolFlags.Accessor) { errorMessage = Diagnostics.Class_0_defines_instance_member_accessor_1_but_extended_class_2_defines_it_as_instance_member_function; } else { errorMessage = Diagnostics.Class_0_defines_instance_member_property_1_but_extended_class_2_defines_it_as_instance_member_function; } error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, typeToString(baseType), symbolToString(base), typeToString(type)); } } } function isPropertyAbstractOrInterface(declaration: Declaration, baseDeclarationFlags: ModifierFlags) { return baseDeclarationFlags & ModifierFlags.Abstract && (!isPropertyDeclaration(declaration) || !declaration.initializer) || isInterfaceDeclaration(declaration.parent); } function getNonInheritedProperties(type: InterfaceType, baseTypes: BaseType[], properties: Symbol[]) { if (!length(baseTypes)) { return properties; } const seen = new Map<__String, Symbol>(); forEach(properties, p => { seen.set(p.escapedName, p); }); for (const base of baseTypes) { const properties = getPropertiesOfType(getTypeWithThisArgument(base, type.thisType)); for (const prop of properties) { const existing = seen.get(prop.escapedName); if (existing && prop.parent === existing.parent) { seen.delete(prop.escapedName); } } } return arrayFrom(seen.values()); } function checkInheritedPropertiesAreIdentical(type: InterfaceType, typeNode: Node): boolean { const baseTypes = getBaseTypes(type); if (baseTypes.length < 2) { return true; } interface InheritanceInfoMap { prop: Symbol; containingType: Type; } const seen = new Map<__String, InheritanceInfoMap>(); forEach(resolveDeclaredMembers(type).declaredProperties, p => { seen.set(p.escapedName, { prop: p, containingType: type }); }); let ok = true; for (const base of baseTypes) { const properties = getPropertiesOfType(getTypeWithThisArgument(base, type.thisType)); for (const prop of properties) { const existing = seen.get(prop.escapedName); if (!existing) { seen.set(prop.escapedName, { prop, containingType: base }); } else { const isInheritedProperty = existing.containingType !== type; if (isInheritedProperty && !isPropertyIdenticalTo(existing.prop, prop)) { ok = false; const typeName1 = typeToString(existing.containingType); const typeName2 = typeToString(base); let errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Named_property_0_of_types_1_and_2_are_not_identical, symbolToString(prop), typeName1, typeName2); errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Interface_0_cannot_simultaneously_extend_types_1_and_2, typeToString(type), typeName1, typeName2); diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(typeNode), typeNode, errorInfo)); } } } } return ok; } function checkPropertyInitialization(node: ClassLikeDeclaration) { if (!strictNullChecks || !strictPropertyInitialization || node.flags & NodeFlags.Ambient) { return; } const constructor = findConstructorDeclaration(node); for (const member of node.members) { if (getEffectiveModifierFlags(member) & ModifierFlags.Ambient) { continue; } if (!isStatic(member) && isPropertyWithoutInitializer(member)) { const propName = (member as PropertyDeclaration).name; if (isIdentifier(propName) || isPrivateIdentifier(propName) || isComputedPropertyName(propName)) { const type = getTypeOfSymbol(getSymbolOfDeclaration(member)); if (!(type.flags & TypeFlags.AnyOrUnknown || containsUndefinedType(type))) { if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) { error(member.name, Diagnostics.Property_0_has_no_initializer_and_is_not_definitely_assigned_in_the_constructor, declarationNameToString(propName)); } } } } } } function isPropertyWithoutInitializer(node: Node) { return node.kind === SyntaxKind.PropertyDeclaration && !hasAbstractModifier(node) && !(node as PropertyDeclaration).exclamationToken && !(node as PropertyDeclaration).initializer; } function isPropertyInitializedInStaticBlocks(propName: Identifier | PrivateIdentifier, propType: Type, staticBlocks: readonly ClassStaticBlockDeclaration[], startPos: number, endPos: number) { for (const staticBlock of staticBlocks) { // static block must be within the provided range as they are evaluated in document order (unlike constructors) if (staticBlock.pos >= startPos && staticBlock.pos <= endPos) { const reference = factory.createPropertyAccessExpression(factory.createThis(), propName); setParent(reference.expression, reference); setParent(reference, staticBlock); reference.flowNode = staticBlock.returnFlowNode; const flowType = getFlowTypeOfReference(reference, propType, getOptionalType(propType)); if (!containsUndefinedType(flowType)) { return true; } } } return false; } function isPropertyInitializedInConstructor(propName: Identifier | PrivateIdentifier | ComputedPropertyName, propType: Type, constructor: ConstructorDeclaration) { const reference = isComputedPropertyName(propName) ? factory.createElementAccessExpression(factory.createThis(), propName.expression) : factory.createPropertyAccessExpression(factory.createThis(), propName); setParent(reference.expression, reference); setParent(reference, constructor); reference.flowNode = constructor.returnFlowNode; const flowType = getFlowTypeOfReference(reference, propType, getOptionalType(propType)); return !containsUndefinedType(flowType); } function checkInterfaceDeclaration(node: InterfaceDeclaration) { // Grammar checking if (!checkGrammarModifiers(node)) checkGrammarInterfaceDeclaration(node); checkTypeParameters(node.typeParameters); addLazyDiagnostic(() => { checkTypeNameIsReserved(node.name, Diagnostics.Interface_name_cannot_be_0); checkExportsOnMergedDeclarations(node); const symbol = getSymbolOfDeclaration(node); checkTypeParameterListsIdentical(symbol); // Only check this symbol once const firstInterfaceDecl = getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration); if (node === firstInterfaceDecl) { const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; const typeWithThis = getTypeWithThisArgument(type); // run subsequent checks only if first set succeeded if (checkInheritedPropertiesAreIdentical(type, node.name)) { for (const baseType of getBaseTypes(type)) { checkTypeAssignableTo(typeWithThis, getTypeWithThisArgument(baseType, type.thisType), node.name, Diagnostics.Interface_0_incorrectly_extends_interface_1); } checkIndexConstraints(type, symbol); } } checkObjectTypeForDuplicateDeclarations(node); }); forEach(getInterfaceBaseTypeNodes(node), heritageElement => { if (!isEntityNameExpression(heritageElement.expression) || isOptionalChain(heritageElement.expression)) { error(heritageElement.expression, Diagnostics.An_interface_can_only_extend_an_identifier_Slashqualified_name_with_optional_type_arguments); } checkTypeReferenceNode(heritageElement); }); forEach(node.members, checkSourceElement); addLazyDiagnostic(() => { checkTypeForDuplicateIndexSignatures(node); registerForUnusedIdentifiersCheck(node); }); } function checkTypeAliasDeclaration(node: TypeAliasDeclaration) { // Grammar checking checkGrammarModifiers(node); checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0); checkExportsOnMergedDeclarations(node); checkTypeParameters(node.typeParameters); if (node.type.kind === SyntaxKind.IntrinsicKeyword) { if (!intrinsicTypeKinds.has(node.name.escapedText as string) || length(node.typeParameters) !== 1) { error(node.type, Diagnostics.The_intrinsic_keyword_can_only_be_used_to_declare_compiler_provided_intrinsic_types); } } else { checkSourceElement(node.type); registerForUnusedIdentifiersCheck(node); } } function computeEnumMemberValues(node: EnumDeclaration) { const nodeLinks = getNodeLinks(node); if (!(nodeLinks.flags & NodeCheckFlags.EnumValuesComputed)) { nodeLinks.flags |= NodeCheckFlags.EnumValuesComputed; let autoValue: number | undefined = 0; for (const member of node.members) { const value = computeMemberValue(member, autoValue); getNodeLinks(member).enumMemberValue = value; autoValue = typeof value === "number" ? value + 1 : undefined; } } } function computeMemberValue(member: EnumMember, autoValue: number | undefined) { if (isComputedNonLiteralName(member.name)) { error(member.name, Diagnostics.Computed_property_names_are_not_allowed_in_enums); } else { const text = getTextOfPropertyName(member.name); if (isNumericLiteralName(text) && !isInfinityOrNaNString(text)) { error(member.name, Diagnostics.An_enum_member_cannot_have_a_numeric_name); } } if (member.initializer) { return computeConstantValue(member); } // In ambient non-const numeric enum declarations, enum members without initializers are // considered computed members (as opposed to having auto-incremented values). if (member.parent.flags & NodeFlags.Ambient && !isEnumConst(member.parent)) { return undefined; } // If the member declaration specifies no value, the member is considered a constant enum member. // If the member is the first member in the enum declaration, it is assigned the value zero. // Otherwise, it is assigned the value of the immediately preceding member plus one, and an error // occurs if the immediately preceding member is not a constant enum member. if (autoValue !== undefined) { return autoValue; } error(member.name, Diagnostics.Enum_member_must_have_initializer); return undefined; } function computeConstantValue(member: EnumMember): string | number | undefined { const isConstEnum = isEnumConst(member.parent); const initializer = member.initializer!; const value = evaluate(initializer, member); if (value !== undefined) { if (isConstEnum && typeof value === "number" && !isFinite(value)) { error(initializer, isNaN(value) ? Diagnostics.const_enum_member_initializer_was_evaluated_to_disallowed_value_NaN : Diagnostics.const_enum_member_initializer_was_evaluated_to_a_non_finite_value); } } else if (isConstEnum) { error(initializer, Diagnostics.const_enum_member_initializers_must_be_constant_expressions); } else if (member.parent.flags & NodeFlags.Ambient) { error(initializer, Diagnostics.In_ambient_enum_declarations_member_initializer_must_be_constant_expression); } else { checkTypeAssignableTo(checkExpression(initializer), numberType, initializer, Diagnostics.Type_0_is_not_assignable_to_type_1_as_required_for_computed_enum_member_values); } return value; } function evaluate(expr: Expression, location: Declaration): string | number | undefined { switch (expr.kind) { case SyntaxKind.PrefixUnaryExpression: const value = evaluate((expr as PrefixUnaryExpression).operand, location); if (typeof value === "number") { switch ((expr as PrefixUnaryExpression).operator) { case SyntaxKind.PlusToken: return value; case SyntaxKind.MinusToken: return -value; case SyntaxKind.TildeToken: return ~value; } } break; case SyntaxKind.BinaryExpression: const left = evaluate((expr as BinaryExpression).left, location); const right = evaluate((expr as BinaryExpression).right, location); if (typeof left === "number" && typeof right === "number") { switch ((expr as BinaryExpression).operatorToken.kind) { case SyntaxKind.BarToken: return left | right; case SyntaxKind.AmpersandToken: return left & right; case SyntaxKind.GreaterThanGreaterThanToken: return left >> right; case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: return left >>> right; case SyntaxKind.LessThanLessThanToken: return left << right; case SyntaxKind.CaretToken: return left ^ right; case SyntaxKind.AsteriskToken: return left * right; case SyntaxKind.SlashToken: return left / right; case SyntaxKind.PlusToken: return left + right; case SyntaxKind.MinusToken: return left - right; case SyntaxKind.PercentToken: return left % right; case SyntaxKind.AsteriskAsteriskToken: return left ** right; } } else if ((typeof left === "string" || typeof left === "number") && (typeof right === "string" || typeof right === "number") && (expr as BinaryExpression).operatorToken.kind === SyntaxKind.PlusToken) { return "" + left + right; } break; case SyntaxKind.StringLiteral: case SyntaxKind.NoSubstitutionTemplateLiteral: return (expr as StringLiteralLike).text; case SyntaxKind.TemplateExpression: return evaluateTemplateExpression(expr as TemplateExpression, location); case SyntaxKind.NumericLiteral: checkGrammarNumericLiteral(expr as NumericLiteral); return +(expr as NumericLiteral).text; case SyntaxKind.ParenthesizedExpression: return evaluate((expr as ParenthesizedExpression).expression, location); case SyntaxKind.Identifier: if (isInfinityOrNaNString((expr as Identifier).escapedText)) { return +((expr as Identifier).escapedText); } // falls through case SyntaxKind.PropertyAccessExpression: if (isEntityNameExpression(expr)) { const symbol = resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true); if (symbol) { if (symbol.flags & SymbolFlags.EnumMember) { return evaluateEnumMember(expr, symbol, location); } if (isConstVariable(symbol)) { const declaration = symbol.valueDeclaration as VariableDeclaration | undefined; if (declaration && !declaration.type && declaration.initializer && declaration !== location && isBlockScopedNameDeclaredBeforeUse(declaration, location)) { return evaluate(declaration.initializer, declaration); } } } } break; case SyntaxKind.ElementAccessExpression: const root = (expr as ElementAccessExpression).expression; if (isEntityNameExpression(root) && isStringLiteralLike((expr as ElementAccessExpression).argumentExpression)) { const rootSymbol = resolveEntityName(root, SymbolFlags.Value, /*ignoreErrors*/ true); if (rootSymbol && rootSymbol.flags & SymbolFlags.Enum) { const name = escapeLeadingUnderscores(((expr as ElementAccessExpression).argumentExpression as StringLiteralLike).text); const member = rootSymbol.exports!.get(name); if (member) { return evaluateEnumMember(expr, member, location); } } } break; } return undefined; } function evaluateEnumMember(expr: Expression, symbol: Symbol, location: Declaration) { const declaration = symbol.valueDeclaration; if (!declaration || declaration === location) { error(expr, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(symbol)); return undefined; } if (!isBlockScopedNameDeclaredBeforeUse(declaration, location)) { error(expr, Diagnostics.A_member_initializer_in_a_enum_declaration_cannot_reference_members_declared_after_it_including_members_defined_in_other_enums); return 0; } return getEnumMemberValue(declaration as EnumMember); } function evaluateTemplateExpression(expr: TemplateExpression, location: Declaration) { let result = expr.head.text; for (const span of expr.templateSpans) { const value = evaluate(span.expression, location); if (value === undefined) { return undefined; } result += value; result += span.literal.text; } return result; } function checkEnumDeclaration(node: EnumDeclaration) { addLazyDiagnostic(() => checkEnumDeclarationWorker(node)); } function checkEnumDeclarationWorker(node: EnumDeclaration) { // Grammar checking checkGrammarModifiers(node); checkCollisionsForDeclarationName(node, node.name); checkExportsOnMergedDeclarations(node); node.members.forEach(checkEnumMember); computeEnumMemberValues(node); // Spec 2014 - Section 9.3: // It isn't possible for one enum declaration to continue the automatic numbering sequence of another, // and when an enum type has multiple declarations, only one declaration is permitted to omit a value // for the first member. // // Only perform this check once per symbol const enumSymbol = getSymbolOfDeclaration(node); const firstDeclaration = getDeclarationOfKind(enumSymbol, node.kind); if (node === firstDeclaration) { if (enumSymbol.declarations && enumSymbol.declarations.length > 1) { const enumIsConst = isEnumConst(node); // check that const is placed\omitted on all enum declarations forEach(enumSymbol.declarations, decl => { if (isEnumDeclaration(decl) && isEnumConst(decl) !== enumIsConst) { error(getNameOfDeclaration(decl), Diagnostics.Enum_declarations_must_all_be_const_or_non_const); } }); } let seenEnumMissingInitialInitializer = false; forEach(enumSymbol.declarations, declaration => { // return true if we hit a violation of the rule, false otherwise if (declaration.kind !== SyntaxKind.EnumDeclaration) { return false; } const enumDeclaration = declaration as EnumDeclaration; if (!enumDeclaration.members.length) { return false; } const firstEnumMember = enumDeclaration.members[0]; if (!firstEnumMember.initializer) { if (seenEnumMissingInitialInitializer) { error(firstEnumMember.name, Diagnostics.In_an_enum_with_multiple_declarations_only_one_declaration_can_omit_an_initializer_for_its_first_enum_element); } else { seenEnumMissingInitialInitializer = true; } } }); } } function checkEnumMember(node: EnumMember) { if (isPrivateIdentifier(node.name)) { error(node, Diagnostics.An_enum_member_cannot_be_named_with_a_private_identifier); } if (node.initializer) { checkExpression(node.initializer); } } function getFirstNonAmbientClassOrFunctionDeclaration(symbol: Symbol): Declaration | undefined { const declarations = symbol.declarations; if (declarations) { for (const declaration of declarations) { if ((declaration.kind === SyntaxKind.ClassDeclaration || (declaration.kind === SyntaxKind.FunctionDeclaration && nodeIsPresent((declaration as FunctionLikeDeclaration).body))) && !(declaration.flags & NodeFlags.Ambient)) { return declaration; } } } return undefined; } function inSameLexicalScope(node1: Node, node2: Node) { const container1 = getEnclosingBlockScopeContainer(node1); const container2 = getEnclosingBlockScopeContainer(node2); if (isGlobalSourceFile(container1)) { return isGlobalSourceFile(container2); } else if (isGlobalSourceFile(container2)) { return false; } else { return container1 === container2; } } function checkModuleDeclaration(node: ModuleDeclaration) { if (node.body) { checkSourceElement(node.body); if (!isGlobalScopeAugmentation(node)) { registerForUnusedIdentifiersCheck(node); } } addLazyDiagnostic(checkModuleDeclarationDiagnostics); function checkModuleDeclarationDiagnostics() { // Grammar checking const isGlobalAugmentation = isGlobalScopeAugmentation(node); const inAmbientContext = node.flags & NodeFlags.Ambient; if (isGlobalAugmentation && !inAmbientContext) { error(node.name, Diagnostics.Augmentations_for_the_global_scope_should_have_declare_modifier_unless_they_appear_in_already_ambient_context); } const isAmbientExternalModule: boolean = isAmbientModule(node); const contextErrorMessage = isAmbientExternalModule ? Diagnostics.An_ambient_module_declaration_is_only_allowed_at_the_top_level_in_a_file : Diagnostics.A_namespace_declaration_is_only_allowed_at_the_top_level_of_a_namespace_or_module; if (checkGrammarModuleElementContext(node, contextErrorMessage)) { // If we hit a module declaration in an illegal context, just bail out to avoid cascading errors. return; } if (!checkGrammarModifiers(node)) { if (!inAmbientContext && node.name.kind === SyntaxKind.StringLiteral) { grammarErrorOnNode(node.name, Diagnostics.Only_ambient_modules_can_use_quoted_names); } } if (isIdentifier(node.name)) { checkCollisionsForDeclarationName(node, node.name); } checkExportsOnMergedDeclarations(node); const symbol = getSymbolOfDeclaration(node); // The following checks only apply on a non-ambient instantiated module declaration. if (symbol.flags & SymbolFlags.ValueModule && !inAmbientContext && isInstantiatedModule(node, shouldPreserveConstEnums(compilerOptions)) ) { if (getIsolatedModules(compilerOptions) && !getSourceFileOfNode(node).externalModuleIndicator) { // This could be loosened a little if needed. The only problem we are trying to avoid is unqualified // references to namespace members declared in other files. But use of namespaces is discouraged anyway, // so for now we will just not allow them in scripts, which is the only place they can merge cross-file. error(node.name, Diagnostics.Namespaces_are_not_allowed_in_global_script_files_when_0_is_enabled_If_this_file_is_not_intended_to_be_a_global_script_set_moduleDetection_to_force_or_add_an_empty_export_statement, isolatedModulesLikeFlagName); } if (symbol.declarations?.length! > 1) { const firstNonAmbientClassOrFunc = getFirstNonAmbientClassOrFunctionDeclaration(symbol); if (firstNonAmbientClassOrFunc) { if (getSourceFileOfNode(node) !== getSourceFileOfNode(firstNonAmbientClassOrFunc)) { error(node.name, Diagnostics.A_namespace_declaration_cannot_be_in_a_different_file_from_a_class_or_function_with_which_it_is_merged); } else if (node.pos < firstNonAmbientClassOrFunc.pos) { error(node.name, Diagnostics.A_namespace_declaration_cannot_be_located_prior_to_a_class_or_function_with_which_it_is_merged); } } // if the module merges with a class declaration in the same lexical scope, // we need to track this to ensure the correct emit. const mergedClass = getDeclarationOfKind(symbol, SyntaxKind.ClassDeclaration); if (mergedClass && inSameLexicalScope(node, mergedClass)) { getNodeLinks(node).flags |= NodeCheckFlags.LexicalModuleMergesWithClass; } } if (compilerOptions.verbatimModuleSyntax && node.parent.kind === SyntaxKind.SourceFile && (moduleKind === ModuleKind.CommonJS || node.parent.impliedNodeFormat === ModuleKind.CommonJS) ) { const exportModifier = node.modifiers?.find(m => m.kind === SyntaxKind.ExportKeyword); if (exportModifier) { error(exportModifier, Diagnostics.A_top_level_export_modifier_cannot_be_used_on_value_declarations_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); } } } if (isAmbientExternalModule) { if (isExternalModuleAugmentation(node)) { // body of the augmentation should be checked for consistency only if augmentation was applied to its target (either global scope or module) // otherwise we'll be swamped in cascading errors. // We can detect if augmentation was applied using following rules: // - augmentation for a global scope is always applied // - augmentation for some external module is applied if symbol for augmentation is merged (it was combined with target module). const checkBody = isGlobalAugmentation || (getSymbolOfDeclaration(node).flags & SymbolFlags.Transient); if (checkBody && node.body) { for (const statement of node.body.statements) { checkModuleAugmentationElement(statement, isGlobalAugmentation); } } } else if (isGlobalSourceFile(node.parent)) { if (isGlobalAugmentation) { error(node.name, Diagnostics.Augmentations_for_the_global_scope_can_only_be_directly_nested_in_external_modules_or_ambient_module_declarations); } else if (isExternalModuleNameRelative(getTextOfIdentifierOrLiteral(node.name))) { error(node.name, Diagnostics.Ambient_module_declaration_cannot_specify_relative_module_name); } } else { if (isGlobalAugmentation) { error(node.name, Diagnostics.Augmentations_for_the_global_scope_can_only_be_directly_nested_in_external_modules_or_ambient_module_declarations); } else { // Node is not an augmentation and is not located on the script level. // This means that this is declaration of ambient module that is located in other module or namespace which is prohibited. error(node.name, Diagnostics.Ambient_modules_cannot_be_nested_in_other_modules_or_namespaces); } } } } } function checkModuleAugmentationElement(node: Node, isGlobalAugmentation: boolean): void { switch (node.kind) { case SyntaxKind.VariableStatement: // error each individual name in variable statement instead of marking the entire variable statement for (const decl of (node as VariableStatement).declarationList.declarations) { checkModuleAugmentationElement(decl, isGlobalAugmentation); } break; case SyntaxKind.ExportAssignment: case SyntaxKind.ExportDeclaration: grammarErrorOnFirstToken(node, Diagnostics.Exports_and_export_assignments_are_not_permitted_in_module_augmentations); break; case SyntaxKind.ImportEqualsDeclaration: case SyntaxKind.ImportDeclaration: grammarErrorOnFirstToken(node, Diagnostics.Imports_are_not_permitted_in_module_augmentations_Consider_moving_them_to_the_enclosing_external_module); break; case SyntaxKind.BindingElement: case SyntaxKind.VariableDeclaration: const name = (node as VariableDeclaration | BindingElement).name; if (isBindingPattern(name)) { for (const el of name.elements) { // mark individual names in binding pattern checkModuleAugmentationElement(el, isGlobalAugmentation); } break; } // falls through case SyntaxKind.ClassDeclaration: case SyntaxKind.EnumDeclaration: case SyntaxKind.FunctionDeclaration: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.ModuleDeclaration: case SyntaxKind.TypeAliasDeclaration: if (isGlobalAugmentation) { return; } break; } } function getFirstNonModuleExportsIdentifier(node: EntityNameOrEntityNameExpression): Identifier { switch (node.kind) { case SyntaxKind.Identifier: return node; case SyntaxKind.QualifiedName: do { node = node.left; } while (node.kind !== SyntaxKind.Identifier); return node; case SyntaxKind.PropertyAccessExpression: do { if (isModuleExportsAccessExpression(node.expression) && !isPrivateIdentifier(node.name)) { return node.name; } node = node.expression; } while (node.kind !== SyntaxKind.Identifier); return node; } } function checkExternalImportOrExportDeclaration(node: ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration): boolean { const moduleName = getExternalModuleName(node); if (!moduleName || nodeIsMissing(moduleName)) { // Should be a parse error. return false; } if (!isStringLiteral(moduleName)) { error(moduleName, Diagnostics.String_literal_expected); return false; } const inAmbientExternalModule = node.parent.kind === SyntaxKind.ModuleBlock && isAmbientModule(node.parent.parent); if (node.parent.kind !== SyntaxKind.SourceFile && !inAmbientExternalModule) { error(moduleName, node.kind === SyntaxKind.ExportDeclaration ? Diagnostics.Export_declarations_are_not_permitted_in_a_namespace : Diagnostics.Import_declarations_in_a_namespace_cannot_reference_a_module); return false; } if (inAmbientExternalModule && isExternalModuleNameRelative(moduleName.text)) { // we have already reported errors on top level imports/exports in external module augmentations in checkModuleDeclaration // no need to do this again. if (!isTopLevelInExternalModuleAugmentation(node)) { // TypeScript 1.0 spec (April 2013): 12.1.6 // An ExternalImportDeclaration in an AmbientExternalModuleDeclaration may reference // other external modules only through top - level external module names. // Relative external module names are not permitted. error(node, Diagnostics.Import_or_export_declaration_in_an_ambient_module_declaration_cannot_reference_module_through_relative_module_name); return false; } } if (!isImportEqualsDeclaration(node) && node.assertClause) { let hasError = false; for (const clause of node.assertClause.elements) { if (!isStringLiteral(clause.value)) { hasError = true; error(clause.value, Diagnostics.Import_assertion_values_must_be_string_literal_expressions); } } return !hasError; } return true; } function checkAliasSymbol(node: AliasDeclarationNode) { let symbol = getSymbolOfDeclaration(node); const target = resolveAlias(symbol); if (target !== unknownSymbol) { // For external modules, `symbol` represents the local symbol for an alias. // This local symbol will merge any other local declarations (excluding other aliases) // and symbol.flags will contains combined representation for all merged declaration. // Based on symbol.flags we can compute a set of excluded meanings (meaning that resolved alias should not have, // otherwise it will conflict with some local declaration). Note that in addition to normal flags we include matching SymbolFlags.Export* // in order to prevent collisions with declarations that were exported from the current module (they still contribute to local names). symbol = getMergedSymbol(symbol.exportSymbol || symbol); // A type-only import/export will already have a grammar error in a JS file, so no need to issue more errors within if (isInJSFile(node) && !(target.flags & SymbolFlags.Value) && !isTypeOnlyImportOrExportDeclaration(node)) { const errorNode = isImportOrExportSpecifier(node) ? node.propertyName || node.name : isNamedDeclaration(node) ? node.name : node; Debug.assert(node.kind !== SyntaxKind.NamespaceExport); if (node.kind === SyntaxKind.ExportSpecifier) { const diag = error(errorNode, Diagnostics.Types_cannot_appear_in_export_declarations_in_JavaScript_files); const alreadyExportedSymbol = getSourceFileOfNode(node).symbol?.exports?.get((node.propertyName || node.name).escapedText); if (alreadyExportedSymbol === target) { const exportingDeclaration = alreadyExportedSymbol.declarations?.find(isJSDocNode); if (exportingDeclaration) { addRelatedInfo(diag, createDiagnosticForNode( exportingDeclaration, Diagnostics._0_is_automatically_exported_here, unescapeLeadingUnderscores(alreadyExportedSymbol.escapedName))); } } } else { Debug.assert(node.kind !== SyntaxKind.VariableDeclaration); const importDeclaration = findAncestor(node, or(isImportDeclaration, isImportEqualsDeclaration)); const moduleSpecifier = (importDeclaration && tryGetModuleSpecifierFromDeclaration(importDeclaration)?.text) ?? "..."; const importedIdentifier = unescapeLeadingUnderscores(isIdentifier(errorNode) ? errorNode.escapedText : symbol.escapedName); error( errorNode, Diagnostics._0_is_a_type_and_cannot_be_imported_in_JavaScript_files_Use_1_in_a_JSDoc_type_annotation, importedIdentifier, `import("${moduleSpecifier}").${importedIdentifier}`); } return; } const targetFlags = getAllSymbolFlags(target); const excludedMeanings = (symbol.flags & (SymbolFlags.Value | SymbolFlags.ExportValue) ? SymbolFlags.Value : 0) | (symbol.flags & SymbolFlags.Type ? SymbolFlags.Type : 0) | (symbol.flags & SymbolFlags.Namespace ? SymbolFlags.Namespace : 0); if (targetFlags & excludedMeanings) { const message = node.kind === SyntaxKind.ExportSpecifier ? Diagnostics.Export_declaration_conflicts_with_exported_declaration_of_0 : Diagnostics.Import_declaration_conflicts_with_local_declaration_of_0; error(node, message, symbolToString(symbol)); } if (getIsolatedModules(compilerOptions) && !isTypeOnlyImportOrExportDeclaration(node) && !(node.flags & NodeFlags.Ambient)) { const typeOnlyAlias = getTypeOnlyAliasDeclaration(symbol); const isType = !(targetFlags & SymbolFlags.Value); if (isType || typeOnlyAlias) { switch (node.kind) { case SyntaxKind.ImportClause: case SyntaxKind.ImportSpecifier: case SyntaxKind.ImportEqualsDeclaration: { if (compilerOptions.preserveValueImports || compilerOptions.verbatimModuleSyntax) { Debug.assertIsDefined(node.name, "An ImportClause with a symbol should have a name"); const message = compilerOptions.verbatimModuleSyntax && isInternalModuleImportEqualsDeclaration(node) ? Diagnostics.An_import_alias_cannot_resolve_to_a_type_or_type_only_declaration_when_verbatimModuleSyntax_is_enabled : isType ? compilerOptions.verbatimModuleSyntax ? Diagnostics._0_is_a_type_and_must_be_imported_using_a_type_only_import_when_verbatimModuleSyntax_is_enabled : Diagnostics._0_is_a_type_and_must_be_imported_using_a_type_only_import_when_preserveValueImports_and_isolatedModules_are_both_enabled : compilerOptions.verbatimModuleSyntax ? Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_imported_using_a_type_only_import_when_verbatimModuleSyntax_is_enabled : Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_imported_using_a_type_only_import_when_preserveValueImports_and_isolatedModules_are_both_enabled; const name = idText(node.kind === SyntaxKind.ImportSpecifier ? node.propertyName || node.name : node.name); addTypeOnlyDeclarationRelatedInfo( error(node, message, name), isType ? undefined : typeOnlyAlias, name ); } if (isType && node.kind === SyntaxKind.ImportEqualsDeclaration && hasEffectiveModifier(node, ModifierFlags.Export)) { error(node, Diagnostics.Cannot_use_export_import_on_a_type_or_type_only_namespace_when_0_is_enabled, isolatedModulesLikeFlagName); } break; } case SyntaxKind.ExportSpecifier: { // Don't allow re-exporting an export that will be elided when `--isolatedModules` is set. // The exception is that `import type { A } from './a'; export { A }` is allowed // because single-file analysis can determine that the export should be dropped. if (compilerOptions.verbatimModuleSyntax || getSourceFileOfNode(typeOnlyAlias) !== getSourceFileOfNode(node)) { const name = idText(node.propertyName || node.name); const diagnostic = isType ? error(node, Diagnostics.Re_exporting_a_type_when_0_is_enabled_requires_using_export_type, isolatedModulesLikeFlagName) : error(node, Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_re_exported_using_a_type_only_re_export_when_1_is_enabled, name, isolatedModulesLikeFlagName); addTypeOnlyDeclarationRelatedInfo(diagnostic, isType ? undefined : typeOnlyAlias, name); break; } } } } if (compilerOptions.verbatimModuleSyntax && node.kind !== SyntaxKind.ImportEqualsDeclaration && !isInJSFile(node) && (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) ) { error(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); } } if (isImportSpecifier(node)) { const targetSymbol = checkDeprecatedAliasedSymbol(symbol, node); if (isDeprecatedAliasedSymbol(targetSymbol) && targetSymbol.declarations) { addDeprecatedSuggestion(node, targetSymbol.declarations, targetSymbol.escapedName as string); } } } } function isDeprecatedAliasedSymbol(symbol: Symbol) { return !!symbol.declarations && every(symbol.declarations, d => !!(getCombinedNodeFlags(d) & NodeFlags.Deprecated)); } function checkDeprecatedAliasedSymbol(symbol: Symbol, location: Node) { if (!(symbol.flags & SymbolFlags.Alias)) return symbol; const targetSymbol = resolveAlias(symbol); if (targetSymbol === unknownSymbol) return targetSymbol; while (symbol.flags & SymbolFlags.Alias) { const target = getImmediateAliasedSymbol(symbol); if (target) { if (target === targetSymbol) break; if (target.declarations && length(target.declarations)) { if (isDeprecatedAliasedSymbol(target)) { addDeprecatedSuggestion(location, target.declarations, target.escapedName as string); break; } else { if (symbol === targetSymbol) break; symbol = target; } } } else { break; } } return targetSymbol; } function checkImportBinding(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportSpecifier) { checkCollisionsForDeclarationName(node, node.name); checkAliasSymbol(node); if (node.kind === SyntaxKind.ImportSpecifier && idText(node.propertyName || node.name) === "default" && getESModuleInterop(compilerOptions) && moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportDefault); } } function checkAssertClause(declaration: ImportDeclaration | ExportDeclaration) { if (declaration.assertClause) { const validForTypeAssertions = isExclusivelyTypeOnlyImportOrExport(declaration); const override = getResolutionModeOverrideForClause(declaration.assertClause, validForTypeAssertions ? grammarErrorOnNode : undefined); if (validForTypeAssertions && override) { if (!isNightly()) { grammarErrorOnNode(declaration.assertClause, Diagnostics.resolution_mode_assertions_are_unstable_Use_nightly_TypeScript_to_silence_this_error_Try_updating_with_npm_install_D_typescript_next); } if (getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Node16 && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.NodeNext) { return grammarErrorOnNode(declaration.assertClause, Diagnostics.resolution_mode_assertions_are_only_supported_when_moduleResolution_is_node16_or_nodenext); } return; // Other grammar checks do not apply to type-only imports with resolution mode assertions } const mode = (moduleKind === ModuleKind.NodeNext) && declaration.moduleSpecifier && getUsageModeForExpression(declaration.moduleSpecifier); if (mode !== ModuleKind.ESNext && moduleKind !== ModuleKind.ESNext) { return grammarErrorOnNode(declaration.assertClause, moduleKind === ModuleKind.NodeNext ? Diagnostics.Import_assertions_are_not_allowed_on_statements_that_transpile_to_commonjs_require_calls : Diagnostics.Import_assertions_are_only_supported_when_the_module_option_is_set_to_esnext_or_nodenext); } if (isImportDeclaration(declaration) ? declaration.importClause?.isTypeOnly : declaration.isTypeOnly) { return grammarErrorOnNode(declaration.assertClause, Diagnostics.Import_assertions_cannot_be_used_with_type_only_imports_or_exports); } if (override) { return grammarErrorOnNode(declaration.assertClause, Diagnostics.resolution_mode_can_only_be_set_for_type_only_imports); } } } function checkImportDeclaration(node: ImportDeclaration) { if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors. return; } if (!checkGrammarModifiers(node) && hasEffectiveModifiers(node)) { grammarErrorOnFirstToken(node, Diagnostics.An_import_declaration_cannot_have_modifiers); } if (checkExternalImportOrExportDeclaration(node)) { const importClause = node.importClause; if (importClause && !checkGrammarImportClause(importClause)) { if (importClause.name) { checkImportBinding(importClause); } if (importClause.namedBindings) { if (importClause.namedBindings.kind === SyntaxKind.NamespaceImport) { checkImportBinding(importClause.namedBindings); if (moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && getESModuleInterop(compilerOptions)) { // import * as ns from "foo"; checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportStar); } } else { const moduleExisted = resolveExternalModuleName(node, node.moduleSpecifier); if (moduleExisted) { forEach(importClause.namedBindings.elements, checkImportBinding); } } } } } checkAssertClause(node); } function checkImportEqualsDeclaration(node: ImportEqualsDeclaration) { if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors. return; } checkGrammarModifiers(node); if (isInternalModuleImportEqualsDeclaration(node) || checkExternalImportOrExportDeclaration(node)) { checkImportBinding(node); if (hasSyntacticModifier(node, ModifierFlags.Export)) { markExportAsReferenced(node); } if (node.moduleReference.kind !== SyntaxKind.ExternalModuleReference) { const target = resolveAlias(getSymbolOfDeclaration(node)); if (target !== unknownSymbol) { const targetFlags = getAllSymbolFlags(target); if (targetFlags & SymbolFlags.Value) { // Target is a value symbol, check that it is not hidden by a local declaration with the same name const moduleName = getFirstIdentifier(node.moduleReference); if (!(resolveEntityName(moduleName, SymbolFlags.Value | SymbolFlags.Namespace)!.flags & SymbolFlags.Namespace)) { error(moduleName, Diagnostics.Module_0_is_hidden_by_a_local_declaration_with_the_same_name, declarationNameToString(moduleName)); } } if (targetFlags & SymbolFlags.Type) { checkTypeNameIsReserved(node.name, Diagnostics.Import_name_cannot_be_0); } } if (node.isTypeOnly) { grammarErrorOnNode(node, Diagnostics.An_import_alias_cannot_use_import_type); } } else { if (moduleKind >= ModuleKind.ES2015 && getSourceFileOfNode(node).impliedNodeFormat === undefined && !node.isTypeOnly && !(node.flags & NodeFlags.Ambient)) { // Import equals declaration is deprecated in es6 or above grammarErrorOnNode(node, Diagnostics.Import_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead); } } } } function checkExportDeclaration(node: ExportDeclaration) { if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_export_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_export_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { // If we hit an export in an illegal context, just bail out to avoid cascading errors. return; } if (!checkGrammarModifiers(node) && hasSyntacticModifiers(node)) { grammarErrorOnFirstToken(node, Diagnostics.An_export_declaration_cannot_have_modifiers); } if (node.moduleSpecifier && node.exportClause && isNamedExports(node.exportClause) && length(node.exportClause.elements) && languageVersion === ScriptTarget.ES3) { checkExternalEmitHelpers(node, ExternalEmitHelpers.CreateBinding); } checkGrammarExportDeclaration(node); if (!node.moduleSpecifier || checkExternalImportOrExportDeclaration(node)) { if (node.exportClause && !isNamespaceExport(node.exportClause)) { // export { x, y } // export { x, y } from "foo" forEach(node.exportClause.elements, checkExportSpecifier); const inAmbientExternalModule = node.parent.kind === SyntaxKind.ModuleBlock && isAmbientModule(node.parent.parent); const inAmbientNamespaceDeclaration = !inAmbientExternalModule && node.parent.kind === SyntaxKind.ModuleBlock && !node.moduleSpecifier && node.flags & NodeFlags.Ambient; if (node.parent.kind !== SyntaxKind.SourceFile && !inAmbientExternalModule && !inAmbientNamespaceDeclaration) { error(node, Diagnostics.Export_declarations_are_not_permitted_in_a_namespace); } } else { // export * from "foo" // export * as ns from "foo"; const moduleSymbol = resolveExternalModuleName(node, node.moduleSpecifier!); if (moduleSymbol && hasExportAssignmentSymbol(moduleSymbol)) { error(node.moduleSpecifier, Diagnostics.Module_0_uses_export_and_cannot_be_used_with_export_Asterisk, symbolToString(moduleSymbol)); } else if (node.exportClause) { checkAliasSymbol(node.exportClause); } if (moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { if (node.exportClause) { // export * as ns from "foo"; // For ES2015 modules, we emit it as a pair of `import * as a_1 ...; export { a_1 as ns }` and don't need the helper. // We only use the helper here when in esModuleInterop if (getESModuleInterop(compilerOptions)) { checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportStar); } } else { // export * from "foo" checkExternalEmitHelpers(node, ExternalEmitHelpers.ExportStar); } } } } checkAssertClause(node); } function checkGrammarExportDeclaration(node: ExportDeclaration): boolean { if (node.isTypeOnly && node.exportClause?.kind === SyntaxKind.NamedExports) { return checkGrammarNamedImportsOrExports(node.exportClause); } return false; } function checkGrammarModuleElementContext(node: Statement, errorMessage: DiagnosticMessage): boolean { const isInAppropriateContext = node.parent.kind === SyntaxKind.SourceFile || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.ModuleDeclaration; if (!isInAppropriateContext) { grammarErrorOnFirstToken(node, errorMessage); } return !isInAppropriateContext; } function importClauseContainsReferencedImport(importClause: ImportClause) { return forEachImportClauseDeclaration(importClause, declaration => { return !!getSymbolOfDeclaration(declaration).isReferenced; }); } function importClauseContainsConstEnumUsedAsValue(importClause: ImportClause) { return forEachImportClauseDeclaration(importClause, declaration => { return !!getSymbolLinks(getSymbolOfDeclaration(declaration)).constEnumReferenced; }); } function canConvertImportDeclarationToTypeOnly(statement: Statement) { return isImportDeclaration(statement) && statement.importClause && !statement.importClause.isTypeOnly && importClauseContainsReferencedImport(statement.importClause) && !isReferencedAliasDeclaration(statement.importClause, /*checkChildren*/ true) && !importClauseContainsConstEnumUsedAsValue(statement.importClause); } function canConvertImportEqualsDeclarationToTypeOnly(statement: Statement) { return isImportEqualsDeclaration(statement) && isExternalModuleReference(statement.moduleReference) && !statement.isTypeOnly && getSymbolOfDeclaration(statement).isReferenced && !isReferencedAliasDeclaration(statement, /*checkChildren*/ false) && !getSymbolLinks(getSymbolOfDeclaration(statement)).constEnumReferenced; } function checkImportsForTypeOnlyConversion(sourceFile: SourceFile) { for (const statement of sourceFile.statements) { if (canConvertImportDeclarationToTypeOnly(statement) || canConvertImportEqualsDeclarationToTypeOnly(statement)) { error( statement, Diagnostics.This_import_is_never_used_as_a_value_and_must_use_import_type_because_importsNotUsedAsValues_is_set_to_error); } } } function checkExportSpecifier(node: ExportSpecifier) { checkAliasSymbol(node); if (getEmitDeclarations(compilerOptions)) { collectLinkedAliases(node.propertyName || node.name, /*setVisibility*/ true); } if (!node.parent.parent.moduleSpecifier) { const exportedName = node.propertyName || node.name; // find immediate value referenced by exported name (SymbolFlags.Alias is set so we don't chase down aliases) const symbol = resolveName(exportedName, exportedName.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ true); if (symbol && (symbol === undefinedSymbol || symbol === globalThisSymbol || symbol.declarations && isGlobalSourceFile(getDeclarationContainer(symbol.declarations[0])))) { error(exportedName, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, idText(exportedName)); } else { if (!node.isTypeOnly && !node.parent.parent.isTypeOnly) { markExportAsReferenced(node); } const target = symbol && (symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol); if (!target || getAllSymbolFlags(target) & SymbolFlags.Value) { checkExpressionCached(node.propertyName || node.name); } } } else { if (getESModuleInterop(compilerOptions) && moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && idText(node.propertyName || node.name) === "default") { checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportDefault); } } } function checkExportAssignment(node: ExportAssignment) { const illegalContextMessage = node.isExportEquals ? Diagnostics.An_export_assignment_must_be_at_the_top_level_of_a_file_or_module_declaration : Diagnostics.A_default_export_must_be_at_the_top_level_of_a_file_or_module_declaration; if (checkGrammarModuleElementContext(node, illegalContextMessage)) { // If we hit an export assignment in an illegal context, just bail out to avoid cascading errors. return; } const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent as ModuleDeclaration; if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) { if (node.isExportEquals) { error(node, Diagnostics.An_export_assignment_cannot_be_used_in_a_namespace); } else { error(node, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module); } return; } // Grammar checking if (!checkGrammarModifiers(node) && hasEffectiveModifiers(node)) { grammarErrorOnFirstToken(node, Diagnostics.An_export_assignment_cannot_have_modifiers); } const typeAnnotationNode = getEffectiveTypeAnnotationNode(node); if (typeAnnotationNode) { checkTypeAssignableTo(checkExpressionCached(node.expression), getTypeFromTypeNode(typeAnnotationNode), node.expression); } const isIllegalExportDefaultInCJS = !node.isExportEquals && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax && (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS); if (node.expression.kind === SyntaxKind.Identifier) { const id = node.expression as Identifier; const sym = getExportSymbolOfValueSymbolIfExported(resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, node)); if (sym) { markAliasReferenced(sym, id); // If not a value, we're interpreting the identifier as a type export, along the lines of (`export { Id as default }`) if (getAllSymbolFlags(sym) & SymbolFlags.Value) { // However if it is a value, we need to check it's being used correctly checkExpressionCached(id); if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax && getTypeOnlyAliasDeclaration(sym, SymbolFlags.Value)) { error(id, node.isExportEquals ? Diagnostics.An_export_declaration_must_reference_a_real_value_when_verbatimModuleSyntax_is_enabled_but_0_resolves_to_a_type_only_declaration : Diagnostics.An_export_default_must_reference_a_real_value_when_verbatimModuleSyntax_is_enabled_but_0_resolves_to_a_type_only_declaration, idText(id)); } } else if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax) { error(id, node.isExportEquals ? Diagnostics.An_export_declaration_must_reference_a_value_when_verbatimModuleSyntax_is_enabled_but_0_only_refers_to_a_type : Diagnostics.An_export_default_must_reference_a_value_when_verbatimModuleSyntax_is_enabled_but_0_only_refers_to_a_type, idText(id)); } } else { checkExpressionCached(id); // doesn't resolve, check as expression to mark as error } if (getEmitDeclarations(compilerOptions)) { collectLinkedAliases(id, /*setVisibility*/ true); } } else { checkExpressionCached(node.expression); } if (isIllegalExportDefaultInCJS) { error(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); } checkExternalModuleExports(container); if ((node.flags & NodeFlags.Ambient) && !isEntityNameExpression(node.expression)) { grammarErrorOnNode(node.expression, Diagnostics.The_expression_of_an_export_assignment_must_be_an_identifier_or_qualified_name_in_an_ambient_context); } if (node.isExportEquals) { // Forbid export= in esm implementation files, and esm mode declaration files if (moduleKind >= ModuleKind.ES2015 && ((node.flags & NodeFlags.Ambient && getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.ESNext) || (!(node.flags & NodeFlags.Ambient) && getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.CommonJS))) { // export assignment is not supported in es6 modules grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_export_default_or_another_module_format_instead); } else if (moduleKind === ModuleKind.System && !(node.flags & NodeFlags.Ambient)) { // system modules does not support export assignment grammarErrorOnNode(node, Diagnostics.Export_assignment_is_not_supported_when_module_flag_is_system); } } } function hasExportedMembers(moduleSymbol: Symbol) { return forEachEntry(moduleSymbol.exports!, (_, id) => id !== "export="); } function checkExternalModuleExports(node: SourceFile | ModuleDeclaration) { const moduleSymbol = getSymbolOfDeclaration(node); const links = getSymbolLinks(moduleSymbol); if (!links.exportsChecked) { const exportEqualsSymbol = moduleSymbol.exports!.get("export=" as __String); if (exportEqualsSymbol && hasExportedMembers(moduleSymbol)) { const declaration = getDeclarationOfAliasSymbol(exportEqualsSymbol) || exportEqualsSymbol.valueDeclaration; if (declaration && !isTopLevelInExternalModuleAugmentation(declaration) && !isInJSFile(declaration)) { error(declaration, Diagnostics.An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements); } } // Checks for export * conflicts const exports = getExportsOfModule(moduleSymbol); if (exports) { exports.forEach(({ declarations, flags }, id) => { if (id === "__export") { return; } // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. // (TS Exceptions: namespaces, function overloads, enums, and interfaces) if (flags & (SymbolFlags.Namespace | SymbolFlags.Enum)) { return; } const exportedDeclarationsCount = countWhere(declarations, and(isNotOverloadAndNotAccessor, not(isInterfaceDeclaration))); if (flags & SymbolFlags.TypeAlias && exportedDeclarationsCount <= 2) { // it is legal to merge type alias with other values // so count should be either 1 (just type alias) or 2 (type alias + merged value) return; } if (exportedDeclarationsCount > 1) { if (!isDuplicatedCommonJSExport(declarations)) { for (const declaration of declarations!) { if (isNotOverload(declaration)) { diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Cannot_redeclare_exported_variable_0, unescapeLeadingUnderscores(id))); } } } } }); } links.exportsChecked = true; } } function isDuplicatedCommonJSExport(declarations: Declaration[] | undefined) { return declarations && declarations.length > 1 && declarations.every(d => isInJSFile(d) && isAccessExpression(d) && (isExportsIdentifier(d.expression) || isModuleExportsAccessExpression(d.expression))); } function checkSourceElement(node: Node | undefined): void { if (node) { const saveCurrentNode = currentNode; currentNode = node; instantiationCount = 0; checkSourceElementWorker(node); currentNode = saveCurrentNode; } } function checkSourceElementWorker(node: Node): void { if (canHaveJSDoc(node)) { forEach(node.jsDoc, ({ comment, tags }) => { checkJSDocCommentWorker(comment); forEach(tags, tag => { checkJSDocCommentWorker(tag.comment); if (isInJSFile(node)) { checkSourceElement(tag); } }); }); } const kind = node.kind; if (cancellationToken) { // Only bother checking on a few construct kinds. We don't want to be excessively // hitting the cancellation token on every node we check. switch (kind) { case SyntaxKind.ModuleDeclaration: case SyntaxKind.ClassDeclaration: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.FunctionDeclaration: cancellationToken.throwIfCancellationRequested(); } } if (kind >= SyntaxKind.FirstStatement && kind <= SyntaxKind.LastStatement && canHaveFlowNode(node) && node.flowNode && !isReachableFlowNode(node.flowNode)) { errorOrSuggestion(compilerOptions.allowUnreachableCode === false, node, Diagnostics.Unreachable_code_detected); } switch (kind) { case SyntaxKind.TypeParameter: return checkTypeParameter(node as TypeParameterDeclaration); case SyntaxKind.Parameter: return checkParameter(node as ParameterDeclaration); case SyntaxKind.PropertyDeclaration: return checkPropertyDeclaration(node as PropertyDeclaration); case SyntaxKind.PropertySignature: return checkPropertySignature(node as PropertySignature); case SyntaxKind.ConstructorType: case SyntaxKind.FunctionType: case SyntaxKind.CallSignature: case SyntaxKind.ConstructSignature: case SyntaxKind.IndexSignature: return checkSignatureDeclaration(node as SignatureDeclaration); case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: return checkMethodDeclaration(node as MethodDeclaration | MethodSignature); case SyntaxKind.ClassStaticBlockDeclaration: return checkClassStaticBlockDeclaration(node as ClassStaticBlockDeclaration); case SyntaxKind.Constructor: return checkConstructorDeclaration(node as ConstructorDeclaration); case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: return checkAccessorDeclaration(node as AccessorDeclaration); case SyntaxKind.TypeReference: return checkTypeReferenceNode(node as TypeReferenceNode); case SyntaxKind.TypePredicate: return checkTypePredicate(node as TypePredicateNode); case SyntaxKind.TypeQuery: return checkTypeQuery(node as TypeQueryNode); case SyntaxKind.TypeLiteral: return checkTypeLiteral(node as TypeLiteralNode); case SyntaxKind.ArrayType: return checkArrayType(node as ArrayTypeNode); case SyntaxKind.TupleType: return checkTupleType(node as TupleTypeNode); case SyntaxKind.UnionType: case SyntaxKind.IntersectionType: return checkUnionOrIntersectionType(node as UnionOrIntersectionTypeNode); case SyntaxKind.ParenthesizedType: case SyntaxKind.OptionalType: case SyntaxKind.RestType: return checkSourceElement((node as ParenthesizedTypeNode | OptionalTypeNode | RestTypeNode).type); case SyntaxKind.ThisType: return checkThisType(node as ThisTypeNode); case SyntaxKind.TypeOperator: return checkTypeOperator(node as TypeOperatorNode); case SyntaxKind.ConditionalType: return checkConditionalType(node as ConditionalTypeNode); case SyntaxKind.InferType: return checkInferType(node as InferTypeNode); case SyntaxKind.TemplateLiteralType: return checkTemplateLiteralType(node as TemplateLiteralTypeNode); case SyntaxKind.ImportType: return checkImportType(node as ImportTypeNode); case SyntaxKind.NamedTupleMember: return checkNamedTupleMember(node as NamedTupleMember); case SyntaxKind.JSDocAugmentsTag: return checkJSDocAugmentsTag(node as JSDocAugmentsTag); case SyntaxKind.JSDocImplementsTag: return checkJSDocImplementsTag(node as JSDocImplementsTag); case SyntaxKind.JSDocTypedefTag: case SyntaxKind.JSDocCallbackTag: case SyntaxKind.JSDocEnumTag: return checkJSDocTypeAliasTag(node as JSDocTypedefTag); case SyntaxKind.JSDocTemplateTag: return checkJSDocTemplateTag(node as JSDocTemplateTag); case SyntaxKind.JSDocTypeTag: return checkJSDocTypeTag(node as JSDocTypeTag); case SyntaxKind.JSDocLink: case SyntaxKind.JSDocLinkCode: case SyntaxKind.JSDocLinkPlain: return checkJSDocLinkLikeTag(node as JSDocLink | JSDocLinkCode | JSDocLinkPlain); case SyntaxKind.JSDocParameterTag: return checkJSDocParameterTag(node as JSDocParameterTag); case SyntaxKind.JSDocPropertyTag: return checkJSDocPropertyTag(node as JSDocPropertyTag); case SyntaxKind.JSDocFunctionType: checkJSDocFunctionType(node as JSDocFunctionType); // falls through case SyntaxKind.JSDocNonNullableType: case SyntaxKind.JSDocNullableType: case SyntaxKind.JSDocAllType: case SyntaxKind.JSDocUnknownType: case SyntaxKind.JSDocTypeLiteral: checkJSDocTypeIsInJsFile(node); forEachChild(node, checkSourceElement); return; case SyntaxKind.JSDocVariadicType: checkJSDocVariadicType(node as JSDocVariadicType); return; case SyntaxKind.JSDocTypeExpression: return checkSourceElement((node as JSDocTypeExpression).type); case SyntaxKind.JSDocPublicTag: case SyntaxKind.JSDocProtectedTag: case SyntaxKind.JSDocPrivateTag: return checkJSDocAccessibilityModifiers(node as JSDocPublicTag | JSDocProtectedTag | JSDocPrivateTag); case SyntaxKind.JSDocSatisfiesTag: return checkJSDocSatisfiesTag(node as JSDocSatisfiesTag); case SyntaxKind.IndexedAccessType: return checkIndexedAccessType(node as IndexedAccessTypeNode); case SyntaxKind.MappedType: return checkMappedType(node as MappedTypeNode); case SyntaxKind.FunctionDeclaration: return checkFunctionDeclaration(node as FunctionDeclaration); case SyntaxKind.Block: case SyntaxKind.ModuleBlock: return checkBlock(node as Block); case SyntaxKind.VariableStatement: return checkVariableStatement(node as VariableStatement); case SyntaxKind.ExpressionStatement: return checkExpressionStatement(node as ExpressionStatement); case SyntaxKind.IfStatement: return checkIfStatement(node as IfStatement); case SyntaxKind.DoStatement: return checkDoStatement(node as DoStatement); case SyntaxKind.WhileStatement: return checkWhileStatement(node as WhileStatement); case SyntaxKind.ForStatement: return checkForStatement(node as ForStatement); case SyntaxKind.ForInStatement: return checkForInStatement(node as ForInStatement); case SyntaxKind.ForOfStatement: return checkForOfStatement(node as ForOfStatement); case SyntaxKind.ContinueStatement: case SyntaxKind.BreakStatement: return checkBreakOrContinueStatement(node as BreakOrContinueStatement); case SyntaxKind.ReturnStatement: return checkReturnStatement(node as ReturnStatement); case SyntaxKind.WithStatement: return checkWithStatement(node as WithStatement); case SyntaxKind.SwitchStatement: return checkSwitchStatement(node as SwitchStatement); case SyntaxKind.LabeledStatement: return checkLabeledStatement(node as LabeledStatement); case SyntaxKind.ThrowStatement: return checkThrowStatement(node as ThrowStatement); case SyntaxKind.TryStatement: return checkTryStatement(node as TryStatement); case SyntaxKind.VariableDeclaration: return checkVariableDeclaration(node as VariableDeclaration); case SyntaxKind.BindingElement: return checkBindingElement(node as BindingElement); case SyntaxKind.ClassDeclaration: return checkClassDeclaration(node as ClassDeclaration); case SyntaxKind.InterfaceDeclaration: return checkInterfaceDeclaration(node as InterfaceDeclaration); case SyntaxKind.TypeAliasDeclaration: return checkTypeAliasDeclaration(node as TypeAliasDeclaration); case SyntaxKind.EnumDeclaration: return checkEnumDeclaration(node as EnumDeclaration); case SyntaxKind.ModuleDeclaration: return checkModuleDeclaration(node as ModuleDeclaration); case SyntaxKind.ImportDeclaration: return checkImportDeclaration(node as ImportDeclaration); case SyntaxKind.ImportEqualsDeclaration: return checkImportEqualsDeclaration(node as ImportEqualsDeclaration); case SyntaxKind.ExportDeclaration: return checkExportDeclaration(node as ExportDeclaration); case SyntaxKind.ExportAssignment: return checkExportAssignment(node as ExportAssignment); case SyntaxKind.EmptyStatement: case SyntaxKind.DebuggerStatement: checkGrammarStatementInAmbientContext(node); return; case SyntaxKind.MissingDeclaration: return checkMissingDeclaration(node); } } function checkJSDocCommentWorker(node: string | readonly JSDocComment[] | undefined) { if (isArray(node)) { forEach(node, tag => { if (isJSDocLinkLike(tag)) { checkSourceElement(tag); } }); } } function checkJSDocTypeIsInJsFile(node: Node): void { if (!isInJSFile(node)) { if (isJSDocNonNullableType(node) || isJSDocNullableType(node)) { const token = tokenToString(isJSDocNonNullableType(node) ? SyntaxKind.ExclamationToken : SyntaxKind.QuestionToken); const diagnostic = node.postfix ? Diagnostics._0_at_the_end_of_a_type_is_not_valid_TypeScript_syntax_Did_you_mean_to_write_1 : Diagnostics._0_at_the_start_of_a_type_is_not_valid_TypeScript_syntax_Did_you_mean_to_write_1; const typeNode = node.type; const type = getTypeFromTypeNode(typeNode); grammarErrorOnNode(node, diagnostic, token, typeToString( isJSDocNullableType(node) && !(type === neverType || type === voidType) ? getUnionType(append([type, undefinedType], node.postfix ? undefined : nullType)) : type)); } else { grammarErrorOnNode(node, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); } } } function checkJSDocVariadicType(node: JSDocVariadicType): void { checkJSDocTypeIsInJsFile(node); checkSourceElement(node.type); // Only legal location is in the *last* parameter tag or last parameter of a JSDoc function. const { parent } = node; if (isParameter(parent) && isJSDocFunctionType(parent.parent)) { if (last(parent.parent.parameters) !== parent) { error(node, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); } return; } if (!isJSDocTypeExpression(parent)) { error(node, Diagnostics.JSDoc_may_only_appear_in_the_last_parameter_of_a_signature); } const paramTag = node.parent.parent; if (!isJSDocParameterTag(paramTag)) { error(node, Diagnostics.JSDoc_may_only_appear_in_the_last_parameter_of_a_signature); return; } const param = getParameterSymbolFromJSDoc(paramTag); if (!param) { // We will error in `checkJSDocParameterTag`. return; } const host = getHostSignatureFromJSDoc(paramTag); if (!host || last(host.parameters).symbol !== param) { error(node, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); } } function getTypeFromJSDocVariadicType(node: JSDocVariadicType): Type { const type = getTypeFromTypeNode(node.type); const { parent } = node; const paramTag = node.parent.parent; if (isJSDocTypeExpression(node.parent) && isJSDocParameterTag(paramTag)) { // Else we will add a diagnostic, see `checkJSDocVariadicType`. const host = getHostSignatureFromJSDoc(paramTag); const isCallbackTag = isJSDocCallbackTag(paramTag.parent.parent); if (host || isCallbackTag) { /* Only return an array type if the corresponding parameter is marked as a rest parameter, or if there are no parameters. So in the following situation we will not create an array type: /** @param {...number} a * / function f(a) {} Because `a` will just be of type `number | undefined`. A synthetic `...args` will also be added, which *will* get an array type. */ const lastParamDeclaration = isCallbackTag ? lastOrUndefined((paramTag.parent.parent as unknown as JSDocCallbackTag).typeExpression.parameters) : lastOrUndefined(host!.parameters); const symbol = getParameterSymbolFromJSDoc(paramTag); if (!lastParamDeclaration || symbol && lastParamDeclaration.symbol === symbol && isRestParameter(lastParamDeclaration)) { return createArrayType(type); } } } if (isParameter(parent) && isJSDocFunctionType(parent.parent)) { return createArrayType(type); } return addOptionality(type); } // Function and class expression bodies are checked after all statements in the enclosing body. This is // to ensure constructs like the following are permitted: // const foo = function () { // const s = foo(); // return "hello"; // } // Here, performing a full type check of the body of the function expression whilst in the process of // determining the type of foo would cause foo to be given type any because of the recursive reference. // Delaying the type check of the body ensures foo has been assigned a type. function checkNodeDeferred(node: Node) { const enclosingFile = getSourceFileOfNode(node); const links = getNodeLinks(enclosingFile); if (!(links.flags & NodeCheckFlags.TypeChecked)) { links.deferredNodes ||= new Set(); links.deferredNodes.add(node); } else { Debug.assert(!links.deferredNodes, "A type-checked file should have no deferred nodes."); } } function checkDeferredNodes(context: SourceFile) { const links = getNodeLinks(context); if (links.deferredNodes) { links.deferredNodes.forEach(checkDeferredNode); } links.deferredNodes = undefined; } function checkDeferredNode(node: Node) { tracing?.push(tracing.Phase.Check, "checkDeferredNode", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); const saveCurrentNode = currentNode; currentNode = node; instantiationCount = 0; switch (node.kind) { case SyntaxKind.CallExpression: case SyntaxKind.NewExpression: case SyntaxKind.TaggedTemplateExpression: case SyntaxKind.Decorator: case SyntaxKind.JsxOpeningElement: // These node kinds are deferred checked when overload resolution fails // To save on work, we ensure the arguments are checked just once, in // a deferred way resolveUntypedCall(node as CallLikeExpression); break; case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: checkFunctionExpressionOrObjectLiteralMethodDeferred(node as FunctionExpression); break; case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: checkAccessorDeclaration(node as AccessorDeclaration); break; case SyntaxKind.ClassExpression: checkClassExpressionDeferred(node as ClassExpression); break; case SyntaxKind.TypeParameter: checkTypeParameterDeferred(node as TypeParameterDeclaration); break; case SyntaxKind.JsxSelfClosingElement: checkJsxSelfClosingElementDeferred(node as JsxSelfClosingElement); break; case SyntaxKind.JsxElement: checkJsxElementDeferred(node as JsxElement); break; } currentNode = saveCurrentNode; tracing?.pop(); } function checkSourceFile(node: SourceFile) { tracing?.push(tracing.Phase.Check, "checkSourceFile", { path: node.path }, /*separateBeginAndEnd*/ true); performance.mark("beforeCheck"); checkSourceFileWorker(node); performance.mark("afterCheck"); performance.measure("Check", "beforeCheck", "afterCheck"); tracing?.pop(); } function unusedIsError(kind: UnusedKind, isAmbient: boolean): boolean { if (isAmbient) { return false; } switch (kind) { case UnusedKind.Local: return !!compilerOptions.noUnusedLocals; case UnusedKind.Parameter: return !!compilerOptions.noUnusedParameters; default: return Debug.assertNever(kind); } } function getPotentiallyUnusedIdentifiers(sourceFile: SourceFile): readonly PotentiallyUnusedIdentifier[] { return allPotentiallyUnusedIdentifiers.get(sourceFile.path) || emptyArray; } // Fully type check a source file and collect the relevant diagnostics. function checkSourceFileWorker(node: SourceFile) { const links = getNodeLinks(node); if (!(links.flags & NodeCheckFlags.TypeChecked)) { if (skipTypeChecking(node, compilerOptions, host)) { return; } // Grammar checking checkGrammarSourceFile(node); clear(potentialThisCollisions); clear(potentialNewTargetCollisions); clear(potentialWeakMapSetCollisions); clear(potentialReflectCollisions); clear(potentialUnusedRenamedBindingElementsInTypes); forEach(node.statements, checkSourceElement); checkSourceElement(node.endOfFileToken); checkDeferredNodes(node); if (isExternalOrCommonJsModule(node)) { registerForUnusedIdentifiersCheck(node); } addLazyDiagnostic(() => { // This relies on the results of other lazy diagnostics, so must be computed after them if (!node.isDeclarationFile && (compilerOptions.noUnusedLocals || compilerOptions.noUnusedParameters)) { checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(node), (containingNode, kind, diag) => { if (!containsParseError(containingNode) && unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { diagnostics.add(diag); } }); } if (!node.isDeclarationFile) { checkPotentialUncheckedRenamedBindingElementsInTypes(); } }); if (compilerOptions.importsNotUsedAsValues === ImportsNotUsedAsValues.Error && !node.isDeclarationFile && isExternalModule(node) ) { checkImportsForTypeOnlyConversion(node); } if (isExternalOrCommonJsModule(node)) { checkExternalModuleExports(node); } if (potentialThisCollisions.length) { forEach(potentialThisCollisions, checkIfThisIsCapturedInEnclosingScope); clear(potentialThisCollisions); } if (potentialNewTargetCollisions.length) { forEach(potentialNewTargetCollisions, checkIfNewTargetIsCapturedInEnclosingScope); clear(potentialNewTargetCollisions); } if (potentialWeakMapSetCollisions.length) { forEach(potentialWeakMapSetCollisions, checkWeakMapSetCollision); clear(potentialWeakMapSetCollisions); } if (potentialReflectCollisions.length) { forEach(potentialReflectCollisions, checkReflectCollision); clear(potentialReflectCollisions); } links.flags |= NodeCheckFlags.TypeChecked; } } function getDiagnostics(sourceFile: SourceFile, ct: CancellationToken): Diagnostic[] { try { // Record the cancellation token so it can be checked later on during checkSourceElement. // Do this in a finally block so we can ensure that it gets reset back to nothing after // this call is done. cancellationToken = ct; return getDiagnosticsWorker(sourceFile); } finally { cancellationToken = undefined; } } function ensurePendingDiagnosticWorkComplete() { // Invoke any existing lazy diagnostics to add them, clear the backlog of diagnostics for (const cb of deferredDiagnosticsCallbacks) { cb(); } deferredDiagnosticsCallbacks = []; } function checkSourceFileWithEagerDiagnostics(sourceFile: SourceFile) { ensurePendingDiagnosticWorkComplete(); // then setup diagnostics for immediate invocation (as we are about to collect them, and // this avoids the overhead of longer-lived callbacks we don't need to allocate) // This also serves to make the shift to possibly lazy diagnostics transparent to serial command-line scenarios // (as in those cases, all the diagnostics will still be computed as the appropriate place in the tree, // thus much more likely retaining the same union ordering as before we had lazy diagnostics) const oldAddLazyDiagnostics = addLazyDiagnostic; addLazyDiagnostic = cb => cb(); checkSourceFile(sourceFile); addLazyDiagnostic = oldAddLazyDiagnostics; } function getDiagnosticsWorker(sourceFile: SourceFile): Diagnostic[] { if (sourceFile) { ensurePendingDiagnosticWorkComplete(); // Some global diagnostics are deferred until they are needed and // may not be reported in the first call to getGlobalDiagnostics. // We should catch these changes and report them. const previousGlobalDiagnostics = diagnostics.getGlobalDiagnostics(); const previousGlobalDiagnosticsSize = previousGlobalDiagnostics.length; checkSourceFileWithEagerDiagnostics(sourceFile); const semanticDiagnostics = diagnostics.getDiagnostics(sourceFile.fileName); const currentGlobalDiagnostics = diagnostics.getGlobalDiagnostics(); if (currentGlobalDiagnostics !== previousGlobalDiagnostics) { // If the arrays are not the same reference, new diagnostics were added. const deferredGlobalDiagnostics = relativeComplement(previousGlobalDiagnostics, currentGlobalDiagnostics, compareDiagnostics); return concatenate(deferredGlobalDiagnostics, semanticDiagnostics); } else if (previousGlobalDiagnosticsSize === 0 && currentGlobalDiagnostics.length > 0) { // If the arrays are the same reference, but the length has changed, a single // new diagnostic was added as DiagnosticCollection attempts to reuse the // same array. return concatenate(currentGlobalDiagnostics, semanticDiagnostics); } return semanticDiagnostics; } // Global diagnostics are always added when a file is not provided to // getDiagnostics forEach(host.getSourceFiles(), checkSourceFileWithEagerDiagnostics); return diagnostics.getDiagnostics(); } function getGlobalDiagnostics(): Diagnostic[] { ensurePendingDiagnosticWorkComplete(); return diagnostics.getGlobalDiagnostics(); } // Language service support function getSymbolsInScope(location: Node, meaning: SymbolFlags): Symbol[] { if (location.flags & NodeFlags.InWithStatement) { // We cannot answer semantic questions within a with block, do not proceed any further return []; } const symbols = createSymbolTable(); let isStaticSymbol = false; populateSymbols(); symbols.delete(InternalSymbolName.This); // Not a symbol, a keyword return symbolsToArray(symbols); function populateSymbols() { while (location) { if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { copySymbols(location.locals, meaning); } switch (location.kind) { case SyntaxKind.SourceFile: if (!isExternalModule(location as SourceFile)) break; // falls through case SyntaxKind.ModuleDeclaration: copyLocallyVisibleExportSymbols(getSymbolOfDeclaration(location as ModuleDeclaration | SourceFile).exports!, meaning & SymbolFlags.ModuleMember); break; case SyntaxKind.EnumDeclaration: copySymbols(getSymbolOfDeclaration(location as EnumDeclaration).exports!, meaning & SymbolFlags.EnumMember); break; case SyntaxKind.ClassExpression: const className = (location as ClassExpression).name; if (className) { copySymbol((location as ClassExpression).symbol, meaning); } // this fall-through is necessary because we would like to handle // type parameter inside class expression similar to how we handle it in classDeclaration and interface Declaration. // falls through case SyntaxKind.ClassDeclaration: case SyntaxKind.InterfaceDeclaration: // If we didn't come from static member of class or interface, // add the type parameters into the symbol table // (type parameters of classDeclaration/classExpression and interface are in member property of the symbol. // Note: that the memberFlags come from previous iteration. if (!isStaticSymbol) { copySymbols(getMembersOfSymbol(getSymbolOfDeclaration(location as ClassDeclaration | InterfaceDeclaration)), meaning & SymbolFlags.Type); } break; case SyntaxKind.FunctionExpression: const funcName = (location as FunctionExpression).name; if (funcName) { copySymbol((location as FunctionExpression).symbol, meaning); } break; } if (introducesArgumentsExoticObject(location)) { copySymbol(argumentsSymbol, meaning); } isStaticSymbol = isStatic(location); location = location.parent; } copySymbols(globals, meaning); } /** * Copy the given symbol into symbol tables if the symbol has the given meaning * and it doesn't already existed in the symbol table * @param key a key for storing in symbol table; if undefined, use symbol.name * @param symbol the symbol to be added into symbol table * @param meaning meaning of symbol to filter by before adding to symbol table */ function copySymbol(symbol: Symbol, meaning: SymbolFlags): void { if (getCombinedLocalAndExportSymbolFlags(symbol) & meaning) { const id = symbol.escapedName; // We will copy all symbol regardless of its reserved name because // symbolsToArray will check whether the key is a reserved name and // it will not copy symbol with reserved name to the array if (!symbols.has(id)) { symbols.set(id, symbol); } } } function copySymbols(source: SymbolTable, meaning: SymbolFlags): void { if (meaning) { source.forEach(symbol => { copySymbol(symbol, meaning); }); } } function copyLocallyVisibleExportSymbols(source: SymbolTable, meaning: SymbolFlags): void { if (meaning) { source.forEach(symbol => { // Similar condition as in `resolveNameHelper` if (!getDeclarationOfKind(symbol, SyntaxKind.ExportSpecifier) && !getDeclarationOfKind(symbol, SyntaxKind.NamespaceExport)) { copySymbol(symbol, meaning); } }); } } } function isTypeDeclarationName(name: Node): boolean { return name.kind === SyntaxKind.Identifier && isTypeDeclaration(name.parent) && getNameOfDeclaration(name.parent) === name; } // True if the given identifier is part of a type reference function isTypeReferenceIdentifier(node: EntityName): boolean { while (node.parent.kind === SyntaxKind.QualifiedName) { node = node.parent as QualifiedName; } return node.parent.kind === SyntaxKind.TypeReference; } function isInNameOfExpressionWithTypeArguments(node: Node): boolean { while (node.parent.kind === SyntaxKind.PropertyAccessExpression) { node = node.parent; } return node.parent.kind === SyntaxKind.ExpressionWithTypeArguments; } function forEachEnclosingClass(node: Node, callback: (node: ClassLikeDeclaration) => T | undefined): T | undefined { let result: T | undefined; let containingClass = getContainingClass(node); while (containingClass) { if (result = callback(containingClass)) break; containingClass = getContainingClass(containingClass); } return result; } function isNodeUsedDuringClassInitialization(node: Node) { return !!findAncestor(node, element => { if (isConstructorDeclaration(element) && nodeIsPresent(element.body) || isPropertyDeclaration(element)) { return true; } else if (isClassLike(element) || isFunctionLikeDeclaration(element)) { return "quit"; } return false; }); } function isNodeWithinClass(node: Node, classDeclaration: ClassLikeDeclaration) { return !!forEachEnclosingClass(node, n => n === classDeclaration); } function getLeftSideOfImportEqualsOrExportAssignment(nodeOnRightSide: EntityName): ImportEqualsDeclaration | ExportAssignment | undefined { while (nodeOnRightSide.parent.kind === SyntaxKind.QualifiedName) { nodeOnRightSide = nodeOnRightSide.parent as QualifiedName; } if (nodeOnRightSide.parent.kind === SyntaxKind.ImportEqualsDeclaration) { return (nodeOnRightSide.parent as ImportEqualsDeclaration).moduleReference === nodeOnRightSide ? nodeOnRightSide.parent as ImportEqualsDeclaration : undefined; } if (nodeOnRightSide.parent.kind === SyntaxKind.ExportAssignment) { return (nodeOnRightSide.parent as ExportAssignment).expression === nodeOnRightSide as Node ? nodeOnRightSide.parent as ExportAssignment : undefined; } return undefined; } function isInRightSideOfImportOrExportAssignment(node: EntityName) { return getLeftSideOfImportEqualsOrExportAssignment(node) !== undefined; } function getSpecialPropertyAssignmentSymbolFromEntityName(entityName: EntityName | PropertyAccessExpression) { const specialPropertyAssignmentKind = getAssignmentDeclarationKind(entityName.parent.parent as BinaryExpression); switch (specialPropertyAssignmentKind) { case AssignmentDeclarationKind.ExportsProperty: case AssignmentDeclarationKind.PrototypeProperty: return getSymbolOfNode(entityName.parent); case AssignmentDeclarationKind.ThisProperty: case AssignmentDeclarationKind.ModuleExports: case AssignmentDeclarationKind.Property: return getSymbolOfDeclaration(entityName.parent.parent as BinaryExpression); } } function isImportTypeQualifierPart(node: EntityName): ImportTypeNode | undefined { let parent = node.parent; while (isQualifiedName(parent)) { node = parent; parent = parent.parent; } if (parent && parent.kind === SyntaxKind.ImportType && (parent as ImportTypeNode).qualifier === node) { return parent as ImportTypeNode; } return undefined; } function getSymbolOfNameOrPropertyAccessExpression(name: EntityName | PrivateIdentifier | PropertyAccessExpression | JSDocMemberName): Symbol | undefined { if (isDeclarationName(name)) { return getSymbolOfNode(name.parent); } if (isInJSFile(name) && name.parent.kind === SyntaxKind.PropertyAccessExpression && name.parent === (name.parent.parent as BinaryExpression).left) { // Check if this is a special property assignment if (!isPrivateIdentifier(name) && !isJSDocMemberName(name)) { const specialPropertyAssignmentSymbol = getSpecialPropertyAssignmentSymbolFromEntityName(name); if (specialPropertyAssignmentSymbol) { return specialPropertyAssignmentSymbol; } } } if (name.parent.kind === SyntaxKind.ExportAssignment && isEntityNameExpression(name)) { // Even an entity name expression that doesn't resolve as an entityname may still typecheck as a property access expression const success = resolveEntityName(name, /*all meanings*/ SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*ignoreErrors*/ true); if (success && success !== unknownSymbol) { return success; } } else if (isEntityName(name) && isInRightSideOfImportOrExportAssignment(name)) { // Since we already checked for ExportAssignment, this really could only be an Import const importEqualsDeclaration = getAncestor(name, SyntaxKind.ImportEqualsDeclaration); Debug.assert(importEqualsDeclaration !== undefined); return getSymbolOfPartOfRightHandSideOfImportEquals(name, /*dontResolveAlias*/ true); } if (isEntityName(name)) { const possibleImportNode = isImportTypeQualifierPart(name); if (possibleImportNode) { getTypeFromTypeNode(possibleImportNode); const sym = getNodeLinks(name).resolvedSymbol; return sym === unknownSymbol ? undefined : sym; } } while (isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName(name)) { name = name.parent as QualifiedName | PropertyAccessEntityNameExpression | JSDocMemberName; } if (isInNameOfExpressionWithTypeArguments(name)) { let meaning = SymbolFlags.None; if (name.parent.kind === SyntaxKind.ExpressionWithTypeArguments) { // An 'ExpressionWithTypeArguments' may appear in type space (interface Foo extends Bar), // value space (return foo), or both(class Foo extends Bar); ensure the meaning matches. meaning = isPartOfTypeNode(name) ? SymbolFlags.Type : SymbolFlags.Value; // In a class 'extends' clause we are also looking for a value. if (isExpressionWithTypeArgumentsInClassExtendsClause(name.parent)) { meaning |= SymbolFlags.Value; } } else { meaning = SymbolFlags.Namespace; } meaning |= SymbolFlags.Alias; const entityNameSymbol = isEntityNameExpression(name) ? resolveEntityName(name, meaning) : undefined; if (entityNameSymbol) { return entityNameSymbol; } } if (name.parent.kind === SyntaxKind.JSDocParameterTag) { return getParameterSymbolFromJSDoc(name.parent as JSDocParameterTag); } if (name.parent.kind === SyntaxKind.TypeParameter && name.parent.parent.kind === SyntaxKind.JSDocTemplateTag) { Debug.assert(!isInJSFile(name)); // Otherwise `isDeclarationName` would have been true. const typeParameter = getTypeParameterFromJsDoc(name.parent as TypeParameterDeclaration & { parent: JSDocTemplateTag }); return typeParameter && typeParameter.symbol; } if (isExpressionNode(name)) { if (nodeIsMissing(name)) { // Missing entity name. return undefined; } const isJSDoc = findAncestor(name, or(isJSDocLinkLike, isJSDocNameReference, isJSDocMemberName)); const meaning = isJSDoc ? SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value : SymbolFlags.Value; if (name.kind === SyntaxKind.Identifier) { if (isJSXTagName(name) && isJsxIntrinsicIdentifier(name)) { const symbol = getIntrinsicTagSymbol(name.parent as JsxOpeningLikeElement); return symbol === unknownSymbol ? undefined : symbol; } const result = resolveEntityName(name, meaning, /*ignoreErrors*/ false, /* dontResolveAlias */ true, getHostSignatureFromJSDoc(name)); if (!result && isJSDoc) { const container = findAncestor(name, or(isClassLike, isInterfaceDeclaration)); if (container) { return resolveJSDocMemberName(name, /*ignoreErrors*/ false, getSymbolOfDeclaration(container)); } } if (result && isJSDoc) { const container = getJSDocHost(name); if (container && isEnumMember(container) && container === result.valueDeclaration) { return resolveEntityName(name, meaning, /*ignoreErrors*/ true, /* dontResolveAlias */ true, getSourceFileOfNode(container)) || result; } } return result; } else if (isPrivateIdentifier(name)) { return getSymbolForPrivateIdentifierExpression(name); } else if (name.kind === SyntaxKind.PropertyAccessExpression || name.kind === SyntaxKind.QualifiedName) { const links = getNodeLinks(name); if (links.resolvedSymbol) { return links.resolvedSymbol; } if (name.kind === SyntaxKind.PropertyAccessExpression) { checkPropertyAccessExpression(name, CheckMode.Normal); if (!links.resolvedSymbol) { const expressionType = checkExpressionCached(name.expression); const infos = getApplicableIndexInfos(expressionType, getLiteralTypeFromPropertyName(name.name)); if (infos.length && (expressionType as ObjectType).members) { const resolved = resolveStructuredTypeMembers(expressionType as ObjectType); const symbol = resolved.members.get(InternalSymbolName.Index); if (infos === getIndexInfosOfType(expressionType)) { links.resolvedSymbol = symbol; } else if (symbol) { const symbolLinks = getSymbolLinks(symbol); const declarationList = mapDefined(infos, i => i.declaration); const nodeListId = map(declarationList, getNodeId).join(","); if (!symbolLinks.filteredIndexSymbolCache) { symbolLinks.filteredIndexSymbolCache = new Map(); } if (symbolLinks.filteredIndexSymbolCache.has(nodeListId)) { links.resolvedSymbol = symbolLinks.filteredIndexSymbolCache.get(nodeListId)!; } else { const copy = createSymbol(SymbolFlags.Signature, InternalSymbolName.Index); copy.declarations = mapDefined(infos, i => i.declaration); copy.parent = expressionType.aliasSymbol ? expressionType.aliasSymbol : expressionType.symbol ? expressionType.symbol : getSymbolAtLocation(copy.declarations[0].parent); symbolLinks.filteredIndexSymbolCache.set(nodeListId, copy); links.resolvedSymbol = symbolLinks.filteredIndexSymbolCache.get(nodeListId)!; } } } } } else { checkQualifiedName(name, CheckMode.Normal); } if (!links.resolvedSymbol && isJSDoc && isQualifiedName(name)) { return resolveJSDocMemberName(name); } return links.resolvedSymbol; } else if (isJSDocMemberName(name)) { return resolveJSDocMemberName(name); } } else if (isTypeReferenceIdentifier(name as EntityName)) { const meaning = name.parent.kind === SyntaxKind.TypeReference ? SymbolFlags.Type : SymbolFlags.Namespace; const symbol = resolveEntityName(name as EntityName, meaning, /*ignoreErrors*/ false, /*dontResolveAlias*/ true); return symbol && symbol !== unknownSymbol ? symbol : getUnresolvedSymbolForEntityName(name as EntityName); } if (name.parent.kind === SyntaxKind.TypePredicate) { return resolveEntityName(name as Identifier, /*meaning*/ SymbolFlags.FunctionScopedVariable); } return undefined; } /** * Recursively resolve entity names and jsdoc instance references: * 1. K#m as K.prototype.m for a class (or other value) K * 2. K.m as K.prototype.m * 3. I.m as I.m for a type I, or any other I.m that fails to resolve in (1) or (2) * * For unqualified names, a container K may be provided as a second argument. */ function resolveJSDocMemberName(name: EntityName | JSDocMemberName, ignoreErrors?: boolean, container?: Symbol): Symbol | undefined { if (isEntityName(name)) { // resolve static values first const meaning = SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value; let symbol = resolveEntityName(name, meaning, ignoreErrors, /*dontResolveAlias*/ true, getHostSignatureFromJSDoc(name)); if (!symbol && isIdentifier(name) && container) { symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(container), name.escapedText, meaning)); } if (symbol) { return symbol; } } const left = isIdentifier(name) ? container : resolveJSDocMemberName(name.left, ignoreErrors, container); const right = isIdentifier(name) ? name.escapedText : name.right.escapedText; if (left) { const proto = left.flags & SymbolFlags.Value && getPropertyOfType(getTypeOfSymbol(left), "prototype" as __String); const t = proto ? getTypeOfSymbol(proto) : getDeclaredTypeOfSymbol(left); return getPropertyOfType(t, right); } } function getSymbolAtLocation(node: Node, ignoreErrors?: boolean): Symbol | undefined { if (isSourceFile(node)) { return isExternalModule(node) ? getMergedSymbol(node.symbol) : undefined; } const { parent } = node; const grandParent = parent.parent; if (node.flags & NodeFlags.InWithStatement) { // We cannot answer semantic questions within a with block, do not proceed any further return undefined; } if (isDeclarationNameOrImportPropertyName(node)) { // This is a declaration, call getSymbolOfNode const parentSymbol = getSymbolOfDeclaration(parent as Declaration)!; return isImportOrExportSpecifier(node.parent) && node.parent.propertyName === node ? getImmediateAliasedSymbol(parentSymbol) : parentSymbol; } else if (isLiteralComputedPropertyDeclarationName(node)) { return getSymbolOfDeclaration(parent.parent as Declaration); } if (node.kind === SyntaxKind.Identifier) { if (isInRightSideOfImportOrExportAssignment(node as Identifier)) { return getSymbolOfNameOrPropertyAccessExpression(node as Identifier); } else if (parent.kind === SyntaxKind.BindingElement && grandParent.kind === SyntaxKind.ObjectBindingPattern && node === (parent as BindingElement).propertyName) { const typeOfPattern = getTypeOfNode(grandParent); const propertyDeclaration = getPropertyOfType(typeOfPattern, (node as Identifier).escapedText); if (propertyDeclaration) { return propertyDeclaration; } } else if (isMetaProperty(parent) && parent.name === node) { if (parent.keywordToken === SyntaxKind.NewKeyword && idText(node as Identifier) === "target") { // `target` in `new.target` return checkNewTargetMetaProperty(parent).symbol; } // The `meta` in `import.meta` could be given `getTypeOfNode(parent).symbol` (the `ImportMeta` interface symbol), but // we have a fake expression type made for other reasons already, whose transient `meta` // member should more exactly be the kind of (declarationless) symbol we want. // (See #44364 and #45031 for relevant implementation PRs) if (parent.keywordToken === SyntaxKind.ImportKeyword && idText(node as Identifier) === "meta") { return getGlobalImportMetaExpressionType().members!.get("meta" as __String); } // no other meta properties are valid syntax, thus no others should have symbols return undefined; } } switch (node.kind) { case SyntaxKind.Identifier: case SyntaxKind.PrivateIdentifier: case SyntaxKind.PropertyAccessExpression: case SyntaxKind.QualifiedName: if (!isThisInTypeQuery(node)) { return getSymbolOfNameOrPropertyAccessExpression(node as EntityName | PrivateIdentifier | PropertyAccessExpression); } // falls through case SyntaxKind.ThisKeyword: const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); if (isFunctionLike(container)) { const sig = getSignatureFromDeclaration(container); if (sig.thisParameter) { return sig.thisParameter; } } if (isInExpressionContext(node)) { return checkExpression(node as Expression).symbol; } // falls through case SyntaxKind.ThisType: return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode).symbol; case SyntaxKind.SuperKeyword: return checkExpression(node as Expression).symbol; case SyntaxKind.ConstructorKeyword: // constructor keyword for an overload, should take us to the definition if it exist const constructorDeclaration = node.parent; if (constructorDeclaration && constructorDeclaration.kind === SyntaxKind.Constructor) { return (constructorDeclaration.parent as ClassDeclaration).symbol; } return undefined; case SyntaxKind.StringLiteral: case SyntaxKind.NoSubstitutionTemplateLiteral: // 1). import x = require("./mo/*gotToDefinitionHere*/d") // 2). External module name in an import declaration // 3). Dynamic import call or require in javascript // 4). type A = import("./f/*gotToDefinitionHere*/oo") if ((isExternalModuleImportEqualsDeclaration(node.parent.parent) && getExternalModuleImportEqualsDeclarationExpression(node.parent.parent) === node) || ((node.parent.kind === SyntaxKind.ImportDeclaration || node.parent.kind === SyntaxKind.ExportDeclaration) && (node.parent as ImportDeclaration).moduleSpecifier === node) || ((isInJSFile(node) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Bundler && isRequireCall(node.parent, /*checkArgumentIsStringLiteralLike*/ false)) || isImportCall(node.parent)) || (isLiteralTypeNode(node.parent) && isLiteralImportTypeNode(node.parent.parent) && node.parent.parent.argument === node.parent) ) { return resolveExternalModuleName(node, node as LiteralExpression, ignoreErrors); } if (isCallExpression(parent) && isBindableObjectDefinePropertyCall(parent) && parent.arguments[1] === node) { return getSymbolOfDeclaration(parent); } // falls through case SyntaxKind.NumericLiteral: // index access const objectType = isElementAccessExpression(parent) ? parent.argumentExpression === node ? getTypeOfExpression(parent.expression) : undefined : isLiteralTypeNode(parent) && isIndexedAccessTypeNode(grandParent) ? getTypeFromTypeNode(grandParent.objectType) : undefined; return objectType && getPropertyOfType(objectType, escapeLeadingUnderscores((node as StringLiteral | NumericLiteral).text)); case SyntaxKind.DefaultKeyword: case SyntaxKind.FunctionKeyword: case SyntaxKind.EqualsGreaterThanToken: case SyntaxKind.ClassKeyword: return getSymbolOfNode(node.parent); case SyntaxKind.ImportType: return isLiteralImportTypeNode(node) ? getSymbolAtLocation(node.argument.literal, ignoreErrors) : undefined; case SyntaxKind.ExportKeyword: return isExportAssignment(node.parent) ? Debug.checkDefined(node.parent.symbol) : undefined; case SyntaxKind.ImportKeyword: case SyntaxKind.NewKeyword: return isMetaProperty(node.parent) ? checkMetaPropertyKeyword(node.parent).symbol : undefined; case SyntaxKind.MetaProperty: return checkExpression(node as Expression).symbol; default: return undefined; } } function getIndexInfosAtLocation(node: Node): readonly IndexInfo[] | undefined { if (isIdentifier(node) && isPropertyAccessExpression(node.parent) && node.parent.name === node) { const keyType = getLiteralTypeFromPropertyName(node); const objectType = getTypeOfExpression(node.parent.expression); const objectTypes = objectType.flags & TypeFlags.Union ? (objectType as UnionType).types : [objectType]; return flatMap(objectTypes, t => filter(getIndexInfosOfType(t), info => isApplicableIndexType(keyType, info.keyType))); } return undefined; } function getShorthandAssignmentValueSymbol(location: Node | undefined): Symbol | undefined { if (location && location.kind === SyntaxKind.ShorthandPropertyAssignment) { return resolveEntityName((location as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Alias); } return undefined; } /** Returns the target of an export specifier without following aliases */ function getExportSpecifierLocalTargetSymbol(node: ExportSpecifier | Identifier): Symbol | undefined { if (isExportSpecifier(node)) { return node.parent.parent.moduleSpecifier ? getExternalModuleMember(node.parent.parent, node) : resolveEntityName(node.propertyName || node.name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); } else { return resolveEntityName(node, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); } } function getTypeOfNode(node: Node): Type { if (isSourceFile(node) && !isExternalModule(node)) { return errorType; } if (node.flags & NodeFlags.InWithStatement) { // We cannot answer semantic questions within a with block, do not proceed any further return errorType; } const classDecl = tryGetClassImplementingOrExtendingExpressionWithTypeArguments(node); const classType = classDecl && getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(classDecl.class)); if (isPartOfTypeNode(node)) { const typeFromTypeNode = getTypeFromTypeNode(node as TypeNode); return classType ? getTypeWithThisArgument(typeFromTypeNode, classType.thisType) : typeFromTypeNode; } if (isExpressionNode(node)) { return getRegularTypeOfExpression(node as Expression); } if (classType && !classDecl.isImplements) { // A SyntaxKind.ExpressionWithTypeArguments is considered a type node, except when it occurs in the // extends clause of a class. We handle that case here. const baseType = firstOrUndefined(getBaseTypes(classType)); return baseType ? getTypeWithThisArgument(baseType, classType.thisType) : errorType; } if (isTypeDeclaration(node)) { // In this case, we call getSymbolOfNode instead of getSymbolAtLocation because it is a declaration const symbol = getSymbolOfDeclaration(node); return getDeclaredTypeOfSymbol(symbol); } if (isTypeDeclarationName(node)) { const symbol = getSymbolAtLocation(node); return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; } if (isDeclaration(node)) { // In this case, we call getSymbolOfNode instead of getSymbolAtLocation because it is a declaration const symbol = getSymbolOfDeclaration(node); return symbol ? getTypeOfSymbol(symbol) : errorType; } if (isDeclarationNameOrImportPropertyName(node)) { const symbol = getSymbolAtLocation(node); if (symbol) { return getTypeOfSymbol(symbol); } return errorType; } if (isBindingPattern(node)) { return getTypeForVariableLikeDeclaration(node.parent, /*includeOptionality*/ true, CheckMode.Normal) || errorType; } if (isInRightSideOfImportOrExportAssignment(node as Identifier)) { const symbol = getSymbolAtLocation(node); if (symbol) { const declaredType = getDeclaredTypeOfSymbol(symbol); return !isErrorType(declaredType) ? declaredType : getTypeOfSymbol(symbol); } } if (isMetaProperty(node.parent) && node.parent.keywordToken === node.kind) { return checkMetaPropertyKeyword(node.parent); } return errorType; } // Gets the type of object literal or array literal of destructuring assignment. // { a } from // for ( { a } of elems) { // } // [ a ] from // [a] = [ some array ...] function getTypeOfAssignmentPattern(expr: AssignmentPattern): Type | undefined { Debug.assert(expr.kind === SyntaxKind.ObjectLiteralExpression || expr.kind === SyntaxKind.ArrayLiteralExpression); // If this is from "for of" // for ( { a } of elems) { // } if (expr.parent.kind === SyntaxKind.ForOfStatement) { const iteratedType = checkRightHandSideOfForOf(expr.parent as ForOfStatement); return checkDestructuringAssignment(expr, iteratedType || errorType); } // If this is from "for" initializer // for ({a } = elems[0];.....) { } if (expr.parent.kind === SyntaxKind.BinaryExpression) { const iteratedType = getTypeOfExpression((expr.parent as BinaryExpression).right); return checkDestructuringAssignment(expr, iteratedType || errorType); } // If this is from nested object binding pattern // for ({ skills: { primary, secondary } } = multiRobot, i = 0; i < 1; i++) { if (expr.parent.kind === SyntaxKind.PropertyAssignment) { const node = cast(expr.parent.parent, isObjectLiteralExpression); const typeOfParentObjectLiteral = getTypeOfAssignmentPattern(node) || errorType; const propertyIndex = indexOfNode(node.properties, expr.parent); return checkObjectLiteralDestructuringPropertyAssignment(node, typeOfParentObjectLiteral, propertyIndex); } // Array literal assignment - array destructuring pattern const node = cast(expr.parent, isArrayLiteralExpression); // [{ property1: p1, property2 }] = elems; const typeOfArrayLiteral = getTypeOfAssignmentPattern(node) || errorType; const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring, typeOfArrayLiteral, undefinedType, expr.parent) || errorType; return checkArrayLiteralDestructuringElementAssignment(node, typeOfArrayLiteral, node.elements.indexOf(expr), elementType); } // Gets the property symbol corresponding to the property in destructuring assignment // 'property1' from // for ( { property1: a } of elems) { // } // 'property1' at location 'a' from: // [a] = [ property1, property2 ] function getPropertySymbolOfDestructuringAssignment(location: Identifier) { // Get the type of the object or array literal and then look for property of given name in the type const typeOfObjectLiteral = getTypeOfAssignmentPattern(cast(location.parent.parent, isAssignmentPattern)); return typeOfObjectLiteral && getPropertyOfType(typeOfObjectLiteral, location.escapedText); } function getRegularTypeOfExpression(expr: Expression): Type { if (isRightSideOfQualifiedNameOrPropertyAccess(expr)) { expr = expr.parent as Expression; } return getRegularTypeOfLiteralType(getTypeOfExpression(expr)); } /** * Gets either the static or instance type of a class element, based on * whether the element is declared as "static". */ function getParentTypeOfClassElement(node: ClassElement) { const classSymbol = getSymbolOfNode(node.parent)!; return isStatic(node) ? getTypeOfSymbol(classSymbol) : getDeclaredTypeOfSymbol(classSymbol); } function getClassElementPropertyKeyType(element: ClassElement) { const name = element.name!; switch (name.kind) { case SyntaxKind.Identifier: return getStringLiteralType(idText(name)); case SyntaxKind.NumericLiteral: case SyntaxKind.StringLiteral: return getStringLiteralType(name.text); case SyntaxKind.ComputedPropertyName: const nameType = checkComputedPropertyName(name); return isTypeAssignableToKind(nameType, TypeFlags.ESSymbolLike) ? nameType : stringType; default: return Debug.fail("Unsupported property name."); } } // Return the list of properties of the given type, augmented with properties from Function // if the type has call or construct signatures function getAugmentedPropertiesOfType(type: Type): Symbol[] { type = getApparentType(type); const propsByName = createSymbolTable(getPropertiesOfType(type)); const functionType = getSignaturesOfType(type, SignatureKind.Call).length ? globalCallableFunctionType : getSignaturesOfType(type, SignatureKind.Construct).length ? globalNewableFunctionType : undefined; if (functionType) { forEach(getPropertiesOfType(functionType), p => { if (!propsByName.has(p.escapedName)) { propsByName.set(p.escapedName, p); } }); } return getNamedMembers(propsByName); } function typeHasCallOrConstructSignatures(type: Type): boolean { return getSignaturesOfType(type, SignatureKind.Call).length !== 0 || getSignaturesOfType(type, SignatureKind.Construct).length !== 0; } function getRootSymbols(symbol: Symbol): readonly Symbol[] { const roots = getImmediateRootSymbols(symbol); return roots ? flatMap(roots, getRootSymbols) : [symbol]; } function getImmediateRootSymbols(symbol: Symbol): readonly Symbol[] | undefined { if (getCheckFlags(symbol) & CheckFlags.Synthetic) { return mapDefined(getSymbolLinks(symbol).containingType!.types, type => getPropertyOfType(type, symbol.escapedName)); } else if (symbol.flags & SymbolFlags.Transient) { const { links: { leftSpread, rightSpread, syntheticOrigin } } = symbol as TransientSymbol; return leftSpread ? [leftSpread, rightSpread!] : syntheticOrigin ? [syntheticOrigin] : singleElementArray(tryGetTarget(symbol)); } return undefined; } function tryGetTarget(symbol: Symbol): Symbol | undefined { let target: Symbol | undefined; let next: Symbol | undefined = symbol; while (next = getSymbolLinks(next).target) { target = next; } return target; } // Emitter support function isArgumentsLocalBinding(nodeIn: Identifier): boolean { // Note: does not handle isShorthandPropertyAssignment (and probably a few more) if (isGeneratedIdentifier(nodeIn)) return false; const node = getParseTreeNode(nodeIn, isIdentifier); if (!node) return false; const parent = node.parent; if (!parent) return false; const isPropertyName = ((isPropertyAccessExpression(parent) || isPropertyAssignment(parent)) && parent.name === node); return !isPropertyName && getReferencedValueSymbol(node) === argumentsSymbol; } function moduleExportsSomeValue(moduleReferenceExpression: Expression): boolean { let moduleSymbol = resolveExternalModuleName(moduleReferenceExpression.parent, moduleReferenceExpression); if (!moduleSymbol || isShorthandAmbientModuleSymbol(moduleSymbol)) { // If the module is not found or is shorthand, assume that it may export a value. return true; } const hasExportAssignment = hasExportAssignmentSymbol(moduleSymbol); // if module has export assignment then 'resolveExternalModuleSymbol' will return resolved symbol for export assignment // otherwise it will return moduleSymbol itself moduleSymbol = resolveExternalModuleSymbol(moduleSymbol); const symbolLinks = getSymbolLinks(moduleSymbol); if (symbolLinks.exportsSomeValue === undefined) { // for export assignments - check if resolved symbol for RHS is itself a value // otherwise - check if at least one export is value symbolLinks.exportsSomeValue = hasExportAssignment ? !!(moduleSymbol.flags & SymbolFlags.Value) : forEachEntry(getExportsOfModule(moduleSymbol), isValue); } return symbolLinks.exportsSomeValue!; function isValue(s: Symbol): boolean { s = resolveSymbol(s); return s && !!(getAllSymbolFlags(s) & SymbolFlags.Value); } } function isNameOfModuleOrEnumDeclaration(node: Identifier) { return isModuleOrEnumDeclaration(node.parent) && node === node.parent.name; } // When resolved as an expression identifier, if the given node references an exported entity, return the declaration // node of the exported entity's container. Otherwise, return undefined. function getReferencedExportContainer(nodeIn: Identifier, prefixLocals?: boolean): SourceFile | ModuleDeclaration | EnumDeclaration | undefined { const node = getParseTreeNode(nodeIn, isIdentifier); if (node) { // When resolving the export container for the name of a module or enum // declaration, we need to start resolution at the declaration's container. // Otherwise, we could incorrectly resolve the export container as the // declaration if it contains an exported member with the same name. let symbol = getReferencedValueSymbol(node, /*startInDeclarationContainer*/ isNameOfModuleOrEnumDeclaration(node)); if (symbol) { if (symbol.flags & SymbolFlags.ExportValue) { // If we reference an exported entity within the same module declaration, then whether // we prefix depends on the kind of entity. SymbolFlags.ExportHasLocal encompasses all the // kinds that we do NOT prefix. const exportSymbol = getMergedSymbol(symbol.exportSymbol!); if (!prefixLocals && exportSymbol.flags & SymbolFlags.ExportHasLocal && !(exportSymbol.flags & SymbolFlags.Variable)) { return undefined; } symbol = exportSymbol; } const parentSymbol = getParentOfSymbol(symbol); if (parentSymbol) { if (parentSymbol.flags & SymbolFlags.ValueModule && parentSymbol.valueDeclaration?.kind === SyntaxKind.SourceFile) { const symbolFile = parentSymbol.valueDeclaration as SourceFile; const referenceFile = getSourceFileOfNode(node); // If `node` accesses an export and that export isn't in the same file, then symbol is a namespace export, so return undefined. const symbolIsUmdExport = symbolFile !== referenceFile; return symbolIsUmdExport ? undefined : symbolFile; } return findAncestor(node.parent, (n): n is ModuleDeclaration | EnumDeclaration => isModuleOrEnumDeclaration(n) && getSymbolOfDeclaration(n) === parentSymbol); } } } } // When resolved as an expression identifier, if the given node references an import, return the declaration of // that import. Otherwise, return undefined. function getReferencedImportDeclaration(nodeIn: Identifier): Declaration | undefined { const specifier = getIdentifierGeneratedImportReference(nodeIn); if (specifier) { return specifier; } const node = getParseTreeNode(nodeIn, isIdentifier); if (node) { const symbol = getReferencedValueOrAliasSymbol(node); // We should only get the declaration of an alias if there isn't a local value // declaration for the symbol if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !getTypeOnlyAliasDeclaration(symbol, SymbolFlags.Value)) { return getDeclarationOfAliasSymbol(symbol); } } return undefined; } function isSymbolOfDestructuredElementOfCatchBinding(symbol: Symbol) { return symbol.valueDeclaration && isBindingElement(symbol.valueDeclaration) && walkUpBindingElementsAndPatterns(symbol.valueDeclaration).parent.kind === SyntaxKind.CatchClause; } function isSymbolOfDeclarationWithCollidingName(symbol: Symbol): boolean { if (symbol.flags & SymbolFlags.BlockScoped && symbol.valueDeclaration && !isSourceFile(symbol.valueDeclaration)) { const links = getSymbolLinks(symbol); if (links.isDeclarationWithCollidingName === undefined) { const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); if (isStatementWithLocals(container) || isSymbolOfDestructuredElementOfCatchBinding(symbol)) { const nodeLinks = getNodeLinks(symbol.valueDeclaration); if (resolveName(container.parent, symbol.escapedName, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ false)) { // redeclaration - always should be renamed links.isDeclarationWithCollidingName = true; } else if (nodeLinks.flags & NodeCheckFlags.CapturedBlockScopedBinding) { // binding is captured in the function // should be renamed if: // - binding is not top level - top level bindings never collide with anything // AND // - binding is not declared in loop, should be renamed to avoid name reuse across siblings // let a, b // { let x = 1; a = () => x; } // { let x = 100; b = () => x; } // console.log(a()); // should print '1' // console.log(b()); // should print '100' // OR // - binding is declared inside loop but not in inside initializer of iteration statement or directly inside loop body // * variables from initializer are passed to rewritten loop body as parameters so they are not captured directly // * variables that are declared immediately in loop body will become top level variable after loop is rewritten and thus // they will not collide with anything const isDeclaredInLoop = nodeLinks.flags & NodeCheckFlags.BlockScopedBindingInLoop; const inLoopInitializer = isIterationStatement(container, /*lookInLabeledStatements*/ false); const inLoopBodyBlock = container.kind === SyntaxKind.Block && isIterationStatement(container.parent, /*lookInLabeledStatements*/ false); links.isDeclarationWithCollidingName = !isBlockScopedContainerTopLevel(container) && (!isDeclaredInLoop || (!inLoopInitializer && !inLoopBodyBlock)); } else { links.isDeclarationWithCollidingName = false; } } } return links.isDeclarationWithCollidingName!; } return false; } // When resolved as an expression identifier, if the given node references a nested block scoped entity with // a name that either hides an existing name or might hide it when compiled downlevel, // return the declaration of that entity. Otherwise, return undefined. function getReferencedDeclarationWithCollidingName(nodeIn: Identifier): Declaration | undefined { if (!isGeneratedIdentifier(nodeIn)) { const node = getParseTreeNode(nodeIn, isIdentifier); if (node) { const symbol = getReferencedValueSymbol(node); if (symbol && isSymbolOfDeclarationWithCollidingName(symbol)) { return symbol.valueDeclaration; } } } return undefined; } // Return true if the given node is a declaration of a nested block scoped entity with a name that either hides an // existing name or might hide a name when compiled downlevel function isDeclarationWithCollidingName(nodeIn: Declaration): boolean { const node = getParseTreeNode(nodeIn, isDeclaration); if (node) { const symbol = getSymbolOfDeclaration(node); if (symbol) { return isSymbolOfDeclarationWithCollidingName(symbol); } } return false; } function isValueAliasDeclaration(node: Node): boolean { Debug.assert(!compilerOptions.verbatimModuleSyntax); switch (node.kind) { case SyntaxKind.ImportEqualsDeclaration: return isAliasResolvedToValue(getSymbolOfDeclaration(node as ImportEqualsDeclaration)); case SyntaxKind.ImportClause: case SyntaxKind.NamespaceImport: case SyntaxKind.ImportSpecifier: case SyntaxKind.ExportSpecifier: const symbol = getSymbolOfDeclaration(node as ImportClause | NamespaceImport | ImportSpecifier | ExportSpecifier); return !!symbol && isAliasResolvedToValue(symbol) && !getTypeOnlyAliasDeclaration(symbol, SymbolFlags.Value); case SyntaxKind.ExportDeclaration: const exportClause = (node as ExportDeclaration).exportClause; return !!exportClause && ( isNamespaceExport(exportClause) || some(exportClause.elements, isValueAliasDeclaration) ); case SyntaxKind.ExportAssignment: return (node as ExportAssignment).expression && (node as ExportAssignment).expression.kind === SyntaxKind.Identifier ? isAliasResolvedToValue(getSymbolOfDeclaration(node as ExportAssignment)) : true; } return false; } function isTopLevelValueImportEqualsWithEntityName(nodeIn: ImportEqualsDeclaration): boolean { const node = getParseTreeNode(nodeIn, isImportEqualsDeclaration); if (node === undefined || node.parent.kind !== SyntaxKind.SourceFile || !isInternalModuleImportEqualsDeclaration(node)) { // parent is not source file or it is not reference to internal module return false; } const isValue = isAliasResolvedToValue(getSymbolOfDeclaration(node)); return isValue && node.moduleReference && !nodeIsMissing(node.moduleReference); } function isAliasResolvedToValue(symbol: Symbol | undefined): boolean { if (!symbol) { return false; } const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol)); if (target === unknownSymbol) { return true; } // const enums and modules that contain only const enums are not considered values from the emit perspective // unless 'preserveConstEnums' option is set to true return !!((getAllSymbolFlags(target) ?? -1) & SymbolFlags.Value) && (shouldPreserveConstEnums(compilerOptions) || !isConstEnumOrConstEnumOnlyModule(target)); } function isConstEnumOrConstEnumOnlyModule(s: Symbol): boolean { return isConstEnumSymbol(s) || !!s.constEnumOnlyModule; } function isReferencedAliasDeclaration(node: Node, checkChildren?: boolean): boolean { Debug.assert(!compilerOptions.verbatimModuleSyntax); if (isAliasSymbolDeclaration(node)) { const symbol = getSymbolOfDeclaration(node as Declaration); const links = symbol && getSymbolLinks(symbol); if (links?.referenced) { return true; } const target = getSymbolLinks(symbol).aliasTarget; if (target && getEffectiveModifierFlags(node) & ModifierFlags.Export && getAllSymbolFlags(target) & SymbolFlags.Value && (shouldPreserveConstEnums(compilerOptions) || !isConstEnumOrConstEnumOnlyModule(target))) { // An `export import ... =` of a value symbol is always considered referenced return true; } } if (checkChildren) { return !!forEachChild(node, node => isReferencedAliasDeclaration(node, checkChildren)); } return false; } function isImplementationOfOverload(node: SignatureDeclaration) { if (nodeIsPresent((node as FunctionLikeDeclaration).body)) { if (isGetAccessor(node) || isSetAccessor(node)) return false; // Get or set accessors can never be overload implementations, but can have up to 2 signatures const symbol = getSymbolOfDeclaration(node); const signaturesOfSymbol = getSignaturesOfSymbol(symbol); // If this function body corresponds to function with multiple signature, it is implementation of overload // e.g.: function foo(a: string): string; // function foo(a: number): number; // function foo(a: any) { // This is implementation of the overloads // return a; // } return signaturesOfSymbol.length > 1 || // If there is single signature for the symbol, it is overload if that signature isn't coming from the node // e.g.: function foo(a: string): string; // function foo(a: any) { // This is implementation of the overloads // return a; // } (signaturesOfSymbol.length === 1 && signaturesOfSymbol[0].declaration !== node); } return false; } function isRequiredInitializedParameter(parameter: ParameterDeclaration | JSDocParameterTag): boolean { return !!strictNullChecks && !isOptionalParameter(parameter) && !isJSDocParameterTag(parameter) && !!parameter.initializer && !hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier); } function isOptionalUninitializedParameterProperty(parameter: ParameterDeclaration) { return strictNullChecks && isOptionalParameter(parameter) && !parameter.initializer && hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier); } function isExpandoFunctionDeclaration(node: Declaration): boolean { const declaration = getParseTreeNode(node, isFunctionDeclaration); if (!declaration) { return false; } const symbol = getSymbolOfDeclaration(declaration); if (!symbol || !(symbol.flags & SymbolFlags.Function)) { return false; } return !!forEachEntry(getExportsOfSymbol(symbol), p => p.flags & SymbolFlags.Value && p.valueDeclaration && isPropertyAccessExpression(p.valueDeclaration)); } function getPropertiesOfContainerFunction(node: Declaration): Symbol[] { const declaration = getParseTreeNode(node, isFunctionDeclaration); if (!declaration) { return emptyArray; } const symbol = getSymbolOfDeclaration(declaration); return symbol && getPropertiesOfType(getTypeOfSymbol(symbol)) || emptyArray; } function getNodeCheckFlags(node: Node): NodeCheckFlags { const nodeId = node.id || 0; if (nodeId < 0 || nodeId >= nodeLinks.length) return 0; return nodeLinks[nodeId]?.flags || 0; } function getEnumMemberValue(node: EnumMember): string | number | undefined { computeEnumMemberValues(node.parent); return getNodeLinks(node).enumMemberValue; } function canHaveConstantValue(node: Node): node is EnumMember | AccessExpression { switch (node.kind) { case SyntaxKind.EnumMember: case SyntaxKind.PropertyAccessExpression: case SyntaxKind.ElementAccessExpression: return true; } return false; } function getConstantValue(node: EnumMember | AccessExpression): string | number | undefined { if (node.kind === SyntaxKind.EnumMember) { return getEnumMemberValue(node); } const symbol = getNodeLinks(node).resolvedSymbol; if (symbol && (symbol.flags & SymbolFlags.EnumMember)) { // inline property\index accesses only for const enums const member = symbol.valueDeclaration as EnumMember; if (isEnumConst(member.parent)) { return getEnumMemberValue(member); } } return undefined; } function isFunctionType(type: Type): boolean { return !!(type.flags & TypeFlags.Object) && getSignaturesOfType(type, SignatureKind.Call).length > 0; } function getTypeReferenceSerializationKind(typeNameIn: EntityName, location?: Node): TypeReferenceSerializationKind { // ensure both `typeName` and `location` are parse tree nodes. const typeName = getParseTreeNode(typeNameIn, isEntityName); if (!typeName) return TypeReferenceSerializationKind.Unknown; if (location) { location = getParseTreeNode(location); if (!location) return TypeReferenceSerializationKind.Unknown; } // Resolve the symbol as a value to ensure the type can be reached at runtime during emit. let isTypeOnly = false; if (isQualifiedName(typeName)) { const rootValueSymbol = resolveEntityName(getFirstIdentifier(typeName), SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); isTypeOnly = !!rootValueSymbol?.declarations?.every(isTypeOnlyImportOrExportDeclaration); } const valueSymbol = resolveEntityName(typeName, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); const resolvedSymbol = valueSymbol && valueSymbol.flags & SymbolFlags.Alias ? resolveAlias(valueSymbol) : valueSymbol; isTypeOnly ||= !!(valueSymbol && getTypeOnlyAliasDeclaration(valueSymbol, SymbolFlags.Value)); // Resolve the symbol as a type so that we can provide a more useful hint for the type serializer. const typeSymbol = resolveEntityName(typeName, SymbolFlags.Type, /*ignoreErrors*/ true, /*dontResolveAlias*/ false, location); if (resolvedSymbol && resolvedSymbol === typeSymbol) { const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); if (globalPromiseSymbol && resolvedSymbol === globalPromiseSymbol) { return TypeReferenceSerializationKind.Promise; } const constructorType = getTypeOfSymbol(resolvedSymbol); if (constructorType && isConstructorType(constructorType)) { return isTypeOnly ? TypeReferenceSerializationKind.TypeWithCallSignature : TypeReferenceSerializationKind.TypeWithConstructSignatureAndValue; } } // We might not be able to resolve type symbol so use unknown type in that case (eg error case) if (!typeSymbol) { return isTypeOnly ? TypeReferenceSerializationKind.ObjectType : TypeReferenceSerializationKind.Unknown; } const type = getDeclaredTypeOfSymbol(typeSymbol); if (isErrorType(type)) { return isTypeOnly ? TypeReferenceSerializationKind.ObjectType : TypeReferenceSerializationKind.Unknown; } else if (type.flags & TypeFlags.AnyOrUnknown) { return TypeReferenceSerializationKind.ObjectType; } else if (isTypeAssignableToKind(type, TypeFlags.Void | TypeFlags.Nullable | TypeFlags.Never)) { return TypeReferenceSerializationKind.VoidNullableOrNeverType; } else if (isTypeAssignableToKind(type, TypeFlags.BooleanLike)) { return TypeReferenceSerializationKind.BooleanType; } else if (isTypeAssignableToKind(type, TypeFlags.NumberLike)) { return TypeReferenceSerializationKind.NumberLikeType; } else if (isTypeAssignableToKind(type, TypeFlags.BigIntLike)) { return TypeReferenceSerializationKind.BigIntLikeType; } else if (isTypeAssignableToKind(type, TypeFlags.StringLike)) { return TypeReferenceSerializationKind.StringLikeType; } else if (isTupleType(type)) { return TypeReferenceSerializationKind.ArrayLikeType; } else if (isTypeAssignableToKind(type, TypeFlags.ESSymbolLike)) { return TypeReferenceSerializationKind.ESSymbolType; } else if (isFunctionType(type)) { return TypeReferenceSerializationKind.TypeWithCallSignature; } else if (isArrayType(type)) { return TypeReferenceSerializationKind.ArrayLikeType; } else { return TypeReferenceSerializationKind.ObjectType; } } function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker, addUndefined?: boolean) { const declaration = getParseTreeNode(declarationIn, isVariableLikeOrAccessor); if (!declaration) { return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; } // Get type of the symbol if this is the valid symbol otherwise get type at location const symbol = getSymbolOfDeclaration(declaration); let type = symbol && !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.Signature)) ? getWidenedLiteralType(getTypeOfSymbol(symbol)) : errorType; if (type.flags & TypeFlags.UniqueESSymbol && type.symbol === symbol) { flags |= NodeBuilderFlags.AllowUniqueESSymbolType; } if (addUndefined) { type = getOptionalType(type); } return nodeBuilder.typeToTypeNode(type, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); } function createReturnTypeOfSignatureDeclaration(signatureDeclarationIn: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { const signatureDeclaration = getParseTreeNode(signatureDeclarationIn, isFunctionLike); if (!signatureDeclaration) { return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; } const signature = getSignatureFromDeclaration(signatureDeclaration); return nodeBuilder.typeToTypeNode(getReturnTypeOfSignature(signature), enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); } function createTypeOfExpression(exprIn: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { const expr = getParseTreeNode(exprIn, isExpression); if (!expr) { return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; } const type = getWidenedType(getRegularTypeOfExpression(expr)); return nodeBuilder.typeToTypeNode(type, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); } function hasGlobalName(name: string): boolean { return globals.has(escapeLeadingUnderscores(name)); } function getReferencedValueSymbol(reference: Identifier, startInDeclarationContainer?: boolean): Symbol | undefined { const resolvedSymbol = getNodeLinks(reference).resolvedSymbol; if (resolvedSymbol) { return resolvedSymbol; } let location: Node = reference; if (startInDeclarationContainer) { // When resolving the name of a declaration as a value, we need to start resolution // at a point outside of the declaration. const parent = reference.parent; if (isDeclaration(parent) && reference === parent.name) { location = getDeclarationContainer(parent); } } return resolveName(location, reference.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue | SymbolFlags.Alias, /*nodeNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ true); } /** * Get either a value-meaning symbol or an alias symbol. * Unlike `getReferencedValueSymbol`, if the cached resolved symbol is the unknown symbol, * we call `resolveName` to find a symbol. * This is because when caching the resolved symbol, we only consider value symbols, but here * we want to also get an alias symbol if one exists. */ function getReferencedValueOrAliasSymbol(reference: Identifier): Symbol | undefined { const resolvedSymbol = getNodeLinks(reference).resolvedSymbol; if (resolvedSymbol && resolvedSymbol !== unknownSymbol) { return resolvedSymbol; } return resolveName( reference, reference.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue | SymbolFlags.Alias, /*nodeNotFoundMessage*/ undefined, /*nameArg*/ undefined, /*isUse*/ true, /*excludeGlobals*/ undefined, /*getSpellingSuggestions*/ undefined); } function getReferencedValueDeclaration(referenceIn: Identifier): Declaration | undefined { if (!isGeneratedIdentifier(referenceIn)) { const reference = getParseTreeNode(referenceIn, isIdentifier); if (reference) { const symbol = getReferencedValueSymbol(reference); if (symbol) { return getExportSymbolOfValueSymbolIfExported(symbol).valueDeclaration; } } } return undefined; } function isLiteralConstDeclaration(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration): boolean { if (isDeclarationReadonly(node) || isVariableDeclaration(node) && isVarConst(node)) { return isFreshLiteralType(getTypeOfSymbol(getSymbolOfDeclaration(node))); } return false; } function literalTypeToNode(type: FreshableType, enclosing: Node, tracker: SymbolTracker): Expression { const enumResult = type.flags & TypeFlags.EnumLike ? nodeBuilder.symbolToExpression(type.symbol, SymbolFlags.Value, enclosing, /*flags*/ undefined, tracker) : type === trueType ? factory.createTrue() : type === falseType && factory.createFalse(); if (enumResult) return enumResult; const literalValue = (type as LiteralType).value; return typeof literalValue === "object" ? factory.createBigIntLiteral(literalValue) : typeof literalValue === "number" ? factory.createNumericLiteral(literalValue) : factory.createStringLiteral(literalValue); } function createLiteralConstValue(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration, tracker: SymbolTracker) { const type = getTypeOfSymbol(getSymbolOfDeclaration(node)); return literalTypeToNode(type as FreshableType, node, tracker); } function getJsxFactoryEntity(location: Node): EntityName | undefined { return location ? (getJsxNamespace(location), (getSourceFileOfNode(location).localJsxFactory || _jsxFactoryEntity)) : _jsxFactoryEntity; } function getJsxFragmentFactoryEntity(location: Node): EntityName | undefined { if (location) { const file = getSourceFileOfNode(location); if (file) { if (file.localJsxFragmentFactory) { return file.localJsxFragmentFactory; } const jsxFragPragmas = file.pragmas.get("jsxfrag"); const jsxFragPragma = isArray(jsxFragPragmas) ? jsxFragPragmas[0] : jsxFragPragmas; if (jsxFragPragma) { file.localJsxFragmentFactory = parseIsolatedEntityName(jsxFragPragma.arguments.factory, languageVersion); return file.localJsxFragmentFactory; } } } if (compilerOptions.jsxFragmentFactory) { return parseIsolatedEntityName(compilerOptions.jsxFragmentFactory, languageVersion); } } function createResolver(): EmitResolver { // this variable and functions that use it are deliberately moved here from the outer scope // to avoid scope pollution const resolvedTypeReferenceDirectives = host.getResolvedTypeReferenceDirectives(); let fileToDirective: Map; if (resolvedTypeReferenceDirectives) { // populate reverse mapping: file path -> type reference directive that was resolved to this file fileToDirective = new Map(); resolvedTypeReferenceDirectives.forEach(({ resolvedTypeReferenceDirective }, key, mode) => { if (!resolvedTypeReferenceDirective?.resolvedFileName) { return; } const file = host.getSourceFile(resolvedTypeReferenceDirective.resolvedFileName); if (file) { // Add the transitive closure of path references loaded by this file (as long as they are not) // part of an existing type reference. addReferencedFilesToTypeDirective(file, key, mode); } }); } return { getReferencedExportContainer, getReferencedImportDeclaration, getReferencedDeclarationWithCollidingName, isDeclarationWithCollidingName, isValueAliasDeclaration: nodeIn => { const node = getParseTreeNode(nodeIn); // Synthesized nodes are always treated like values. return node ? isValueAliasDeclaration(node) : true; }, hasGlobalName, isReferencedAliasDeclaration: (nodeIn, checkChildren?) => { const node = getParseTreeNode(nodeIn); // Synthesized nodes are always treated as referenced. return node ? isReferencedAliasDeclaration(node, checkChildren) : true; }, getNodeCheckFlags: nodeIn => { const node = getParseTreeNode(nodeIn); return node ? getNodeCheckFlags(node) : 0; }, isTopLevelValueImportEqualsWithEntityName, isDeclarationVisible, isImplementationOfOverload, isRequiredInitializedParameter, isOptionalUninitializedParameterProperty, isExpandoFunctionDeclaration, getPropertiesOfContainerFunction, createTypeOfDeclaration, createReturnTypeOfSignatureDeclaration, createTypeOfExpression, createLiteralConstValue, isSymbolAccessible, isEntityNameVisible, getConstantValue: nodeIn => { const node = getParseTreeNode(nodeIn, canHaveConstantValue); return node ? getConstantValue(node) : undefined; }, collectLinkedAliases, getReferencedValueDeclaration, getTypeReferenceSerializationKind, isOptionalParameter, moduleExportsSomeValue, isArgumentsLocalBinding, getExternalModuleFileFromDeclaration: nodeIn => { const node = getParseTreeNode(nodeIn, hasPossibleExternalModuleReference); return node && getExternalModuleFileFromDeclaration(node); }, getTypeReferenceDirectivesForEntityName, getTypeReferenceDirectivesForSymbol, isLiteralConstDeclaration, isLateBound: (nodeIn: Declaration): nodeIn is LateBoundDeclaration => { const node = getParseTreeNode(nodeIn, isDeclaration); const symbol = node && getSymbolOfDeclaration(node); return !!(symbol && getCheckFlags(symbol) & CheckFlags.Late); }, getJsxFactoryEntity, getJsxFragmentFactoryEntity, getAllAccessorDeclarations(accessor: AccessorDeclaration): AllAccessorDeclarations { accessor = getParseTreeNode(accessor, isGetOrSetAccessorDeclaration)!; // TODO: GH#18217 const otherKind = accessor.kind === SyntaxKind.SetAccessor ? SyntaxKind.GetAccessor : SyntaxKind.SetAccessor; const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(accessor), otherKind); const firstAccessor = otherAccessor && (otherAccessor.pos < accessor.pos) ? otherAccessor : accessor; const secondAccessor = otherAccessor && (otherAccessor.pos < accessor.pos) ? accessor : otherAccessor; const setAccessor = accessor.kind === SyntaxKind.SetAccessor ? accessor : otherAccessor as SetAccessorDeclaration; const getAccessor = accessor.kind === SyntaxKind.GetAccessor ? accessor : otherAccessor as GetAccessorDeclaration; return { firstAccessor, secondAccessor, setAccessor, getAccessor }; }, getSymbolOfExternalModuleSpecifier: moduleName => resolveExternalModuleNameWorker(moduleName, moduleName, /*moduleNotFoundError*/ undefined), isBindingCapturedByNode: (node, decl) => { const parseNode = getParseTreeNode(node); const parseDecl = getParseTreeNode(decl); return !!parseNode && !!parseDecl && (isVariableDeclaration(parseDecl) || isBindingElement(parseDecl)) && isBindingCapturedByNode(parseNode, parseDecl); }, getDeclarationStatementsForSourceFile: (node, flags, tracker, bundled) => { const n = getParseTreeNode(node) as SourceFile; Debug.assert(n && n.kind === SyntaxKind.SourceFile, "Non-sourcefile node passed into getDeclarationsForSourceFile"); const sym = getSymbolOfDeclaration(node); if (!sym) { return !node.locals ? [] : nodeBuilder.symbolTableToDeclarationStatements(node.locals, node, flags, tracker, bundled); } return !sym.exports ? [] : nodeBuilder.symbolTableToDeclarationStatements(sym.exports, node, flags, tracker, bundled); }, isImportRequiredByAugmentation, }; function isImportRequiredByAugmentation(node: ImportDeclaration) { const file = getSourceFileOfNode(node); if (!file.symbol) return false; const importTarget = getExternalModuleFileFromDeclaration(node); if (!importTarget) return false; if (importTarget === file) return false; const exports = getExportsOfModule(file.symbol); for (const s of arrayFrom(exports.values())) { if (s.mergeId) { const merged = getMergedSymbol(s); if (merged.declarations) { for (const d of merged.declarations) { const declFile = getSourceFileOfNode(d); if (declFile === importTarget) { return true; } } } } } return false; } function isInHeritageClause(node: PropertyAccessEntityNameExpression) { return node.parent && node.parent.kind === SyntaxKind.ExpressionWithTypeArguments && node.parent.parent && node.parent.parent.kind === SyntaxKind.HeritageClause; } // defined here to avoid outer scope pollution function getTypeReferenceDirectivesForEntityName(node: EntityNameOrEntityNameExpression): [specifier: string, mode: ResolutionMode][] | undefined { // program does not have any files with type reference directives - bail out if (!fileToDirective) { return undefined; } // computed property name should use node as value // property access can only be used as values, or types when within an expression with type arguments inside a heritage clause // qualified names can only be used as types\namespaces // identifiers are treated as values only if they appear in type queries let meaning; if (node.parent.kind === SyntaxKind.ComputedPropertyName) { meaning = SymbolFlags.Value | SymbolFlags.ExportValue; } else { meaning = SymbolFlags.Type | SymbolFlags.Namespace; if ((node.kind === SyntaxKind.Identifier && isInTypeQuery(node)) || (node.kind === SyntaxKind.PropertyAccessExpression && !isInHeritageClause(node))) { meaning = SymbolFlags.Value | SymbolFlags.ExportValue; } } const symbol = resolveEntityName(node, meaning, /*ignoreErrors*/ true); return symbol && symbol !== unknownSymbol ? getTypeReferenceDirectivesForSymbol(symbol, meaning) : undefined; } // defined here to avoid outer scope pollution function getTypeReferenceDirectivesForSymbol(symbol: Symbol, meaning?: SymbolFlags): [specifier: string, mode: ResolutionMode][] | undefined { // program does not have any files with type reference directives - bail out if (!fileToDirective || !isSymbolFromTypeDeclarationFile(symbol)) { return undefined; } // check what declarations in the symbol can contribute to the target meaning let typeReferenceDirectives: [specifier: string, mode: ResolutionMode][] | undefined; for (const decl of symbol.declarations!) { // check meaning of the local symbol to see if declaration needs to be analyzed further if (decl.symbol && decl.symbol.flags & meaning!) { const file = getSourceFileOfNode(decl); const typeReferenceDirective = fileToDirective.get(file.path); if (typeReferenceDirective) { (typeReferenceDirectives || (typeReferenceDirectives = [])).push(typeReferenceDirective); } else { // found at least one entry that does not originate from type reference directive return undefined; } } } return typeReferenceDirectives; } function isSymbolFromTypeDeclarationFile(symbol: Symbol): boolean { // bail out if symbol does not have associated declarations (i.e. this is transient symbol created for property in binding pattern) if (!symbol.declarations) { return false; } // walk the parent chain for symbols to make sure that top level parent symbol is in the global scope // external modules cannot define or contribute to type declaration files let current = symbol; while (true) { const parent = getParentOfSymbol(current); if (parent) { current = parent; } else { break; } } if (current.valueDeclaration && current.valueDeclaration.kind === SyntaxKind.SourceFile && current.flags & SymbolFlags.ValueModule) { return false; } // check that at least one declaration of top level symbol originates from type declaration file for (const decl of symbol.declarations) { const file = getSourceFileOfNode(decl); if (fileToDirective.has(file.path)) { return true; } } return false; } function addReferencedFilesToTypeDirective(file: SourceFile, key: string, mode: ResolutionMode) { if (fileToDirective.has(file.path)) return; fileToDirective.set(file.path, [key, mode]); for (const { fileName, resolutionMode } of file.referencedFiles) { const resolvedFile = resolveTripleslashReference(fileName, file.fileName); const referencedFile = host.getSourceFile(resolvedFile); if (referencedFile) { addReferencedFilesToTypeDirective(referencedFile, key, resolutionMode || file.impliedNodeFormat); } } } } function getExternalModuleFileFromDeclaration(declaration: AnyImportOrReExport | ModuleDeclaration | ImportTypeNode | ImportCall): SourceFile | undefined { const specifier = declaration.kind === SyntaxKind.ModuleDeclaration ? tryCast(declaration.name, isStringLiteral) : getExternalModuleName(declaration); const moduleSymbol = resolveExternalModuleNameWorker(specifier!, specifier!, /*moduleNotFoundError*/ undefined); // TODO: GH#18217 if (!moduleSymbol) { return undefined; } return getDeclarationOfKind(moduleSymbol, SyntaxKind.SourceFile); } function initializeTypeChecker() { // Bind all source files and propagate errors for (const file of host.getSourceFiles()) { bindSourceFile(file, compilerOptions); } amalgamatedDuplicates = new Map(); // Initialize global symbol table let augmentations: (readonly (StringLiteral | Identifier)[])[] | undefined; for (const file of host.getSourceFiles()) { if (file.redirectInfo) { continue; } if (!isExternalOrCommonJsModule(file)) { // It is an error for a non-external-module (i.e. script) to declare its own `globalThis`. // We can't use `builtinGlobals` for this due to synthetic expando-namespace generation in JS files. const fileGlobalThisSymbol = file.locals!.get("globalThis" as __String); if (fileGlobalThisSymbol?.declarations) { for (const declaration of fileGlobalThisSymbol.declarations) { diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0, "globalThis")); } } mergeSymbolTable(globals, file.locals!); } if (file.jsGlobalAugmentations) { mergeSymbolTable(globals, file.jsGlobalAugmentations); } if (file.patternAmbientModules && file.patternAmbientModules.length) { patternAmbientModules = concatenate(patternAmbientModules, file.patternAmbientModules); } if (file.moduleAugmentations.length) { (augmentations || (augmentations = [])).push(file.moduleAugmentations); } if (file.symbol && file.symbol.globalExports) { // Merge in UMD exports with first-in-wins semantics (see #9771) const source = file.symbol.globalExports; source.forEach((sourceSymbol, id) => { if (!globals.has(id)) { globals.set(id, sourceSymbol); } }); } } // We do global augmentations separately from module augmentations (and before creating global types) because they // 1. Affect global types. We won't have the correct global types until global augmentations are merged. Also, // 2. Module augmentation instantiation requires creating the type of a module, which, in turn, can require // checking for an export or property on the module (if export=) which, in turn, can fall back to the // apparent type of the module - either globalObjectType or globalFunctionType - which wouldn't exist if we // did module augmentations prior to finalizing the global types. if (augmentations) { // merge _global_ module augmentations. // this needs to be done after global symbol table is initialized to make sure that all ambient modules are indexed for (const list of augmentations) { for (const augmentation of list) { if (!isGlobalScopeAugmentation(augmentation.parent as ModuleDeclaration)) continue; mergeModuleAugmentation(augmentation); } } } // Setup global builtins addToSymbolTable(globals, builtinGlobals, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0); getSymbolLinks(undefinedSymbol).type = undefinedWideningType; getSymbolLinks(argumentsSymbol).type = getGlobalType("IArguments" as __String, /*arity*/ 0, /*reportErrors*/ true); getSymbolLinks(unknownSymbol).type = errorType; getSymbolLinks(globalThisSymbol).type = createObjectType(ObjectFlags.Anonymous, globalThisSymbol); // Initialize special types globalArrayType = getGlobalType("Array" as __String, /*arity*/ 1, /*reportErrors*/ true); globalObjectType = getGlobalType("Object" as __String, /*arity*/ 0, /*reportErrors*/ true); globalFunctionType = getGlobalType("Function" as __String, /*arity*/ 0, /*reportErrors*/ true); globalCallableFunctionType = strictBindCallApply && getGlobalType("CallableFunction" as __String, /*arity*/ 0, /*reportErrors*/ true) || globalFunctionType; globalNewableFunctionType = strictBindCallApply && getGlobalType("NewableFunction" as __String, /*arity*/ 0, /*reportErrors*/ true) || globalFunctionType; globalStringType = getGlobalType("String" as __String, /*arity*/ 0, /*reportErrors*/ true); globalNumberType = getGlobalType("Number" as __String, /*arity*/ 0, /*reportErrors*/ true); globalBooleanType = getGlobalType("Boolean" as __String, /*arity*/ 0, /*reportErrors*/ true); globalRegExpType = getGlobalType("RegExp" as __String, /*arity*/ 0, /*reportErrors*/ true); anyArrayType = createArrayType(anyType); autoArrayType = createArrayType(autoType); if (autoArrayType === emptyObjectType) { // autoArrayType is used as a marker, so even if global Array type is not defined, it needs to be a unique type autoArrayType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, emptyArray); } globalReadonlyArrayType = getGlobalTypeOrUndefined("ReadonlyArray" as __String, /*arity*/ 1) as GenericType || globalArrayType; anyReadonlyArrayType = globalReadonlyArrayType ? createTypeFromGenericGlobalType(globalReadonlyArrayType, [anyType]) : anyArrayType; globalThisType = getGlobalTypeOrUndefined("ThisType" as __String, /*arity*/ 1) as GenericType; if (augmentations) { // merge _nonglobal_ module augmentations. // this needs to be done after global symbol table is initialized to make sure that all ambient modules are indexed for (const list of augmentations) { for (const augmentation of list) { if (isGlobalScopeAugmentation(augmentation.parent as ModuleDeclaration)) continue; mergeModuleAugmentation(augmentation); } } } amalgamatedDuplicates.forEach(({ firstFile, secondFile, conflictingSymbols }) => { // If not many things conflict, issue individual errors if (conflictingSymbols.size < 8) { conflictingSymbols.forEach(({ isBlockScoped, firstFileLocations, secondFileLocations }, symbolName) => { const message = isBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 : Diagnostics.Duplicate_identifier_0; for (const node of firstFileLocations) { addDuplicateDeclarationError(node, message, symbolName, secondFileLocations); } for (const node of secondFileLocations) { addDuplicateDeclarationError(node, message, symbolName, firstFileLocations); } }); } else { // Otherwise issue top-level error since the files appear very identical in terms of what they contain const list = arrayFrom(conflictingSymbols.keys()).join(", "); diagnostics.add(addRelatedInfo( createDiagnosticForNode(firstFile, Diagnostics.Definitions_of_the_following_identifiers_conflict_with_those_in_another_file_Colon_0, list), createDiagnosticForNode(secondFile, Diagnostics.Conflicts_are_in_this_file) )); diagnostics.add(addRelatedInfo( createDiagnosticForNode(secondFile, Diagnostics.Definitions_of_the_following_identifiers_conflict_with_those_in_another_file_Colon_0, list), createDiagnosticForNode(firstFile, Diagnostics.Conflicts_are_in_this_file) )); } }); amalgamatedDuplicates = undefined; } function checkExternalEmitHelpers(location: Node, helpers: ExternalEmitHelpers) { if ((requestedExternalEmitHelpers & helpers) !== helpers && compilerOptions.importHelpers) { const sourceFile = getSourceFileOfNode(location); if (isEffectiveExternalModule(sourceFile, compilerOptions) && !(location.flags & NodeFlags.Ambient)) { const helpersModule = resolveHelpersModule(sourceFile, location); if (helpersModule !== unknownSymbol) { const uncheckedHelpers = helpers & ~requestedExternalEmitHelpers; for (let helper = ExternalEmitHelpers.FirstEmitHelper; helper <= ExternalEmitHelpers.LastEmitHelper; helper <<= 1) { if (uncheckedHelpers & helper) { for (const name of getHelperNames(helper)) { if (requestedExternalEmitHelperNames.has(name)) continue; requestedExternalEmitHelperNames.add(name); const symbol = getSymbol(helpersModule.exports!, escapeLeadingUnderscores(name), SymbolFlags.Value); if (!symbol) { error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_which_does_not_exist_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name); } else if (helper & ExternalEmitHelpers.ClassPrivateFieldGet) { if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 3)) { error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 4); } } else if (helper & ExternalEmitHelpers.ClassPrivateFieldSet) { if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 4)) { error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 5); } } else if (helper & ExternalEmitHelpers.SpreadArray) { if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 2)) { error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 3); } } } } } } requestedExternalEmitHelpers |= helpers; } } } function getHelperNames(helper: ExternalEmitHelpers) { switch (helper) { case ExternalEmitHelpers.Extends: return ["__extends"]; case ExternalEmitHelpers.Assign: return ["__assign"]; case ExternalEmitHelpers.Rest: return ["__rest"]; case ExternalEmitHelpers.Decorate: return legacyDecorators ? ["__decorate"] : ["__esDecorate", "__runInitializers"]; case ExternalEmitHelpers.Metadata: return ["__metadata"]; case ExternalEmitHelpers.Param: return ["__param"]; case ExternalEmitHelpers.Awaiter: return ["__awaiter"]; case ExternalEmitHelpers.Generator: return ["__generator"]; case ExternalEmitHelpers.Values: return ["__values"]; case ExternalEmitHelpers.Read: return ["__read"]; case ExternalEmitHelpers.SpreadArray: return ["__spreadArray"]; case ExternalEmitHelpers.Await: return ["__await"]; case ExternalEmitHelpers.AsyncGenerator: return ["__asyncGenerator"]; case ExternalEmitHelpers.AsyncDelegator: return ["__asyncDelegator"]; case ExternalEmitHelpers.AsyncValues: return ["__asyncValues"]; case ExternalEmitHelpers.ExportStar: return ["__exportStar"]; case ExternalEmitHelpers.ImportStar: return ["__importStar"]; case ExternalEmitHelpers.ImportDefault: return ["__importDefault"]; case ExternalEmitHelpers.MakeTemplateObject: return ["__makeTemplateObject"]; case ExternalEmitHelpers.ClassPrivateFieldGet: return ["__classPrivateFieldGet"]; case ExternalEmitHelpers.ClassPrivateFieldSet: return ["__classPrivateFieldSet"]; case ExternalEmitHelpers.ClassPrivateFieldIn: return ["__classPrivateFieldIn"]; case ExternalEmitHelpers.CreateBinding: return ["__createBinding"]; case ExternalEmitHelpers.SetFunctionName: return ["__setFunctionName"]; case ExternalEmitHelpers.PropKey: return ["__propKey"]; default: return Debug.fail("Unrecognized helper"); } } function resolveHelpersModule(node: SourceFile, errorNode: Node) { if (!externalHelpersModule) { externalHelpersModule = resolveExternalModule(node, externalHelpersModuleNameText, Diagnostics.This_syntax_requires_an_imported_helper_but_module_0_cannot_be_found, errorNode) || unknownSymbol; } return externalHelpersModule; } // GRAMMAR CHECKING function checkGrammarModifiers(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators): boolean { const quickResult = reportObviousDecoratorErrors(node) || reportObviousModifierErrors(node); if (quickResult !== undefined) { return quickResult; } if (isParameter(node) && parameterIsThisKeyword(node)) { return grammarErrorOnFirstToken(node, Diagnostics.Neither_decorators_nor_modifiers_may_be_applied_to_this_parameters); } let lastStatic: Node | undefined, lastDeclare: Node | undefined, lastAsync: Node | undefined, lastOverride: Node | undefined, firstDecorator: Decorator | undefined; let flags = ModifierFlags.None; let sawExportBeforeDecorators = false; // We parse decorators and modifiers in four contiguous chunks: // [...leadingDecorators, ...leadingModifiers, ...trailingDecorators, ...trailingModifiers]. It is an error to // have both leading and trailing decorators. let hasLeadingDecorators = false; for (const modifier of (node as HasModifiers).modifiers!) { if (isDecorator(modifier)) { if (!nodeCanBeDecorated(legacyDecorators, node, node.parent, node.parent.parent)) { if (node.kind === SyntaxKind.MethodDeclaration && !nodeIsPresent(node.body)) { return grammarErrorOnFirstToken(node, Diagnostics.A_decorator_can_only_decorate_a_method_implementation_not_an_overload); } else { return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here); } } else if (legacyDecorators && (node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor)) { const accessors = getAllAccessorDeclarations((node.parent as ClassDeclaration).members, node as AccessorDeclaration); if (hasDecorators(accessors.firstAccessor) && node === accessors.secondAccessor) { return grammarErrorOnFirstToken(node, Diagnostics.Decorators_cannot_be_applied_to_multiple_get_Slashset_accessors_of_the_same_name); } } // if we've seen any modifiers aside from `export`, `default`, or another decorator, then this is an invalid position if (flags & ~(ModifierFlags.ExportDefault | ModifierFlags.Decorator)) { return grammarErrorOnNode(modifier, Diagnostics.Decorators_are_not_valid_here); } // if we've already seen leading decorators and leading modifiers, then trailing decorators are an invalid position if (hasLeadingDecorators && flags & ModifierFlags.Modifier) { Debug.assertIsDefined(firstDecorator); const sourceFile = getSourceFileOfNode(modifier); if (!hasParseDiagnostics(sourceFile)) { addRelatedInfo( error(modifier, Diagnostics.Decorators_may_not_appear_after_export_or_export_default_if_they_also_appear_before_export), createDiagnosticForNode(firstDecorator, Diagnostics.Decorator_used_before_export_here)); return true; } return false; } flags |= ModifierFlags.Decorator; // if we have not yet seen a modifier, then these are leading decorators if (!(flags & ModifierFlags.Modifier)) { hasLeadingDecorators = true; } else if (flags & ModifierFlags.Export) { sawExportBeforeDecorators = true; } firstDecorator ??= modifier; } else { if (modifier.kind !== SyntaxKind.ReadonlyKeyword) { if (node.kind === SyntaxKind.PropertySignature || node.kind === SyntaxKind.MethodSignature) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_type_member, tokenToString(modifier.kind)); } if (node.kind === SyntaxKind.IndexSignature && (modifier.kind !== SyntaxKind.StaticKeyword || !isClassLike(node.parent))) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_index_signature, tokenToString(modifier.kind)); } } if (modifier.kind !== SyntaxKind.InKeyword && modifier.kind !== SyntaxKind.OutKeyword && modifier.kind !== SyntaxKind.ConstKeyword) { if (node.kind === SyntaxKind.TypeParameter) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_type_parameter, tokenToString(modifier.kind)); } } switch (modifier.kind) { case SyntaxKind.ConstKeyword: if (node.kind !== SyntaxKind.EnumDeclaration && node.kind !== SyntaxKind.TypeParameter) { return grammarErrorOnNode(node, Diagnostics.A_class_member_cannot_have_the_0_keyword, tokenToString(SyntaxKind.ConstKeyword)); } const parent = node.parent; if (node.kind === SyntaxKind.TypeParameter && !(isFunctionLikeDeclaration(parent) || isClassLike(parent) || isFunctionTypeNode(parent) || isConstructorTypeNode(parent) || isCallSignatureDeclaration(parent) || isConstructSignatureDeclaration(parent) || isMethodSignature(parent))) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_can_only_appear_on_a_type_parameter_of_a_function_method_or_class, tokenToString(modifier.kind)); } break; case SyntaxKind.OverrideKeyword: // If node.kind === SyntaxKind.Parameter, checkParameter reports an error if it's not a parameter property. if (flags & ModifierFlags.Override) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "override"); } else if (flags & ModifierFlags.Ambient) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "override", "declare"); } else if (flags & ModifierFlags.Readonly) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "readonly"); } else if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "accessor"); } else if (flags & ModifierFlags.Async) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "async"); } flags |= ModifierFlags.Override; lastOverride = modifier; break; case SyntaxKind.PublicKeyword: case SyntaxKind.ProtectedKeyword: case SyntaxKind.PrivateKeyword: const text = visibilityToString(modifierToFlag(modifier.kind)); if (flags & ModifierFlags.AccessibilityModifier) { return grammarErrorOnNode(modifier, Diagnostics.Accessibility_modifier_already_seen); } else if (flags & ModifierFlags.Override) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "override"); } else if (flags & ModifierFlags.Static) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "static"); } else if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "accessor"); } else if (flags & ModifierFlags.Readonly) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "readonly"); } else if (flags & ModifierFlags.Async) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "async"); } else if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_module_or_namespace_element, text); } else if (flags & ModifierFlags.Abstract) { if (modifier.kind === SyntaxKind.PrivateKeyword) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, text, "abstract"); } else { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "abstract"); } } else if (isPrivateIdentifierClassElementDeclaration(node)) { return grammarErrorOnNode(modifier, Diagnostics.An_accessibility_modifier_cannot_be_used_with_a_private_identifier); } flags |= modifierToFlag(modifier.kind); break; case SyntaxKind.StaticKeyword: if (flags & ModifierFlags.Static) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "static"); } else if (flags & ModifierFlags.Readonly) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "readonly"); } else if (flags & ModifierFlags.Async) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "async"); } else if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "accessor"); } else if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_module_or_namespace_element, "static"); } else if (node.kind === SyntaxKind.Parameter) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "static"); } else if (flags & ModifierFlags.Abstract) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "static", "abstract"); } else if (flags & ModifierFlags.Override) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "override"); } flags |= ModifierFlags.Static; lastStatic = modifier; break; case SyntaxKind.AccessorKeyword: if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "accessor"); } else if (flags & ModifierFlags.Readonly) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "accessor", "readonly"); } else if (flags & ModifierFlags.Ambient) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "accessor", "declare"); } else if (node.kind !== SyntaxKind.PropertyDeclaration) { return grammarErrorOnNode(modifier, Diagnostics.accessor_modifier_can_only_appear_on_a_property_declaration); } flags |= ModifierFlags.Accessor; break; case SyntaxKind.ReadonlyKeyword: if (flags & ModifierFlags.Readonly) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "readonly"); } else if (node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.PropertySignature && node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.Parameter) { // If node.kind === SyntaxKind.Parameter, checkParameter reports an error if it's not a parameter property. return grammarErrorOnNode(modifier, Diagnostics.readonly_modifier_can_only_appear_on_a_property_declaration_or_index_signature); } else if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "readonly", "accessor"); } flags |= ModifierFlags.Readonly; break; case SyntaxKind.ExportKeyword: if (compilerOptions.verbatimModuleSyntax && !(node.flags & NodeFlags.Ambient) && node.kind !== SyntaxKind.TypeAliasDeclaration && node.kind !== SyntaxKind.InterfaceDeclaration && // ModuleDeclaration needs to be checked that it is uninstantiated later node.kind !== SyntaxKind.ModuleDeclaration && node.parent.kind === SyntaxKind.SourceFile && (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) ) { return grammarErrorOnNode(modifier, Diagnostics.A_top_level_export_modifier_cannot_be_used_on_value_declarations_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); } if (flags & ModifierFlags.Export) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "export"); } else if (flags & ModifierFlags.Ambient) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "declare"); } else if (flags & ModifierFlags.Abstract) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "abstract"); } else if (flags & ModifierFlags.Async) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "async"); } else if (isClassLike(node.parent)) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_class_elements_of_this_kind, "export"); } else if (node.kind === SyntaxKind.Parameter) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "export"); } flags |= ModifierFlags.Export; break; case SyntaxKind.DefaultKeyword: const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent; if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) { return grammarErrorOnNode(modifier, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module); } else if (!(flags & ModifierFlags.Export)) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "default"); } else if (sawExportBeforeDecorators) { return grammarErrorOnNode(firstDecorator!, Diagnostics.Decorators_are_not_valid_here); } flags |= ModifierFlags.Default; break; case SyntaxKind.DeclareKeyword: if (flags & ModifierFlags.Ambient) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "declare"); } else if (flags & ModifierFlags.Async) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "async"); } else if (flags & ModifierFlags.Override) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "override"); } else if (isClassLike(node.parent) && !isPropertyDeclaration(node)) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_class_elements_of_this_kind, "declare"); } else if (node.kind === SyntaxKind.Parameter) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "declare"); } else if ((node.parent.flags & NodeFlags.Ambient) && node.parent.kind === SyntaxKind.ModuleBlock) { return grammarErrorOnNode(modifier, Diagnostics.A_declare_modifier_cannot_be_used_in_an_already_ambient_context); } else if (isPrivateIdentifierClassElementDeclaration(node)) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_a_private_identifier, "declare"); } else if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "declare", "accessor"); } flags |= ModifierFlags.Ambient; lastDeclare = modifier; break; case SyntaxKind.AbstractKeyword: if (flags & ModifierFlags.Abstract) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "abstract"); } if (node.kind !== SyntaxKind.ClassDeclaration && node.kind !== SyntaxKind.ConstructorType) { if (node.kind !== SyntaxKind.MethodDeclaration && node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.GetAccessor && node.kind !== SyntaxKind.SetAccessor) { return grammarErrorOnNode(modifier, Diagnostics.abstract_modifier_can_only_appear_on_a_class_method_or_property_declaration); } if (!(node.parent.kind === SyntaxKind.ClassDeclaration && hasSyntacticModifier(node.parent, ModifierFlags.Abstract))) { return grammarErrorOnNode(modifier, Diagnostics.Abstract_methods_can_only_appear_within_an_abstract_class); } if (flags & ModifierFlags.Static) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "static", "abstract"); } if (flags & ModifierFlags.Private) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "private", "abstract"); } if (flags & ModifierFlags.Async && lastAsync) { return grammarErrorOnNode(lastAsync, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "async", "abstract"); } if (flags & ModifierFlags.Override) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "abstract", "override"); } if (flags & ModifierFlags.Accessor) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "abstract", "accessor"); } } if (isNamedDeclaration(node) && node.name.kind === SyntaxKind.PrivateIdentifier) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_a_private_identifier, "abstract"); } flags |= ModifierFlags.Abstract; break; case SyntaxKind.AsyncKeyword: if (flags & ModifierFlags.Async) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "async"); } else if (flags & ModifierFlags.Ambient || node.parent.flags & NodeFlags.Ambient) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "async"); } else if (node.kind === SyntaxKind.Parameter) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "async"); } if (flags & ModifierFlags.Abstract) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "async", "abstract"); } flags |= ModifierFlags.Async; lastAsync = modifier; break; case SyntaxKind.InKeyword: case SyntaxKind.OutKeyword: const inOutFlag = modifier.kind === SyntaxKind.InKeyword ? ModifierFlags.In : ModifierFlags.Out; const inOutText = modifier.kind === SyntaxKind.InKeyword ? "in" : "out"; if (node.kind !== SyntaxKind.TypeParameter || !(isInterfaceDeclaration(node.parent) || isClassLike(node.parent) || isTypeAliasDeclaration(node.parent))) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_can_only_appear_on_a_type_parameter_of_a_class_interface_or_type_alias, inOutText); } if (flags & inOutFlag) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, inOutText); } if (inOutFlag & ModifierFlags.In && flags & ModifierFlags.Out) { return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "in", "out"); } flags |= inOutFlag; break; } } } if (node.kind === SyntaxKind.Constructor) { if (flags & ModifierFlags.Static) { return grammarErrorOnNode(lastStatic!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "static"); } if (flags & ModifierFlags.Override) { return grammarErrorOnNode(lastOverride!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "override"); // TODO: GH#18217 } if (flags & ModifierFlags.Async) { return grammarErrorOnNode(lastAsync!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "async"); } return false; } else if ((node.kind === SyntaxKind.ImportDeclaration || node.kind === SyntaxKind.ImportEqualsDeclaration) && flags & ModifierFlags.Ambient) { return grammarErrorOnNode(lastDeclare!, Diagnostics.A_0_modifier_cannot_be_used_with_an_import_declaration, "declare"); } else if (node.kind === SyntaxKind.Parameter && (flags & ModifierFlags.ParameterPropertyModifier) && isBindingPattern(node.name)) { return grammarErrorOnNode(node, Diagnostics.A_parameter_property_may_not_be_declared_using_a_binding_pattern); } else if (node.kind === SyntaxKind.Parameter && (flags & ModifierFlags.ParameterPropertyModifier) && node.dotDotDotToken) { return grammarErrorOnNode(node, Diagnostics.A_parameter_property_cannot_be_declared_using_a_rest_parameter); } if (flags & ModifierFlags.Async) { return checkGrammarAsyncModifier(node, lastAsync!); } return false; } /** * true | false: Early return this value from checkGrammarModifiers. * undefined: Need to do full checking on the modifiers. */ function reportObviousModifierErrors(node: HasModifiers | HasIllegalModifiers): boolean | undefined { if (!node.modifiers) return false; const modifier = findFirstIllegalModifier(node); return modifier && grammarErrorOnFirstToken(modifier, Diagnostics.Modifiers_cannot_appear_here); } function findFirstModifierExcept(node: HasModifiers, allowedModifier: SyntaxKind): Modifier | undefined { const modifier = find(node.modifiers, isModifier); return modifier && modifier.kind !== allowedModifier ? modifier : undefined; } function findFirstIllegalModifier(node: HasModifiers | HasIllegalModifiers): Modifier | undefined { switch (node.kind) { case SyntaxKind.GetAccessor: case SyntaxKind.SetAccessor: case SyntaxKind.Constructor: case SyntaxKind.PropertyDeclaration: case SyntaxKind.PropertySignature: case SyntaxKind.MethodDeclaration: case SyntaxKind.MethodSignature: case SyntaxKind.IndexSignature: case SyntaxKind.ModuleDeclaration: case SyntaxKind.ImportDeclaration: case SyntaxKind.ImportEqualsDeclaration: case SyntaxKind.ExportDeclaration: case SyntaxKind.ExportAssignment: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: case SyntaxKind.Parameter: case SyntaxKind.TypeParameter: return undefined; case SyntaxKind.ClassStaticBlockDeclaration: case SyntaxKind.PropertyAssignment: case SyntaxKind.ShorthandPropertyAssignment: case SyntaxKind.NamespaceExportDeclaration: case SyntaxKind.MissingDeclaration: return find(node.modifiers, isModifier); default: if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { return undefined; } switch (node.kind) { case SyntaxKind.FunctionDeclaration: return findFirstModifierExcept(node, SyntaxKind.AsyncKeyword); case SyntaxKind.ClassDeclaration: case SyntaxKind.ConstructorType: return findFirstModifierExcept(node, SyntaxKind.AbstractKeyword); case SyntaxKind.ClassExpression: case SyntaxKind.InterfaceDeclaration: case SyntaxKind.VariableStatement: case SyntaxKind.TypeAliasDeclaration: return find(node.modifiers, isModifier); case SyntaxKind.EnumDeclaration: return findFirstModifierExcept(node, SyntaxKind.ConstKeyword); default: Debug.assertNever(node); } } } function reportObviousDecoratorErrors(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators) { const decorator = findFirstIllegalDecorator(node); return decorator && grammarErrorOnFirstToken(decorator, Diagnostics.Decorators_are_not_valid_here); } function findFirstIllegalDecorator(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators): Decorator | undefined { return canHaveIllegalDecorators(node) ? find(node.modifiers, isDecorator) : undefined; } function checkGrammarAsyncModifier(node: Node, asyncModifier: Node): boolean { switch (node.kind) { case SyntaxKind.MethodDeclaration: case SyntaxKind.FunctionDeclaration: case SyntaxKind.FunctionExpression: case SyntaxKind.ArrowFunction: return false; } return grammarErrorOnNode(asyncModifier, Diagnostics._0_modifier_cannot_be_used_here, "async"); } function checkGrammarForDisallowedTrailingComma(list: NodeArray | undefined, diag = Diagnostics.Trailing_comma_not_allowed): boolean { if (list && list.hasTrailingComma) { return grammarErrorAtPos(list[0], list.end - ",".length, ",".length, diag); } return false; } function checkGrammarTypeParameterList(typeParameters: NodeArray | undefined, file: SourceFile): boolean { if (typeParameters && typeParameters.length === 0) { const start = typeParameters.pos - "<".length; const end = skipTrivia(file.text, typeParameters.end) + ">".length; return grammarErrorAtPos(file, start, end - start, Diagnostics.Type_parameter_list_cannot_be_empty); } return false; } function checkGrammarParameterList(parameters: NodeArray) { let seenOptionalParameter = false; const parameterCount = parameters.length; for (let i = 0; i < parameterCount; i++) { const parameter = parameters[i]; if (parameter.dotDotDotToken) { if (i !== (parameterCount - 1)) { return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); } if (!(parameter.flags & NodeFlags.Ambient)) { // Allow `...foo,` in ambient declarations; see GH#23070 checkGrammarForDisallowedTrailingComma(parameters, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); } if (parameter.questionToken) { return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_rest_parameter_cannot_be_optional); } if (parameter.initializer) { return grammarErrorOnNode(parameter.name, Diagnostics.A_rest_parameter_cannot_have_an_initializer); } } else if (isOptionalParameter(parameter)) { seenOptionalParameter = true; if (parameter.questionToken && parameter.initializer) { return grammarErrorOnNode(parameter.name, Diagnostics.Parameter_cannot_have_question_mark_and_initializer); } } else if (seenOptionalParameter && !parameter.initializer) { return grammarErrorOnNode(parameter.name, Diagnostics.A_required_parameter_cannot_follow_an_optional_parameter); } } } function getNonSimpleParameters(parameters: readonly ParameterDeclaration[]): readonly ParameterDeclaration[] { return filter(parameters, parameter => !!parameter.initializer || isBindingPattern(parameter.name) || isRestParameter(parameter)); } function checkGrammarForUseStrictSimpleParameterList(node: FunctionLikeDeclaration): boolean { if (languageVersion >= ScriptTarget.ES2016) { const useStrictDirective = node.body && isBlock(node.body) && findUseStrictPrologue(node.body.statements); if (useStrictDirective) { const nonSimpleParameters = getNonSimpleParameters(node.parameters); if (length(nonSimpleParameters)) { forEach(nonSimpleParameters, parameter => { addRelatedInfo( error(parameter, Diagnostics.This_parameter_is_not_allowed_with_use_strict_directive), createDiagnosticForNode(useStrictDirective, Diagnostics.use_strict_directive_used_here) ); }); const diagnostics = nonSimpleParameters.map((parameter, index) => ( index === 0 ? createDiagnosticForNode(parameter, Diagnostics.Non_simple_parameter_declared_here) : createDiagnosticForNode(parameter, Diagnostics.and_here) )) as [DiagnosticWithLocation, ...DiagnosticWithLocation[]]; addRelatedInfo(error(useStrictDirective, Diagnostics.use_strict_directive_cannot_be_used_with_non_simple_parameter_list), ...diagnostics); return true; } } } return false; } function checkGrammarFunctionLikeDeclaration(node: FunctionLikeDeclaration | MethodSignature): boolean { // Prevent cascading error by short-circuit const file = getSourceFileOfNode(node); return checkGrammarModifiers(node) || checkGrammarTypeParameterList(node.typeParameters, file) || checkGrammarParameterList(node.parameters) || checkGrammarArrowFunction(node, file) || (isFunctionLikeDeclaration(node) && checkGrammarForUseStrictSimpleParameterList(node)); } function checkGrammarClassLikeDeclaration(node: ClassLikeDeclaration): boolean { const file = getSourceFileOfNode(node); return checkGrammarClassDeclarationHeritageClauses(node) || checkGrammarTypeParameterList(node.typeParameters, file); } function checkGrammarArrowFunction(node: Node, file: SourceFile): boolean { if (!isArrowFunction(node)) { return false; } if (node.typeParameters && !(length(node.typeParameters) > 1 || node.typeParameters.hasTrailingComma || node.typeParameters[0].constraint)) { if (file && fileExtensionIsOneOf(file.fileName, [Extension.Mts, Extension.Cts])) { grammarErrorOnNode(node.typeParameters[0], Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Add_a_trailing_comma_or_explicit_constraint); } } const { equalsGreaterThanToken } = node; const startLine = getLineAndCharacterOfPosition(file, equalsGreaterThanToken.pos).line; const endLine = getLineAndCharacterOfPosition(file, equalsGreaterThanToken.end).line; return startLine !== endLine && grammarErrorOnNode(equalsGreaterThanToken, Diagnostics.Line_terminator_not_permitted_before_arrow); } function checkGrammarIndexSignatureParameters(node: SignatureDeclaration): boolean { const parameter = node.parameters[0]; if (node.parameters.length !== 1) { if (parameter) { return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_must_have_exactly_one_parameter); } else { return grammarErrorOnNode(node, Diagnostics.An_index_signature_must_have_exactly_one_parameter); } } checkGrammarForDisallowedTrailingComma(node.parameters, Diagnostics.An_index_signature_cannot_have_a_trailing_comma); if (parameter.dotDotDotToken) { return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.An_index_signature_cannot_have_a_rest_parameter); } if (hasEffectiveModifiers(parameter)) { return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_cannot_have_an_accessibility_modifier); } if (parameter.questionToken) { return grammarErrorOnNode(parameter.questionToken, Diagnostics.An_index_signature_parameter_cannot_have_a_question_mark); } if (parameter.initializer) { return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_cannot_have_an_initializer); } if (!parameter.type) { return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_must_have_a_type_annotation); } const type = getTypeFromTypeNode(parameter.type); if (someType(type, t => !!(t.flags & TypeFlags.StringOrNumberLiteralOrUnique)) || isGenericType(type)) { return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_type_cannot_be_a_literal_type_or_generic_type_Consider_using_a_mapped_object_type_instead); } if (!everyType(type, isValidIndexKeyType)) { return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_type_must_be_string_number_symbol_or_a_template_literal_type); } if (!node.type) { return grammarErrorOnNode(node, Diagnostics.An_index_signature_must_have_a_type_annotation); } return false; } function checkGrammarIndexSignature(node: IndexSignatureDeclaration) { // Prevent cascading error by short-circuit return checkGrammarModifiers(node) || checkGrammarIndexSignatureParameters(node); } function checkGrammarForAtLeastOneTypeArgument(node: Node, typeArguments: NodeArray | undefined): boolean { if (typeArguments && typeArguments.length === 0) { const sourceFile = getSourceFileOfNode(node); const start = typeArguments.pos - "<".length; const end = skipTrivia(sourceFile.text, typeArguments.end) + ">".length; return grammarErrorAtPos(sourceFile, start, end - start, Diagnostics.Type_argument_list_cannot_be_empty); } return false; } function checkGrammarTypeArguments(node: Node, typeArguments: NodeArray | undefined): boolean { return checkGrammarForDisallowedTrailingComma(typeArguments) || checkGrammarForAtLeastOneTypeArgument(node, typeArguments); } function checkGrammarTaggedTemplateChain(node: TaggedTemplateExpression): boolean { if (node.questionDotToken || node.flags & NodeFlags.OptionalChain) { return grammarErrorOnNode(node.template, Diagnostics.Tagged_template_expressions_are_not_permitted_in_an_optional_chain); } return false; } function checkGrammarHeritageClause(node: HeritageClause): boolean { const types = node.types; if (checkGrammarForDisallowedTrailingComma(types)) { return true; } if (types && types.length === 0) { const listType = tokenToString(node.token); return grammarErrorAtPos(node, types.pos, 0, Diagnostics._0_list_cannot_be_empty, listType); } return some(types, checkGrammarExpressionWithTypeArguments); } function checkGrammarExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { if (isExpressionWithTypeArguments(node) && isImportKeyword(node.expression) && node.typeArguments) { return grammarErrorOnNode(node, Diagnostics.This_use_of_import_is_invalid_import_calls_can_be_written_but_they_must_have_parentheses_and_cannot_have_type_arguments); } return checkGrammarTypeArguments(node, node.typeArguments); } function checkGrammarClassDeclarationHeritageClauses(node: ClassLikeDeclaration) { let seenExtendsClause = false; let seenImplementsClause = false; if (!checkGrammarModifiers(node) && node.heritageClauses) { for (const heritageClause of node.heritageClauses) { if (heritageClause.token === SyntaxKind.ExtendsKeyword) { if (seenExtendsClause) { return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_already_seen); } if (seenImplementsClause) { return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_must_precede_implements_clause); } if (heritageClause.types.length > 1) { return grammarErrorOnFirstToken(heritageClause.types[1], Diagnostics.Classes_can_only_extend_a_single_class); } seenExtendsClause = true; } else { Debug.assert(heritageClause.token === SyntaxKind.ImplementsKeyword); if (seenImplementsClause) { return grammarErrorOnFirstToken(heritageClause, Diagnostics.implements_clause_already_seen); } seenImplementsClause = true; } // Grammar checking heritageClause inside class declaration checkGrammarHeritageClause(heritageClause); } } } function checkGrammarInterfaceDeclaration(node: InterfaceDeclaration) { let seenExtendsClause = false; if (node.heritageClauses) { for (const heritageClause of node.heritageClauses) { if (heritageClause.token === SyntaxKind.ExtendsKeyword) { if (seenExtendsClause) { return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_already_seen); } seenExtendsClause = true; } else { Debug.assert(heritageClause.token === SyntaxKind.ImplementsKeyword); return grammarErrorOnFirstToken(heritageClause, Diagnostics.Interface_declaration_cannot_have_implements_clause); } // Grammar checking heritageClause inside class declaration checkGrammarHeritageClause(heritageClause); } } return false; } function checkGrammarComputedPropertyName(node: Node): boolean { // If node is not a computedPropertyName, just skip the grammar checking if (node.kind !== SyntaxKind.ComputedPropertyName) { return false; } const computedPropertyName = node as ComputedPropertyName; if (computedPropertyName.expression.kind === SyntaxKind.BinaryExpression && (computedPropertyName.expression as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken) { return grammarErrorOnNode(computedPropertyName.expression, Diagnostics.A_comma_expression_is_not_allowed_in_a_computed_property_name); } return false; } function checkGrammarForGenerator(node: FunctionLikeDeclaration) { if (node.asteriskToken) { Debug.assert( node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.FunctionExpression || node.kind === SyntaxKind.MethodDeclaration); if (node.flags & NodeFlags.Ambient) { return grammarErrorOnNode(node.asteriskToken, Diagnostics.Generators_are_not_allowed_in_an_ambient_context); } if (!node.body) { return grammarErrorOnNode(node.asteriskToken, Diagnostics.An_overload_signature_cannot_be_declared_as_a_generator); } } } function checkGrammarForInvalidQuestionMark(questionToken: QuestionToken | undefined, message: DiagnosticMessage): boolean { return !!questionToken && grammarErrorOnNode(questionToken, message); } function checkGrammarForInvalidExclamationToken(exclamationToken: ExclamationToken | undefined, message: DiagnosticMessage): boolean { return !!exclamationToken && grammarErrorOnNode(exclamationToken, message); } function checkGrammarObjectLiteralExpression(node: ObjectLiteralExpression, inDestructuring: boolean) { const seen = new Map<__String, DeclarationMeaning>(); for (const prop of node.properties) { if (prop.kind === SyntaxKind.SpreadAssignment) { if (inDestructuring) { // a rest property cannot be destructured any further const expression = skipParentheses(prop.expression); if (isArrayLiteralExpression(expression) || isObjectLiteralExpression(expression)) { return grammarErrorOnNode(prop.expression, Diagnostics.A_rest_element_cannot_contain_a_binding_pattern); } } continue; } const name = prop.name; if (name.kind === SyntaxKind.ComputedPropertyName) { // If the name is not a ComputedPropertyName, the grammar checking will skip it checkGrammarComputedPropertyName(name); } if (prop.kind === SyntaxKind.ShorthandPropertyAssignment && !inDestructuring && prop.objectAssignmentInitializer) { // having objectAssignmentInitializer is only valid in ObjectAssignmentPattern // outside of destructuring it is a syntax error grammarErrorOnNode(prop.equalsToken!, Diagnostics.Did_you_mean_to_use_a_Colon_An_can_only_follow_a_property_name_when_the_containing_object_literal_is_part_of_a_destructuring_pattern); } if (name.kind === SyntaxKind.PrivateIdentifier) { grammarErrorOnNode(name, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); } // Modifiers are never allowed on properties except for 'async' on a method declaration if (canHaveModifiers(prop) && prop.modifiers) { for (const mod of prop.modifiers) { if (isModifier(mod) && (mod.kind !== SyntaxKind.AsyncKeyword || prop.kind !== SyntaxKind.MethodDeclaration)) { grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod)); } } } else if (canHaveIllegalModifiers(prop) && prop.modifiers) { for (const mod of prop.modifiers) { if (isModifier(mod)) { grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod)); } } } // ECMA-262 11.1.5 Object Initializer // If previous is not undefined then throw a SyntaxError exception if any of the following conditions are true // a.This production is contained in strict code and IsDataDescriptor(previous) is true and // IsDataDescriptor(propId.descriptor) is true. // b.IsDataDescriptor(previous) is true and IsAccessorDescriptor(propId.descriptor) is true. // c.IsAccessorDescriptor(previous) is true and IsDataDescriptor(propId.descriptor) is true. // d.IsAccessorDescriptor(previous) is true and IsAccessorDescriptor(propId.descriptor) is true // and either both previous and propId.descriptor have[[Get]] fields or both previous and propId.descriptor have[[Set]] fields let currentKind: DeclarationMeaning; switch (prop.kind) { case SyntaxKind.ShorthandPropertyAssignment: case SyntaxKind.PropertyAssignment: // Grammar checking for computedPropertyName and shorthandPropertyAssignment checkGrammarForInvalidExclamationToken(prop.exclamationToken, Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context); checkGrammarForInvalidQuestionMark(prop.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional); if (name.kind === SyntaxKind.NumericLiteral) { checkGrammarNumericLiteral(name); } currentKind = DeclarationMeaning.PropertyAssignment; break; case SyntaxKind.MethodDeclaration: currentKind = DeclarationMeaning.Method; break; case SyntaxKind.GetAccessor: currentKind = DeclarationMeaning.GetAccessor; break; case SyntaxKind.SetAccessor: currentKind = DeclarationMeaning.SetAccessor; break; default: throw Debug.assertNever(prop, "Unexpected syntax kind:" + (prop as Node).kind); } if (!inDestructuring) { const effectiveName = getPropertyNameForPropertyNameNode(name); if (effectiveName === undefined) { continue; } const existingKind = seen.get(effectiveName); if (!existingKind) { seen.set(effectiveName, currentKind); } else { if ((currentKind & DeclarationMeaning.Method) && (existingKind & DeclarationMeaning.Method)) { grammarErrorOnNode(name, Diagnostics.Duplicate_identifier_0, getTextOfNode(name)); } else if ((currentKind & DeclarationMeaning.PropertyAssignment) && (existingKind & DeclarationMeaning.PropertyAssignment)) { grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_multiple_properties_with_the_same_name, getTextOfNode(name)); } else if ((currentKind & DeclarationMeaning.GetOrSetAccessor) && (existingKind & DeclarationMeaning.GetOrSetAccessor)) { if (existingKind !== DeclarationMeaning.GetOrSetAccessor && currentKind !== existingKind) { seen.set(effectiveName, currentKind | existingKind); } else { return grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name); } } else { return grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name); } } } } } function checkGrammarJsxElement(node: JsxOpeningLikeElement) { checkGrammarJsxName(node.tagName); checkGrammarTypeArguments(node, node.typeArguments); const seen = new Map<__String, boolean>(); for (const attr of node.attributes.properties) { if (attr.kind === SyntaxKind.JsxSpreadAttribute) { continue; } const { name, initializer } = attr; if (!seen.get(name.escapedText)) { seen.set(name.escapedText, true); } else { return grammarErrorOnNode(name, Diagnostics.JSX_elements_cannot_have_multiple_attributes_with_the_same_name); } if (initializer && initializer.kind === SyntaxKind.JsxExpression && !initializer.expression) { return grammarErrorOnNode(initializer, Diagnostics.JSX_attributes_must_only_be_assigned_a_non_empty_expression); } } } function checkGrammarJsxName(node: JsxTagNameExpression) { if (isPropertyAccessExpression(node)) { let propName: JsxTagNameExpression = node; do { const check = checkGrammarJsxNestedIdentifier(propName.name); if (check) { return check; } propName = propName.expression; } while (isPropertyAccessExpression(propName)); const check = checkGrammarJsxNestedIdentifier(propName); if (check) { return check; } } function checkGrammarJsxNestedIdentifier(name: MemberName | ThisExpression) { if (isIdentifier(name) && idText(name).indexOf(":") !== -1) { return grammarErrorOnNode(name, Diagnostics.JSX_property_access_expressions_cannot_include_JSX_namespace_names); } } } function checkGrammarJsxExpression(node: JsxExpression) { if (node.expression && isCommaSequence(node.expression)) { return grammarErrorOnNode(node.expression, Diagnostics.JSX_expressions_may_not_use_the_comma_operator_Did_you_mean_to_write_an_array); } } function checkGrammarForInOrForOfStatement(forInOrOfStatement: ForInOrOfStatement): boolean { if (checkGrammarStatementInAmbientContext(forInOrOfStatement)) { return true; } if (forInOrOfStatement.kind === SyntaxKind.ForOfStatement && forInOrOfStatement.awaitModifier) { if (!(forInOrOfStatement.flags & NodeFlags.AwaitContext)) { const sourceFile = getSourceFileOfNode(forInOrOfStatement); if (isInTopLevelContext(forInOrOfStatement)) { if (!hasParseDiagnostics(sourceFile)) { if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { diagnostics.add(createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.for_await_loops_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module)); } switch (moduleKind) { case ModuleKind.Node16: case ModuleKind.NodeNext: if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { diagnostics.add( createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level) ); break; } // fallthrough case ModuleKind.ES2022: case ModuleKind.ESNext: case ModuleKind.System: if (languageVersion >= ScriptTarget.ES2017) { break; } // fallthrough default: diagnostics.add( createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.Top_level_for_await_loops_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_or_nodenext_and_the_target_option_is_set_to_es2017_or_higher ) ); break; } } } else { // use of 'for-await-of' in non-async function if (!hasParseDiagnostics(sourceFile)) { const diagnostic = createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.for_await_loops_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules); const func = getContainingFunction(forInOrOfStatement); if (func && func.kind !== SyntaxKind.Constructor) { Debug.assert((getFunctionFlags(func) & FunctionFlags.Async) === 0, "Enclosing function should never be an async function."); const relatedInfo = createDiagnosticForNode(func, Diagnostics.Did_you_mean_to_mark_this_function_as_async); addRelatedInfo(diagnostic, relatedInfo); } diagnostics.add(diagnostic); return true; } } return false; } } if (isForOfStatement(forInOrOfStatement) && !(forInOrOfStatement.flags & NodeFlags.AwaitContext) && isIdentifier(forInOrOfStatement.initializer) && forInOrOfStatement.initializer.escapedText === "async") { grammarErrorOnNode(forInOrOfStatement.initializer, Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_async); return false; } if (forInOrOfStatement.initializer.kind === SyntaxKind.VariableDeclarationList) { const variableList = forInOrOfStatement.initializer as VariableDeclarationList; if (!checkGrammarVariableDeclarationList(variableList)) { const declarations = variableList.declarations; // declarations.length can be zero if there is an error in variable declaration in for-of or for-in // See http://www.ecma-international.org/ecma-262/6.0/#sec-for-in-and-for-of-statements for details // For example: // var let = 10; // for (let of [1,2,3]) {} // this is invalid ES6 syntax // for (let in [1,2,3]) {} // this is invalid ES6 syntax // We will then want to skip on grammar checking on variableList declaration if (!declarations.length) { return false; } if (declarations.length > 1) { const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement ? Diagnostics.Only_a_single_variable_declaration_is_allowed_in_a_for_in_statement : Diagnostics.Only_a_single_variable_declaration_is_allowed_in_a_for_of_statement; return grammarErrorOnFirstToken(variableList.declarations[1], diagnostic); } const firstDeclaration = declarations[0]; if (firstDeclaration.initializer) { const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement ? Diagnostics.The_variable_declaration_of_a_for_in_statement_cannot_have_an_initializer : Diagnostics.The_variable_declaration_of_a_for_of_statement_cannot_have_an_initializer; return grammarErrorOnNode(firstDeclaration.name, diagnostic); } if (firstDeclaration.type) { const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement ? Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_use_a_type_annotation : Diagnostics.The_left_hand_side_of_a_for_of_statement_cannot_use_a_type_annotation; return grammarErrorOnNode(firstDeclaration, diagnostic); } } } return false; } function checkGrammarAccessor(accessor: AccessorDeclaration): boolean { if (!(accessor.flags & NodeFlags.Ambient) && (accessor.parent.kind !== SyntaxKind.TypeLiteral) && (accessor.parent.kind !== SyntaxKind.InterfaceDeclaration)) { if (languageVersion < ScriptTarget.ES5) { return grammarErrorOnNode(accessor.name, Diagnostics.Accessors_are_only_available_when_targeting_ECMAScript_5_and_higher); } if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(accessor.name)) { return grammarErrorOnNode(accessor.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); } if (accessor.body === undefined && !hasSyntacticModifier(accessor, ModifierFlags.Abstract)) { return grammarErrorAtPos(accessor, accessor.end - 1, ";".length, Diagnostics._0_expected, "{"); } } if (accessor.body) { if (hasSyntacticModifier(accessor, ModifierFlags.Abstract)) { return grammarErrorOnNode(accessor, Diagnostics.An_abstract_accessor_cannot_have_an_implementation); } if (accessor.parent.kind === SyntaxKind.TypeLiteral || accessor.parent.kind === SyntaxKind.InterfaceDeclaration) { return grammarErrorOnNode(accessor.body, Diagnostics.An_implementation_cannot_be_declared_in_ambient_contexts); } } if (accessor.typeParameters) { return grammarErrorOnNode(accessor.name, Diagnostics.An_accessor_cannot_have_type_parameters); } if (!doesAccessorHaveCorrectParameterCount(accessor)) { return grammarErrorOnNode(accessor.name, accessor.kind === SyntaxKind.GetAccessor ? Diagnostics.A_get_accessor_cannot_have_parameters : Diagnostics.A_set_accessor_must_have_exactly_one_parameter); } if (accessor.kind === SyntaxKind.SetAccessor) { if (accessor.type) { return grammarErrorOnNode(accessor.name, Diagnostics.A_set_accessor_cannot_have_a_return_type_annotation); } const parameter = Debug.checkDefined(getSetAccessorValueParameter(accessor), "Return value does not match parameter count assertion."); if (parameter.dotDotDotToken) { return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.A_set_accessor_cannot_have_rest_parameter); } if (parameter.questionToken) { return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_set_accessor_cannot_have_an_optional_parameter); } if (parameter.initializer) { return grammarErrorOnNode(accessor.name, Diagnostics.A_set_accessor_parameter_cannot_have_an_initializer); } } return false; } /** Does the accessor have the right number of parameters? * A get accessor has no parameters or a single `this` parameter. * A set accessor has one parameter or a `this` parameter and one more parameter. */ function doesAccessorHaveCorrectParameterCount(accessor: AccessorDeclaration) { return getAccessorThisParameter(accessor) || accessor.parameters.length === (accessor.kind === SyntaxKind.GetAccessor ? 0 : 1); } function getAccessorThisParameter(accessor: AccessorDeclaration): ParameterDeclaration | undefined { if (accessor.parameters.length === (accessor.kind === SyntaxKind.GetAccessor ? 1 : 2)) { return getThisParameter(accessor); } } function checkGrammarTypeOperatorNode(node: TypeOperatorNode) { if (node.operator === SyntaxKind.UniqueKeyword) { if (node.type.kind !== SyntaxKind.SymbolKeyword) { return grammarErrorOnNode(node.type, Diagnostics._0_expected, tokenToString(SyntaxKind.SymbolKeyword)); } let parent = walkUpParenthesizedTypes(node.parent); if (isInJSFile(parent) && isJSDocTypeExpression(parent)) { const host = getJSDocHost(parent); if (host) { parent = getSingleVariableOfVariableStatement(host) || host; } } switch (parent.kind) { case SyntaxKind.VariableDeclaration: const decl = parent as VariableDeclaration; if (decl.name.kind !== SyntaxKind.Identifier) { return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_may_not_be_used_on_a_variable_declaration_with_a_binding_name); } if (!isVariableDeclarationInVariableStatement(decl)) { return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_are_only_allowed_on_variables_in_a_variable_statement); } if (!(decl.parent.flags & NodeFlags.Const)) { return grammarErrorOnNode((parent as VariableDeclaration).name, Diagnostics.A_variable_whose_type_is_a_unique_symbol_type_must_be_const); } break; case SyntaxKind.PropertyDeclaration: if (!isStatic(parent) || !hasEffectiveReadonlyModifier(parent)) { return grammarErrorOnNode((parent as PropertyDeclaration).name, Diagnostics.A_property_of_a_class_whose_type_is_a_unique_symbol_type_must_be_both_static_and_readonly); } break; case SyntaxKind.PropertySignature: if (!hasSyntacticModifier(parent, ModifierFlags.Readonly)) { return grammarErrorOnNode((parent as PropertySignature).name, Diagnostics.A_property_of_an_interface_or_type_literal_whose_type_is_a_unique_symbol_type_must_be_readonly); } break; default: return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_are_not_allowed_here); } } else if (node.operator === SyntaxKind.ReadonlyKeyword) { if (node.type.kind !== SyntaxKind.ArrayType && node.type.kind !== SyntaxKind.TupleType) { return grammarErrorOnFirstToken(node, Diagnostics.readonly_type_modifier_is_only_permitted_on_array_and_tuple_literal_types, tokenToString(SyntaxKind.SymbolKeyword)); } } } function checkGrammarForInvalidDynamicName(node: DeclarationName, message: DiagnosticMessage) { if (isNonBindableDynamicName(node)) { return grammarErrorOnNode(node, message); } } function checkGrammarMethod(node: MethodDeclaration | MethodSignature) { if (checkGrammarFunctionLikeDeclaration(node)) { return true; } if (node.kind === SyntaxKind.MethodDeclaration) { if (node.parent.kind === SyntaxKind.ObjectLiteralExpression) { // We only disallow modifier on a method declaration if it is a property of object-literal-expression if (node.modifiers && !(node.modifiers.length === 1 && first(node.modifiers).kind === SyntaxKind.AsyncKeyword)) { return grammarErrorOnFirstToken(node, Diagnostics.Modifiers_cannot_appear_here); } else if (checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional)) { return true; } else if (checkGrammarForInvalidExclamationToken(node.exclamationToken, Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context)) { return true; } else if (node.body === undefined) { return grammarErrorAtPos(node, node.end - 1, ";".length, Diagnostics._0_expected, "{"); } } if (checkGrammarForGenerator(node)) { return true; } } if (isClassLike(node.parent)) { if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(node.name)) { return grammarErrorOnNode(node.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); } // Technically, computed properties in ambient contexts is disallowed // for property declarations and accessors too, not just methods. // However, property declarations disallow computed names in general, // and accessors are not allowed in ambient contexts in general, // so this error only really matters for methods. if (node.flags & NodeFlags.Ambient) { return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_ambient_context_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); } else if (node.kind === SyntaxKind.MethodDeclaration && !node.body) { return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_method_overload_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); } } else if (node.parent.kind === SyntaxKind.InterfaceDeclaration) { return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_interface_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); } else if (node.parent.kind === SyntaxKind.TypeLiteral) { return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_type_literal_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); } } function checkGrammarBreakOrContinueStatement(node: BreakOrContinueStatement): boolean { let current: Node = node; while (current) { if (isFunctionLikeOrClassStaticBlockDeclaration(current)) { return grammarErrorOnNode(node, Diagnostics.Jump_target_cannot_cross_function_boundary); } switch (current.kind) { case SyntaxKind.LabeledStatement: if (node.label && (current as LabeledStatement).label.escapedText === node.label.escapedText) { // found matching label - verify that label usage is correct // continue can only target labels that are on iteration statements const isMisplacedContinueLabel = node.kind === SyntaxKind.ContinueStatement && !isIterationStatement((current as LabeledStatement).statement, /*lookInLabeledStatement*/ true); if (isMisplacedContinueLabel) { return grammarErrorOnNode(node, Diagnostics.A_continue_statement_can_only_jump_to_a_label_of_an_enclosing_iteration_statement); } return false; } break; case SyntaxKind.SwitchStatement: if (node.kind === SyntaxKind.BreakStatement && !node.label) { // unlabeled break within switch statement - ok return false; } break; default: if (isIterationStatement(current, /*lookInLabeledStatement*/ false) && !node.label) { // unlabeled break or continue within iteration statement - ok return false; } break; } current = current.parent; } if (node.label) { const message = node.kind === SyntaxKind.BreakStatement ? Diagnostics.A_break_statement_can_only_jump_to_a_label_of_an_enclosing_statement : Diagnostics.A_continue_statement_can_only_jump_to_a_label_of_an_enclosing_iteration_statement; return grammarErrorOnNode(node, message); } else { const message = node.kind === SyntaxKind.BreakStatement ? Diagnostics.A_break_statement_can_only_be_used_within_an_enclosing_iteration_or_switch_statement : Diagnostics.A_continue_statement_can_only_be_used_within_an_enclosing_iteration_statement; return grammarErrorOnNode(node, message); } } function checkGrammarBindingElement(node: BindingElement) { if (node.dotDotDotToken) { const elements = node.parent.elements; if (node !== last(elements)) { return grammarErrorOnNode(node, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); } checkGrammarForDisallowedTrailingComma(elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); if (node.propertyName) { return grammarErrorOnNode(node.name, Diagnostics.A_rest_element_cannot_have_a_property_name); } } if (node.dotDotDotToken && node.initializer) { // Error on equals token which immediately precedes the initializer return grammarErrorAtPos(node, node.initializer.pos - 1, 1, Diagnostics.A_rest_element_cannot_have_an_initializer); } } function isStringOrNumberLiteralExpression(expr: Expression) { return isStringOrNumericLiteralLike(expr) || expr.kind === SyntaxKind.PrefixUnaryExpression && (expr as PrefixUnaryExpression).operator === SyntaxKind.MinusToken && (expr as PrefixUnaryExpression).operand.kind === SyntaxKind.NumericLiteral; } function isBigIntLiteralExpression(expr: Expression) { return expr.kind === SyntaxKind.BigIntLiteral || expr.kind === SyntaxKind.PrefixUnaryExpression && (expr as PrefixUnaryExpression).operator === SyntaxKind.MinusToken && (expr as PrefixUnaryExpression).operand.kind === SyntaxKind.BigIntLiteral; } function isSimpleLiteralEnumReference(expr: Expression) { if ((isPropertyAccessExpression(expr) || (isElementAccessExpression(expr) && isStringOrNumberLiteralExpression(expr.argumentExpression))) && isEntityNameExpression(expr.expression)) { return !!(checkExpressionCached(expr).flags & TypeFlags.EnumLike); } } function checkAmbientInitializer(node: VariableDeclaration | PropertyDeclaration | PropertySignature) { const initializer = node.initializer; if (initializer) { const isInvalidInitializer = !( isStringOrNumberLiteralExpression(initializer) || isSimpleLiteralEnumReference(initializer) || initializer.kind === SyntaxKind.TrueKeyword || initializer.kind === SyntaxKind.FalseKeyword || isBigIntLiteralExpression(initializer) ); const isConstOrReadonly = isDeclarationReadonly(node) || isVariableDeclaration(node) && isVarConst(node); if (isConstOrReadonly && !node.type) { if (isInvalidInitializer) { return grammarErrorOnNode(initializer, Diagnostics.A_const_initializer_in_an_ambient_context_must_be_a_string_or_numeric_literal_or_literal_enum_reference); } } else { return grammarErrorOnNode(initializer, Diagnostics.Initializers_are_not_allowed_in_ambient_contexts); } } } function checkGrammarVariableDeclaration(node: VariableDeclaration) { if (node.parent.parent.kind !== SyntaxKind.ForInStatement && node.parent.parent.kind !== SyntaxKind.ForOfStatement) { if (node.flags & NodeFlags.Ambient) { checkAmbientInitializer(node); } else if (!node.initializer) { if (isBindingPattern(node.name) && !isBindingPattern(node.parent)) { return grammarErrorOnNode(node, Diagnostics.A_destructuring_declaration_must_have_an_initializer); } if (isVarConst(node)) { return grammarErrorOnNode(node, Diagnostics.const_declarations_must_be_initialized); } } } if (node.exclamationToken && (node.parent.parent.kind !== SyntaxKind.VariableStatement || !node.type || node.initializer || node.flags & NodeFlags.Ambient)) { const message = node.initializer ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions : !node.type ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context; return grammarErrorOnNode(node.exclamationToken, message); } if ((moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && moduleKind !== ModuleKind.System && !(node.parent.parent.flags & NodeFlags.Ambient) && hasSyntacticModifier(node.parent.parent, ModifierFlags.Export)) { checkESModuleMarker(node.name); } const checkLetConstNames = (isLet(node) || isVarConst(node)); // 1. LexicalDeclaration : LetOrConst BindingList ; // It is a Syntax Error if the BoundNames of BindingList contains "let". // 2. ForDeclaration: ForDeclaration : LetOrConst ForBinding // It is a Syntax Error if the BoundNames of ForDeclaration contains "let". // It is a SyntaxError if a VariableDeclaration or VariableDeclarationNoIn occurs within strict code // and its Identifier is eval or arguments return checkLetConstNames && checkGrammarNameInLetOrConstDeclarations(node.name); } function checkESModuleMarker(name: Identifier | BindingPattern): boolean { if (name.kind === SyntaxKind.Identifier) { if (idText(name) === "__esModule") { return grammarErrorOnNodeSkippedOn("noEmit", name, Diagnostics.Identifier_expected_esModule_is_reserved_as_an_exported_marker_when_transforming_ECMAScript_modules); } } else { const elements = name.elements; for (const element of elements) { if (!isOmittedExpression(element)) { return checkESModuleMarker(element.name); } } } return false; } function checkGrammarNameInLetOrConstDeclarations(name: Identifier | BindingPattern): boolean { if (name.kind === SyntaxKind.Identifier) { if (name.escapedText === "let") { return grammarErrorOnNode(name, Diagnostics.let_is_not_allowed_to_be_used_as_a_name_in_let_or_const_declarations); } } else { const elements = name.elements; for (const element of elements) { if (!isOmittedExpression(element)) { checkGrammarNameInLetOrConstDeclarations(element.name); } } } return false; } function checkGrammarVariableDeclarationList(declarationList: VariableDeclarationList): boolean { const declarations = declarationList.declarations; if (checkGrammarForDisallowedTrailingComma(declarationList.declarations)) { return true; } if (!declarationList.declarations.length) { return grammarErrorAtPos(declarationList, declarations.pos, declarations.end - declarations.pos, Diagnostics.Variable_declaration_list_cannot_be_empty); } return false; } function allowLetAndConstDeclarations(parent: Node): boolean { switch (parent.kind) { case SyntaxKind.IfStatement: case SyntaxKind.DoStatement: case SyntaxKind.WhileStatement: case SyntaxKind.WithStatement: case SyntaxKind.ForStatement: case SyntaxKind.ForInStatement: case SyntaxKind.ForOfStatement: return false; case SyntaxKind.LabeledStatement: return allowLetAndConstDeclarations(parent.parent); } return true; } function checkGrammarForDisallowedLetOrConstStatement(node: VariableStatement) { if (!allowLetAndConstDeclarations(node.parent)) { if (isLet(node.declarationList)) { return grammarErrorOnNode(node, Diagnostics.let_declarations_can_only_be_declared_inside_a_block); } else if (isVarConst(node.declarationList)) { return grammarErrorOnNode(node, Diagnostics.const_declarations_can_only_be_declared_inside_a_block); } } } function checkGrammarMetaProperty(node: MetaProperty) { const escapedText = node.name.escapedText; switch (node.keywordToken) { case SyntaxKind.NewKeyword: if (escapedText !== "target") { return grammarErrorOnNode(node.name, Diagnostics._0_is_not_a_valid_meta_property_for_keyword_1_Did_you_mean_2, node.name.escapedText, tokenToString(node.keywordToken), "target"); } break; case SyntaxKind.ImportKeyword: if (escapedText !== "meta") { return grammarErrorOnNode(node.name, Diagnostics._0_is_not_a_valid_meta_property_for_keyword_1_Did_you_mean_2, node.name.escapedText, tokenToString(node.keywordToken), "meta"); } break; } } function hasParseDiagnostics(sourceFile: SourceFile): boolean { return sourceFile.parseDiagnostics.length > 0; } function grammarErrorOnFirstToken(node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any): boolean { const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { const span = getSpanOfTokenAtPosition(sourceFile, node.pos); diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, message, arg0, arg1, arg2)); return true; } return false; } function grammarErrorAtPos(nodeForSourceFile: Node, start: number, length: number, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any): boolean { const sourceFile = getSourceFileOfNode(nodeForSourceFile); if (!hasParseDiagnostics(sourceFile)) { diagnostics.add(createFileDiagnostic(sourceFile, start, length, message, arg0, arg1, arg2)); return true; } return false; } function grammarErrorOnNodeSkippedOn(key: keyof CompilerOptions, node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any): boolean { const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { errorSkippedOn(key, node, message, arg0, arg1, arg2); return true; } return false; } function grammarErrorOnNode(node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any): boolean { const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { diagnostics.add(createDiagnosticForNode(node, message, arg0, arg1, arg2)); return true; } return false; } function checkGrammarConstructorTypeParameters(node: ConstructorDeclaration) { const jsdocTypeParameters = isInJSFile(node) ? getJSDocTypeParameterDeclarations(node) : undefined; const range = node.typeParameters || jsdocTypeParameters && firstOrUndefined(jsdocTypeParameters); if (range) { const pos = range.pos === range.end ? range.pos : skipTrivia(getSourceFileOfNode(node).text, range.pos); return grammarErrorAtPos(node, pos, range.end - pos, Diagnostics.Type_parameters_cannot_appear_on_a_constructor_declaration); } } function checkGrammarConstructorTypeAnnotation(node: ConstructorDeclaration) { const type = node.type || getEffectiveReturnTypeNode(node); if (type) { return grammarErrorOnNode(type, Diagnostics.Type_annotation_cannot_appear_on_a_constructor_declaration); } } function checkGrammarProperty(node: PropertyDeclaration | PropertySignature) { if (isComputedPropertyName(node.name) && isBinaryExpression(node.name.expression) && node.name.expression.operatorToken.kind === SyntaxKind.InKeyword) { return grammarErrorOnNode(node.parent.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); } if (isClassLike(node.parent)) { if (isStringLiteral(node.name) && node.name.text === "constructor") { return grammarErrorOnNode(node.name, Diagnostics.Classes_may_not_have_a_field_named_constructor); } if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_class_property_declaration_must_have_a_simple_literal_type_or_a_unique_symbol_type)) { return true; } if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(node.name)) { return grammarErrorOnNode(node.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); } if (languageVersion < ScriptTarget.ES2015 && isAutoAccessorPropertyDeclaration(node)) { return grammarErrorOnNode(node.name, Diagnostics.Properties_with_the_accessor_modifier_are_only_available_when_targeting_ECMAScript_2015_and_higher); } if (isAutoAccessorPropertyDeclaration(node) && checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_accessor_property_cannot_be_declared_optional)) { return true; } } else if (node.parent.kind === SyntaxKind.InterfaceDeclaration) { if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_interface_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) { return true; } // Interfaces cannot contain property declarations Debug.assertNode(node, isPropertySignature); if (node.initializer) { return grammarErrorOnNode(node.initializer, Diagnostics.An_interface_property_cannot_have_an_initializer); } } else if (isTypeLiteralNode(node.parent)) { if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_type_literal_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) { return true; } // Type literals cannot contain property declarations Debug.assertNode(node, isPropertySignature); if (node.initializer) { return grammarErrorOnNode(node.initializer, Diagnostics.A_type_literal_property_cannot_have_an_initializer); } } if (node.flags & NodeFlags.Ambient) { checkAmbientInitializer(node); } if (isPropertyDeclaration(node) && node.exclamationToken && (!isClassLike(node.parent) || !node.type || node.initializer || node.flags & NodeFlags.Ambient || isStatic(node) || hasAbstractModifier(node))) { const message = node.initializer ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions : !node.type ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context; return grammarErrorOnNode(node.exclamationToken, message); } } function checkGrammarTopLevelElementForRequiredDeclareModifier(node: Node): boolean { // A declare modifier is required for any top level .d.ts declaration except export=, export default, export as namespace // interfaces and imports categories: // // DeclarationElement: // ExportAssignment // export_opt InterfaceDeclaration // export_opt TypeAliasDeclaration // export_opt ImportDeclaration // export_opt ExternalImportDeclaration // export_opt AmbientDeclaration // // TODO: The spec needs to be amended to reflect this grammar. if (node.kind === SyntaxKind.InterfaceDeclaration || node.kind === SyntaxKind.TypeAliasDeclaration || node.kind === SyntaxKind.ImportDeclaration || node.kind === SyntaxKind.ImportEqualsDeclaration || node.kind === SyntaxKind.ExportDeclaration || node.kind === SyntaxKind.ExportAssignment || node.kind === SyntaxKind.NamespaceExportDeclaration || hasSyntacticModifier(node, ModifierFlags.Ambient | ModifierFlags.Export | ModifierFlags.Default)) { return false; } return grammarErrorOnFirstToken(node, Diagnostics.Top_level_declarations_in_d_ts_files_must_start_with_either_a_declare_or_export_modifier); } function checkGrammarTopLevelElementsForRequiredDeclareModifier(file: SourceFile): boolean { for (const decl of file.statements) { if (isDeclaration(decl) || decl.kind === SyntaxKind.VariableStatement) { if (checkGrammarTopLevelElementForRequiredDeclareModifier(decl)) { return true; } } } return false; } function checkGrammarSourceFile(node: SourceFile): boolean { return !!(node.flags & NodeFlags.Ambient) && checkGrammarTopLevelElementsForRequiredDeclareModifier(node); } function checkGrammarStatementInAmbientContext(node: Node): boolean { if (node.flags & NodeFlags.Ambient) { // Find containing block which is either Block, ModuleBlock, SourceFile const links = getNodeLinks(node); if (!links.hasReportedStatementInAmbientContext && (isFunctionLike(node.parent) || isAccessor(node.parent))) { return getNodeLinks(node).hasReportedStatementInAmbientContext = grammarErrorOnFirstToken(node, Diagnostics.An_implementation_cannot_be_declared_in_ambient_contexts); } // We are either parented by another statement, or some sort of block. // If we're in a block, we only want to really report an error once // to prevent noisiness. So use a bit on the block to indicate if // this has already been reported, and don't report if it has. // if (node.parent.kind === SyntaxKind.Block || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { const links = getNodeLinks(node.parent); // Check if the containing block ever report this error if (!links.hasReportedStatementInAmbientContext) { return links.hasReportedStatementInAmbientContext = grammarErrorOnFirstToken(node, Diagnostics.Statements_are_not_allowed_in_ambient_contexts); } } else { // We must be parented by a statement. If so, there's no need // to report the error as our parent will have already done it. // Debug.assert(isStatement(node.parent)); } } return false; } function checkGrammarNumericLiteral(node: NumericLiteral): boolean { // Grammar checking if (node.numericLiteralFlags & TokenFlags.Octal) { let diagnosticMessage: DiagnosticMessage | undefined; if (languageVersion >= ScriptTarget.ES5) { diagnosticMessage = Diagnostics.Octal_literals_are_not_available_when_targeting_ECMAScript_5_and_higher_Use_the_syntax_0; } else if (isChildOfNodeWithKind(node, SyntaxKind.LiteralType)) { diagnosticMessage = Diagnostics.Octal_literal_types_must_use_ES2015_syntax_Use_the_syntax_0; } else if (isChildOfNodeWithKind(node, SyntaxKind.EnumMember)) { diagnosticMessage = Diagnostics.Octal_literals_are_not_allowed_in_enums_members_initializer_Use_the_syntax_0; } if (diagnosticMessage) { const withMinus = isPrefixUnaryExpression(node.parent) && node.parent.operator === SyntaxKind.MinusToken; const literal = (withMinus ? "-" : "") + "0o" + node.text; return grammarErrorOnNode(withMinus ? node.parent : node, diagnosticMessage, literal); } } // Realism (size) checking checkNumericLiteralValueSize(node); return false; } function checkNumericLiteralValueSize(node: NumericLiteral) { // We should test against `getTextOfNode(node)` rather than `node.text`, because `node.text` for large numeric literals can contain "." // e.g. `node.text` for numeric literal `1100000000000000000000` is `1.1e21`. const isFractional = getTextOfNode(node).indexOf(".") !== -1; const isScientific = node.numericLiteralFlags & TokenFlags.Scientific; // Scientific notation (e.g. 2e54 and 1e00000000010) can't be converted to bigint // Fractional numbers (e.g. 9000000000000000.001) are inherently imprecise anyway if (isFractional || isScientific) { return; } // Here `node` is guaranteed to be a numeric literal representing an integer. // We need to judge whether the integer `node` represents is <= 2 ** 53 - 1, which can be accomplished by comparing to `value` defined below because: // 1) when `node` represents an integer <= 2 ** 53 - 1, `node.text` is its exact string representation and thus `value` precisely represents the integer. // 2) otherwise, although `node.text` may be imprecise string representation, its mathematical value and consequently `value` cannot be less than 2 ** 53, // thus the result of the predicate won't be affected. const value = +node.text; if (value <= 2 ** 53 - 1) { return; } addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.Numeric_literals_with_absolute_values_equal_to_2_53_or_greater_are_too_large_to_be_represented_accurately_as_integers)); } function checkGrammarBigIntLiteral(node: BigIntLiteral): boolean { const literalType = isLiteralTypeNode(node.parent) || isPrefixUnaryExpression(node.parent) && isLiteralTypeNode(node.parent.parent); if (!literalType) { if (languageVersion < ScriptTarget.ES2020) { if (grammarErrorOnNode(node, Diagnostics.BigInt_literals_are_not_available_when_targeting_lower_than_ES2020)) { return true; } } } return false; } function grammarErrorAfterFirstToken(node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any): boolean { const sourceFile = getSourceFileOfNode(node); if (!hasParseDiagnostics(sourceFile)) { const span = getSpanOfTokenAtPosition(sourceFile, node.pos); diagnostics.add(createFileDiagnostic(sourceFile, textSpanEnd(span), /*length*/ 0, message, arg0, arg1, arg2)); return true; } return false; } function getAmbientModules(): Symbol[] { if (!ambientModulesCache) { ambientModulesCache = []; globals.forEach((global, sym) => { // No need to `unescapeLeadingUnderscores`, an escaped symbol is never an ambient module. if (ambientModuleSymbolRegex.test(sym as string)) { ambientModulesCache!.push(global); } }); } return ambientModulesCache; } function checkGrammarImportClause(node: ImportClause): boolean { if (node.isTypeOnly && node.name && node.namedBindings) { return grammarErrorOnNode(node, Diagnostics.A_type_only_import_can_specify_a_default_import_or_named_bindings_but_not_both); } if (node.isTypeOnly && node.namedBindings?.kind === SyntaxKind.NamedImports) { return checkGrammarNamedImportsOrExports(node.namedBindings); } return false; } function checkGrammarNamedImportsOrExports(namedBindings: NamedImportsOrExports): boolean { return !!forEach(namedBindings.elements, specifier => { if (specifier.isTypeOnly) { return grammarErrorOnFirstToken( specifier, specifier.kind === SyntaxKind.ImportSpecifier ? Diagnostics.The_type_modifier_cannot_be_used_on_a_named_import_when_import_type_is_used_on_its_import_statement : Diagnostics.The_type_modifier_cannot_be_used_on_a_named_export_when_export_type_is_used_on_its_export_statement); } }); } function checkGrammarImportCallExpression(node: ImportCall): boolean { if (compilerOptions.verbatimModuleSyntax && moduleKind === ModuleKind.CommonJS) { return grammarErrorOnNode(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); } if (moduleKind === ModuleKind.ES2015) { return grammarErrorOnNode(node, Diagnostics.Dynamic_imports_are_only_supported_when_the_module_flag_is_set_to_es2020_es2022_esnext_commonjs_amd_system_umd_node16_or_nodenext); } if (node.typeArguments) { return grammarErrorOnNode(node, Diagnostics.This_use_of_import_is_invalid_import_calls_can_be_written_but_they_must_have_parentheses_and_cannot_have_type_arguments); } const nodeArguments = node.arguments; if (moduleKind !== ModuleKind.ESNext && moduleKind !== ModuleKind.NodeNext && moduleKind !== ModuleKind.Node16) { // We are allowed trailing comma after proposal-import-assertions. checkGrammarForDisallowedTrailingComma(nodeArguments); if (nodeArguments.length > 1) { const assertionArgument = nodeArguments[1]; return grammarErrorOnNode(assertionArgument, Diagnostics.Dynamic_imports_only_support_a_second_argument_when_the_module_option_is_set_to_esnext_node16_or_nodenext); } } if (nodeArguments.length === 0 || nodeArguments.length > 2) { return grammarErrorOnNode(node, Diagnostics.Dynamic_imports_can_only_accept_a_module_specifier_and_an_optional_assertion_as_arguments); } // see: parseArgumentOrArrayLiteralElement...we use this function which parse arguments of callExpression to parse specifier for dynamic import. // parseArgumentOrArrayLiteralElement allows spread element to be in an argument list which is not allowed as specifier in dynamic import. const spreadElement = find(nodeArguments, isSpreadElement); if (spreadElement) { return grammarErrorOnNode(spreadElement, Diagnostics.Argument_of_dynamic_import_cannot_be_spread_element); } return false; } function findMatchingTypeReferenceOrTypeAliasReference(source: Type, unionTarget: UnionOrIntersectionType) { const sourceObjectFlags = getObjectFlags(source); if (sourceObjectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous) && unionTarget.flags & TypeFlags.Union) { return find(unionTarget.types, target => { if (target.flags & TypeFlags.Object) { const overlapObjFlags = sourceObjectFlags & getObjectFlags(target); if (overlapObjFlags & ObjectFlags.Reference) { return (source as TypeReference).target === (target as TypeReference).target; } if (overlapObjFlags & ObjectFlags.Anonymous) { return !!(source as AnonymousType).aliasSymbol && (source as AnonymousType).aliasSymbol === (target as AnonymousType).aliasSymbol; } } return false; }); } } function findBestTypeForObjectLiteral(source: Type, unionTarget: UnionOrIntersectionType) { if (getObjectFlags(source) & ObjectFlags.ObjectLiteral && someType(unionTarget, isArrayLikeType)) { return find(unionTarget.types, t => !isArrayLikeType(t)); } } function findBestTypeForInvokable(source: Type, unionTarget: UnionOrIntersectionType) { let signatureKind = SignatureKind.Call; const hasSignatures = getSignaturesOfType(source, signatureKind).length > 0 || (signatureKind = SignatureKind.Construct, getSignaturesOfType(source, signatureKind).length > 0); if (hasSignatures) { return find(unionTarget.types, t => getSignaturesOfType(t, signatureKind).length > 0); } } function findMostOverlappyType(source: Type, unionTarget: UnionOrIntersectionType) { let bestMatch: Type | undefined; if (!(source.flags & (TypeFlags.Primitive | TypeFlags.InstantiablePrimitive))) { let matchingCount = 0; for (const target of unionTarget.types) { if (!(target.flags & (TypeFlags.Primitive | TypeFlags.InstantiablePrimitive))) { const overlap = getIntersectionType([getIndexType(source), getIndexType(target)]); if (overlap.flags & TypeFlags.Index) { // perfect overlap of keys return target; } else if (isUnitType(overlap) || overlap.flags & TypeFlags.Union) { // We only want to account for literal types otherwise. // If we have a union of index types, it seems likely that we // needed to elaborate between two generic mapped types anyway. const len = overlap.flags & TypeFlags.Union ? countWhere((overlap as UnionType).types, isUnitType) : 1; if (len >= matchingCount) { bestMatch = target; matchingCount = len; } } } } } return bestMatch; } function filterPrimitivesIfContainsNonPrimitive(type: UnionType) { if (maybeTypeOfKind(type, TypeFlags.NonPrimitive)) { const result = filterType(type, t => !(t.flags & TypeFlags.Primitive)); if (!(result.flags & TypeFlags.Never)) { return result; } } return type; } // Keep this up-to-date with the same logic within `getApparentTypeOfContextualType`, since they should behave similarly function findMatchingDiscriminantType(source: Type, target: Type, isRelatedTo: (source: Type, target: Type) => Ternary, skipPartial?: boolean) { if (target.flags & TypeFlags.Union && source.flags & (TypeFlags.Intersection | TypeFlags.Object)) { const match = getMatchingUnionConstituentForType(target as UnionType, source); if (match) { return match; } const sourceProperties = getPropertiesOfType(source); if (sourceProperties) { const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); if (sourcePropertiesFiltered) { return discriminateTypeByDiscriminableItems(target as UnionType, map(sourcePropertiesFiltered, p => ([() => getTypeOfSymbol(p), p.escapedName] as [() => Type, __String])), isRelatedTo, /*defaultValue*/ undefined, skipPartial); } } } return undefined; } } function isNotAccessor(declaration: Declaration): boolean { // Accessors check for their own matching duplicates, and in contexts where they are valid, there are already duplicate identifier checks return !isAccessor(declaration); } function isNotOverload(declaration: Declaration): boolean { return (declaration.kind !== SyntaxKind.FunctionDeclaration && declaration.kind !== SyntaxKind.MethodDeclaration) || !!(declaration as FunctionDeclaration).body; } /** Like 'isDeclarationName', but returns true for LHS of `import { x as y }` or `export { x as y }`. */ function isDeclarationNameOrImportPropertyName(name: Node): boolean { switch (name.parent.kind) { case SyntaxKind.ImportSpecifier: case SyntaxKind.ExportSpecifier: return isIdentifier(name); default: return isDeclarationName(name); } } namespace JsxNames { export const JSX = "JSX" as __String; export const IntrinsicElements = "IntrinsicElements" as __String; export const ElementClass = "ElementClass" as __String; export const ElementAttributesPropertyNameContainer = "ElementAttributesProperty" as __String; // TODO: Deprecate and remove support export const ElementChildrenAttributeNameContainer = "ElementChildrenAttribute" as __String; export const Element = "Element" as __String; export const IntrinsicAttributes = "IntrinsicAttributes" as __String; export const IntrinsicClassAttributes = "IntrinsicClassAttributes" as __String; export const LibraryManagedAttributes = "LibraryManagedAttributes" as __String; } function getIterationTypesKeyFromIterationTypeKind(typeKind: IterationTypeKind) { switch (typeKind) { case IterationTypeKind.Yield: return "yieldType"; case IterationTypeKind.Return: return "returnType"; case IterationTypeKind.Next: return "nextType"; } } /** @internal */ export function signatureHasRestParameter(s: Signature) { return !!(s.flags & SignatureFlags.HasRestParameter); } /** @internal */ export function signatureHasLiteralTypes(s: Signature) { return !!(s.flags & SignatureFlags.HasLiteralTypes); } function createBasicNodeBuilderModuleSpecifierResolutionHost(host: TypeCheckerHost): ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string } { return { getCommonSourceDirectory: !!(host as Program).getCommonSourceDirectory ? () => (host as Program).getCommonSourceDirectory() : () => "", getCurrentDirectory: () => host.getCurrentDirectory(), getSymlinkCache: maybeBind(host, host.getSymlinkCache), getPackageJsonInfoCache: () => host.getPackageJsonInfoCache?.(), useCaseSensitiveFileNames: maybeBind(host, host.useCaseSensitiveFileNames), redirectTargetsMap: host.redirectTargetsMap, getProjectReferenceRedirect: fileName => host.getProjectReferenceRedirect(fileName), isSourceOfProjectReferenceRedirect: fileName => host.isSourceOfProjectReferenceRedirect(fileName), fileExists: fileName => host.fileExists(fileName), getFileIncludeReasons: () => host.getFileIncludeReasons(), readFile: host.readFile ? (fileName => host.readFile!(fileName)) : undefined, }; } interface NodeBuilderContext { enclosingDeclaration: Node | undefined; flags: NodeBuilderFlags; tracker: SymbolTrackerImpl; // State encounteredError: boolean; reportedDiagnostic: boolean; visitedTypes: Set | undefined; symbolDepth: Map | undefined; inferTypeParameters: TypeParameter[] | undefined; approximateLength: number; truncating?: boolean; typeParameterSymbolList?: Set; typeParameterNames?: Map; typeParameterNamesByText?: Set; typeParameterNamesByTextNextNameCount?: Map; usedSymbolNames?: Set; remappedSymbolNames?: Map; reverseMappedStack?: ReverseMappedSymbol[]; } class SymbolTrackerImpl implements SymbolTracker { moduleResolverHost: ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string } | undefined = undefined; context: NodeBuilderContext; readonly inner: SymbolTracker | undefined = undefined; readonly canTrackSymbol: boolean; disableTrackSymbol = false; constructor(context: NodeBuilderContext, tracker: SymbolTracker | undefined, moduleResolverHost: ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string } | undefined) { while (tracker instanceof SymbolTrackerImpl) { tracker = tracker.inner; } this.inner = tracker; this.moduleResolverHost = moduleResolverHost; this.context = context; this.canTrackSymbol = !!this.inner?.trackSymbol; } trackSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): boolean { if (this.inner?.trackSymbol && !this.disableTrackSymbol) { if (this.inner.trackSymbol(symbol, enclosingDeclaration, meaning)) { this.onDiagnosticReported(); return true; } } return false; } reportInaccessibleThisError(): void { if (this.inner?.reportInaccessibleThisError) { this.onDiagnosticReported(); this.inner.reportInaccessibleThisError(); } } reportPrivateInBaseOfClassExpression(propertyName: string): void { if (this.inner?.reportPrivateInBaseOfClassExpression) { this.onDiagnosticReported(); this.inner.reportPrivateInBaseOfClassExpression(propertyName); } } reportInaccessibleUniqueSymbolError(): void { if (this.inner?.reportInaccessibleUniqueSymbolError) { this.onDiagnosticReported(); this.inner.reportInaccessibleUniqueSymbolError(); } } reportCyclicStructureError(): void { if (this.inner?.reportCyclicStructureError) { this.onDiagnosticReported(); this.inner.reportCyclicStructureError(); } } reportLikelyUnsafeImportRequiredError(specifier: string): void { if (this.inner?.reportLikelyUnsafeImportRequiredError) { this.onDiagnosticReported(); this.inner.reportLikelyUnsafeImportRequiredError(specifier); } } reportTruncationError(): void { if (this.inner?.reportTruncationError) { this.onDiagnosticReported(); this.inner.reportTruncationError(); } } trackReferencedAmbientModule(decl: ModuleDeclaration, symbol: Symbol): void { if (this.inner?.trackReferencedAmbientModule) { this.onDiagnosticReported(); this.inner.trackReferencedAmbientModule(decl, symbol); } } trackExternalModuleSymbolOfImportTypeNode(symbol: Symbol): void { if (this.inner?.trackExternalModuleSymbolOfImportTypeNode) { this.onDiagnosticReported(); this.inner.trackExternalModuleSymbolOfImportTypeNode(symbol); } } reportNonlocalAugmentation(containingFile: SourceFile, parentSymbol: Symbol, augmentingSymbol: Symbol): void { if (this.inner?.reportNonlocalAugmentation) { this.onDiagnosticReported(); this.inner.reportNonlocalAugmentation(containingFile, parentSymbol, augmentingSymbol); } } reportNonSerializableProperty(propertyName: string): void { if (this.inner?.reportNonSerializableProperty) { this.onDiagnosticReported(); this.inner.reportNonSerializableProperty(propertyName); } } reportImportTypeNodeResolutionModeOverride(): void { if (this.inner?.reportImportTypeNodeResolutionModeOverride) { this.onDiagnosticReported(); this.inner.reportImportTypeNodeResolutionModeOverride(); } } private onDiagnosticReported() { this.context.reportedDiagnostic = true; } }