include(CMakePushCheckState)
include(CheckCCompilerFlag)
include(CheckCXXCompilerFlag)
include(CheckLibraryExists)
include(LLVMCheckCompilerLinkerFlag)
include(CheckSymbolExists)
include(CheckCSourceCompiles)

# The compiler driver may be implicitly trying to link against libunwind, which
# might not work if libunwind doesn't exist yet. Try to check if
# --unwindlib=none is supported, and use that if possible.
llvm_check_compiler_linker_flag(C "--unwindlib=none" CXX_SUPPORTS_UNWINDLIB_EQ_NONE_FLAG)

if (HAIKU)
  check_library_exists(root fopen "" LIBUNWIND_HAS_ROOT_LIB)
else()
  check_library_exists(c fopen "" LIBUNWIND_HAS_C_LIB)
endif()

if (NOT LIBUNWIND_USE_COMPILER_RT)
  if (ANDROID)
    check_library_exists(gcc __gcc_personality_v0 "" LIBUNWIND_HAS_GCC_LIB)
  else ()
    check_library_exists(gcc_s __gcc_personality_v0 "" LIBUNWIND_HAS_GCC_S_LIB)
    check_library_exists(gcc __absvdi2 "" LIBUNWIND_HAS_GCC_LIB)
  endif ()
endif()

if (CXX_SUPPORTS_NOSTDLIBXX_FLAG OR C_SUPPORTS_NODEFAULTLIBS_FLAG)
  if (CMAKE_C_FLAGS MATCHES -fsanitize OR CMAKE_CXX_FLAGS MATCHES -fsanitize)
    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fno-sanitize=all")
  endif ()
  if (CMAKE_C_FLAGS MATCHES -fsanitize-coverage OR CMAKE_CXX_FLAGS MATCHES -fsanitize-coverage)
    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fsanitize-coverage=0")
  endif ()
endif ()

# Check compiler pragmas
if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  cmake_push_check_state()
  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unknown-pragmas")
  check_c_source_compiles("
#pragma comment(lib, \"c\")
int main(void) { return 0; }
" C_SUPPORTS_COMMENT_LIB_PRAGMA)
  cmake_pop_check_state()
endif()

# Check compiler flags
check_cxx_compiler_flag(-nostdinc++ CXX_SUPPORTS_NOSTDINCXX_FLAG)

# Check symbols
check_symbol_exists(__arm__ "" LIBUNWIND_TARGET_ARM)
check_symbol_exists(__USING_SJLJ_EXCEPTIONS__ "" LIBUNWIND_USES_SJLJ_EXCEPTIONS)
check_symbol_exists(__ARM_DWARF_EH__ "" LIBUNWIND_USES_DWARF_EH)

if(LIBUNWIND_TARGET_ARM AND NOT LIBUNWIND_USES_SJLJ_EXCEPTIONS AND NOT LIBUNWIND_USES_DWARF_EH)
  # This condition is copied from __libunwind_config.h
  set(LIBUNWIND_USES_ARM_EHABI ON)
endif()

# Check libraries
if(FUCHSIA)
  set(LIBUNWIND_HAS_DL_LIB NO)
  set(LIBUNWIND_HAS_PTHREAD_LIB NO)
else()
  check_library_exists(dl dladdr "" LIBUNWIND_HAS_DL_LIB)
  check_library_exists(pthread pthread_once "" LIBUNWIND_HAS_PTHREAD_LIB)
endif()

if(HAIKU)
  check_library_exists(bsd dl_iterate_phdr "" LIBUNWIND_HAS_BSD_LIB)
endif()