# This module sets the variable "ITK_PRIVATE_DYNAMIC_CAST".
#
# This modules performs a try compile and execution to determine if
# the compiler and standard C++ run-time library supports
# dynamic_cast-ing of a private (hidden) Run-Time-Type-Information
# (RTTI). This can happen when private symbols (of instantiated
# templates) are duplicated in different libraries or executables.
#

function(_itkCheckPrivateDynamicCast)
  set(VARIABLE "ITK_PRIVATE_DYNAMIC_CAST")

  if(MSVC)
    set(
      "${VARIABLE}"
      1
      CACHE INTERNAL
      "MSVC is know to support dynamic_cast of private symbols."
      FORCE
    )
    return()
  endif()

  set(test_project_dir "${PROJECT_BINARY_DIR}/CMakeTmp/${VARIABLE}")

  file(
    WRITE
    "${test_project_dir}/base.h"
    "
struct __attribute__ ((visibility (\"default\"))) base
{
  virtual ~base() = 0;
};

template <typename T> struct derived : public base{ ~derived() {};};

base* create(void) __attribute__ ((visibility (\"default\")));
"
  )

  file(
    WRITE
    "${test_project_dir}/base.cxx"
    "
#include \"base.h\"

base::~base() {}
base* create(void) { return new derived<int>(); }
"
  )

  file(
    WRITE
    "${test_project_dir}/main.cxx"
    "
#include \"base.h\"

int main(void)
{
  return bool(dynamic_cast<derived<int>*>(create()))?0:1;
}"
  )

  # we cannot use a "try_run" here because of the complexity of the
  # test project with shared libraries, and visibility flags. The run is
  # accomplished with a custom command as a post build step for the
  # compilation of the executable.
  file(
    WRITE
    "${test_project_dir}/CMakeLists.txt"
    "
cmake_minimum_required(VERSION 3.16.3 FATAL_ERROR)
foreach(p
    ## Only policies introduced after the cmake_minimum_required
    ## version need to explicitly be set to NEW.
    CMP0070 #3.10.0 Define ``file(GENERATE)`` behavior for relative paths.
    CMP0071 #3.10.0 Let ``AUTOMOC`` and ``AUTOUIC`` process ``GENERATED`` files.
    )
  if(POLICY ${p})
    cmake_policy(SET ${p} NEW)
  endif()
endforeach()
project(support_private_dynamic_cast CXX)
add_library(base SHARED \"base.cxx\")
set_target_properties(base PROPERTIES CXX_VISIBILITY_PRESET hidden)
add_executable(test_cast \"main.cxx\")
target_link_libraries(test_cast PRIVATE base)
add_custom_command(TARGET test_cast POST_BUILD COMMAND $<TARGET_FILE:test_cast>)
"
  )

  try_compile(
    ${VARIABLE}
    "${test_project_dir}"
    "${test_project_dir}"
    support_private_dynamic_cast
    CMAKE_FLAGS
      "-DCMAKE_MACOSX_RPATH=OFF"
    OUTPUT_VARIABLE output
  )

  if(${VARIABLE})
    message(STATUS "Performing Test ${VARIABLE} - Success")
  else()
    message(STATUS "Performing Test ${VARIABLE} - Failed")
    file(
      APPEND
      ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
      "Performing Test ${VARIABLE} failed with the following output:\n"
      "${OUTPUT}\n"
    )
  endif()
endfunction()

_itkcheckprivatedynamiccast()