cmake_minimum_required(VERSION 3.0)

project(CompileFeatures)

if (NOT CMAKE_C_COMPILE_FEATURES AND NOT CMAKE_CXX_COMPILE_FEATURES)
  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/dummy.cpp"
    "int main(int,char**) { return 0; }\n"
  )
  add_executable(CompileFeatures "${CMAKE_CURRENT_BINARY_DIR}/dummy.cpp")
  return()
endif()

macro(run_test feature lang)
  if (";${CMAKE_${lang}_COMPILE_FEATURES};" MATCHES ${feature})
    add_library(test_${feature} OBJECT ${feature})
    set_property(TARGET test_${feature}
      PROPERTY COMPILE_FEATURES "${feature}"
    )
  else()
    list(APPEND ${lang}_non_features ${feature})
  endif()
endmacro()

get_property(c_features GLOBAL PROPERTY CMAKE_C_KNOWN_FEATURES)
foreach(feature ${c_features})
  run_test(${feature} C)
endforeach()
get_property(cxx_features GLOBAL PROPERTY CMAKE_CXX_KNOWN_FEATURES)
foreach(feature ${cxx_features})
  run_test(${feature} CXX)
endforeach()

if (CMAKE_CXX_COMPILER_ID STREQUAL GNU
    AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
  list(REMOVE_ITEM CXX_non_features
    cxx_alignof
  )
endif()
if (CMAKE_CXX_COMPILER_ID STREQUAL GNU
    AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)
  # GNU prior to 4.9 does not set any preprocessor define to distinguish
  # c++1y from c++11, so CMake does not support c++1y features before GNU 4.9.
  list(REMOVE_ITEM CXX_non_features
    # GNU 4.8 knows cxx_attributes, but doesn't know [[deprecated]]
    # and warns that it is unknown and ignored.
    cxx_attribute_deprecated
    cxx_binary_literals
    cxx_lambda_init_captures
    cxx_return_type_deduction
  )
endif()

set(C_ext c)
set(C_standard_flag 11)
set(CXX_ext cpp)
set(CXX_standard_flag 14)
foreach(lang CXX C)
  if (CMAKE_${lang}_COMPILE_FEATURES)
    foreach(feature ${${lang}_non_features})
      message("Testing feature : ${feature}")
      try_compile(${feature}_works
        "${CMAKE_CURRENT_BINARY_DIR}/${feature}_test"
        "${CMAKE_CURRENT_SOURCE_DIR}/feature_test.${${lang}_ext}"
        COMPILE_DEFINITIONS "-DTEST=${CMAKE_CURRENT_SOURCE_DIR}/${feature}.${${lang}_ext}"
        CMAKE_FLAGS "-DCMAKE_${lang}_STANDARD=${${lang}_standard_flag}"
        OUTPUT_VARIABLE OUTPUT
      )
      if (${feature}_works)
        message(SEND_ERROR
          "Feature ${feature} expected not to work for ${lang} ${CMAKE_${lang}_COMPILER_ID}-${CMAKE_${lang}_COMPILER_VERSION}.
  Update the supported features or blacklist it.\n${OUTPUT}")
      else()
        message("Testing feature : ${feature} -- Fails, as expected.")
      endif()
    endforeach()
  endif()
endforeach()

if (CMAKE_C_COMPILE_FEATURES)
  string(FIND "${CMAKE_C_FLAGS}" "-std=" std_flag_idx)
  if (std_flag_idx EQUAL -1)
    add_executable(default_dialect_C default_dialect.c)
    target_compile_definitions(default_dialect_C PRIVATE
      DEFAULT_C11=$<EQUAL:${CMAKE_C_STANDARD_DEFAULT},11>
      DEFAULT_C99=$<EQUAL:${CMAKE_C_STANDARD_DEFAULT},99>
      DEFAULT_C90=$<EQUAL:${CMAKE_C_STANDARD_DEFAULT},90>
    )
  endif()
endif()

if (CMAKE_CXX_COMPILE_FEATURES)
  string(FIND "${CMAKE_CXX_FLAGS}" "-std=" std_flag_idx)
  if (std_flag_idx EQUAL -1)
    add_executable(default_dialect default_dialect.cpp)
    target_compile_definitions(default_dialect PRIVATE
      DEFAULT_CXX14=$<EQUAL:${CMAKE_CXX_STANDARD_DEFAULT},14>
      DEFAULT_CXX11=$<EQUAL:${CMAKE_CXX_STANDARD_DEFAULT},11>
      DEFAULT_CXX98=$<EQUAL:${CMAKE_CXX_STANDARD_DEFAULT},98>
    )
  endif()

  add_executable(CompileFeatures main.cpp)
  set_property(TARGET CompileFeatures
    PROPERTY COMPILE_FEATURES "cxx_auto_type"
  )
  set_property(TARGET CompileFeatures
    PROPERTY CXX_STANDARD_REQUIRED TRUE
  )

  add_executable(GenexCompileFeatures main.cpp)
  set_property(TARGET GenexCompileFeatures
    PROPERTY COMPILE_FEATURES "$<1:cxx_auto_type>;$<0:not_a_feature>"
  )

  add_library(iface INTERFACE)
  set_property(TARGET iface
    PROPERTY INTERFACE_COMPILE_FEATURES "cxx_auto_type"
  )
  add_executable(IfaceCompileFeatures main.cpp)
  target_link_libraries(IfaceCompileFeatures iface)

  add_executable(CompileFeaturesGenex genex_test.cpp)
  set_property(TARGET CompileFeaturesGenex PROPERTY CXX_STANDARD 11)
  target_compile_definitions(CompileFeaturesGenex PRIVATE HAVE_OVERRIDE_CONTROL=$<COMPILE_FEATURES:cxx_final,cxx_override>)

  add_executable(CompileFeaturesGenex2 genex_test.cpp)
  target_compile_features(CompileFeaturesGenex2 PRIVATE cxx_constexpr)
  target_compile_definitions(CompileFeaturesGenex2 PRIVATE HAVE_OVERRIDE_CONTROL=$<COMPILE_FEATURES:cxx_final,cxx_override>)

  add_library(noexcept_iface INTERFACE)
  target_compile_features(noexcept_iface INTERFACE cxx_noexcept)
  add_executable(CompileFeaturesGenex3 genex_test.cpp)
  target_link_libraries(CompileFeaturesGenex3 PRIVATE noexcept_iface)
  target_compile_definitions(CompileFeaturesGenex3 PRIVATE HAVE_OVERRIDE_CONTROL=$<COMPILE_FEATURES:cxx_final,cxx_override>)
endif()