Commit faeddf64 authored by Stephen Kelly's avatar Stephen Kelly

project: Add infrastructure for recording CXX compiler features

Add a feature test using the compiler macros and the preprocessor to
determine available features.

Add a CMAKE_CXX_COMPILE_FEATURES variable which contains all features
known to the loaded compiler, and a CMAKE_CXX_KNOWN_FEATURES variable
containing all features known to CMake.  Add language standard specific
variables for internal use to determine the standard-specific compile
flags to use.

This will be extended to other languages in the future.  Follow-up
commits will add features which will be recorded by the feature test.
parent 913394af
......@@ -257,6 +257,8 @@ Variables for Languages
:maxdepth: 1
/variable/CMAKE_COMPILER_IS_GNULANG
/variable/CMAKE_CXX_COMPILE_FEATURES
/variable/CMAKE_CXX_KNOWN_FEATURES
/variable/CMAKE_CXX_STANDARD
/variable/CMAKE_CXX_EXTENSIONS
/variable/CMAKE_Fortran_MODDIR_DEFAULT
......
CMAKE_CXX_COMPILE_FEATURES
--------------------------
List of features known to the C++ compiler
These features are known to be available for use with the C++ compiler. This
list is a subset of the features listed in the :variable:`CMAKE_CXX_KNOWN_FEATURES`
variable.
CMAKE_CXX_KNOWN_FEATURES
------------------------
List of C++ features known to this version of CMake.
The features listed in this variable may be known to be available to the
C++ compiler. If the feature is available with the C++ compiler, it will
be listed in the :variable:`CMAKE_CXX_COMPILE_FEATURES` variable.
......@@ -2,6 +2,9 @@ set(CMAKE_CXX_COMPILER "@CMAKE_CXX_COMPILER@")
set(CMAKE_CXX_COMPILER_ARG1 "@CMAKE_CXX_COMPILER_ARG1@")
set(CMAKE_CXX_COMPILER_ID "@CMAKE_CXX_COMPILER_ID@")
set(CMAKE_CXX_COMPILER_VERSION "@CMAKE_CXX_COMPILER_VERSION@")
set(CMAKE_CXX_COMPILE_FEATURES "@CMAKE_CXX_COMPILE_FEATURES@")
set(CMAKE_CXX11_COMPILE_FEATURES "@CMAKE_CXX11_COMPILE_FEATURES@")
set(CMAKE_CXX_PLATFORM_ID "@CMAKE_CXX_PLATFORM_ID@")
set(CMAKE_CXX_SIMULATE_ID "@CMAKE_CXX_SIMULATE_ID@")
set(CMAKE_CXX_SIMULATE_VERSION "@CMAKE_CXX_SIMULATE_VERSION@")
......
#=============================================================================
# Copyright 2013 Stephen Kelly <steveire@gmail.com>
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
# License text for the above reference.)
function(cmake_determine_compile_features lang)
if(lang STREQUAL CXX AND COMMAND cmake_record_cxx_compile_features)
message(STATUS "Detecting ${lang} compile features")
set(CMAKE_CXX11_COMPILE_FEATURES)
include("${CMAKE_ROOT}/Modules/Internal/FeatureTesting.cmake")
cmake_record_cxx_compile_features()
if(NOT _result EQUAL 0)
message(STATUS "Detecting ${lang} compile features - failed")
return()
endif()
if(NOT CMAKE_CXX_COMPILE_FEATURES)
set(CMAKE_CXX_COMPILE_FEATURES
${CMAKE_CXX11_COMPILE_FEATURES}
)
endif()
set(CMAKE_CXX_COMPILE_FEATURES ${CMAKE_CXX_COMPILE_FEATURES} PARENT_SCOPE)
set(CMAKE_CXX11_COMPILE_FEATURES ${CMAKE_CXX11_COMPILE_FEATURES} PARENT_SCOPE)
message(STATUS "Detecting ${lang} compile features - done")
endif()
endfunction()
......@@ -66,6 +66,9 @@ else()
# Try to identify the ABI and configure it into CMakeCXXCompiler.cmake
include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerABI.cmake)
CMAKE_DETERMINE_COMPILER_ABI(CXX ${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp)
# Try to identify the compiler features
include(${CMAKE_ROOT}/Modules/CMakeDetermineCompileFeatures.cmake)
CMAKE_DETERMINE_COMPILE_FEATURES(CXX)
# Re-configure to save learned information.
configure_file(
......
macro(record_compiler_features lang compile_flags feature_list)
include("${CMAKE_ROOT}/Modules/Compiler/${CMAKE_${lang}_COMPILER_ID}-${lang}-FeatureTests.cmake" OPTIONAL)
string(TOLOWER ${lang} lang_lc)
file(REMOVE "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.bin")
file(WRITE "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}" "
extern const char features[] = {\"\"\n")
foreach(feature ${CMAKE_${lang}_KNOWN_FEATURES})
if (_cmake_feature_test_${feature})
if (${_cmake_feature_test_${feature}} STREQUAL 1)
set(_feature_condition "\"1\" ")
else()
set(_feature_condition "#if ${_cmake_feature_test_${feature}}\n\"1\"\n#else\n\"0\"\n#endif\n")
endif()
file(APPEND "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}" "\"${lang}_FEATURE:\"\n${_feature_condition}\"${feature}\\n\"\n")
endif()
endforeach()
file(APPEND "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}"
"\n};\n\nint main(int, char **) { return 0; }\n")
try_compile(CMAKE_${lang}_FEATURE_TEST
${CMAKE_BINARY_DIR} "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}"
COMPILE_DEFINITIONS "${compile_flags}"
OUTPUT_VARIABLE _output
COPY_FILE "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.bin"
COPY_FILE_ERROR _copy_error
)
if(CMAKE_${lang}_FEATURE_TEST AND NOT _copy_error)
set(_result 0)
else()
set(_result 255)
endif()
unset(CMAKE_${lang}_FEATURE_TEST CACHE)
if (_result EQUAL 0)
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
"\n\nDetecting ${lang} [${compile_flags}] compiler features compiled with the following output:\n${_output}\n\n")
if(EXISTS "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.bin")
file(STRINGS "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.bin"
features REGEX "${lang}_FEATURE:.*")
foreach(info ${features})
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
" Feature record: ${info}\n")
string(REPLACE "${lang}_FEATURE:" "" info ${info})
string(SUBSTRING ${info} 0 1 has_feature)
if(has_feature)
string(REGEX REPLACE "^1" "" feature ${info})
list(APPEND ${feature_list} ${feature})
endif()
endforeach()
endif()
else()
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Detecting ${lang} [${compile_flags}] compiler features failed to compile with the following output:\n${_output}\n${_copy_error}\n\n")
endif()
endmacro()
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