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108 lines
3.9 KiB
CMake
108 lines
3.9 KiB
CMake
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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# file Copyright.txt or https://cmake.org/licensing for details.
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#[=======================================================================[.rst:
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CheckCompilerFlag
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---------------------
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.. versionadded:: 3.19
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Check whether the compiler supports a given flag.
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.. command:: check_compiler_flag
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.. code-block:: cmake
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check_compiler_flag(<lang> <flag> <var>)
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Check that the ``<flag>`` is accepted by the compiler without a diagnostic.
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Stores the result in an internal cache entry named ``<var>``.
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This command temporarily sets the ``CMAKE_REQUIRED_DEFINITIONS`` variable
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and calls the ``check_source_compiles(<LANG>`` function from the
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:module:`CheckSourceCompiles` module. See documentation of that
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module for a listing of variables that can otherwise modify the build.
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A positive result from this check indicates only that the compiler did not
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issue a diagnostic message when given the flag. Whether the flag has any
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effect or even a specific one is beyond the scope of this module.
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.. note::
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Since the :command:`try_compile` command forwards flags from variables
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like :variable:`CMAKE_<LANG>_FLAGS <CMAKE_<LANG>_FLAGS>`, unknown flags
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in such variables may cause a false negative for this check.
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#]=======================================================================]
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include_guard(GLOBAL)
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include(CheckSourceCompiles)
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include(CMakeCheckCompilerFlagCommonPatterns)
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cmake_policy(PUSH)
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cmake_policy(SET CMP0054 NEW) # if() quoted variables not dereferenced
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cmake_policy(SET CMP0057 NEW) # if() supports IN_LIST
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function(CHECK_COMPILER_FLAG _lang _flag _var)
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if(_lang STREQUAL C)
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set(_lang_src "int main(void) { return 0; }")
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set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for C")
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elseif(_lang STREQUAL CXX)
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set(_lang_src "int main() { return 0; }")
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set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for C\\+\\+")
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elseif(_lang STREQUAL Fortran)
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set(_lang_src " program test\n stop\n end program")
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set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for Fortran")
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elseif(_lang STREQUAL OBJC)
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set(_lang_src [=[
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#ifndef __OBJC__
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# error "Not an Objective-C compiler"
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#endif
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int main(void) { return 0; }]=])
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set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for Objective-C" # GNU
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FAIL_REGEX "argument unused during compilation: .*") # Clang
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elseif(_lang STREQUAL OBJCXX)
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set(_lang_src [=[
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#ifndef __OBJC__
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# error "Not an Objective-C++ compiler"
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#endif
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int main(void) { return 0; }]=])
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set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for Objective-C\\+\\+" # GNU
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FAIL_REGEX "argument unused during compilation: .*") # Clang
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elseif(_lang STREQUAL ISPC)
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set(_lang_src "float func(uniform int32, float a) { return a / 2.25; }")
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else()
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message (SEND_ERROR "check_compiler_flag: ${_lang}: unknown language.")
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return()
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endif()
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get_property (_supported_languages GLOBAL PROPERTY ENABLED_LANGUAGES)
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if (NOT _lang IN_LIST _supported_languages)
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message (SEND_ERROR "check_compiler_flag: ${_lang}: needs to be enabled before use.")
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return()
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endif()
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set(CMAKE_REQUIRED_DEFINITIONS ${_flag})
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# Normalize locale during test compilation.
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set(_locale_vars LC_ALL LC_MESSAGES LANG)
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foreach(v IN LISTS _locale_vars)
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set(_locale_vars_saved_${v} "$ENV{${v}}")
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set(ENV{${v}} C)
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endforeach()
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check_compiler_flag_common_patterns(_common_patterns)
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check_source_compiles(${_lang}
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"${_lang_src}"
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${_var}
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${_lang_fail_regex}
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${_common_patterns}
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)
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foreach(v IN LISTS _locale_vars)
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set(ENV{${v}} ${_locale_vars_saved_${v}})
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endforeach()
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set(${_var} "${${_var}}" PARENT_SCOPE)
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endfunction ()
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cmake_policy(POP)
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