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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#.rst:
# CheckCXXCompilerFlag
# --------------------
#
# Check whether the CXX compiler supports a given flag.
#
# CHECK_CXX_COMPILER_FLAG(<flag> <var>)
#
# ::
#
# <flag> - the compiler flag
# <var> - variable to store the result
#
# This internally calls the check_cxx_source_compiles macro and sets
# CMAKE_REQUIRED_DEFINITIONS to <flag>. See help for
# CheckCXXSourceCompiles for a listing of variables that can otherwise
# modify the build. The result only tells that the compiler does not
# give an error message when it encounters the flag. If the flag has
# any effect or even a specific one is beyond the scope of this module.
include(CheckCXXSourceCompiles)
include(CMakeCheckCompilerFlagCommonPatterns)
macro (CHECK_CXX_COMPILER_FLAG _FLAG _RESULT)
set(SAFE_CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS}")
set(CMAKE_REQUIRED_DEFINITIONS "${_FLAG}")
# Normalize locale during test compilation.
set(_CheckCXXCompilerFlag_LOCALE_VARS LC_ALL LC_MESSAGES LANG)
foreach(v ${_CheckCXXCompilerFlag_LOCALE_VARS})
set(_CheckCXXCompilerFlag_SAVED_${v} "$ENV{${v}}")
set(ENV{${v}} C)
endforeach()
CHECK_COMPILER_FLAG_COMMON_PATTERNS(_CheckCXXCompilerFlag_COMMON_PATTERNS)
CHECK_CXX_SOURCE_COMPILES("int main() { return 0; }" ${_RESULT}
# Some compilers do not fail with a bad flag
FAIL_REGEX "command line option .* is valid for .* but not for C\\\\+\\\\+" # GNU
${_CheckCXXCompilerFlag_COMMON_PATTERNS}
)
foreach(v ${_CheckCXXCompilerFlag_LOCALE_VARS})
set(ENV{${v}} ${_CheckCXXCompilerFlag_SAVED_${v}})
unset(_CheckCXXCompilerFlag_SAVED_${v})
endforeach()
unset(_CheckCXXCompilerFlag_LOCALE_VARS)
unset(_CheckCXXCompilerFlag_COMMON_PATTERNS)
set (CMAKE_REQUIRED_DEFINITIONS "${SAFE_CMAKE_REQUIRED_DEFINITIONS}")
endmacro ()
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