CheckCXXCompilerFlag.cmake 2.48 KB
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#.rst:
# CheckCXXCompilerFlag
# --------------------
#
# Check whether the CXX compiler supports a given flag.
#
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# CHECK_CXX_COMPILER_FLAG(<flag> <var>)
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#
# ::
#
#   <flag> - the compiler flag
#   <var>  - variable to store the result
#
# This internally calls the check_cxx_source_compiles macro and sets
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# CMAKE_REQUIRED_DEFINITIONS to <flag>.  See help for
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# 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.
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#=============================================================================
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# Copyright 2006-2010 Kitware, Inc.
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# Copyright 2006 Alexander Neundorf <neundorf@kde.org>
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# Copyright 2011 Matthias Kretz <kretz@kde.org>
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#
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# 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.
#=============================================================================
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# (To distribute this file outside of CMake, substitute the full
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#  License text for the above reference.)
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include(CheckCXXSourceCompiles)
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include(CMakeCheckCompilerFlagCommonPatterns)
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macro (CHECK_CXX_COMPILER_FLAG _FLAG _RESULT)
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   set(SAFE_CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS}")
   set(CMAKE_REQUIRED_DEFINITIONS "${_FLAG}")
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   # 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()
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   CHECK_COMPILER_FLAG_COMMON_PATTERNS(_CheckCXXCompilerFlag_COMMON_PATTERNS)
   CHECK_CXX_SOURCE_COMPILES("int main() { return 0; }" ${_RESULT}
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     # Some compilers do not fail with a bad flag
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     FAIL_REGEX "command line option .* is valid for .* but not for C\\\\+\\\\+" # GNU
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     ${_CheckCXXCompilerFlag_COMMON_PATTERNS}
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     )
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   foreach(v ${_CheckCXXCompilerFlag_LOCALE_VARS})
     set(ENV{${v}} ${_CheckCXXCompilerFlag_SAVED_${v}})
     unset(_CheckCXXCompilerFlag_SAVED_${v})
   endforeach()
   unset(_CheckCXXCompilerFlag_LOCALE_VARS)
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   unset(_CheckCXXCompilerFlag_COMMON_PATTERNS)
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   set (CMAKE_REQUIRED_DEFINITIONS "${SAFE_CMAKE_REQUIRED_DEFINITIONS}")
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endmacro ()
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