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# Detect if compiler version is sufficient for supporting C++11.
# If it is, CMAKE_CXX_FLAGS are modified appropriately and HAVE_CXX11
# is set to a true value. Else, CMake exits with a fatal error message.
# This currently only works for GCC and Clang compilers.
# In Cmake 3.1+, CMAKE_CXX_STANDARD_REQUIRED should be able to replace
# all the logic below.
if ( DEFINED HAVE_CXX11 )
return()
endif ()
include(CheckCXXSourceCompiles)
set(required_gcc_version 4.8)
set(required_clang_version 3.3)
macro(cxx11_compile_test)
# test a header file that has to be present in C++11
check_cxx_source_compiles("
#include <array>
#include <iostream>
int main() {
std::array<int, 2> a{ {1, 2} };
for (const auto& e: a)
std::cout << e << ' ';
std::cout << std::endl;
}
" cxx11_header_works)
if (NOT cxx11_header_works)
message(FATAL_ERROR "C++11 headers cannot be used for compilation")
endif ()
endmacro()
# CMAKE_CXX_COMPILER_VERSION may not always be available (e.g. particularly
# for CMakes older than 2.8.10, but use it if it exists.
if ( DEFINED CMAKE_CXX_COMPILER_VERSION )
if ( CMAKE_CXX_COMPILER_ID STREQUAL "GNU" )
if ( CMAKE_CXX_COMPILER_VERSION VERSION_LESS ${required_gcc_version} )
message(FATAL_ERROR "GCC version must be at least "
"${required_gcc_version} for C++11 support, detected: "
"${CMAKE_CXX_COMPILER_VERSION}")
endif ()
elseif ( CMAKE_CXX_COMPILER_ID STREQUAL "Clang" )
if ( CMAKE_CXX_COMPILER_VERSION VERSION_LESS ${required_clang_version} )
message(FATAL_ERROR "Clang version must be at least "
"${required_clang_version} for C++11 support, detected: "
"${CMAKE_CXX_COMPILER_VERSION}")
endif ()
endif ()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
cxx11_compile_test()
set(HAVE_CXX11 true)
return()
endif ()
# Need to manually retrieve compiler version.
if ( CMAKE_CXX_COMPILER_ID STREQUAL "GNU" )
execute_process(COMMAND ${CMAKE_CXX_COMPILER} -dumpversion OUTPUT_VARIABLE
gcc_version)
if ( ${gcc_version} VERSION_LESS ${required_gcc_version} )
message(FATAL_ERROR "GCC version must be at least "
"${required_gcc_version} for C++11 support, manually detected: "
"${CMAKE_CXX_COMPILER_VERSION}")
endif ()
elseif ( CMAKE_CXX_COMPILER_ID STREQUAL "Clang" )
# TODO: don't seem to be any great/easy ways to get a clang version string.
endif ()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
cxx11_compile_test()
set(HAVE_CXX11 true)
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