1# - Compile and run code to check for C++ features 2# 3# This functions compiles a source file under the `cmake` folder 4# and adds the corresponding `HAVE_[FILENAME]` flag to the CMake 5# environment 6# 7# cxx_feature_check(<FLAG> [<VARIANT>]) 8# 9# - Example 10# 11# include(CXXFeatureCheck) 12# cxx_feature_check(STD_REGEX) 13# Requires CMake 2.8.12+ 14 15if(__cxx_feature_check) 16 return() 17endif() 18set(__cxx_feature_check INCLUDED) 19 20function(cxx_feature_check FILE) 21 string(TOLOWER ${FILE} FILE) 22 string(TOUPPER ${FILE} VAR) 23 string(TOUPPER "HAVE_${VAR}" FEATURE) 24 if (DEFINED HAVE_${VAR}) 25 set(HAVE_${VAR} 1 PARENT_SCOPE) 26 add_definitions(-DHAVE_${VAR}) 27 return() 28 endif() 29 30 message("-- Performing Test ${FEATURE}") 31 if(CMAKE_CROSSCOMPILING) 32 try_compile(COMPILE_${FEATURE} 33 ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp 34 CMAKE_FLAGS ${BENCHMARK_CXX_LINKER_FLAGS} 35 LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES}) 36 if(COMPILE_${FEATURE}) 37 message(WARNING 38 "If you see build failures due to cross compilation, try setting HAVE_${VAR} to 0") 39 set(RUN_${FEATURE} 0) 40 else() 41 set(RUN_${FEATURE} 1) 42 endif() 43 else() 44 message("-- Performing Test ${FEATURE}") 45 try_run(RUN_${FEATURE} COMPILE_${FEATURE} 46 ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp 47 CMAKE_FLAGS ${BENCHMARK_CXX_LINKER_FLAGS} 48 LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES}) 49 endif() 50 51 if(RUN_${FEATURE} EQUAL 0) 52 message("-- Performing Test ${FEATURE} -- success") 53 set(HAVE_${VAR} 1 PARENT_SCOPE) 54 add_definitions(-DHAVE_${VAR}) 55 else() 56 if(NOT COMPILE_${FEATURE}) 57 message("-- Performing Test ${FEATURE} -- failed to compile") 58 else() 59 message("-- Performing Test ${FEATURE} -- compiled but failed to run") 60 endif() 61 endif() 62endfunction() 63