third-party/benchmark/cmake/CXXFeatureCheck.cmake

   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
  15 if(__cxx_feature_check)
  16   return()
  17 endif()
  18 set(__cxx_feature_check INCLUDED)
  19
  20 option(CXXFEATURECHECK_DEBUG OFF)
  21
  22 function(cxx_feature_check FILE)
  23   string(TOLOWER ${FILE} FILE)
  24   string(TOUPPER ${FILE} VAR)
  25   string(TOUPPER "HAVE_${VAR}" FEATURE)
  26   if (DEFINED HAVE_${VAR})
  27     set(HAVE_${VAR} 1 PARENT_SCOPE)
  28     add_definitions(-DHAVE_${VAR})
  29     return()
  30   endif()
  31
  32   set(FEATURE_CHECK_CMAKE_FLAGS ${BENCHMARK_CXX_LINKER_FLAGS})
  33   if (ARGC GREATER 1)
  34     message(STATUS "Enabling additional flags: ${ARGV1}")
  35     list(APPEND FEATURE_CHECK_CMAKE_FLAGS ${ARGV1})
  36   endif()
  37
  38   if (NOT DEFINED COMPILE_${FEATURE})
  39     if(CMAKE_CROSSCOMPILING)
  40       message(STATUS "Cross-compiling to test ${FEATURE}")
  41       try_compile(COMPILE_${FEATURE}
  42               ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp
  43               CXX_STANDARD 11
  44               CXX_STANDARD_REQUIRED ON
  45               CMAKE_FLAGS ${FEATURE_CHECK_CMAKE_FLAGS}
  46               LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES}
  47               OUTPUT_VARIABLE COMPILE_OUTPUT_VAR)
  48       if(COMPILE_${FEATURE})
  49         message(WARNING
  50               "If you see build failures due to cross compilation, try setting HAVE_${VAR} to 0")
  51         set(RUN_${FEATURE} 0 CACHE INTERNAL "")
  52       else()
  53         set(RUN_${FEATURE} 1 CACHE INTERNAL "")
  54       endif()
  55     else()
  56       message(STATUS "Compiling and running to test ${FEATURE}")
  57       try_run(RUN_${FEATURE} COMPILE_${FEATURE}
  58               ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp
  59               CXX_STANDARD 11
  60               CXX_STANDARD_REQUIRED ON
  61               CMAKE_FLAGS ${FEATURE_CHECK_CMAKE_FLAGS}
  62               LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES}
  63               COMPILE_OUTPUT_VARIABLE COMPILE_OUTPUT_VAR)
  64     endif()
  65   endif()
  66
  67   if(RUN_${FEATURE} EQUAL 0)
  68     message(STATUS "Performing Test ${FEATURE} -- success")
  69     set(HAVE_${VAR} 1 PARENT_SCOPE)
  70     add_definitions(-DHAVE_${VAR})
  71   else()
  72     if(NOT COMPILE_${FEATURE})
  73       if(CXXFEATURECHECK_DEBUG)
  74         message(STATUS "Performing Test ${FEATURE} -- failed to compile: ${COMPILE_OUTPUT_VAR}")
  75       else()
  76         message(STATUS "Performing Test ${FEATURE} -- failed to compile")
  77       endif()
  78     else()
  79       message(STATUS "Performing Test ${FEATURE} -- compiled but failed to run")
  80     endif()
  81   endif()
  82 endfunction()