third-party/benchmark/cmake/AddCXXCompilerFlag.cmake

   1 # - Adds a compiler flag if it is supported by the compiler
   2 #
   3 # This function checks that the supplied compiler flag is supported and then
   4 # adds it to the corresponding compiler flags
   5 #
   6 #  add_cxx_compiler_flag(<FLAG> [<VARIANT>])
   7 #
   8 # - Example
   9 #
  10 # include(AddCXXCompilerFlag)
  11 # add_cxx_compiler_flag(-Wall)
  12 # add_cxx_compiler_flag(-no-strict-aliasing RELEASE)
  13 # Requires CMake 2.6+
  14
  15 if(__add_cxx_compiler_flag)
  16   return()
  17 endif()
  18 set(__add_cxx_compiler_flag INCLUDED)
  19
  20 include(CheckCXXCompilerFlag)
  21
  22 function(mangle_compiler_flag FLAG OUTPUT)
  23   string(TOUPPER "HAVE_CXX_FLAG_${FLAG}" SANITIZED_FLAG)
  24   string(REPLACE "+" "X" SANITIZED_FLAG ${SANITIZED_FLAG})
  25   string(REGEX REPLACE "[^A-Za-z_0-9]" "_" SANITIZED_FLAG ${SANITIZED_FLAG})
  26   string(REGEX REPLACE "_+" "_" SANITIZED_FLAG ${SANITIZED_FLAG})
  27   set(${OUTPUT} "${SANITIZED_FLAG}" PARENT_SCOPE)
  28 endfunction(mangle_compiler_flag)
  29
  30 function(add_cxx_compiler_flag FLAG)
  31   mangle_compiler_flag("${FLAG}" MANGLED_FLAG)
  32   set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
  33   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}")
  34   check_cxx_compiler_flag("${FLAG}" ${MANGLED_FLAG})
  35   set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
  36   if(${MANGLED_FLAG})
  37     if(ARGC GREATER 1)
  38       set(VARIANT ${ARGV1})
  39       string(TOUPPER "_${VARIANT}" VARIANT)
  40     else()
  41       set(VARIANT "")
  42     endif()
  43     set(CMAKE_CXX_FLAGS${VARIANT} "${CMAKE_CXX_FLAGS${VARIANT}} ${BENCHMARK_CXX_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
  44   endif()
  45 endfunction()
  46
  47 function(add_required_cxx_compiler_flag FLAG)
  48   mangle_compiler_flag("${FLAG}" MANGLED_FLAG)
  49   set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
  50   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}")
  51   check_cxx_compiler_flag("${FLAG}" ${MANGLED_FLAG})
  52   set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
  53   if(${MANGLED_FLAG})
  54     if(ARGC GREATER 1)
  55       set(VARIANT ${ARGV1})
  56       string(TOUPPER "_${VARIANT}" VARIANT)
  57     else()
  58       set(VARIANT "")
  59     endif()
  60     set(CMAKE_CXX_FLAGS${VARIANT} "${CMAKE_CXX_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
  61     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
  62     set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
  63     set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
  64     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}" PARENT_SCOPE)
  65   else()
  66     message(FATAL_ERROR "Required flag '${FLAG}' is not supported by the compiler")
  67   endif()
  68 endfunction()
  69
  70 function(check_cxx_warning_flag FLAG)
  71   mangle_compiler_flag("${FLAG}" MANGLED_FLAG)
  72   set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
  73   # Add -Werror to ensure the compiler generates an error if the warning flag
  74   # doesn't exist.
  75   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror ${FLAG}")
  76   check_cxx_compiler_flag("${FLAG}" ${MANGLED_FLAG})
  77   set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
  78 endfunction()