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
15if(__add_cxx_compiler_flag)
16  return()
17endif()
18set(__add_cxx_compiler_flag INCLUDED)
19
20include(CheckCXXCompilerFlag)
21
22function(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} "${SANITIZED_FLAG}" PARENT_SCOPE)
28endfunction(mangle_compiler_flag)
29
30function(add_cxx_compiler_flag FLAG)
31  mangle_compiler_flag("${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    set(VARIANT ${ARGV1})
38    if(ARGV1)
39      string(TOUPPER "_${VARIANT}" VARIANT)
40    endif()
41    set(CMAKE_CXX_FLAGS${VARIANT} "${CMAKE_CXX_FLAGS${VARIANT}} ${BENCHMARK_CXX_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
42  endif()
43endfunction()
44
45function(add_required_cxx_compiler_flag FLAG)
46  mangle_compiler_flag("${FLAG}" MANGLED_FLAG)
47  set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
48  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}")
49  check_cxx_compiler_flag("${FLAG}" ${MANGLED_FLAG})
50  set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
51  if(${MANGLED_FLAG})
52    set(VARIANT ${ARGV1})
53    if(ARGV1)
54      string(TOUPPER "_${VARIANT}" VARIANT)
55    endif()
56    set(CMAKE_CXX_FLAGS${VARIANT} "${CMAKE_CXX_FLAGS${VARIANT}} ${FLAG}" PARENT_SCOPE)
57    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
58    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
59    set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${FLAG}" PARENT_SCOPE)
60    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${FLAG}" PARENT_SCOPE)
61  else()
62    message(FATAL_ERROR "Required flag '${FLAG}' is not supported by the compiler")
63  endif()
64endfunction()
65
66function(check_cxx_warning_flag FLAG)
67  mangle_compiler_flag("${FLAG}" MANGLED_FLAG)
68  set(OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
69  # Add -Werror to ensure the compiler generates an error if the warning flag
70  # doesn't exist.
71  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror ${FLAG}")
72  check_cxx_compiler_flag("${FLAG}" ${MANGLED_FLAG})
73  set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
74endfunction()
75