CMake/Modules/CMakeDetermineCXXCompiler.cmake

#=============================================================================
# Copyright 2002-2009 Kitware, Inc.
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
#  License text for the above reference.)

# determine the compiler to use for C++ programs
# NOTE, a generator may set CMAKE_CXX_COMPILER before
# loading this file to force a compiler.
# use environment variable CXX first if defined by user, next use
# the cmake variable CMAKE_GENERATOR_CXX which can be defined by a generator
# as a default compiler
# If the internal cmake variable _CMAKE_TOOLCHAIN_PREFIX is set, this is used
# as prefix for the tools (e.g. arm-elf-g++, arm-elf-ar etc.)
#
# Sets the following variables:
#   CMAKE_CXX_COMPILER
#   CMAKE_COMPILER_IS_GNUCXX
#   CMAKE_AR
#   CMAKE_RANLIB
#
# If not already set before, it also sets
#   _CMAKE_TOOLCHAIN_PREFIX

include(${CMAKE_ROOT}/Modules/CMakeDetermineCompiler.cmake)

# Load system-specific compiler preferences for this language.
include(Platform/${CMAKE_SYSTEM_NAME}-CXX OPTIONAL)
if(NOT CMAKE_CXX_COMPILER_NAMES)
  set(CMAKE_CXX_COMPILER_NAMES CC)
endif()

if(${CMAKE_GENERATOR} MATCHES "Visual Studio")
  set(CMAKE_CXX_COMPILER_ID_RUN 1)
  set(CMAKE_CXX_PLATFORM_ID "Windows")
  set(CMAKE_CXX_COMPILER_ID "MSVC")
  set(CMAKE_CXX_COMPILER "${CMAKE_GENERATOR_CXX}")
else()
  if(NOT CMAKE_CXX_COMPILER)
    set(CMAKE_CXX_COMPILER_INIT NOTFOUND)

    # prefer the environment variable CXX
    if($ENV{CXX} MATCHES ".+")
      get_filename_component(CMAKE_CXX_COMPILER_INIT $ENV{CXX} PROGRAM PROGRAM_ARGS CMAKE_CXX_FLAGS_ENV_INIT)
      if(CMAKE_CXX_FLAGS_ENV_INIT)
        set(CMAKE_CXX_COMPILER_ARG1 "${CMAKE_CXX_FLAGS_ENV_INIT}" CACHE STRING "First argument to CXX compiler")
      endif()
      if(NOT EXISTS ${CMAKE_CXX_COMPILER_INIT})
        message(FATAL_ERROR "Could not find compiler set in environment variable CXX:\n$ENV{CXX}.\n${CMAKE_CXX_COMPILER_INIT}")
      endif()
    endif()

    # next prefer the generator specified compiler
    if(CMAKE_GENERATOR_CXX)
      if(NOT CMAKE_CXX_COMPILER_INIT)
        set(CMAKE_CXX_COMPILER_INIT ${CMAKE_GENERATOR_CXX})
      endif()
    endif()

    # finally list compilers to try
    if(NOT CMAKE_CXX_COMPILER_INIT)
      set(CMAKE_CXX_COMPILER_LIST CC ${_CMAKE_TOOLCHAIN_PREFIX}c++ ${_CMAKE_TOOLCHAIN_PREFIX}g++ aCC cl bcc xlC clang++)
    endif()

    _cmake_find_compiler(CXX)
  else()

    # we only get here if CMAKE_CXX_COMPILER was specified using -D or a pre-made CMakeCache.txt
    # (e.g. via ctest) or set in CMAKE_TOOLCHAIN_FILE
    #
    # if CMAKE_CXX_COMPILER is a list of length 2, use the first item as
    # CMAKE_CXX_COMPILER and the 2nd one as CMAKE_CXX_COMPILER_ARG1

    list(LENGTH CMAKE_CXX_COMPILER _CMAKE_CXX_COMPILER_LIST_LENGTH)
    if("${_CMAKE_CXX_COMPILER_LIST_LENGTH}" EQUAL 2)
      list(GET CMAKE_CXX_COMPILER 1 CMAKE_CXX_COMPILER_ARG1)
      list(GET CMAKE_CXX_COMPILER 0 CMAKE_CXX_COMPILER)
    endif()

    # if a compiler was specified by the user but without path,
    # now try to find it with the full path
    # if it is found, force it into the cache,
    # if not, don't overwrite the setting (which was given by the user) with "NOTFOUND"
    # if the CXX compiler already had a path, reuse it for searching the C compiler
    get_filename_component(_CMAKE_USER_CXX_COMPILER_PATH "${CMAKE_CXX_COMPILER}" PATH)
    if(NOT _CMAKE_USER_CXX_COMPILER_PATH)
      find_program(CMAKE_CXX_COMPILER_WITH_PATH NAMES ${CMAKE_CXX_COMPILER})
      mark_as_advanced(CMAKE_CXX_COMPILER_WITH_PATH)
      if(CMAKE_CXX_COMPILER_WITH_PATH)
        set(CMAKE_CXX_COMPILER ${CMAKE_CXX_COMPILER_WITH_PATH} CACHE STRING "CXX compiler" FORCE)
      endif()
    endif()
  endif()
  mark_as_advanced(CMAKE_CXX_COMPILER)

  # Each entry in this list is a set of extra flags to try
  # adding to the compile line to see if it helps produce
  # a valid identification file.
  set(CMAKE_CXX_COMPILER_ID_TEST_FLAGS
    # Try compiling to an object file only.
    "-c"
    )
endif()

# Build a small source file to identify the compiler.
if(NOT CMAKE_CXX_COMPILER_ID_RUN)
  set(CMAKE_CXX_COMPILER_ID_RUN 1)

  # Try to identify the compiler.
  set(CMAKE_CXX_COMPILER_ID)
  file(READ ${CMAKE_ROOT}/Modules/CMakePlatformId.h.in
    CMAKE_CXX_COMPILER_ID_PLATFORM_CONTENT)
  include(${CMAKE_ROOT}/Modules/CMakeDetermineCompilerId.cmake)
  CMAKE_DETERMINE_COMPILER_ID(CXX CXXFLAGS CMakeCXXCompilerId.cpp)

  # Set old compiler and platform id variables.
  if("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
    set(CMAKE_COMPILER_IS_GNUCXX 1)
  endif()
  if("${CMAKE_CXX_PLATFORM_ID}" MATCHES "MinGW")
    set(CMAKE_COMPILER_IS_MINGW 1)
  elseif("${CMAKE_CXX_PLATFORM_ID}" MATCHES "Cygwin")
    set(CMAKE_COMPILER_IS_CYGWIN 1)
  endif()
endif()

if (NOT _CMAKE_TOOLCHAIN_LOCATION)
  get_filename_component(_CMAKE_TOOLCHAIN_LOCATION "${CMAKE_CXX_COMPILER}" PATH)
endif ()

# if we have a g++ cross compiler, they have usually some prefix, like
# e.g. powerpc-linux-g++, arm-elf-g++ or i586-mingw32msvc-g++ , optionally
# with a 3-component version number at the end (e.g. arm-eabi-gcc-4.5.2).
# The other tools of the toolchain usually have the same prefix
# NAME_WE cannot be used since then this test will fail for names lile
# "arm-unknown-nto-qnx6.3.0-gcc.exe", where BASENAME would be
# "arm-unknown-nto-qnx6" instead of the correct "arm-unknown-nto-qnx6.3.0-"
if (CMAKE_CROSSCOMPILING
    AND "${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU"
    AND NOT _CMAKE_TOOLCHAIN_PREFIX)
  get_filename_component(COMPILER_BASENAME "${CMAKE_CXX_COMPILER}" NAME)
  if (COMPILER_BASENAME MATCHES "^(.+-)[gc]\\+\\+(-[0-9]+\\.[0-9]+\\.[0-9]+)?(\\.exe)?$")
    set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_MATCH_1})
  endif ()

  # if "llvm-" is part of the prefix, remove it, since llvm doesn't have its own binutils
  # but uses the regular ar, objcopy, etc. (instead of llvm-objcopy etc.)
  if ("${_CMAKE_TOOLCHAIN_PREFIX}" MATCHES "(.+-)?llvm-$")
    set(_CMAKE_TOOLCHAIN_PREFIX ${CMAKE_MATCH_1})
  endif ()

endif (CMAKE_CROSSCOMPILING
    AND "${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU"
    AND NOT _CMAKE_TOOLCHAIN_PREFIX)

include(${CMAKE_ROOT}/Modules/CMakeClDeps.cmake)
include(CMakeFindBinUtils)
if(MSVC_CXX_ARCHITECTURE_ID)
  set(SET_MSVC_CXX_ARCHITECTURE_ID
    "set(MSVC_CXX_ARCHITECTURE_ID ${MSVC_CXX_ARCHITECTURE_ID})")
endif()
# configure all variables set in this file
configure_file(${CMAKE_ROOT}/Modules/CMakeCXXCompiler.cmake.in
  ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeCXXCompiler.cmake
  @ONLY IMMEDIATE # IMMEDIATE must be here for compatibility mode <= 2.0
  )

set(CMAKE_CXX_COMPILER_ENV_VAR "CXX")