path: root/Modules/CMakeDetermineCompilerId.cmake

#=============================================================================
# Copyright 2007-2009 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.)

# Function to compile a source file to identify the compiler.  This is
# used internally by CMake and should not be included by user code.
# If successful, sets CMAKE_<lang>_COMPILER_ID and CMAKE_<lang>_PLATFORM_ID

function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
  # Make sure the compiler arguments are clean.
  string(STRIP "${CMAKE_${lang}_COMPILER_ARG1}" CMAKE_${lang}_COMPILER_ID_ARG1)
  string(REGEX REPLACE " +" ";" CMAKE_${lang}_COMPILER_ID_ARG1 "${CMAKE_${lang}_COMPILER_ID_ARG1}")

  # Make sure user-specified compiler flags are used.
  if(CMAKE_${lang}_FLAGS)
    set(CMAKE_${lang}_COMPILER_ID_FLAGS ${CMAKE_${lang}_FLAGS})
  else()
    set(CMAKE_${lang}_COMPILER_ID_FLAGS $ENV{${flagvar}})
  endif()
  string(REGEX REPLACE " " ";" CMAKE_${lang}_COMPILER_ID_FLAGS_LIST "${CMAKE_${lang}_COMPILER_ID_FLAGS}")

  # Compute the directory in which to run the test.
  set(CMAKE_${lang}_COMPILER_ID_DIR ${CMAKE_PLATFORM_INFO_DIR}/CompilerId${lang})

  # Try building with no extra flags and then try each set
  # of helper flags.  Stop when the compiler is identified.
  foreach(flags "" ${CMAKE_${lang}_COMPILER_ID_TEST_FLAGS})
    if(NOT CMAKE_${lang}_COMPILER_ID)
      CMAKE_DETERMINE_COMPILER_ID_BUILD("${lang}" "${flags}" "${src}")
      foreach(file ${COMPILER_${lang}_PRODUCED_FILES})
        CMAKE_DETERMINE_COMPILER_ID_CHECK("${lang}" "${CMAKE_${lang}_COMPILER_ID_DIR}/${file}" "${src}")
      endforeach()
    endif()
  endforeach()

  # If the compiler is still unknown, try to query its vendor.
  if(CMAKE_${lang}_COMPILER AND NOT CMAKE_${lang}_COMPILER_ID)
    CMAKE_DETERMINE_COMPILER_ID_VENDOR(${lang})
  endif()

  if (COMPILER_QNXNTO AND CMAKE_${lang}_COMPILER_ID STREQUAL GNU)
    execute_process(
      COMMAND "${CMAKE_${lang}_COMPILER}"
      -V
      OUTPUT_VARIABLE output ERROR_VARIABLE output
      RESULT_VARIABLE result
      TIMEOUT 10
      )
    if (output MATCHES "targets available")
      set(CMAKE_${lang}_COMPILER_ID QCC)
      # http://community.qnx.com/sf/discussion/do/listPosts/projects.community/discussion.qnx_momentics_community_support.topc3555?_pagenum=2
      # The qcc driver does not itself have a version.
    endif()
  endif()

  # if the format is unknown after all files have been checked, put "Unknown" in the cache
  if(NOT CMAKE_EXECUTABLE_FORMAT)
    set(CMAKE_EXECUTABLE_FORMAT "Unknown" CACHE INTERNAL "Executable file format")
  endif()

  # Display the final identification result.
  if(CMAKE_${lang}_COMPILER_ID)
    if(CMAKE_${lang}_COMPILER_VERSION)
      set(_version " ${CMAKE_${lang}_COMPILER_VERSION}")
    else()
      set(_version "")
    endif()
    message(STATUS "The ${lang} compiler identification is "
      "${CMAKE_${lang}_COMPILER_ID}${_version}")
  else()
    message(STATUS "The ${lang} compiler identification is unknown")
  endif()

  # Check if compiler id detection gave us the compiler tool.
  if(CMAKE_${lang}_COMPILER_ID_TOOL)
    set(CMAKE_${lang}_COMPILER "${CMAKE_${lang}_COMPILER_ID_TOOL}" PARENT_SCOPE)
  elseif(NOT CMAKE_${lang}_COMPILER)
    set(CMAKE_${lang}_COMPILER "CMAKE_${lang}_COMPILER-NOTFOUND" PARENT_SCOPE)
  endif()

  set(CMAKE_${lang}_COMPILER_ID "${CMAKE_${lang}_COMPILER_ID}" PARENT_SCOPE)
  set(CMAKE_${lang}_PLATFORM_ID "${CMAKE_${lang}_PLATFORM_ID}" PARENT_SCOPE)
  set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
    PARENT_SCOPE)
  set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
  set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
  set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
endfunction()

#-----------------------------------------------------------------------------
# Function to write the compiler id source file.
function(CMAKE_DETERMINE_COMPILER_ID_WRITE lang src)
  find_file(src_in ${src}.in PATHS ${CMAKE_ROOT}/Modules ${CMAKE_MODULE_PATH} NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
  file(READ ${src_in} ID_CONTENT_IN)
  unset(src_in CACHE)
  string(CONFIGURE "${ID_CONTENT_IN}" ID_CONTENT_OUT @ONLY)
  file(WRITE ${CMAKE_${lang}_COMPILER_ID_DIR}/${src} "${ID_CONTENT_OUT}")
endfunction()

#-----------------------------------------------------------------------------
# Function to build the compiler id source file and look for output
# files.
function(CMAKE_DETERMINE_COMPILER_ID_BUILD lang testflags src)
  # Create a clean working directory.
  file(REMOVE_RECURSE ${CMAKE_${lang}_COMPILER_ID_DIR})
  file(MAKE_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR})
  CMAKE_DETERMINE_COMPILER_ID_WRITE("${lang}" "${src}")

  # Construct a description of this test case.
  set(COMPILER_DESCRIPTION
    "Compiler: ${CMAKE_${lang}_COMPILER} ${CMAKE_${lang}_COMPILER_ID_ARG1}
Build flags: ${CMAKE_${lang}_COMPILER_ID_FLAGS_LIST}
Id flags: ${testflags}
")

  # Compile the compiler identification source.
  if(CMAKE_GENERATOR STREQUAL "Visual Studio 6" AND
      lang STREQUAL "Fortran")
    set(CMAKE_${lang}_COMPILER_ID_RESULT 1)
    set(CMAKE_${lang}_COMPILER_ID_OUTPUT "No Intel Fortran in VS 6")
  elseif("${CMAKE_GENERATOR}" MATCHES "Visual Studio ([0-9]+)")
    set(vs_version ${CMAKE_MATCH_1})
    set(id_platform ${CMAKE_VS_PLATFORM_NAME})
    set(id_lang "${lang}")
    set(id_cl cl.exe)
    if(lang STREQUAL Fortran)
      set(v Intel)
      set(ext vfproj)
      set(id_cl ifort.exe)
    elseif(NOT "${vs_version}" VERSION_LESS 10)
      set(v 10)
      set(ext vcxproj)
    elseif(NOT "${vs_version}" VERSION_LESS 7)
      set(id_version ${vs_version}.00)
      set(v 7)
      set(ext vcproj)
    else()
      set(v 6)
      set(ext dsp)
    endif()
    if("${id_platform}" STREQUAL "Itanium")
      set(id_platform ia64)
    endif()
    if(CMAKE_VS_PLATFORM_TOOLSET)
      set(id_toolset "<PlatformToolset>${CMAKE_VS_PLATFORM_TOOLSET}</PlatformToolset>")
      if(CMAKE_VS_PLATFORM_TOOLSET MATCHES "Intel")
        set(id_cl icl.exe)
      endif()
    else()
      set(id_toolset "")
    endif()
    if(CMAKE_VS_WINCE_VERSION)
      set(id_entrypoint "mainACRTStartup")
      if("${vs_version}" VERSION_LESS 9)
        set(id_subsystem 9)
      else()
        set(id_subsystem 8)
      endif()
    else()
      set(id_subsystem 1)
    endif()
    set(id_dir ${CMAKE_${lang}_COMPILER_ID_DIR})
    get_filename_component(id_src "${src}" NAME)
    configure_file(${CMAKE_ROOT}/Modules/CompilerId/VS-${v}.${ext}.in
      ${id_dir}/CompilerId${lang}.${ext} @ONLY)
    if(CMAKE_VS_MSBUILD_COMMAND AND NOT lang STREQUAL "Fortran")
      set(command "${CMAKE_VS_MSBUILD_COMMAND}" "CompilerId${lang}.${ext}"
        "/p:Configuration=Debug" "/p:Platform=${id_platform}" "/p:VisualStudioVersion=${vs_version}.0"
        )
    elseif(CMAKE_VS_DEVENV_COMMAND)
      set(command "${CMAKE_VS_DEVENV_COMMAND}" "CompilerId${lang}.${ext}" "/build" "Debug")
    elseif(CMAKE_VS_MSDEV_COMMAND)
      set(command "${CMAKE_VS_MSDEV_COMMAND}" "CompilerId${lang}.${ext}" "/make")
    else()
      set(command "")
    endif()
    if(command)
      execute_process(
        COMMAND ${command}
        WORKING_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR}
        OUTPUT_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
        ERROR_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
        RESULT_VARIABLE CMAKE_${lang}_COMPILER_ID_RESULT
        )
    else()
      set(CMAKE_${lang}_COMPILER_ID_RESULT 1)
      set(CMAKE_${lang}_COMPILER_ID_OUTPUT "VS environment not known to support ${lang}")
    endif()
    # Match the compiler location line printed out.
    if("${CMAKE_${lang}_COMPILER_ID_OUTPUT}" MATCHES "CMAKE_${lang}_COMPILER=([^%\r\n]+)[\r\n]")
      # Strip VS diagnostic output from the end of the line.
      string(REGEX REPLACE " \\(TaskId:[0-9]*\\)$" "" _comp "${CMAKE_MATCH_1}")
      if(EXISTS "${_comp}")
        file(TO_CMAKE_PATH "${_comp}" _comp)
        set(CMAKE_${lang}_COMPILER_ID_TOOL "${_comp}" PARENT_SCOPE)
      endif()
    endif()
  elseif("${CMAKE_GENERATOR}" MATCHES "Xcode")
    set(id_lang "${lang}")
    set(id_type ${CMAKE_${lang}_COMPILER_XCODE_TYPE})
    set(id_dir ${CMAKE_${lang}_COMPILER_ID_DIR})
    get_filename_component(id_src "${src}" NAME)
    if(CMAKE_XCODE_PLATFORM_TOOLSET)
      set(id_toolset "GCC_VERSION = ${CMAKE_XCODE_PLATFORM_TOOLSET};")
    else()
      set(id_toolset "")
    endif()
    if(NOT ${XCODE_VERSION} VERSION_LESS 3)
      set(v 3)
      set(ext xcodeproj)
    elseif(NOT ${XCODE_VERSION} VERSION_LESS 2)
      set(v 2)
      set(ext xcodeproj)
    else()
      set(v 1)
      set(ext xcode)
    endif()
    configure_file(${CMAKE_ROOT}/Modules/CompilerId/Xcode-${v}.pbxproj.in
      ${id_dir}/CompilerId${lang}.${ext}/project.pbxproj @ONLY)
    unset(_ENV_MACOSX_DEPLOYMENT_TARGET)
    if(DEFINED ENV{MACOSX_DEPLOYMENT_TARGET})
      set(_ENV_MACOSX_DEPLOYMENT_TARGET "$ENV{MACOSX_DEPLOYMENT_TARGET}")
      set(ENV{MACOSX_DEPLOYMENT_TARGET} "")
    endif()
    execute_process(COMMAND xcodebuild
      WORKING_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR}
      OUTPUT_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
      ERROR_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
      RESULT_VARIABLE CMAKE_${lang}_COMPILER_ID_RESULT
      )
    if(DEFINED _ENV_MACOSX_DEPLOYMENT_TARGET)
      set(ENV{MACOSX_DEPLOYMENT_TARGET} "${_ENV_MACOSX_DEPLOYMENT_TARGET}")
    endif()

    # Match the link line from xcodebuild output of the form
    #  Ld ...
    #      ...
    #      /path/to/cc ...CompilerId${lang}/...
    # to extract the compiler front-end for the language.
    if("${CMAKE_${lang}_COMPILER_ID_OUTPUT}" MATCHES "\nLd[^\n]*(\n[ \t]+[^\n]*)*\n[ \t]+([^ \t\r\n]+)[^\r\n]*-o[^\r\n]*CompilerId${lang}/(\\./)?CompilerId${lang}[ \t\n\\\"]")
      set(_comp "${CMAKE_MATCH_2}")
      if(EXISTS "${_comp}")
        set(CMAKE_${lang}_COMPILER_ID_TOOL "${_comp}" PARENT_SCOPE)
      endif()
    endif()
  else()
    if(COMMAND EXECUTE_PROCESS)
      execute_process(
        COMMAND "${CMAKE_${lang}_COMPILER}"
                ${CMAKE_${lang}_COMPILER_ID_ARG1}
                ${CMAKE_${lang}_COMPILER_ID_FLAGS_LIST}
                ${testflags}
                "${src}"
        WORKING_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR}
        OUTPUT_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
        ERROR_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
        RESULT_VARIABLE CMAKE_${lang}_COMPILER_ID_RESULT
        )
    else()
      exec_program(
        "${CMAKE_${lang}_COMPILER}" ${CMAKE_${lang}_COMPILER_ID_DIR}
        ARGS ${CMAKE_${lang}_COMPILER_ID_ARG1}
             ${CMAKE_${lang}_COMPILER_ID_FLAGS_LIST}
             ${testflags}
             \"${src}\"
        OUTPUT_VARIABLE CMAKE_${lang}_COMPILER_ID_OUTPUT
        RETURN_VALUE CMAKE_${lang}_COMPILER_ID_RESULT
        )
    endif()
  endif()

  # Check the result of compilation.
  if(CMAKE_${lang}_COMPILER_ID_RESULT
     # Intel Fortran warns and ignores preprocessor lines without /fpp
     OR CMAKE_${lang}_COMPILER_ID_OUTPUT MATCHES "Bad # preprocessor line"
     )
    # Compilation failed.
    set(MSG
      "Compiling the ${lang} compiler identification source file \"${src}\" failed.
${COMPILER_DESCRIPTION}
The output was:
${CMAKE_${lang}_COMPILER_ID_RESULT}
${CMAKE_${lang}_COMPILER_ID_OUTPUT}

")
    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log "${MSG}")
    #if(NOT CMAKE_${lang}_COMPILER_ID_ALLOW_FAIL)
    #  message(FATAL_ERROR "${MSG}")
    #endif()

    # No output files should be inspected.
    set(COMPILER_${lang}_PRODUCED_FILES)
  else()
    # Compilation succeeded.
    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
      "Compiling the ${lang} compiler identification source file \"${src}\" succeeded.
${COMPILER_DESCRIPTION}
The output was:
${CMAKE_${lang}_COMPILER_ID_RESULT}
${CMAKE_${lang}_COMPILER_ID_OUTPUT}

")

    # Find the executable produced by the compiler, try all files in the
    # binary dir.
    file(GLOB files
      RELATIVE ${CMAKE_${lang}_COMPILER_ID_DIR}
      ${CMAKE_${lang}_COMPILER_ID_DIR}/*)
    list(REMOVE_ITEM files "${src}")
    set(COMPILER_${lang}_PRODUCED_FILES "")
    foreach(file ${files})
      if(NOT IS_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR}/${file})
        list(APPEND COMPILER_${lang}_PRODUCED_FILES ${file})
        file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
          "Compilation of the ${lang} compiler identification source \""
          "${src}\" produced \"${file}\"\n\n")
      endif()
    endforeach()

    if(NOT COMPILER_${lang}_PRODUCED_FILES)
      # No executable was found.
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
        "Compilation of the ${lang} compiler identification source \""
        "${src}\" did not produce an executable in \""
        "${CMAKE_${lang}_COMPILER_ID_DIR}\".\n\n")
    endif()
  endif()

  # Return the files produced by the compilation.
  set(COMPILER_${lang}_PRODUCED_FILES "${COMPILER_${lang}_PRODUCED_FILES}" PARENT_SCOPE)
endfunction()

#-----------------------------------------------------------------------------
# Function to extract the compiler id from an executable.
function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
  # Look for a compiler id if not yet known.
  if(NOT CMAKE_${lang}_COMPILER_ID)
    # Read the compiler identification string from the executable file.
    set(COMPILER_ID)
    set(COMPILER_VERSION)
    set(PLATFORM_ID)
    set(ARCHITECTURE_ID)
    set(SIMULATE_ID)
    set(SIMULATE_VERSION)
    file(STRINGS ${file}
      CMAKE_${lang}_COMPILER_ID_STRINGS LIMIT_COUNT 6 REGEX "INFO:")
    set(COMPILER_ID_TWICE)
    foreach(info ${CMAKE_${lang}_COMPILER_ID_STRINGS})
      if("${info}" MATCHES ".*INFO:compiler\\[([^]\"]*)\\].*")
        if(COMPILER_ID)
          set(COMPILER_ID_TWICE 1)
        endif()
        set(COMPILER_ID "${CMAKE_MATCH_1}")
      endif()
      if("${info}" MATCHES ".*INFO:platform\\[([^]\"]*)\\].*")
        set(PLATFORM_ID "${CMAKE_MATCH_1}")
      endif()
      if("${info}" MATCHES ".*INFO:arch\\[([^]\"]*)\\].*")
        set(ARCHITECTURE_ID "${CMAKE_MATCH_1}")
      endif()
      if("${info}" MATCHES ".*INFO:compiler_version\\[([^]\"]*)\\].*")
        string(REGEX REPLACE "^0+([0-9])" "\\1" COMPILER_VERSION "${CMAKE_MATCH_1}")
        string(REGEX REPLACE "\\.0+([0-9])" ".\\1" COMPILER_VERSION "${COMPILER_VERSION}")
      endif()
      if("${info}" MATCHES ".*INFO:simulate\\[([^]\"]*)\\].*")
        set(SIMULATE_ID "${CMAKE_MATCH_1}")
      endif()
      if("${info}" MATCHES ".*INFO:simulate_version\\[([^]\"]*)\\].*")
        string(REGEX REPLACE "^0+([0-9])" "\\1" SIMULATE_VERSION "${CMAKE_MATCH_1}")
        string(REGEX REPLACE "\\.0+([0-9])" ".\\1" SIMULATE_VERSION "${SIMULATE_VERSION}")
      endif()
      if("${info}" MATCHES ".*INFO:qnxnto")
        set(COMPILER_QNXNTO 1)
      endif()
    endforeach()

    # Detect the exact architecture from the PE header.
    if(WIN32)
      # The offset to the PE signature is stored at 0x3c.
      file(READ ${file} peoffsethex LIMIT 1 OFFSET 60 HEX)
      string(SUBSTRING "${peoffsethex}" 0 1 peoffsethex1)
      string(SUBSTRING "${peoffsethex}" 1 1 peoffsethex2)
      set(peoffsetexpression "${peoffsethex1} * 16 + ${peoffsethex2}")
      string(REPLACE "a" "10" peoffsetexpression "${peoffsetexpression}")
      string(REPLACE "b" "11" peoffsetexpression "${peoffsetexpression}")
      string(REPLACE "c" "12" peoffsetexpression "${peoffsetexpression}")
      string(REPLACE "d" "13" peoffsetexpression "${peoffsetexpression}")
      string(REPLACE "e" "14" peoffsetexpression "${peoffsetexpression}")
      string(REPLACE "f" "15" peoffsetexpression "${peoffsetexpression}")
      math(EXPR peoffset "${peoffsetexpression}")

      file(READ ${file} peheader LIMIT 6 OFFSET ${peoffset} HEX)
      if(peheader STREQUAL "50450000a201")
        set(ARCHITECTURE_ID "SH3")
      elseif(peheader STREQUAL "50450000a301")
        set(ARCHITECTURE_ID "SH3DSP")
      elseif(peheader STREQUAL "50450000a601")
        set(ARCHITECTURE_ID "SH4")
      elseif(peheader STREQUAL "50450000a801")
        set(ARCHITECTURE_ID "SH5")
      elseif(peheader STREQUAL "50450000c201")
        set(ARCHITECTURE_ID "THUMB")
      endif()
    endif()

    # Check if a valid compiler and platform were found.
    if(COMPILER_ID AND NOT COMPILER_ID_TWICE)
      set(CMAKE_${lang}_COMPILER_ID "${COMPILER_ID}")
      set(CMAKE_${lang}_PLATFORM_ID "${PLATFORM_ID}")
      set(MSVC_${lang}_ARCHITECTURE_ID "${ARCHITECTURE_ID}")
      set(CMAKE_${lang}_COMPILER_VERSION "${COMPILER_VERSION}")
      set(CMAKE_${lang}_SIMULATE_ID "${SIMULATE_ID}")
      set(CMAKE_${lang}_SIMULATE_VERSION "${SIMULATE_VERSION}")
    endif()

    # Check the compiler identification string.
    if(CMAKE_${lang}_COMPILER_ID)
      # The compiler identification was found.
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
        "The ${lang} compiler identification is ${CMAKE_${lang}_COMPILER_ID}, found in \""
        "${file}\"\n\n")
    else()
      # The compiler identification could not be found.
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
        "The ${lang} compiler identification could not be found in \""
        "${file}\"\n\n")
    endif()
  endif()

  # try to figure out the executable format: ELF, COFF, Mach-O
  if(NOT CMAKE_EXECUTABLE_FORMAT)
    file(READ ${file} CMAKE_EXECUTABLE_MAGIC LIMIT 4 HEX)

    # ELF files start with 0x7f"ELF"
    if("${CMAKE_EXECUTABLE_MAGIC}" STREQUAL "7f454c46")
      set(CMAKE_EXECUTABLE_FORMAT "ELF" CACHE INTERNAL "Executable file format")
    endif()

#    # COFF (.exe) files start with "MZ"
#    if("${CMAKE_EXECUTABLE_MAGIC}" MATCHES "4d5a....")
#      set(CMAKE_EXECUTABLE_FORMAT "COFF" CACHE STRING "Executable file format")
#    endif()
#
#    # Mach-O files start with CAFEBABE or FEEDFACE, according to http://radio.weblogs.com/0100490/2003/01/28.html
#    if("${CMAKE_EXECUTABLE_MAGIC}" MATCHES "cafebabe")
#      set(CMAKE_EXECUTABLE_FORMAT "MACHO" CACHE STRING "Executable file format")
#    endif()
#    if("${CMAKE_EXECUTABLE_MAGIC}" MATCHES "feedface")
#      set(CMAKE_EXECUTABLE_FORMAT "MACHO" CACHE STRING "Executable file format")
#    endif()

  endif()
  if(NOT DEFINED CMAKE_EXECUTABLE_FORMAT)
    set(CMAKE_EXECUTABLE_FORMAT)
  endif()
  # Return the information extracted.
  set(CMAKE_${lang}_COMPILER_ID "${CMAKE_${lang}_COMPILER_ID}" PARENT_SCOPE)
  set(CMAKE_${lang}_PLATFORM_ID "${CMAKE_${lang}_PLATFORM_ID}" PARENT_SCOPE)
  set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
    PARENT_SCOPE)
  set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
  set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
  set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
  set(CMAKE_EXECUTABLE_FORMAT "${CMAKE_EXECUTABLE_FORMAT}" PARENT_SCOPE)
  set(COMPILER_QNXNTO "${COMPILER_QNXNTO}" PARENT_SCOPE)
endfunction()

#-----------------------------------------------------------------------------
# Function to query the compiler vendor.
# This uses a table with entries of the form
#   list(APPEND CMAKE_${lang}_COMPILER_ID_VENDORS ${vendor})
#   set(CMAKE_${lang}_COMPILER_ID_VENDOR_FLAGS_${vendor} -some-vendor-flag)
#   set(CMAKE_${lang}_COMPILER_ID_VENDOR_REGEX_${vendor} "Some Vendor Output")
# We try running the compiler with the flag for each vendor and
# matching its regular expression in the output.
function(CMAKE_DETERMINE_COMPILER_ID_VENDOR lang)

  if(NOT CMAKE_${lang}_COMPILER_ID_DIR)
    # We get here when this function is called not from within CMAKE_DETERMINE_COMPILER_ID()
    # This is done e.g. for detecting the compiler ID for assemblers.
    # Compute the directory in which to run the test and Create a clean working directory.
    set(CMAKE_${lang}_COMPILER_ID_DIR ${CMAKE_PLATFORM_INFO_DIR}/CompilerId${lang})
    file(REMOVE_RECURSE ${CMAKE_${lang}_COMPILER_ID_DIR})
    file(MAKE_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR})
  endif()


  foreach(vendor ${CMAKE_${lang}_COMPILER_ID_VENDORS})
    set(flags ${CMAKE_${lang}_COMPILER_ID_VENDOR_FLAGS_${vendor}})
    set(regex ${CMAKE_${lang}_COMPILER_ID_VENDOR_REGEX_${vendor}})
    execute_process(
      COMMAND "${CMAKE_${lang}_COMPILER}"
      ${CMAKE_${lang}_COMPILER_ID_ARG1}
      ${CMAKE_${lang}_COMPILER_ID_FLAGS_LIST}
      ${flags}
      WORKING_DIRECTORY ${CMAKE_${lang}_COMPILER_ID_DIR}
      OUTPUT_VARIABLE output ERROR_VARIABLE output
      RESULT_VARIABLE result
      TIMEOUT 10
      )

    if("${output}" MATCHES "${regex}")
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
        "Checking whether the ${lang} compiler is ${vendor} using \"${flags}\" "
        "matched \"${regex}\":\n${output}")
      set(CMAKE_${lang}_COMPILER_ID "${vendor}" PARENT_SCOPE)
      break()
    else()
      if("${result}" MATCHES  "timeout")
        file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
          "Checking whether the ${lang} compiler is ${vendor} using \"${flags}\" "
          "terminated after 10 s due to timeout.")
      else()
        file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
          "Checking whether the ${lang} compiler is ${vendor} using \"${flags}\" "
          "did not match \"${regex}\":\n${output}")
       endif()
    endif()
  endforeach()
endfunction()