3.8.2/share/cmake-3.8/Modules/CMakeDetermineCompiler.cmake

# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.


macro(_cmake_find_compiler lang)
  # Use already-enabled languages for reference.
  get_property(_languages GLOBAL PROPERTY ENABLED_LANGUAGES)
  list(REMOVE_ITEM _languages "${lang}")

  if(CMAKE_${lang}_COMPILER_INIT)
    # Search only for the specified compiler.
    set(CMAKE_${lang}_COMPILER_LIST "${CMAKE_${lang}_COMPILER_INIT}")
  else()
    # Re-order the compiler list with preferred vendors first.
    set(_${lang}_COMPILER_LIST "${CMAKE_${lang}_COMPILER_LIST}")
    set(CMAKE_${lang}_COMPILER_LIST "")
    # Prefer vendors of compilers from reference languages.
    foreach(l ${_languages})
      list(APPEND CMAKE_${lang}_COMPILER_LIST
        ${_${lang}_COMPILER_NAMES_${CMAKE_${l}_COMPILER_ID}})
    endforeach()
    # Prefer vendors based on the platform.
    list(APPEND CMAKE_${lang}_COMPILER_LIST ${CMAKE_${lang}_COMPILER_NAMES})
    # Append the rest of the list and remove duplicates.
    list(APPEND CMAKE_${lang}_COMPILER_LIST ${_${lang}_COMPILER_LIST})
    unset(_${lang}_COMPILER_LIST)
    list(REMOVE_DUPLICATES CMAKE_${lang}_COMPILER_LIST)
    if(CMAKE_${lang}_COMPILER_EXCLUDE)
      list(REMOVE_ITEM CMAKE_${lang}_COMPILER_LIST
        ${CMAKE_${lang}_COMPILER_EXCLUDE})
    endif()
  endif()

  # Look for directories containing compilers of reference languages.
  set(_${lang}_COMPILER_HINTS)
  foreach(l ${_languages})
    if(CMAKE_${l}_COMPILER AND IS_ABSOLUTE "${CMAKE_${l}_COMPILER}")
      get_filename_component(_hint "${CMAKE_${l}_COMPILER}" PATH)
      if(IS_DIRECTORY "${_hint}")
        list(APPEND _${lang}_COMPILER_HINTS "${_hint}")
      endif()
      unset(_hint)
    endif()
  endforeach()

  # Find the compiler.
  if(_${lang}_COMPILER_HINTS)
    # Prefer directories containing compilers of reference languages.
    list(REMOVE_DUPLICATES _${lang}_COMPILER_HINTS)
    find_program(CMAKE_${lang}_COMPILER
      NAMES ${CMAKE_${lang}_COMPILER_LIST}
      PATHS ${_${lang}_COMPILER_HINTS}
      NO_DEFAULT_PATH
      DOC "${lang} compiler")
  endif()
  find_program(CMAKE_${lang}_COMPILER NAMES ${CMAKE_${lang}_COMPILER_LIST} DOC "${lang} compiler")
  if(CMAKE_${lang}_COMPILER_INIT AND NOT CMAKE_${lang}_COMPILER)
    set_property(CACHE CMAKE_${lang}_COMPILER PROPERTY VALUE "${CMAKE_${lang}_COMPILER_INIT}")
  endif()
  unset(_${lang}_COMPILER_HINTS)
  unset(_languages)

  # Look for a make tool provided by Xcode
  if(CMAKE_HOST_APPLE)
    macro(_query_xcrun compiler_name result_var_keyword result_var)
      if(NOT "x${result_var_keyword}" STREQUAL "xRESULT_VAR")
        message(FATAL_ERROR "Bad arguments to macro")
      endif()
      execute_process(COMMAND xcrun --find ${compiler_name}
        OUTPUT_VARIABLE _xcrun_out OUTPUT_STRIP_TRAILING_WHITESPACE
        ERROR_VARIABLE _xcrun_err)
      set("${result_var}" "${_xcrun_out}")
    endmacro()

    set(xcrun_result)
    if (CMAKE_${lang}_COMPILER MATCHES "^/usr/bin/(.+)$")
      _query_xcrun("${CMAKE_MATCH_1}" RESULT_VAR xcrun_result)
    elseif (CMAKE_${lang}_COMPILER STREQUAL "CMAKE_${lang}_COMPILER-NOTFOUND")
      foreach(comp ${CMAKE_${lang}_COMPILER_LIST})
        _query_xcrun("${comp}" RESULT_VAR xcrun_result)
        if(xcrun_result)
          break()
        endif()
      endforeach()
    endif()
    if (xcrun_result)
      set_property(CACHE CMAKE_${lang}_COMPILER PROPERTY VALUE "${xcrun_result}")
    endif()
  endif()
endmacro()

macro(_cmake_find_compiler_path lang)
  if(CMAKE_${lang}_COMPILER)
    # we only get here if CMAKE_${lang}_COMPILER was specified using -D or a pre-made CMakeCache.txt
    # (e.g. via ctest) or set in CMAKE_TOOLCHAIN_FILE
    # if CMAKE_${lang}_COMPILER is a list of length 2, use the first item as
    # CMAKE_${lang}_COMPILER and the 2nd one as CMAKE_${lang}_COMPILER_ARG1
    list(LENGTH CMAKE_${lang}_COMPILER _CMAKE_${lang}_COMPILER_LIST_LENGTH)
    if("${_CMAKE_${lang}_COMPILER_LIST_LENGTH}" EQUAL 2)
      list(GET CMAKE_${lang}_COMPILER 1 CMAKE_${lang}_COMPILER_ARG1)
      list(GET CMAKE_${lang}_COMPILER 0 CMAKE_${lang}_COMPILER)
    endif()
    unset(_CMAKE_${lang}_COMPILER_LIST_LENGTH)

    # find the compiler in the PATH if necessary
    get_filename_component(_CMAKE_USER_${lang}_COMPILER_PATH "${CMAKE_${lang}_COMPILER}" PATH)
    if(NOT _CMAKE_USER_${lang}_COMPILER_PATH)
      find_program(CMAKE_${lang}_COMPILER_WITH_PATH NAMES ${CMAKE_${lang}_COMPILER})
      if(CMAKE_${lang}_COMPILER_WITH_PATH)
        set(CMAKE_${lang}_COMPILER ${CMAKE_${lang}_COMPILER_WITH_PATH})
        get_property(_CMAKE_${lang}_COMPILER_CACHED CACHE CMAKE_${lang}_COMPILER PROPERTY TYPE)
        if(_CMAKE_${lang}_COMPILER_CACHED)
          set(CMAKE_${lang}_COMPILER "${CMAKE_${lang}_COMPILER}" CACHE STRING "${lang} compiler" FORCE)
        endif()
        unset(_CMAKE_${lang}_COMPILER_CACHED)
      endif()
      unset(CMAKE_${lang}_COMPILER_WITH_PATH CACHE)
    endif()
  endif()
endmacro()