CheckCSourceCompiles.cmake 5.12 KB
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# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

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#[=======================================================================[.rst:
CheckCSourceCompiles
--------------------

Check if given C source compiles and links into an executable.

.. command:: check_c_source_compiles

  ::

    check_c_source_compiles(code resultVar [FAIL_REGEX regex1 [regex2...]])

  Check that the source supplied in ``code`` can be compiled as a C source
  file and linked as an executable (so it must contain at least a ``main()``
  function). The result will be stored in the internal cache variable specified
  by ``resultVar``, with a boolean true value for success and boolean false for
  failure. If ``FAIL_REGEX`` is provided, then failure is determined by
  checking if anything in the output matches any of the specified regular
  expressions.

  The underlying check is performed by the :command:`try_compile` command. The
  compile and link commands can be influenced by setting any of the following
  variables prior to calling ``check_c_source_compiles()``:

  ``CMAKE_REQUIRED_FLAGS``
    Additional flags to pass to the compiler. Note that the contents of
    :variable:`CMAKE_C_FLAGS <CMAKE_<LANG>_FLAGS>` and its associated
    configuration-specific variable are automatically added to the compiler
    command before the contents of ``CMAKE_REQUIRED_FLAGS``.

  ``CMAKE_REQUIRED_DEFINITIONS``
    A :ref:`;-list <CMake Language Lists>` of compiler definitions of the form
    ``-DFOO`` or ``-DFOO=bar``. A definition for the name specified by
    ``resultVar`` will also be added automatically.

  ``CMAKE_REQUIRED_INCLUDES``
    A :ref:`;-list <CMake Language Lists>` of header search paths to pass to
    the compiler. These will be the only header search paths used by
    ``try_compile()``, i.e. the contents of the :prop_dir:`INCLUDE_DIRECTORIES`
    directory property will be ignored.

  ``CMAKE_REQUIRED_LIBRARIES``
    A :ref:`;-list <CMake Language Lists>` of libraries to add to the link
    command. These can be the name of system libraries or they can be
    :ref:`Imported Targets <Imported Targets>` (see :command:`try_compile` for
    further details).

  ``CMAKE_REQUIRED_QUIET``
    If this variable evaluates to a boolean true value, all status messages
    associated with the check will be suppressed.

  The check is only performed once, with the result cached in the variable
  named by ``resultVar``. Every subsequent CMake run will re-use this cached
  value rather than performing the check again, even if the ``code`` changes.
  In order to force the check to be re-evaluated, the variable named by
  ``resultVar`` must be manually removed from the cache.

#]=======================================================================]

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macro(CHECK_C_SOURCE_COMPILES SOURCE VAR)
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  if(NOT DEFINED "${VAR}")
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    set(_FAIL_REGEX)
    set(_key)
    foreach(arg ${ARGN})
      if("${arg}" MATCHES "^(FAIL_REGEX)$")
        set(_key "${arg}")
      elseif(_key)
        list(APPEND _${_key} "${arg}")
      else()
        message(FATAL_ERROR "Unknown argument:\n  ${arg}\n")
      endif()
    endforeach()
    set(MACRO_CHECK_FUNCTION_DEFINITIONS
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      "-D${VAR} ${CMAKE_REQUIRED_FLAGS}")
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    if(CMAKE_REQUIRED_LIBRARIES)
      set(CHECK_C_SOURCE_COMPILES_ADD_LIBRARIES
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        LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
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    else()
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      set(CHECK_C_SOURCE_COMPILES_ADD_LIBRARIES)
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    endif()
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    if(CMAKE_REQUIRED_INCLUDES)
      set(CHECK_C_SOURCE_COMPILES_ADD_INCLUDES
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        "-DINCLUDE_DIRECTORIES:STRING=${CMAKE_REQUIRED_INCLUDES}")
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    else()
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      set(CHECK_C_SOURCE_COMPILES_ADD_INCLUDES)
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    endif()
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    file(WRITE "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.c"
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      "${SOURCE}\n")
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    if(NOT CMAKE_REQUIRED_QUIET)
      message(STATUS "Performing Test ${VAR}")
    endif()
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    try_compile(${VAR}
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      ${CMAKE_BINARY_DIR}
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      ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.c
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      COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
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      ${CHECK_C_SOURCE_COMPILES_ADD_LIBRARIES}
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      CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_FUNCTION_DEFINITIONS}
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      "${CHECK_C_SOURCE_COMPILES_ADD_INCLUDES}"
      OUTPUT_VARIABLE OUTPUT)
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    foreach(_regex ${_FAIL_REGEX})
      if("${OUTPUT}" MATCHES "${_regex}")
        set(${VAR} 0)
      endif()
    endforeach()
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    if(${VAR})
      set(${VAR} 1 CACHE INTERNAL "Test ${VAR}")
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      if(NOT CMAKE_REQUIRED_QUIET)
        message(STATUS "Performing Test ${VAR} - Success")
      endif()
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      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
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        "Performing C SOURCE FILE Test ${VAR} succeeded with the following output:\n"
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        "${OUTPUT}\n"
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        "Source file was:\n${SOURCE}\n")
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    else()
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      if(NOT CMAKE_REQUIRED_QUIET)
        message(STATUS "Performing Test ${VAR} - Failed")
      endif()
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      set(${VAR} "" CACHE INTERNAL "Test ${VAR}")
      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
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        "Performing C SOURCE FILE Test ${VAR} failed with the following output:\n"
        "${OUTPUT}\n"
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        "Source file was:\n${SOURCE}\n")
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    endif()
  endif()
endmacro()
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