| # Distributed under the OSI-approved BSD 3-Clause License. See accompanying |
| # file Copyright.txt or https://cmake.org/licensing for details. |
| |
| #[=======================================================================[.rst: |
| CheckLinkerFlag |
| --------------- |
| |
| Check whether the compiler supports a given link flag. |
| |
| .. command:: check_linker_flag |
| |
| .. code-block:: cmake |
| |
| check_linker_flag(<lang> <flag> <var>) |
| |
| Check that the link ``<flag>`` is accepted by the ``<lang>`` compiler without |
| a diagnostic. Stores the result in an internal cache entry named ``<var>``. |
| |
| This command temporarily sets the ``CMAKE_REQUIRED_LINK_OPTIONS`` variable |
| and calls the ``check_<lang>_source_compiles`` macro from the |
| ``Check<lang>SourceCompiles`` module (:module:`CheckCSourceCompiles`, |
| :module:`CheckCSourceCompiles`, :module:`CheckCXXSourceCompiles`, |
| :module:`CheckOBJCSourceCompiles`, :module:`CheckOBJCXXSourceCompiles` or |
| :module:`CheckFortranSourceCompiles`). See documentation of these |
| modules for a listing of variables that can otherwise modify the build. |
| |
| The underlying implementation rely on :prop_tgt:`LINK_OPTIONS` property to |
| check the specified flag. The ``LINKER:`` prefix, as described in |
| :command:`target_link_options` command, can be used as well. |
| |
| A positive result from this check indicates only that the compiler did not |
| issue a diagnostic message when given the link flag. Whether the flag has any |
| effect or even a specific one is beyond the scope of this module. |
| |
| .. note:: |
| Since the :command:`try_compile` command forwards flags from variables |
| like :variable:`CMAKE_<LANG>_FLAGS`, unknown flags in such variables may |
| cause a false negative for this check. |
| #]=======================================================================] |
| |
| include_guard(GLOBAL) |
| |
| include(CMakeCheckCompilerFlagCommonPatterns) |
| |
| function(CHECK_LINKER_FLAG _lang _flag _var) |
| get_property (_supported_languages GLOBAL PROPERTY ENABLED_LANGUAGES) |
| if (NOT _lang IN_LIST _supported_languages) |
| message (SEND_ERROR "check_linker_flag: ${_lang}: unknown language.") |
| return() |
| endif() |
| |
| include (Check${_lang}SourceCompiles) |
| |
| set(CMAKE_REQUIRED_LINK_OPTIONS "${_flag}") |
| |
| # Normalize locale during test compilation. |
| set(_locale_vars LC_ALL LC_MESSAGES LANG) |
| foreach(v IN LISTS _locale_vars) |
| set(_locale_vars_saved_${v} "$ENV{${v}}") |
| set(ENV{${v}} C) |
| endforeach() |
| |
| if (_lang MATCHES "^(C|CXX)$") |
| set (_source "int main() { return 0; }") |
| elseif (_lang STREQUAL "Fortran") |
| set (_source " program test\n stop\n end program") |
| elseif (_lang MATCHES "^(OBJC|OBJCXX)$") |
| set (_source "#ifndef __OBJC__\n# error \"Not an Objective-C++ compiler\"\n#endif\nint main(void) { return 0; }") |
| else() |
| message (SEND_ERROR "check_linker_flag: ${_lang}: unsupported language.") |
| return() |
| endif() |
| check_compiler_flag_common_patterns(_common_patterns) |
| |
| cmake_language (CALL check_${_lang}_source_compiles "${_source}" ${_var} ${_common_patterns}) |
| |
| foreach(v IN LISTS _locale_vars) |
| set(ENV{${v}} ${_locale_vars_saved_${v}}) |
| endforeach() |
| set(${_var} "${${_var}}" PARENT_SCOPE) |
| endfunction() |