diff options
Diffstat (limited to 'Modules/CheckCCompilerFlag.cmake')
| -rw-r--r-- | Modules/CheckCCompilerFlag.cmake | 39 |
1 files changed, 27 insertions, 12 deletions
diff --git a/Modules/CheckCCompilerFlag.cmake b/Modules/CheckCCompilerFlag.cmake index 335b437..12b0976 100644 --- a/Modules/CheckCCompilerFlag.cmake +++ b/Modules/CheckCCompilerFlag.cmake @@ -11,31 +11,46 @@ Check whether the C compiler supports a given flag. .. code-block:: cmake - check_c_compiler_flag(<flag> <var>) + check_c_compiler_flag(<flag> <resultVar>) Check that the ``<flag>`` is accepted by the compiler without a diagnostic. Stores the result in an internal cache entry - named ``<var>``. - -This command temporarily sets the ``CMAKE_REQUIRED_DEFINITIONS`` variable -and calls the ``check_c_source_compiles`` macro from the -:module:`CheckCSourceCompiles` module. See documentation of that -module for a listing of variables that can otherwise modify the build. + named ``<resultVar>``. A positive result from this check indicates only that the compiler did not issue a diagnostic message when given the 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_C_FLAGS <CMAKE_<LANG>_FLAGS>`, unknown flags - in such variables may cause a false negative for this check. +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. + +The compile and link commands can be influenced by setting any of the +following variables prior to calling ``check_c_compiler_flag()`` + +.. include:: /module/CMAKE_REQUIRED_FLAGS.txt + +.. include:: /module/CMAKE_REQUIRED_DEFINITIONS.txt + +.. include:: /module/CMAKE_REQUIRED_INCLUDES.txt + +.. include:: /module/CMAKE_REQUIRED_LINK_OPTIONS.txt + +.. include:: /module/CMAKE_REQUIRED_LIBRARIES.txt + +.. include:: /module/CMAKE_REQUIRED_QUIET.txt + #]=======================================================================] include_guard(GLOBAL) -include(CheckCSourceCompiles) include(Internal/CheckCompilerFlag) macro (CHECK_C_COMPILER_FLAG _FLAG _RESULT) cmake_check_compiler_flag(C "${_FLAG}" ${_RESULT}) endmacro () + +# FIXME(#24994): The following module is included only for compatibility +# with projects that accidentally relied on it with CMake 3.26 and below. +include(CheckCSourceCompiles) |