diff options
Diffstat (limited to 'Modules/CheckCompilerFlag.cmake')
| -rw-r--r-- | Modules/CheckCompilerFlag.cmake | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/Modules/CheckCompilerFlag.cmake b/Modules/CheckCompilerFlag.cmake index 77c07b9..a18435b 100644 --- a/Modules/CheckCompilerFlag.cmake +++ b/Modules/CheckCompilerFlag.cmake @@ -13,24 +13,36 @@ Check whether the compiler supports a given flag. .. code-block:: cmake - check_compiler_flag(<lang> <flag> <var>) + check_compiler_flag(<lang> <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_source_compiles(<LANG>)`` function from the -:module:`CheckSourceCompiles` module. See documentation of that -module for a listing of variables that can otherwise modify the build. +Stores the result in an internal cache entry 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_<LANG>_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_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) |