1# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
2# file Copyright.txt or https://cmake.org/licensing for details.
3
4#[=======================================================================[.rst:
5CheckCompilerFlag
6---------------------
7
8.. versionadded:: 3.19
9
10Check whether the compiler supports a given flag.
11
12.. command:: check_compiler_flag
13
14  .. code-block:: cmake
15
16    check_compiler_flag(<lang> <flag> <var>)
17
18Check that the ``<flag>`` is accepted by the compiler without a diagnostic.
19Stores the result in an internal cache entry named ``<var>``.
20
21This command temporarily sets the ``CMAKE_REQUIRED_DEFINITIONS`` variable
22and calls the ``check_source_compiles(<LANG>)`` function from the
23:module:`CheckSourceCompiles` module.  See documentation of that
24module for a listing of variables that can otherwise modify the build.
25
26A positive result from this check indicates only that the compiler did not
27issue a diagnostic message when given the flag.  Whether the flag has any
28effect or even a specific one is beyond the scope of this module.
29
30.. note::
31  Since the :command:`try_compile` command forwards flags from variables
32  like :variable:`CMAKE_<LANG>_FLAGS <CMAKE_<LANG>_FLAGS>`, unknown flags
33  in such variables may cause a false negative for this check.
34#]=======================================================================]
35
36include_guard(GLOBAL)
37include(Internal/CheckCompilerFlag)
38
39function(CHECK_COMPILER_FLAG _lang _flag _var)
40  cmake_check_compiler_flag(${_lang} "${_flag}" ${_var})
41endfunction()
42