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:
5CheckCXXCompilerFlag
6------------------------
7
8Check whether the CXX compiler supports a given flag.
9
10.. command:: check_cxx_compiler_flag
11
12  .. code-block:: cmake
13
14    check_cxx_compiler_flag(<flag> <var>)
15
16  Check that the ``<flag>`` is accepted by the compiler without
17  a diagnostic.  Stores the result in an internal cache entry
18  named ``<var>``.
19
20This command temporarily sets the ``CMAKE_REQUIRED_DEFINITIONS`` variable
21and calls the ``check_cxx_source_compiles`` macro from the
22:module:`CheckCXXSourceCompiles` module.  See documentation of that
23module for a listing of variables that can otherwise modify the build.
24
25A positive result from this check indicates only that the compiler did not
26issue a diagnostic message when given the flag.  Whether the flag has any
27effect or even a specific one is beyond the scope of this module.
28
29.. note::
30  Since the :command:`try_compile` command forwards flags from variables
31  like :variable:`CMAKE_CXX_FLAGS <CMAKE_<LANG>_FLAGS>`, unknown flags
32  in such variables may cause a false negative for this check.
33#]=======================================================================]
34
35include_guard(GLOBAL)
36include(CheckCXXSourceCompiles)
37include(Internal/CheckCompilerFlag)
38
39macro (CHECK_CXX_COMPILER_FLAG _FLAG _RESULT)
40  cmake_check_compiler_flag(CXX "${_FLAG}" ${_RESULT})
41endmacro ()
42