70 lines
2.1 KiB
CMake
70 lines
2.1 KiB
CMake
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
|
|
# file LICENSE.rst or https://cmake.org/licensing for details.
|
|
|
|
#[=======================================================================[.rst:
|
|
TestForANSIStreamHeaders
|
|
------------------------
|
|
|
|
This module checks whether the ``CXX`` compiler supports standard library
|
|
headers without the ``.h`` extension (e.g. ``<iostream>``). Early
|
|
versions of C++ (pre-C++98) didn't support including standard headers without
|
|
extensions.
|
|
|
|
This module defines the following cache variable:
|
|
|
|
``CMAKE_NO_ANSI_STREAM_HEADERS``
|
|
A cache variable containing the result of the check. It will be set to value
|
|
``0`` if the standard headers can be included without the ``.h`` extension
|
|
(``C++ 98`` and newer), and to value ``1`` if ``.h`` is required
|
|
(``ANSI C++``).
|
|
|
|
.. note::
|
|
|
|
The C++ standard headers without extensions got formally introduced in the
|
|
``C++ 98`` standard, making this issue obsolete.
|
|
|
|
Examples
|
|
^^^^^^^^
|
|
|
|
Including this module will check how the C++ standard headers can be included
|
|
and define the ``CMAKE_NO_ANSI_STREAM_HEADERS`` cache variable:
|
|
|
|
.. code-block:: cmake
|
|
|
|
include(TestForANSIStreamHeaders)
|
|
file(
|
|
CONFIGURE
|
|
OUTPUT config.h
|
|
CONTENT "#cmakedefine CMAKE_NO_ANSI_STREAM_HEADERS"
|
|
)
|
|
|
|
C++ program can then include the available header conditionally:
|
|
|
|
.. code-block:: c++
|
|
|
|
#include "config.h"
|
|
|
|
#ifdef CMAKE_NO_ANSI_STREAM_HEADERS
|
|
# include <iostream.h>
|
|
#else
|
|
# include <iostream>
|
|
#endif
|
|
|
|
int main() { ... }
|
|
#]=======================================================================]
|
|
|
|
include(${CMAKE_CURRENT_LIST_DIR}/CheckIncludeFileCXX.cmake)
|
|
|
|
if(NOT CMAKE_NO_ANSI_STREAM_HEADERS)
|
|
check_include_file_cxx(iostream CMAKE_ANSI_STREAM_HEADERS)
|
|
if (CMAKE_ANSI_STREAM_HEADERS)
|
|
set (CMAKE_NO_ANSI_STREAM_HEADERS 0 CACHE INTERNAL
|
|
"Does the compiler support headers like iostream.")
|
|
else ()
|
|
set (CMAKE_NO_ANSI_STREAM_HEADERS 1 CACHE INTERNAL
|
|
"Does the compiler support headers like iostream.")
|
|
endif ()
|
|
|
|
mark_as_advanced(CMAKE_NO_ANSI_STREAM_HEADERS)
|
|
endif()
|