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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file LICENSE.rst or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
TestForSTDNamespace
-------------------
This module checks whether the ``CXX`` compiler supports the ``std`` namespace
for the C++ Standard Library.
Load this module in a CMake project with:
.. code-block:: cmake
include(TestForSTDNamespace)
Early versions of C++ (pre-C++98) did not have a requirement for a dedicated
namespace of C++ Standard Template Library (STL) components (e.g. ``list``,
etc.) and other parts of the C++ Standard Library (such as I/O streams
``cout``, ``endl``, etc), so they were available globally.
This module defines the following cache variable:
``CMAKE_NO_STD_NAMESPACE``
A cache variable containing the result of the check. It will be set to value
``0`` if the ``std`` namespace is supported (``C++ 98`` and newer), and to
value ``1`` if not (``ANSI C++``).
.. note::
The ``std`` namespace got formally introduced in ``C++ 98`` standard, making
this issue obsolete.
Examples
^^^^^^^^
Including this module will check for the ``std`` namespace support and define
the ``CMAKE_NO_STD_NAMESPACE`` cache variable:
.. code-block:: cmake
:caption: ``CMakeLists.txt``
include(TestForSTDNamespace)
file(
CONFIGURE
OUTPUT config.h
CONTENT "#cmakedefine CMAKE_NO_STD_NAMESPACE"
)
which can be then used in a C++ program to define the missing namespace:
.. code-block:: c++
:caption: ``example.cxx``
#include "config.h"
#ifdef CMAKE_NO_STD_NAMESPACE
# define std
#endif
See Also
^^^^^^^^
* The :module:`CMakeBackwardCompatibilityCXX` module.
#]=======================================================================]
if(NOT DEFINED CMAKE_STD_NAMESPACE)
message(CHECK_START "Check for STD namespace")
try_compile(CMAKE_STD_NAMESPACE
SOURCES ${CMAKE_ROOT}/Modules/TestForSTDNamespace.cxx
)
if (CMAKE_STD_NAMESPACE)
message(CHECK_PASS "found")
set (CMAKE_NO_STD_NAMESPACE 0 CACHE INTERNAL
"Does the compiler support std::.")
else ()
message(CHECK_FAIL "not found")
set (CMAKE_NO_STD_NAMESPACE 1 CACHE INTERNAL
"Does the compiler support std::.")
endif ()
endif()
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