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26dd965037
This is mainly a sync with other CMake modules for consistency: - Added intro code blocks showing how to include the modules. - Adjusted examples sections. - Added "See Also" sections.
82 lines
2.3 KiB
CMake
82 lines
2.3 KiB
CMake
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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# file LICENSE.rst or https://cmake.org/licensing for details.
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#[=======================================================================[.rst:
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TestForSTDNamespace
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-------------------
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This module checks whether the ``CXX`` compiler supports the ``std`` namespace
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for the C++ Standard Library.
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Load this module in a CMake project with:
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.. code-block:: cmake
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include(TestForSTDNamespace)
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Early versions of C++ (pre-C++98) did not have a requirement for a dedicated
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namespace of C++ Standard Template Library (STL) components (e.g. ``list``,
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etc.) and other parts of the C++ Standard Library (such as I/O streams
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``cout``, ``endl``, etc), so they were available globally.
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This module defines the following cache variable:
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``CMAKE_NO_STD_NAMESPACE``
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A cache variable containing the result of the check. It will be set to value
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``0`` if the ``std`` namespace is supported (``C++ 98`` and newer), and to
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value ``1`` if not (``ANSI C++``).
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.. note::
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The ``std`` namespace got formally introduced in ``C++ 98`` standard, making
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this issue obsolete.
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Examples
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^^^^^^^^
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Including this module will check for the ``std`` namespace support and define
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the ``CMAKE_NO_STD_NAMESPACE`` cache variable:
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.. code-block:: cmake
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:caption: ``CMakeLists.txt``
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include(TestForSTDNamespace)
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file(
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CONFIGURE
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OUTPUT config.h
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CONTENT "#cmakedefine CMAKE_NO_STD_NAMESPACE"
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)
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which can be then used in a C++ program to define the missing namespace:
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.. code-block:: c++
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:caption: ``example.cxx``
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#include "config.h"
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#ifdef CMAKE_NO_STD_NAMESPACE
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# define std
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#endif
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See Also
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^^^^^^^^
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* The :module:`CMakeBackwardCompatibilityCXX` module.
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#]=======================================================================]
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if(NOT DEFINED CMAKE_STD_NAMESPACE)
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message(CHECK_START "Check for STD namespace")
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try_compile(CMAKE_STD_NAMESPACE
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SOURCES ${CMAKE_ROOT}/Modules/TestForSTDNamespace.cxx
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)
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if (CMAKE_STD_NAMESPACE)
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message(CHECK_PASS "found")
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set (CMAKE_NO_STD_NAMESPACE 0 CACHE INTERNAL
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"Does the compiler support std::.")
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else ()
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message(CHECK_FAIL "not found")
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set (CMAKE_NO_STD_NAMESPACE 1 CACHE INTERNAL
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"Does the compiler support std::.")
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endif ()
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endif()
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