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TestForSSTREAM: Update documentation

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This describes the module in more details to make upgrading code easier.

Additionally, also the CMAKE_HAS_ANSI_STRING_STREAM cache variable is
described as it was already briefly documented at the
CMakeBackwardCompatibilityCXX module.
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Peter Kokot 2025-03-11 15:18:47 +01:00
parent 582cbc541d
commit c2eb4b58c0
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Modules/TestForSSTREAM.cmake
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@ -5,13 +5,52 @@
TestForSSTREAM
--------------
Test for compiler support of ANSI sstream header
This module checks whether the C++ standard header ``<sstream>`` exists and
functions correctly. In early versions of C++ (pre-C++98), this header was not
formally standardized and may not have been available.
check if the compiler supports the standard ANSI sstream header
This module defines the following cache variables:
::
``CMAKE_NO_ANSI_STRING_STREAM``
A cache variable indicating whether the ``<sstream>`` header is available. It
will be set to value ``0`` if ``<sstream>`` is available (``C++ 98`` and
newer), and to value ``1`` if ``<sstream>`` is missing (``ANSI C++``).
CMAKE_NO_ANSI_STRING_STREAM - defined by the results
``CMAKE_HAS_ANSI_STRING_STREAM``
A cache variable that is the opposite of ``CMAKE_NO_ANSI_STRING_STREAM``
(true if ``<sstream>`` is available and false if ``<sstream>`` is missing).
.. note::
The ``<sstream>`` header was formally introduced in the ``C++ 98`` standard,
making this check obsolete for modern compilers.
Examples
^^^^^^^^
Including this module will check for ``<sstream>`` support and define the
``CMAKE_NO_ANSI_STRING_STREAM`` cache variable:
.. code-block:: cmake
include(TestForSSTREAM)
file(
CONFIGURE
OUTPUT config.h
CONTENT "#cmakedefine CMAKE_NO_ANSI_STRING_STREAM"
)
Then it can be used in a C++ program:
.. code-block:: c++
#include "config.h"
#ifndef CMAKE_NO_ANSI_STRING_STREAM
# include <sstream>
#endif
int main() { ... }
#]=======================================================================]
if(NOT DEFINED CMAKE_HAS_ANSI_STRING_STREAM)