CMake/Help/prop_tgt/C_STANDARD.rst
Stephen Kelly 60a981ea8e Features: Enable compiler extensions by default.
Compilers enable their extensions by default, and disabling them
implicitly can lead to results which are surprising or non-obvious
to debug.

 http://public.kitware.com/pipermail/cmake-developers/2014-May/010575.html
 http://thread.gmane.org/gmane.comp.programming.tools.cmake.devel/10214
 https://www.mail-archive.com/cmake-developers@cmake.org/msg10116.html
 (Compiler feature extensions by default, 29 May 2014)
2014-05-31 12:16:12 +02:00

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C_STANDARD
----------
The C standard whose features are requested to build this target.
This property specifies the C standard whose features are requested
to build this target. For some compilers, this results in adding a
flag such as ``-std=gnu11`` to the compile line.
Supported values are ``90``, ``99`` and ``11``.
If the value requested does not result in a compile flag being added for
the compiler in use, a previous standard flag will be added instead. This
means that using:
.. code-block:: cmake
set_property(TARGET tgt PROPERTY C_STANDARD 11)
with a compiler which does not support ``-std=gnu11`` or an equivalent
flag will not result in an error or warning, but will instead add the
``-std=gnu99`` or ``-std=gnu90`` flag if supported. This "decay" behavior may
be controlled with the :prop_tgt:`C_STANDARD_REQUIRED` target property.
See the :manual:`cmake-compile-features(7)` manual for information on
compile features.
This property is initialized by the value of
the :variable:`CMAKE_C_STANDARD` variable if it is set when a target
is created.