CMake/Help/prop_tgt/CXX_STANDARD.rst
Brad King 3228fc5049 Features: Define meaning for no language standard default
Define an empty string in CMAKE_<LANG>_STANDARD_DEFAULT to mean that
the toolchain has no notion of lanuage standard levels.  In this case
the <LANG>_STANDARD[_REQUIRED] properties will have no effect.

Update the RunCMake.CompileFeatures test to exclude the
LinkImplementationFeatureCycle test when there is no standard default.
It can never fail because no use of specific features will adjust the
CXX_STANDARD level required for any target since the standard levels
have no meaning in this case.
2015-01-29 15:01:40 -05:00

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CXX_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=gnu++11`` to the compile line. For compilers that
have no notion of a standard level, such as MSVC, this has no effect.
Supported values are ``98``, ``11`` and ``14``.
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 CXX_STANDARD 11)
with a compiler which does not support ``-std=gnu++11`` or an equivalent
flag will not result in an error or warning, but will instead add the
``-std=gnu++98`` flag if supported. This "decay" behavior may be controlled
with the :prop_tgt:`CXX_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_CXX_STANDARD` variable if it is set when a target
is created.