CXX_STANDARD_REQUIRED

.. versionadded:: 3.1

Boolean describing whether the value of :prop_tgt:CXX_STANDARD is a requirement.

If this property is set to ON, then the value of the :prop_tgt:CXX_STANDARD target property is treated as a requirement. If this property is OFF or unset, the :prop_tgt:CXX_STANDARD target property is treated as optional and may "decay" to a previous standard if the requested is not available. For compilers that have no notion of a standard level, such as MSVC 1800 (Visual Studio 2013) and lower, this has no effect.

See the :manual:cmake-compile-features(7) manual for information on compile features and a list of supported compilers.

This property is initialized by the value of the :variable:CMAKE_CXX_STANDARD_REQUIRED variable if it is set when a target is created.

Alternatively, see :ref:Requiring Language Standards.