Boolean specifying whether compiler specific extensions are requested.
This property specifies whether compiler specific extensions should be used. For some compilers, this results in adding a flag such as -std=gnu++11 instead of -std=c++11 to the compile line. This property is ON by default.
See the cmake-compile-features(7) manual for information on compile features.
This property is initialized by the value of the CMAKE_CXX_EXTENSIONS variable if it is set when a target is created.