1CMAKE_<LANG>_EXTENSIONS_DEFAULT 2------------------------------- 3 4.. versionadded:: 3.22 5 6Compiler's default extensions mode. Used as the default for the 7:prop_tgt:`<LANG>_EXTENSIONS` target property when 8:variable:`CMAKE_<LANG>_EXTENSIONS` is not set (see :policy:`CMP0128`). 9 10This variable is read-only. Modifying it is undefined behavior. 11