| CMAKE_<LANG>_EXTENSIONS_DEFAULT | |
| ------------------------------- | |
| .. versionadded:: 3.22 | |
| Compiler's default extensions mode. Used as the default for the | |
| :prop_tgt:`<LANG>_EXTENSIONS` target property when | |
| :variable:`CMAKE_<LANG>_EXTENSIONS` is not set (see :policy:`CMP0128`). | |
| This variable is read-only. Modifying it is undefined behavior. |