| The value of this variable should be set prior to the first |
| :command:`project` or :command:`enable_language` command invocation |
| because it may influence configuration of the toolchain and flags. |
| It is intended to be set locally by the user creating a build tree. |
| This variable should be set as a ``CACHE`` entry (or else CMake may |
| remove it while initializing a cache entry of the same name). |
| |
| Despite the ``OSX`` part in the variable name(s) they apply also to |
| other SDKs than macOS like iOS, tvOS, or watchOS. |
| |
| This variable is ignored on platforms other than Apple. |
