| CMAKE_CROSSCOMPILING |
| -------------------- |
| |
| Intended to indicate whether CMake is cross compiling, but note limitations |
| discussed below. |
| |
| This variable will be set to true by CMake if the :variable:`CMAKE_SYSTEM_NAME` |
| variable has been set manually (i.e. in a toolchain file or as a cache entry |
| from the :manual:`cmake <cmake(1)>` command line). In most cases, manually |
| setting :variable:`CMAKE_SYSTEM_NAME` will only be done when cross compiling, |
| since it will otherwise be given the same value as |
| :variable:`CMAKE_HOST_SYSTEM_NAME` if not manually set, which is correct for |
| the non-cross-compiling case. In the event that :variable:`CMAKE_SYSTEM_NAME` |
| is manually set to the same value as :variable:`CMAKE_HOST_SYSTEM_NAME`, then |
| ``CMAKE_CROSSCOMPILING`` will still be set to true. |
| |
| Another case to be aware of is that builds targeting Apple platforms other than |
| macOS are handled differently to other cross compiling scenarios. Rather than |
| relying on :variable:`CMAKE_SYSTEM_NAME` to select the target platform, Apple |
| device builds use :variable:`CMAKE_OSX_SYSROOT` to select the appropriate SDK, |
| which indirectly determines the target platform. Furthermore, when using the |
| :generator:`Xcode` generator, developers can switch between device and |
| simulator builds at build time rather than having a single |
| choice at configure time, so the concept |
| of whether the build is cross compiling or not is more complex. Therefore, the |
| use of ``CMAKE_CROSSCOMPILING`` is not recommended for projects targeting Apple |
| devices. |
