New in version 3.1.

Generator-specific target platform specification provided by user.

Some CMake generators support a target platform name to be given to the native build system to choose a compiler toolchain. If the user specifies a platform name (e.g. via the cmake(1) -A option or via the CMAKE_GENERATOR_PLATFORM environment variable) the value will be available in this variable.

The value of this variable should never be modified by project code. A toolchain file specified by the CMAKE_TOOLCHAIN_FILE variable may initialize CMAKE_GENERATOR_PLATFORM. Once a given build tree has been initialized with a particular value for this variable, changing the value has undefined behavior.

Platform specification is supported only on specific generators:

See native build system documentation for allowed platform names.

Visual Studio Platform Selection

On Visual Studio Generators the selected platform name is provided in the CMAKE_VS_PLATFORM_NAME variable.