CMAKE_GENERATOR_TOOLSET
-----------------------

Native build system toolset specification provided by user.

Some CMake generators support a toolset specification to tell the
native build system how to choose a compiler.  If the user specifies
a toolset (e.g. via the :manual:`cmake(1)` ``-T`` option or via
the :envvar:`CMAKE_GENERATOR_TOOLSET` 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 :variable:`CMAKE_TOOLCHAIN_FILE`
variable may initialize ``CMAKE_GENERATOR_TOOLSET``.  Once a given
build tree has been initialized with a particular value for this
variable, changing the value has undefined behavior.

Toolset specification is supported only on specific generators:

* :ref:`Visual Studio Generators` for VS 2010 and above
* The :generator:`Xcode` generator for Xcode 3.0 and above
* The :generator:`Green Hills MULTI` generator

See native build system documentation for allowed toolset names.

Visual Studio Toolset Selection
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The :ref:`Visual Studio Generators` support toolset specification
using one of these forms:

* ``toolset``
* ``toolset[,key=value]*``
* ``key=value[,key=value]*``

The ``toolset`` specifies the toolset name.  The selected toolset name
is provided in the :variable:`CMAKE_VS_PLATFORM_TOOLSET` variable.

The ``key=value`` pairs form a comma-separated list of options to
specify generator-specific details of the toolset selection.
Supported pairs are:

``cuda=<version>``
  Specify the CUDA toolkit version to use.  Supported by VS 2010
  and above with the CUDA toolkit VS integration installed.
  See the :variable:`CMAKE_VS_PLATFORM_TOOLSET_CUDA` variable.

``host=<arch>``
  Specify the host tools architecture as ``x64`` or ``x86``.
  Supported by VS 2013 and above.
  See the :variable:`CMAKE_VS_PLATFORM_TOOLSET_HOST_ARCHITECTURE`
  variable.

``version=<version>``
  Specify the toolset version to use.  Supported by VS 2017
  and above with the specified toolset installed.
  See the :variable:`CMAKE_VS_PLATFORM_TOOLSET_VERSION` variable.