CMake/Help/policy/CMP0129.rst

CMP0129
-------

.. versionadded:: 3.23

Compiler id for MCST LCC compilers is now ``LCC``, not ``GNU``.

CMake 3.23 and above recognize MCST LCC compiler as a different from ``GNU``,
with its own command line and set of capabilities.
CMake now prefers to present this to projects by setting the
:variable:`CMAKE_<LANG>_COMPILER_ID` variable to ``LCC`` instead
of ``GNU``. However, existing projects may assume the compiler id for
LCC is ``GNU`` as it was in CMake versions prior to 3.23.
Therefore this policy determines for MCST LCC compiler which
compiler id to report in the :variable:`CMAKE_<LANG>_COMPILER_ID`
variable after language ``<LANG>`` is enabled by the :command:`project`
or :command:`enable_language` command.  The policy must be set prior
to the invocation of either command.

The ``OLD`` behavior for this policy is to use compiler id ``GNU`` (and set
:variable:`CMAKE_<LANG>_COMPILER_VERSION` to the supported GNU compiler version.)
``NEW`` behavior for this policy is to use compiler id ``LCC``, and set
:variable:`CMAKE_<LANG>_SIMULATE_ID` to ``GNU``, and
:variable:`CMAKE_<LANG>_SIMULATE_VERSION` to the supported GNU compiler version.

This policy was introduced in CMake version 3.23.  Use the
:command:`cmake_policy` command to set this policy to ``OLD`` or ``NEW`` explicitly.
Unlike most policies, CMake version |release| does *not* warn
by default when this policy is not set and simply uses ``OLD`` behavior.
See documentation of the
:variable:`CMAKE_POLICY_WARNING_CMP0129 <CMAKE_POLICY_WARNING_CMP<NNNN>>`
variable to control the warning.

.. include:: DEPRECATED.txt