CMP0089
-------

.. versionadded:: 3.15

Compiler id for IBM Clang-based XL compilers is now ``XLClang``.

CMake 3.15 and above recognize that IBM's Clang-based XL compilers
that define ``__ibmxl__`` are a new front-end distinct from ``xlc``
with a different command line and set of capabilities.
CMake now prefers to present this to projects by setting the
:variable:`CMAKE_<LANG>_COMPILER_ID` variable to ``XLClang`` instead
of ``XL``.  However, existing projects may assume the compiler id for
Clang-based XL is just ``XL`` as it was in CMake versions prior to 3.15.
Therefore this policy determines for Clang-based XL compilers 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 ``XL``.  The
``NEW`` behavior for this policy is to use compiler id ``XLClang``.

.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 3.15
.. |WARNS_OR_DOES_NOT_WARN| replace:: does *not* warn by default
.. include:: include/STANDARD_ADVICE.rst

See documentation of the
:variable:`CMAKE_POLICY_WARNING_CMP0089 <CMAKE_POLICY_WARNING_CMP<NNNN>>`
variable to control the warning.

.. include:: include/DEPRECATED.rst
