CMake/Help/policy/CMP0192.rst

CMP0192
-------

.. versionadded:: 4.1

:module:`GNUInstallDirs` uses absolute ``SYSCONFDIR``, ``LOCALSTATEDIR``,
and ``RUNSTATEDIR`` in special prefixes.

The :module:`GNUInstallDirs` module documents
:ref:`special cases <GNUInstallDirs special cases>`
for ``SYSCONFDIR``, ``LOCALSTATEDIR``, and ``RUNSTATEDIR``.
When :variable:`CMAKE_INSTALL_PREFIX` is a special prefix, e.g., ``/usr``,
the absolute paths for these directories may be outside the prefix, e.g.,
``/etc``, ``/var``, and ``/var/run``.

In CMake 4.0 and below, the default values for the ``CMAKE_INSTALL_<dir>``
variables, for ``<dir>`` equal to ``SYSCONFDIR``, ``LOCALSTATEDIR``, and
``RUNSTATEDIR``, always used relative paths (``etc``, ``var``, ``var/run``),
and the special cases were implemented only when computing absolute paths
for the ``CMAKE_INSTALL_FULL_<dir>`` variables.
CMake 4.1 and above prefer to default ``CMAKE_INSTALL_<dir>`` variables to
absolute paths, for ``<dir>`` equal to ``SYSCONFDIR``, ``LOCALSTATEDIR``,
and ``RUNSTATEDIR``, when :variable:`CMAKE_INSTALL_PREFIX` is a special
prefix.  This policy provides compatibility for projects that have not
been updated to expect this behavior.

The ``OLD`` behavior for this policy is to default ``CMAKE_INSTALL_<dir>``
variables to relative paths.  The ``NEW`` behavior for this policy is to
default ``CMAKE_INSTALL_<dir>`` variables to absolute paths, for ``<dir>``
equal to ``SYSCONFDIR``, ``LOCALSTATEDIR``, and ``RUNSTATEDIR``, when
:variable:`CMAKE_INSTALL_PREFIX` is a special prefix.

This policy takes effect at the first call of ``include(GNUInstallDirs)``.
Subsequent calls of ``include(GNUInstallDirs)`` reuse cached
``CMAKE_INSTALL_<dir>`` values from the first call.

.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 4.1
.. |WARNS_OR_DOES_NOT_WARN| replace:: does *not* warn
.. include:: include/STANDARD_ADVICE.rst

.. include:: include/DEPRECATED.rst