CMake/Help/policy/CMP0193.rst

CMP0193
-------

.. versionadded:: 4.1

:module:`GNUInstallDirs` caches ``CMAKE_INSTALL_*`` with leading ``usr/`` for
install prefix ``/``.

When :variable:`CMAKE_INSTALL_PREFIX` is ``/``, the ``CMAKE_INSTALL_<dir>``
variables, for ``<dir>`` equal to ``BINDIR``, ``SBINDIR``, ``LIBEXECDIR``,
``SHAREDSTATEDIR``, ``INCLUDEDIR``, ``OLDINCLUDEDIR``, ``DATAROOTDIR``, and
``LIBDIR``, are prepended with a leading ``usr/`` as documented among the
:ref:`special cases <GNUInstallDirs special cases>`.
In CMake 4.0 and below, these ``CMAKE_INSTALL_<dir>`` variables were cached
without their leading ``usr/``, and it was prepended in normal variables that
shadow their cache entries.
CMake 4.1 and above prefer to cache ``CMAKE_INSTALL_<dir>`` with their leading
``usr/``.  Consequently, the :command:`GNUInstallDirs_get_absolute_install_dir`
command no longer alters the relative input variable argument ``<input-var>``.
This policy provides compatibility for projects that have not been updated to
expect the new behavior.

The ``OLD`` behavior for this policy is to cache ``CMAKE_INSTALL_<dir>``
variables without the leading ``usr/``.  The ``NEW`` behavior for this
policy is to cache ``CMAKE_INSTALL_<dir>`` variables with the leading ``usr/``.

.. |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