Add policy CMP0068 separate install_name and RPATH settings on macOS

BUILD_WITH_INSTALL_RPATH, SKIP_BUILD_RPATH, CMAKE_SKIP_RPATH and
CMAKE_SKIP_INSTALL_RPATH no longer any effect on the install name
of a target on macOS.

Fixes: #16589

1 files changed, 35 insertions, 0 deletions

diff --git a/Help/policy/CMP0068.rst b/Help/policy/CMP0068.rst
new file mode 100644
index 0000000..978a6e3
--- /dev/null
+++ b/Help/policy/CMP0068.rst
@@ -0,0 +1,35 @@
+CMP0068
+-------
+
+``RPATH`` settings on macOS do not affect ``install_name``.
+
+CMake 3.9 and newer remove any effect the following settings may have on the
+``install_name`` of a target on macOS:
+
+* :prop_tgt:`BUILD_WITH_INSTALL_RPATH` target property
+* :prop_tgt:`SKIP_BUILD_RPATH` target property
+* :variable:`CMAKE_SKIP_RPATH` variable
+* :variable:`CMAKE_SKIP_INSTALL_RPATH` variable
+
+Previously, setting :prop_tgt:`BUILD_WITH_INSTALL_RPATH` had the effect of
+setting both the ``install_name`` of a target to :prop_tgt:`INSTALL_NAME_DIR`
+and the ``RPATH`` to :prop_tgt:`INSTALL_RPATH`.  In CMake 3.9, it only affects
+setting of ``RPATH``.  However, if one wants :prop_tgt:`INSTALL_NAME_DIR` to
+apply to the target in the build tree, one may set
+:prop_tgt:`BUILD_WITH_INSTALL_NAME_DIR`.
+
+If :prop_tgt:`SKIP_BUILD_RPATH`, :variable:`CMAKE_SKIP_RPATH` or
+:variable:`CMAKE_SKIP_INSTALL_RPATH` were used to strip the directory portion
+of the ``install_name`` of a target, one may set ``INSTALL_NAME_DIR=""``
+instead.
+
+The ``OLD`` behavior of this policy is to use the ``RPATH`` settings for
+``install_name`` on macOS.  The ``NEW`` behavior of this policy is to ignore
+the ``RPATH`` settings for ``install_name`` on macOS.
+
+This policy was introduced in CMake version 3.9.  CMake version
+|release| warns when the policy is not set and uses ``OLD`` behavior.
+Use the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW``
+explicitly.
+
+.. include:: DEPRECATED.txt