OS X: Add CMP0042 to enable MACOSX_RPATH by default

Also adding documentation for CMAKE_MACOSX_RPATH, and improving
documentation for MACOSX_RPATH.

1 files changed, 19 insertions, 0 deletions

diff --git a/Help/policy/CMP0042.rst b/Help/policy/CMP0042.rst
new file mode 100644
index 0000000..0ed3bd1
--- /dev/null
+++ b/Help/policy/CMP0042.rst
@@ -0,0 +1,19 @@
+CMP0042
+-------
+
+:prop_tgt:`MACOSX_RPATH` is enabled by default.
+
+CMake 2.8.12 and newer has support for using ``@rpath`` in a target's install
+name.  This was enabled by setting the target property
+:prop_tgt:`MACOSX_RPATH`.  The ``@rpath`` in an install name is a more
+flexible and powerful mechanism than ``@executable_path`` or ``@loader_path``
+for locating shared libraries.
+
+CMake 3.0.0 and later prefer this property to be ON by default.  Projects
+wanting ``@rpath`` in a target's install name may remove any setting of
+the :prop_tgt:`INSTALL_NAME_DIR` and :variable:`CMAKE_INSTALL_NAME_DIR`
+variables.
+
+This policy was introduced in CMake version 3.0.0.  CMake version
+|release| warns when the policy is not set and uses OLD behavior.  Use
+the cmake_policy command to set it to OLD or NEW explicitly.