Do not produce legacy _LIB_DEPENDS cache entries

Introduce policy `CMP0073` to avoid producing these cache entries.

Fixes: #16364

1 files changed, 25 insertions, 0 deletions

diff --git a/Help/policy/CMP0073.rst b/Help/policy/CMP0073.rst
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+CMP0073
+-------
+
+Do not produce legacy ``_LIB_DEPENDS`` cache entries.
+
+Ancient CMake versions once used ``<tgt>_LIB_DEPENDS`` cache entries to
+propagate library link dependencies.  This has long been done by other
+means, leaving the :command:`export_library_dependencies` command as the
+only user of these values.  That command has long been disallowed by
+policy :policy:`CMP0033`, but the ``<tgt>_LIB_DEPENDS`` cache entries
+were left for compatibility with possible non-standard uses by projects.
+
+CMake 3.12 and above now prefer to not produce these cache entries
+at all.  This policy provides compatibility with projects that have
+not been updated to avoid using them.
+
+The ``OLD`` behavior for this policy is to set ``<tgt>_LIB_DEPENDS`` cache
+entries.  The ``NEW`` behavior for this policy is to not set them.
+
+This policy was introduced in CMake version 3.12.  Use the
+:command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
+Unlike most policies, CMake version |release| does *not* warn
+when this policy is not set and simply uses ``OLD`` behavior.
+
+.. include:: DEPRECATED.txt