GenEx: Fix TARGET_PROPERTY evaluation of transitive link properties

In commit bbba701899 (Link properties: must be transitive over private
dependency on static library, 2019-12-06, v3.17.0-rc1~323^2) and
commit af9d4f24ae (Link properties: must be transitive over private
dependency on static library, 2019-12-11, v3.17.0-rc1~305^2) we
neglected to implement CMP0099 NEW behavior for `TARGET_PROPERTY`
evaluation.  Add policy CMP0166 to fix this.

5 files changed, 68 insertions, 4 deletions

diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst
index 38fa6f9..31f0573 100644
--- a/Help/manual/cmake-generator-expressions.7.rst
+++ b/Help/manual/cmake-generator-expressions.7.rst
@@ -1282,7 +1282,7 @@ Compile Context
   .. versionadded:: 3.27
 
   Content of ``...``, when collecting
-  :ref:`usage requirements <Target Usage Requirements>`,
+  :ref:`transitive build properties <Transitive Build Properties>`,
   otherwise it is the empty string.  This is intended for use in an
   :prop_tgt:`INTERFACE_LINK_LIBRARIES` and :prop_tgt:`LINK_LIBRARIES` target
   properties, typically populated via the :command:`target_link_libraries` command.
@@ -1670,8 +1670,8 @@ Link Context
 
   .. versionadded:: 3.1
 
-  Content of ``...``, except while collecting
-  :ref:`usage requirements <Target Usage Requirements>`,
+  Content of ``...``, except while collecting usage requirements from
+  :ref:`transitive build properties <Transitive Build Properties>`,
   in which case it is the empty string.  This is intended for use in an
   :prop_tgt:`INTERFACE_LINK_LIBRARIES` target property, typically populated
   via the :command:`target_link_libraries` command, to specify private link
@@ -1788,7 +1788,16 @@ The expressions have special evaluation rules for some properties:
   of the value on the target itself with the values of the same properties on
   targets named by the target's :prop_tgt:`INTERFACE_LINK_LIBRARIES`.
   Evaluation is transitive over the closure of the target's
-  :prop_tgt:`INTERFACE_LINK_LIBRARIES`.
+  :prop_tgt:`INTERFACE_LINK_LIBRARIES`:
+
+  * For :ref:`Transitive Build Properties`, the transitive closure
+    *excludes* entries of :prop_tgt:`INTERFACE_LINK_LIBRARIES` guarded
+    by the :genex:`LINK_ONLY` generator expression.
+
+  * For :ref:`Transitive Link Properties`, the transitive closure is
+    *includes* entries of :prop_tgt:`INTERFACE_LINK_LIBRARIES` guarded
+    by the :genex:`LINK_ONLY` generator expression.
+    See policy :policy:`CMP0166`.
 
   Evaluation of :prop_tgt:`INTERFACE_LINK_LIBRARIES` itself is not transitive.
 
diff --git a/Help/manual/cmake-policies.7.rst b/Help/manual/cmake-policies.7.rst
index dd202a2..826790d 100644
--- a/Help/manual/cmake-policies.7.rst
+++ b/Help/manual/cmake-policies.7.rst
@@ -57,6 +57,7 @@ Policies Introduced by CMake 3.30
 .. toctree::
    :maxdepth: 1
 
+   CMP0166: TARGET_PROPERTY evaluates link properties transitively over private dependencies of static libraries. </policy/CMP0166>
    CMP0165: enable_language() must not be called before project(). </policy/CMP0165>
    CMP0164: add_library() rejects SHARED libraries when not supported by the platform. </policy/CMP0164>
    CMP0163: The GENERATED source file property is now visible in all directories. </policy/CMP0163>
diff --git a/Help/policy/CMP0099.rst b/Help/policy/CMP0099.rst
index e836cf3..0a2b786 100644
--- a/Help/policy/CMP0099.rst
+++ b/Help/policy/CMP0099.rst
@@ -21,6 +21,12 @@ The ``OLD`` behavior for this policy is to not propagate interface link
 properties. The ``NEW`` behavior of this policy is to propagate interface link
 properties.
 
+.. versionadded:: 3.30
+
+  Policy :policy:`CMP0166` makes :genex:`TARGET_PROPERTY` evaluation of
+  these three transitive link properties follow private dependencies of
+  static libraries too.
+
 .. |INTRODUCED_IN_CMAKE_VERSION| replace:: 3.17
 .. |WARNS_OR_DOES_NOT_WARN| replace:: does *not* warn
 .. include:: STANDARD_ADVICE.txt
diff --git a/Help/policy/CMP0166.rst b/Help/policy/CMP0166.rst
new file mode 100644
index 0000000..5c67880
--- /dev/null
+++ b/Help/policy/CMP0166.rst
@@ -0,0 +1,40 @@
+CMP0166
+-------
+
+.. versionadded:: 3.30
+
+:genex:`TARGET_PROPERTY` evaluates link properties transitively over private
+dependencies of static libraries.
+
+In CMake 3.29 and below, the :genex:`TARGET_PROPERTY` generator expression
+evaluates properties :prop_tgt:`INTERFACE_LINK_OPTIONS`,
+:prop_tgt:`INTERFACE_LINK_DIRECTORIES`, and :prop_tgt:`INTERFACE_LINK_DEPENDS`
+as if they were :ref:`Transitive Build Properties` rather than
+:ref:`Transitive Link Properties`, even when policy :policy:`CMP0099` is
+set to ``NEW``.  Private dependencies of static libraries, which appear in
+their :prop_tgt:`INTERFACE_LINK_LIBRARIES` guarded by :genex:`LINK_ONLY`
+generator expressions, are not followed.  This is inconsistent with
+evaluation of the same target properties during buildsystem generation.
+
+CMake 3.30 and above prefer that :genex:`TARGET_PROPERTY` evaluates
+properties :prop_tgt:`INTERFACE_LINK_OPTIONS`,
+:prop_tgt:`INTERFACE_LINK_DIRECTORIES`, and :prop_tgt:`INTERFACE_LINK_DEPENDS`
+as :ref:`Transitive Link Properties` such that private dependencies of static
+libraries, which appear in their :prop_tgt:`INTERFACE_LINK_LIBRARIES` guarded
+by :genex:`LINK_ONLY` generator expressions, are followed.
+This policy provides compatibility for projects that have not been updated
+to expect the new behavior.
+
+The ``OLD`` behavior for this policy is for :genex:`TARGET_PROPERTY` to
+evaluate properties :prop_tgt:`INTERFACE_LINK_OPTIONS`,
+:prop_tgt:`INTERFACE_LINK_DIRECTORIES`, and :prop_tgt:`INTERFACE_LINK_DEPENDS`
+as if they were :ref:`Transitive Build Properties` by not following private
+dependencies of static libraries.  The ``NEW`` behavior for this policy is
+to evaluate them as :ref:`Transitive Link Properties` by following private
+dependencies of static libraries.
+
+.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 3.30
+.. |WARNS_OR_DOES_NOT_WARN| replace:: does *not* warn
+.. include:: STANDARD_ADVICE.txt
+
+.. include:: DEPRECATED.txt
diff --git a/Help/release/dev/genex-link-properties.rst b/Help/release/dev/genex-link-properties.rst
new file mode 100644
index 0000000..e1e84e0
--- /dev/null
+++ b/Help/release/dev/genex-link-properties.rst
@@ -0,0 +1,8 @@
+genex-link-properties
+---------------------
+
+* The :genex:`TARGET_PROPERTY` generator expression now evaluates target
+  properties :prop_tgt:`INTERFACE_LINK_OPTIONS`,
+  :prop_tgt:`INTERFACE_LINK_DIRECTORIES`, and
+  :prop_tgt:`INTERFACE_LINK_DEPENDS` correctly by following private
+  dependencies of static libraries.  See policy :policy:`CMP0166`.