Merge topic 'genex-LINK_LIBRARY-to-decorate-library'

2a6b0415d7 $<LINK_LIBRARY>: Add LINK_LIBRARY_OVERRIDE target property
42965799b4 Genex: Add $<LINK_LIBRARY:...>
78dd7d5292 cmRulePlaceholderExpander: add base class for placeholder expansion reuse
4b55828a9f cmExpandListWithBacktrace: add handling of empty elements.
28d7432468 cmComputeLinkInformation: use cmComputeLinkDepends::LinkEntry

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6769

2 files changed, 99 insertions, 0 deletions

diff --git a/Help/prop_tgt/LINK_LIBRARY_OVERRIDE.rst b/Help/prop_tgt/LINK_LIBRARY_OVERRIDE.rst
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+++ b/Help/prop_tgt/LINK_LIBRARY_OVERRIDE.rst
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+LINK_LIBRARY_OVERRIDE
+---------------------
+
+.. versionadded:: 3.24
+
+To resolve incompatible features introduced by :genex:`LINK_LIBRARY` generator
+expression, this property offers the possibility to override, per ``link-item``
+(``CMake`` target or external library) involved in the link step, any defined
+features with a new one.
+
+This property takes a :ref:`;-list <CMake Language Lists>` of override
+declarations which have the following format:
+
+::
+
+  feature[,link-item]*
+
+For the list of ``link-item`` (``CMake`` target or external library) specified,
+the feature ``feature`` will be used in place of any declared feature. For
+example:
+
+.. code-block:: cmake
+
+  add_library(lib1 ...)
+  target_link_libraries(lib1 PUBLIC $<LINK_LIBRARY:feature1,external>)
+
+  add_library(lib2 ...)
+  target_link_libraries(lib2 PUBLIC $<LINK_LIBRARY:feature2,lib1>)
+
+  add_library(lib3 ...)
+  target_link_libraries(lib3 PRIVATE lib1 lib2)
+  # Here, lib1 has two different features which prevents to link lib3
+  # So, define LINK_LIBRARY_OVERRIDE property to ensure correct link
+  set_property(TARGET lib3 PROPERTY LINK_LIBRARY_OVERRIDE "feature2,lib1,external")
+  # The lib1 and external will be used with FEATURE2 to link lib3
+
+It is also possible to override any feature with the pre-defined feature
+``DEFAULT`` to get the standard behavior (i.e. no feature):
+
+.. code-block:: cmake
+
+  set_property(TARGET lib3 PROPERTY LINK_LIBRARY_OVERRIDE "DEFAULT,lib1"
+                                                          "feature2,external")
+  # The lib1 will be used without any feature and external will use feature2 to link lib3
+
+Contents of ``LINK_LIBRARY_OVERRIDE`` may use
+:manual:`generator expressions <cmake-generator-expressions(7)>`.
+
+See also :prop_tgt:`LINK_LIBRARY_OVERRIDE_<LIBRARY>` target property for
+a per linked target oriented approach to override features.
+
+For more information about features, see
+:variable:`CMAKE_<LANG>_LINK_USING_<FEATURE>`
+and :variable:`CMAKE_LINK_USING_<FEATURE>` variables.
diff --git a/Help/prop_tgt/LINK_LIBRARY_OVERRIDE_LIBRARY.rst b/Help/prop_tgt/LINK_LIBRARY_OVERRIDE_LIBRARY.rst
new file mode 100644
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+LINK_LIBRARY_OVERRIDE_<LIBRARY>
+-------------------------------
+
+.. versionadded:: 3.24
+
+To resolve incompatible features introduced by :genex:`LINK_LIBRARY` generator
+expression, this property offers the possibility to override, for a
+``link-item`` (``CMake`` target or external library) involved in the link step,
+any defined features with a new one.
+
+This property takes a ``feature`` name which will be applied to the
+``link-item`` specified by ``<LIBRARY>`` suffix property. For example:
+
+.. code-block:: cmake
+
+  add_library(lib1 ...)
+  target_link_libraries(lib1 PUBLIC $<LINK_LIBRARY:feature1,external>)
+
+  add_library(lib2 ...)
+  target_link_libraries(lib2 PUBLIC $<LINK_LIBRARY:feature2,lib1>)
+
+  add_library(lib3 ...)
+  target_link_libraries(lib3 PRIVATE lib1 lib2)
+  # Here, lib1 has two different features which prevents to link lib3
+  # So, define LINK_LIBRARY_OVERRIDE_lib1 property to ensure correct link
+  set_property(TARGET lib3 PROPERTY LINK_LIBRARY_OVERRIDE_lib1 feature2)
+  # The lib1 will be used with feature2 to link lib3
+
+It is also possible to override any feature with the pre-defined feature
+``DEFAULT`` to get the standard behavior (i.e. no feature):
+
+.. code-block:: cmake
+
+  set_property(TARGET lib3 PROPERTY LINK_LIBRARY_OVERRIDE_lib1 DEFAULT)
+  # The lib1 will be used without any feature to link lib3
+
+Contents of ``LINK_LIBRARY_OVERRIDE_<LIBRARY>`` may use
+:manual:`generator expressions <cmake-generator-expressions(7)>`.
+
+This property takes precedence over :prop_tgt:`LINK_LIBRARY_OVERRIDE`
+target property.
+
+For more information about features, see
+:variable:`CMAKE_<LANG>_LINK_USING_<FEATURE>`
+and :variable:`CMAKE_LINK_USING_<FEATURE>` variables.