Add usage requirements to update direct link dependencies

Link line construction starts with `LINK_LIBRARIES` and appends
dependencies from the transitive closure of `INTERFACE_LINK_LIBRARIES`.
Only the entries of `LINK_LIBRARIES` are considered direct link
dependencies.  In some advanced use cases, particularly involving static
libraries and static plugins, usage requirements need to update the list
of direct link dependencies.  This may mean adding new items, removing
existing items, or both.

Add target properties to encode these usage requirements:

* INTERFACE_LINK_LIBRARIES_DIRECT
* INTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE

Fixes: #22496

1 files changed, 16 insertions, 0 deletions

diff --git a/Tests/InterfaceLinkLibrariesDirect/static_A_private.c b/Tests/InterfaceLinkLibrariesDirect/static_A_private.c
new file mode 100644
index 0000000..d98a22c
--- /dev/null
+++ b/Tests/InterfaceLinkLibrariesDirect/static_A_private.c
@@ -0,0 +1,16 @@
+#ifndef DEF_DIRECT_FROM_A
+#  error "DEF_DIRECT_FROM_A incorrectly not defined"
+#endif
+#ifdef DEF_DIRECT_FROM_A_FOR_EXE
+#  error "DEF_DIRECT_FROM_A_FOR_EXE incorrectly defined"
+#endif
+#ifndef DEF_DIRECT_FROM_A_OPTIONAL
+#  error "DEF_DIRECT_FROM_A_OPTIONAL incorrectly not defined"
+#endif
+
+extern void a_always(void);
+
+void static_A_private(void)
+{
+  a_always();
+}