Genex: Memoize usage requirement TARGET_PROPERTY existence

For each usage requirement (such as `INTERFACE_COMPILE_DEFINITIONS` or
`INTERFACE_INCLUDE_DIRECTORIES`), the value of the generator expression
`$<TARGET_PROPERTY:target,prop>` includes the values of the same
property from the transitive closure of link libraries of the target.

In cases that a target's transitive closure of dependencies does not
depend on the target being linked (the "head" target), we can memoize
whether or not a usage requirement property exists at all for that
target.  When a usage requirement does not exist for a target, we
can skip evaluating it for every consuming target.

Fixes: #18964, #18965

1 files changed, 5 insertions, 0 deletions

diff --git a/Source/cmGeneratorTarget.h b/Source/cmGeneratorTarget.h
index b875c40..3874738 100644
--- a/Source/cmGeneratorTarget.h
+++ b/Source/cmGeneratorTarget.h
@@ -14,6 +14,7 @@
 #include <set>
 #include <stddef.h>
 #include <string>
+#include <unordered_map>
 #include <utility>
 #include <vector>
 
@@ -856,6 +857,10 @@ private:
   mutable std::vector<AllConfigSource> AllConfigSources;
   void ComputeAllConfigSources() const;
 
+  mutable std::unordered_map<std::string, bool> MaybeInterfacePropertyExists;
+  bool MaybeHaveInterfaceProperty(std::string const& prop,
+                                  cmGeneratorExpressionContext* context) const;
+
   std::vector<TargetPropertyEntry*> IncludeDirectoriesEntries;
   std::vector<TargetPropertyEntry*> CompileOptionsEntries;
   std::vector<TargetPropertyEntry*> CompileFeaturesEntries;