Autogen: Clear sources meta data cache

Adds cmGeneratorTarget::clearSourcesCache() which clears the cache
of precomputed sources lists and object names. The cache gets
recomputed on demand.

Clearing the cache is necessary in case an OBJECT library
gets a source added after a target (ORIGIN) that includes it
computed it's external sources cache.
This may happen in AUTOMOC when ORIGIN is processed before the
OBJECT library which gets a mocs_compilation.cpp file added.

Closes #17152
Closes #17139
Closes #17085
Closes #15967

1 files changed, 6 insertions, 0 deletions

diff --git a/Source/cmQtAutoGeneratorInitializer.cxx b/Source/cmQtAutoGeneratorInitializer.cxx
index 5a06730..2cf2ee9 100644
--- a/Source/cmQtAutoGeneratorInitializer.cxx
+++ b/Source/cmQtAutoGeneratorInitializer.cxx
@@ -919,6 +919,12 @@ void cmQtAutoGeneratorInitializer::InitializeAutogenTarget(
     }
   }
 
+  // cmGeneratorTarget::GetConfigCommonSourceFiles computes the target's
+  // sources meta data cache. Clear it so that OBJECT library targets that
+  // are AUTOGEN initialized after this target get their added
+  // mocs_compilation.cpp source acknowledged by this target.
+  target->ClearSourcesCache();
+
   // Convert std::set to std::vector
   const std::vector<std::string> autogenDepends(autogenDependsSet.begin(),
                                                 autogenDependsSet.end());