Merge topic 'cxxmodules-fileset-cache-fullpath' into release-3.29

0a18f9baad cmGeneratorTarget: collapse paths before querying the fileset cache

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !9286

Source/cmGeneratorTarget.cxx

@@ -9547,7 +9547,8 @@ void cmGeneratorTarget::BuildFileSetInfoCache(std::string const& config) const
 
     for (auto const& it : files) {
       for (auto const& filename : it.second) {
-        per_config.FileSetCache[filename] = file_set;
+        auto collapsedFile = cmSystemTools::CollapseFullPath(filename);
+        per_config.FileSetCache[collapsedFile] = file_set;
       }
     }
   }