Merge topic 'fbuild_byproducts' into release-4.2

b1b3602cda FASTBuild: remove non-existent autogen byproducts

Acked-by: Kitware Robot <[email protected]>
Merge-request: !11405

Source/cmQtAutoGenInitializer.cxx

@@ -1394,7 +1394,9 @@ bool cmQtAutoGenInitializer::InitAutogenTarget()
   if (this->Uic.Enabled) {
     for (auto const& file : this->Uic.UiHeaders) {
       this->AddGeneratedSource(file.first, this->Uic);
-      autogenByproducts.push_back(file.second);
+      if (this->GlobalGen && !GlobalGen->IsFastbuild()) {
+        autogenByproducts.push_back(file.second);
+      }
     }
   }