message: Apply unique constraint to the pass
diff: @@ -134,6 +134,7 @@ void ClassMergingPass::bind_config() {
  bool merge_nonvirt_methods_within_shape;
  bind("merge_nonvirt_methods_within_shape", false,
  merge_nonvirt_methods_within_shape);
  + trait(Traits::Pass::unique, true);
  // load model specifications
  std::vector<Json::Value> models;
  