{"ast_node_type":"other","tokens":[{"end":99,"kind":"keyword","start":0,"text":"(FeatureStability::AcceptedSince(_),"}]}
            (FeatureStability::AcceptedSince(_), Some((FeatureStability::Unstable { .. }, _))) => {
            }
                self.tcx.dcx().emit_err(FeaturePreviouslyDeclared {