{"ast_node_type":"other","tokens":[{"end":87,"kind":"keyword","start":0,"text":"ty::PredicateKind::Clause(ty::ClauseKind::UnstableFeature(symbol))"}]}
                ty::PredicateKind::Clause(ty::ClauseKind::UnstableFeature(symbol)) => {
                }
                    self.compute_unstable_feature_goal(param_env, symbol)