{"ast_node_type":"other","tokens":[{"end":52,"kind":"keyword","start":0,"text":"UndoLog::PushTypeOutlivesConstraint"}]}
            UndoLog::PushTypeOutlivesConstraint => {
            UndoLog::ProjectionCache(undo) => self.projection_cache.reverse(undo),
                let popped = self.region_obligations.pop();