{"ast_node_type":"other","tokens":[{"end":45,"kind":"keyword","start":0,"text":"///"}]}
    /// diagnostic with no change to `specs`.
    /// (e.g. if a forbid was already inserted on the same scope), then emits a
    fn insert_spec(&mut self, id: LintId, LevelAndSource { level, lint_id, src }: LevelAndSource) {