{"ast_node_type":"variable","tokens":[{"end":85,"kind":"keyword","start":0,"text":"if"}]}
        if let Some(old) = self.rbv.late_bound_vars.insert(hir_id.local_id, binder) {
    fn record_late_bound_vars(&mut self, hir_id: HirId, binder: Vec<ty::BoundVariableKind>) {
            bug!(