{"ast_node_type":"variable","tokens":[{"end":81,"kind":"keyword","start":0,"text":"let"}]}
                        let guar = self.dcx().emit_err(SelfInTypeAlias { span });
                        // may not be able to catch all illegal `Self` usages (issue 139082)
                        b.term = replace_dummy_self_with_error(tcx, b.term, guar);