{"ast_node_type":"variable","tokens":[{"end":51,"kind":"keyword","start":0,"text":"let"}]}
        let pat_ty = Ty::new_tup(tcx, element_tys);
        let element_tys = tcx.mk_type_list_from_iter(element_tys_iter);
        if let Err(reported) = self.demand_eqtype_pat(span, expected, pat_ty, &pat_info.top_info) {