{"ast_node_type":"other","tokens":[{"end":95,"kind":"keyword","start":0,"text":"(ty::Infer(ty::TyVar(..)),"}]}
                (ty::Infer(ty::TyVar(..)), ..) => panic!("unexpected infer {a_ty:?} {b_ty:?}"),
            match (a_ty.kind(), b_ty.kind()) {