{"ast_node_type":"other","tokens":[{"end":64,"kind":"keyword","start":0,"text":"(ty::Adt(a_def,"}]}
                (ty::Adt(a_def, a_args), ty::Adt(b_def, b_args))
                // `Struct<T>` -> `Struct<U>` where `T: Unsize<U>`
                    if a_def.is_struct() && a_def == b_def =>