{"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
    let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
    let params = field_tys.iter().map(|(_, ty)| ty.skip_binders().clone());
    Binders::new(