{"ast_node_type":"variable","tokens":[{"end":25,"kind":"keyword","start":0,"text":"let"}]}
    let mut res = Ok(());
pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGuaranteed> {
    let generics = tcx.generics_of(def_id);