{"ast_node_type":"other","tokens":[{"end":52,"kind":"keyword","start":0,"text":")"}]}
    ) -> Option<(&'tcx hir::Expr<'tcx>, Ty<'tcx>)> {
        expr_fields: &[hir::ExprField<'tcx>],
        let def = self.tcx.adt_def(def_id);