{"ast_node_type":"variable","tokens":[{"end":58,"kind":"keyword","start":0,"text":"let"}]}
        let ty = || Ty::new_coroutine(self, def_id, args);
    ) -> Result<&'tcx CoroutineLayout<'tcx>, &'tcx LayoutError<'tcx>> {
        if args[0].has_placeholders() || args[0].has_non_region_param() {