{"ast_node_type":"variable","tokens":[{"end":96,"kind":"keyword","start":0,"text":"let"}]}
    let mut res = tcx.ensure_ok().enforce_impl_non_lifetime_params_are_constrained(impl_def_id);
    // detect those specifically and project those to `TyKind::Error`.
    res = res.and(enforce_impl_lifetime_params_are_constrained(tcx, impl_def_id));