fn type_op_normalize<'tcx, T>(
    infcx: &InferCtxt<'tcx>,
    fulfill_cx: &mut dyn TraitEngine<'tcx>,
    key: ParamEnvAnd<'tcx, Normalize<T>>
) -> Fallible<T>where
    T: Debug + TypeFoldable<'tcx> + Lift<'tcx>,