StandaloneKindSignatures is not supported

(from #11 (closed))

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE StandaloneKindSignatures #-}
{-# LANGUAGE UnsaturatedTypeFamilies #-}
module Bug where

import Data.Kind
import GHC.Exts

type T :: Type -> @U Type
data T a where
  MkT :: a -> @U T a

type D :: Type -> @U Type
data family D a

type C :: Type -> @U Constraint
class C a