{-# LANGUAGE GADTs #-}
{-# LANGUAGE RankNTypes #-}
module T18191 where

data T where
  MkT :: (forall a. a -> b -> T)

data S a where
  MkS :: (forall a. S a)

data U a where
  MkU :: (Show a => U a)

data Z a where
  MkZ1 :: forall a. forall b. { unZ1 :: (a, b) } -> Z (a, b)
  MkZ2 :: Eq a => Eq b => { unZ1 :: (a, b) } -> Z (a, b)