T5217.hs:1:1: Splicing declarations
    [d| data T a b
            where
              T1 :: Int -> T Int Char
              T2 :: a -> T a a
              T3 :: a -> T [a] a
              T4 :: a -> b -> T b [a] |]
  ======>
    T5217.hs:(6,3)-(9,53)
    data T a b
        = (b ~ Char, a ~ Int) => T1 Int |
          b ~ a => T2 a |
          a ~ [b] => T3 b |
          forall a. b ~ [a] => T4 a a