T5290.hs:(7,4)-(9,77): Splicing declarations
    let n = mkName "T"
    in
      return
        [DataD
           []
           n
           []
           Nothing
           [NormalC n [(Bang SourceUnpack SourceStrict, ConT ''Int)]]
           []]
  ======>
    data T = T {-# UNPACK #-} !Int