Singletons/T559.hs:0:0:: Splicing declarations
    singletons [d| type data T = MkT |]
  ======>
    type data T = MkT
    type MkTSym0 :: T
    type family MkTSym0 :: T where
      MkTSym0 = MkT
    data ST :: T -> Type where SMkT :: ST (MkT :: T)
    type instance Sing @T = ST
    instance SingI MkT where
      sing = SMkT