Singletons/PolyKinds.hs:(0,0)-(0,0): Splicing declarations
    singletons
      [d| class Cls (a :: k) where
            fff :: Proxy (a :: k) -> () |]
  ======>
    class Cls (a :: k) where
      fff :: Proxy (a :: k) -> ()
    type FffSym1 (arg0123456789876543210 :: Proxy (a0123456789876543210 :: k0123456789876543210)) =
        Fff arg0123456789876543210
    instance SuppressUnusedWarnings FffSym0 where
      suppressUnusedWarnings = snd (((,) FffSym0KindInference) ())
    data FffSym0 :: forall k0123456789876543210
                           (a0123456789876543210 :: k0123456789876543210).
                    (~>) (Proxy (a0123456789876543210 :: k0123456789876543210)) ()
      where
        FffSym0KindInference :: forall arg0123456789876543210
                                       arg. SameKind (Apply FffSym0 arg) (FffSym1 arg) =>
                                FffSym0 arg0123456789876543210
    type instance Apply FffSym0 arg0123456789876543210 = Fff arg0123456789876543210
    class PCls (a :: k) where
      type Fff (arg :: Proxy (a :: k)) :: ()
    class SCls (a :: k) where
      sFff ::
        forall (t :: Proxy (a :: k)).
        Sing t -> Sing (Apply FffSym0 t :: ())
    instance SCls a =>
             SingI (FffSym0 :: (~>) (Proxy (a :: k)) ()) where
      sing = (singFun1 @FffSym0) sFff