testsuite/tests/gadt/T1999.hs


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{-# LANGUAGE FlexibleContexts, FlexibleInstances, GADTs #-}

module Bug where

class C a where
  f :: G a -> ()

instance (C ()) => C (b c) where
  f (G x) = f x where

data G a where
  G  :: G () -> G (b c)