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{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ViewPatterns #-}
module Bug where
-- Ryan Scott (on MR !2600) said this failed
type T = forall a. a -> ()
toT :: () -> T
toT x _ = x
pattern ToT :: T -> ()
pattern ToT{x} <- (toT -> x)
-- f (toT -> (x::T)) = True
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