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{-# LANGUAGE Haskell2010 #-}
{-# LANGUAGE UndecidableInstances #-}
module ShouldFail where
-- The constraint in the context of an instance declaration
-- is ambiguous, but we have UndecidableInstances on, so
-- it could conceivably be ok (we'd need OverlappingInstances
-- too in this case). So we allow it.
-- See Note [The ambiguity check for type signatures] in GHC.Tc.Utils.TcMType
class Bar a
instance Bar a => Bar Bool
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