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{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
module T5514 where
class Foo a where
foo :: a -> a
instance (Foo a, Foo b) => Foo (a, b) where
foo = foo' ()
-- foo' :: () -> b -> b
foo' es = const id (unitId es)
unitId :: () -> ()
unitId = id
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