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{-# LANGUAGE ScopedTypeVariables, FlexibleInstances, MultiParamTypeClasses,
TypeFamilies, FlexibleContexts, AllowAmbiguousTypes #-}
module InstanceGivenOverlap where
-- See Note [Instance and Given overlap] in GHC.Tc.Solver.Interact.
-- This tests the Note when the Wanted contains a type family.
class P a
class Q a
class R a b
instance P x => Q [x]
instance (x ~ y) => R y [x]
type family F a b where
F [a] a = a
wob :: forall a b. (Q [F a b], R b a) => a -> Int
wob = undefined
g :: forall a. Q [a] => [a] -> Int
g x = wob x
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