testsuite/tests/deriving/should_fail/T10598_fail6.stderr


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T10598_fail6.hs:5:41: error:
    • Can't make a derived instance of ‘Functor F’
        (even with cunning GeneralizedNewtypeDeriving):
        You need DeriveFunctor to derive an instance for this class
    • In the newtype declaration for ‘F’