{-# LANGUAGE DefaultSignatures #-}
unit p where
    signature A where
        class C a where
            f :: a -> a
            g :: a -> a
            {-# MINIMAL f #-}
unit q where
    signature A where
        class C a where
            f :: a -> a
            g :: a -> a
            {-# MINIMAL g #-}
unit r where
    dependency p[A=<A>]
    dependency q[A=<A>]
    module B where
        import A
        instance C Int where
            -- Warns!