T14618.hs:7:14: error:
    • Couldn't match type ‘b’ with ‘forall c. a’
      Expected: a -> b
        Actual: a -> forall c. a
      Cannot equate type variable ‘b’
      with a type involving polytypes: forall c. a
      ‘b’ is a rigid type variable bound by
        the type signature for:
          safeCoerce :: forall a b. a -> b
        at T14618.hs:6:1-20
    • In the expression: f'
      In an equation for ‘safeCoerce’:
          safeCoerce
            = f'
            where
                f :: d -> forall c. d
                f x = x
                f' = f
    • Relevant bindings include
        safeCoerce :: a -> b (bound at T14618.hs:7:1)