"deriving (Functor)" on a polykinded type produces ill-kinded instance

Arose in #10524 (closed), and new since 7.10.

rwbarton@morphism:/tmp$ ~/ghc/inplace/bin/ghc-stage2 --interactive
GHCi, version 7.11.20150615: http://www.haskell.org/ghc/  :? for help
Prelude> :set -XPolyKinds -XDeriveFunctor -ddump-deriv -fprint-explicit-kinds
Prelude> newtype Compose f g a = Compose (f (g a)) deriving Functor

==================== Derived instances ====================
Derived instances:
  instance forall (k_and :: BOX)
                  (f_ane :: k_and -> *)
                  (g_anf :: * -> k_and).
           (GHC.Base.Functor f_ane, GHC.Base.Functor g_anf) =>
           GHC.Base.Functor (Ghci1.Compose k_and * f_ane g_anf) where
    GHC.Base.fmap f_ang (Ghci1.Compose a1_anh)
      = Ghci1.Compose (GHC.Base.fmap (GHC.Base.fmap f_ang) a1_anh)
  

Generic representation:
  
  Generated datatypes for meta-information:
  
  Representation types:


Prelude> :i GHC.Base.Functor
class Functor (f :: * -> *) where
[...]

The context (GHC.Base.Functor f_ane, GHC.Base.Functor g_anf) is ill-kinded except when k_and = *.

Trac metadata

Trac field	Value
Version	7.11
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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