The impossible happened (no skolem info) - untouchable kind variable

{-# LANGUAGE RankNTypes, PolyKinds, DataKinds, TypeFamilies #-}
module GHCBug where

data Proxy p = Proxy

data KProxy (a :: *) = KProxy

h :: forall r . (Proxy ('KProxy :: KProxy k) ~ Proxy ('KProxy :: KProxy *) => r) -> r
h = undefined

GHC reports

GHCBug.hs:8:6:
    Couldn't match kind ‘k’ with ‘*’
      ‘k’ is untouchable
        inside the constraints (Proxy 'KProxy ~ Proxy 'KProxy)
        bound by the type signature for
                   h :: (Proxy 'KProxy ~ Proxy 'KProxy) => r
        at GHCBug.hs:8:6-87ghc: panic! (the 'impossible' happened)
  (GHC version 7.10.1 for x86_64-unknown-linux):
	No skolem info: k_amc[sk]

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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