Kind variable generalization problem

Consider the following tangle of definitions:

{-# LANGUAGE KindSignatures, RankNTypes, PolyKinds, GADTs,
             FlexibleContexts, DataKinds, TypeFamilies #-}

import GHC.Exts

data family Sing (a :: k)
class SingKind (Any :: k) => SingI (s :: k) where
  sing :: Sing s
data SingInstance :: k -> * where 
  SingInstance :: SingI a => SingInstance a
class (b ~ Any) => SingKind (b :: k) where
  singInstance :: forall (a :: k). Sing a -> SingInstance a

When compiling (with 7.5.20120620), I get this error message:

    Kind mis-match
    The first argument of `SingKind' should have kind `k1',
    but `Any' has kind `k'
    In the class declaration for `SingI'

I believe that the code should compile, though I'll admit I'm not 100% convinced.

Trac metadata

Trac field	Value
Version	7.5
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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