GHC accepts multiple conflicting kind signatures in type class declarations

Hi,

Consider this suspicious looking program:

{-# LANGUAGE TypeFamilies #-}

class C (f :: * -> *) where
  type F (f :: *) :: *

I use the same type argument name f but specify different kinds. Now I can never define an instance anymore:

instance C [] where
  -- Error: Type indexes must match class instance head
  -- type F () = ()

  -- Error: Expecting one more argument to `[]'
  -- type F [] = ()

I think GHC should verify, if the same type argument name is used multiple times in a type class definition, that their kinds match. In that case the type class above would be rejected.

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
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CC	sjoerd@w3future.com
Operating system
Architecture