Type-level skolem capture leads to core lint error

The following ill-typed code is accepted.

{-# LANGUAGE PolyKinds, RankNTypes #-}

module Bug where

data SameKind :: k -> k -> *

foo :: forall b. (forall (a :: k). SameKind a b) -> ()
foo = undefined

Indeed, Core Lint catches this. But the type-checker should. The problem is that SameKind forces a and b to have the same kind. But they can't, because a's kind is out of scope at b's binding site. The program should be rejected.

Trac metadata

Trac field	Value
Version	7.10.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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