[GHC] #12922: Kind classes compile with PolyKinds

[GHC]

#12922: Kind classes compile with PolyKinds
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        Reporter:  Tritlo            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 For a simpler example, this compiles in GHC 8.0.1 (but probably shouldn't)
 without `TypeInType`:

 {{{#!hs
 {-# LANGUAGE PolyKinds #-}

 type KindOf (a :: k) = k
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12922#comment:3>
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