[GHC] #11640: Panic because of "updateRole"

[GHC]

#11640: Panic because of "updateRole"
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           Reporter:  Iceland_jack   |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Not the most recent GHC

 {{{#!hs
 {-# LANGUAGE RankNTypes, TypeInType #-}

 import Data.Kind

 data HEq :: forall k1. k1 -> forall k2. k2 -> Type where
 }}}

 gives

 {{{
 % ghci -ignore-dot-ghci tx9F.hs
 GHCi, version 8.1.20160117: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( tx9F.hs, interpreted )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.1.20160117 for x86_64-unknown-linux):
         updateRole
   HEq
   k2_a115
   [a114 :-> 0, a11e :-> 1, a11f :-> 2]

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 >
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11640>
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