[GHC] #13585: ala from Control.Lens.Wrapped panics

[GHC]

#13585: ala from Control.Lens.Wrapped panics
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        Reporter:  fumieval          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by pacak):

 ghc 8.0.1: successfull compilation

 ghc 8.2rc:

 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.2.0.20170404 for x86_64-unknown-linux):
         splitTyConApp
   (Exchange (Unwrapped (First ())) (Unwrapped (First ())) |> <*
                                                               -> * ->
 *>_N) (Maybe
 ()) ((Identity |> <*
 -> *>_N) (Maybe
 ()))
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1134:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1138:37 in
 ghc:Outputable
         pprPanic, called at compiler/types/Type.hs:1105:34 in ghc:Type

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

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13585#comment:6>
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