[GHC] #11356: GHC panic

[GHC]

#11356: GHC panic
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           Reporter:  Iceland_jack   |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
  (Type checker)                     |
           Keywords:                 |  Operating System:  Linux
       Architecture:  x86            |   Type of failure:  Compile-time
                                     |  crash
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 The attached file causes GHC (version 8.1.20160102) panic.

 I tried shrinking, attached code is bogus at this point.

 Interestingly inlining the type synonym `T = Nat` into Category's
 superclass context fixes the panic, and causes a regular error.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11356>
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