[GHC] #12905: Core lint failure with pattern synonym and levity polymorphism

[GHC]

#12905: Core lint failure with pattern synonym and levity polymorphism
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |             Keywords:
      Resolution:                    |  LevityPolymorphism, typeable
Operating System:  Unknown/Multiple  |         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 goldfire):

 Looks like #11714 to me.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12905#comment:5>
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