[GHC] #8853: Alarming looking warning about non-exhaustive pattern

[GHC]

#8853: Alarming looking warning about non-exhaustive pattern
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        Reporter:  MikolajKonarski               |            Owner:
            Type:  bug                           |           Status:  new
        Priority:  normal                        |        Milestone:
       Component:  Compiler                      |          Version:
      Resolution:                                |  7.8.1-rc2
Operating System:  Linux                         |         Keywords:
 Type of failure:  Incorrect warning at          |     Architecture:
  compile-time                                   |  x86_64 (amd64)
       Test Case:                                |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Comment (by nomeata):

 Is the bug about the compiler message, or the behaviour at run-time (which
 looks correct to me)?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8853#comment:1>
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