[GHC] #11984: Pattern match incompleteness / inaccessibility discrepancy

[GHC]

#11984: Pattern match incompleteness / inaccessibility discrepancy
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        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
                                     |  PatternMatchWarnings
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by gkaracha):

 Replying to [comment:1 simonpj]:
 > This looks like a plain bug (in the exhaustiveness checker) to me.
 George?

 Ah, yes, indeed. The checker by design keeps the exhaustiveness and the
 redundancy checker synced, as well as both of them with the type checker.
 This is definitely a bug (or omission when we propagate type constraints
 for nested matches' checking?) of the implementation only. I will look
 into it :-)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11984#comment:2>
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