[GHC] #11806: GHC does not warn for mistakenly empty case

[GHC]

#11806: GHC does not warn for mistakenly empty case
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        Reporter:  dfeuer            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
                                     |  PatternMatchWarnings
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10746, #7669,    |  Differential Rev(s):
  #11390                             |
       Wiki Page:                    |
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Comment (by dfeuer):

 nomeata speaks my mind. When I said "inhabited", I meant properly
 inhabited. Empty case should issue a warning under the conditions he
 indicates. If the type of the scrutinee is not apart from the result types
 of all constructors, then I've made a mistake and I want to know about it.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11806#comment:6>
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