[GHC] #10746: No non-exhaustive pattern match warning given for empty case analysis

[GHC]

#10746: No non-exhaustive pattern match warning given for empty case analysis
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
                                     |  PatternMatchWarnings
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #7669, #11806     |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 Replying to [comment:11 erikd]:
 > Hmm, wit this fix, building base fails due to:
 >
 > {{{
 > absurd :: Void -> a
 > absurd a = case a of {}
 > }}}
 >
 > which triggers:
 >
 > {{{
 > libraries/base/Data/Void.hs:66:12: warning: [-Wincomplete-patterns]
 >     Pattern match(es) are non-exhaustive
 >     In a case alternative: Patterns not matched: _
 > }}}

 Argh! That seems surprising. I'd have expected `mkInitialUncovered` to
 have produced an empty list there.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10746#comment:12>
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