[GHC] #13363: Wildcarn patterns and COMPLETE sets can lead to misleading redundant pattern-match warnings

[GHC]

#13363: Wildcarn patterns and COMPLETE sets can lead to misleading redundant
pattern-match warnings
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms,
                                     |  PatternMatchWarnings
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by mpickering):

 But that is not the problem.

 This warning comes from the built-in constructor set. I think there needs
 to be some more clever augmentation to the intermediate result  in the
 case that a result of `allCompleteMatches` does not contain the
 constructor which was used to do the lookup. For example, if
 `ToGoodToBeTrue` is not in `T, F`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13363#comment:6>
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