[GHC] #14773: MultiWayIf makes it easy to write partial programs that are not catched by -Wall

[GHC]

#14773: MultiWayIf makes it easy to write partial programs that are not catched by
-Wall
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        Reporter:  SimonHengel       |                Owner:  sighingnow
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      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 sighingnow):

 I'm confused with the following comments at Check.hs:
 https://ghc.haskell.org/trac/ghc/browser/ghc/compiler/deSugar/Check.hs#L1904

 {{{#!hs
 1904    exhaustiveWarningFlag (StmtCtxt {}) = Nothing -- Don't warn about
 incomplete patterns
 1905                                           -- in list comprehensions,
 pattern guards
 1906                                           -- etc. They are often
 *supposed* to be
 1907                                           -- incomplete
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14773#comment:9>
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