[GHC] #5724: Confusing warning message for incomplete patterns

[GHC]

#5724: Confusing warning message for incomplete patterns
------------------------------+---------------------------------------------
 Reporter:  AntoineLatter     |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Component:  Compiler        
  Version:  7.3               |       Keywords:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
  Failure:  None/Unknown      |       Testcase:                  
Blockedby:                    |       Blocking:                  
  Related:                    |  
------------------------------+---------------------------------------------
 The following code

 {{{
 {-# OPTIONS_GHC -Wall #-}

 import Data.Word

 f :: Word8 -> Bool
 f 0 = True
 f 1 = False
 f 2 = True
 }}}

 Produces the warning

 {{{
 7:1:
     Warning: Pattern match(es) are non-exhaustive
              In an equation for `f':
                  Patterns not matched: #x with #x `notElem` [0#, 1#, 2#]
 }}}

 While accurate, this is not exactly user friendly.

 Found in GHC 7.4.1 RC 1

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5724>
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