[GHC] #5728: Warnings from -fwarn-incomplete-record-updates even with all constructors matched

[GHC]

#5728: Warnings from -fwarn-incomplete-record-updates even with all constructors
matched
---------------------------------+------------------------------------------
    Reporter:  mjo               |       Owner:                                   
        Type:  bug               |      Status:  new                              
    Priority:  normal            |   Milestone:  _|_                              
   Component:  Compiler          |     Version:  7.4.1                            
    Keywords:  warnings          |          Os:  Unknown/Multiple                 
Architecture:  Unknown/Multiple  |     Failure:  Incorrect warning at compile-time
  Difficulty:  Unknown           |    Testcase:                                   
   Blockedby:                    |    Blocking:                                   
     Related:                    |  
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Changes (by maeder):

  * version:  7.2.1 => 7.4.1


Comment:

 Even for an explicit @-Pattern I get this warning.

 {{{
 {-# OPTIONS -fwarn-incomplete-record-updates #-}
 data Rec = Mt | Rec {a, b, c, d, e, f, g :: Int}

 updA :: Int -> Rec -> Rec
 updA i r@(Rec {}) = r { a = i }
 updA _ Mt = Mt
 }}}

 How should I change just "updA" (without mentioning the other fields) to
 avoid the warning?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5728#comment:2>
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