[GHC] #5340: wrong warning on incomplete case analysis in conjunction with empty data declarations

[GHC]

#5340: wrong warning on incomplete case analysis in conjunction with empty data
declarations
---------------------------------+------------------------------------------
    Reporter:  Lemming           |        Owner:              
        Type:  bug               |       Status:  new         
    Priority:  lowest            |    Milestone:  _|_         
   Component:  Compiler          |      Version:  6.12.3      
    Keywords:                    |     Testcase:              
   Blockedby:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Blocking:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
---------------------------------+------------------------------------------
Changes (by simonpj):

  * priority:  normal => lowest
  * milestone:  => _|_


Comment:

 Well this is very delicate.  Yes, since
  * The data type is empty
  * The `LeftStrict` constructor is strict
 I agree that a pattern `(LeftStrict a)` can never match

 But does this come up often enough to be worth special-casing in the
 compiler.

 I'll mark it priority lowest, but if it becomes importand for someone, do
 yell.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5340#comment:1>
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