[GHC] #4371: ghc panic: ToDo: Match.viewLExprEq

[GHC]

#4371: ghc panic: ToDo: Match.viewLExprEq
---------------------------------+------------------------------------------
    Reporter:  mafo              |       Owner:                    
        Type:  bug               |      Status:  new               
    Priority:  normal            |   Component:  Compiler          
     Version:  7.1               |    Keywords:                    
    Testcase:                    |   Blockedby:                    
          Os:  Unknown/Multiple  |    Blocking:                    
Architecture:  Unknown/Multiple  |     Failure:  Compile-time crash
---------------------------------+------------------------------------------
 The attached test-case triggers a

 ghc: panic! (the 'impossible' happened)
   (GHC version 7.0.0.20100924 for x86_64-unknown-linux):
         ToDo: Match.viewLExprEq

 this is a regression from 6.12.3 where there was no problem.

 In the function Match.viewLExprEq
 one case is not defined
 however the comments say viewLExprEq may safely return False,
 so this is bug is probably trivial to fix ?

 The testcase uses a combination of ViewPatterns
 and a cast from Data.Typeable.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4371>
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