[GHC] #4000: The impossible happened

[GHC]

#4000: The impossible happened
---------------------------------+------------------------------------------
    Reporter:  sabaki            |       Owner:              
        Type:  bug               |      Status:  new         
    Priority:  normal            |   Component:  Compiler    
     Version:  6.12.2            |    Keywords:              
          Os:  Unknown/Multiple  |    Testcase:              
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown
       Patch:  0                 |  
---------------------------------+------------------------------------------
 ghc: panic! (the 'impossible' happened)
   (GHC version 6.12.1 for i386-apple-darwin):
         thread blocked indefinitely in an MVar operation

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4000>
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