[GHC] #7900: The impossible happend

[GHC]

#7900: The impossible happend
-----------------------------+----------------------------------------------
Reporter:  dhjdhj            |          Owner:                  
    Type:  bug               |         Status:  new             
Priority:  normal            |      Component:  Compiler        
 Version:  7.4.2             |       Keywords:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
 Failure:  None/Unknown      |      Blockedby:                  
Blocking:                    |        Related:                  
-----------------------------+----------------------------------------------
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.2 for x86_64-apple-darwin):
         compiler/rename/RnSource.lhs:430:14-81: Irrefutable pattern failed
 for pattern Data.Maybe.Just (inst_tyvars,
                                                         _,
                                                         SrcLoc.L _ cls,
                                                         _)


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

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7900>
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