[GHC] #7358: ghc: panic! (The 'impossible' happened) from RnSource.lhs

[GHC]

#7358: ghc: panic! (The 'impossible' happened) from RnSource.lhs
--------------------------------+-------------------------------------------
 Reporter:  jeffshaw            |          Owner:                
     Type:  bug                 |         Status:  new           
 Priority:  normal              |      Component:  Compiler      
  Version:  7.4.2               |       Keywords:                
       Os:  Linux               |   Architecture:  x86_64 (amd64)
  Failure:  Compile-time crash  |       Testcase:                
Blockedby:                      |       Blocking:                
  Related:                      |  
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Comment(by jeffshaw):

 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.2 for x86_64-unknown-linux):
         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

 Here is the source code that creates this error:

 instance A a => B a => C a where
   c = a

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7358#comment:1>
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