[GHC] #7458: ghc panic

[GHC]

#7458: ghc panic
-------------------------------+--------------------------------------------
Reporter:  timsears            |          Owner:          
    Type:  bug                 |         Status:  new     
Priority:  normal              |      Component:  Compiler
 Version:  7.4.1               |       Keywords:          
      Os:  Linux               |   Architecture:  x86     
 Failure:  Compile-time crash  |      Blockedby:          
Blocking:                      |        Related:          
-------------------------------+--------------------------------------------
 As ghc requested I am reporting this...
 All I can say right now is that I am tracking down a bug involving
 overlapping instances.

 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.1 for i386-unknown-linu
         tcTyVarDetails
     ( t{tv acw0} [tv] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )

 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/7458>
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