[GHC] #8163: ghc.exe: panic! (the 'impossible' happened)

[GHC]

#8163: ghc.exe: panic! (the 'impossible' happened)
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       Reporter:  CodeGuru          |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Compiler          |           Version:  7.4.2
       Keywords:                    |  Operating System:  Windows
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 When compiling an example from ''Real World Haskell'', I get the following
 error message:
 {{{
     Prelude> :l Prettify.hs
     [2 of 2] Compiling Prettify         ( Prettify.hs, interpreted )
     ghc.exe: panic! (the 'impossible' happened)
       (GHC version 7.4.2 for i386-unknown-mingw32):
             nameModule show{tv apB}

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

     >
 }}}
 The example contains simple function stubs which are used by another
 module:
 {{{
     module Prettify
         ( string
         , text
         , double
         ) where

     import SimpleJSON

     data Doc = ToBeDefined
         deriving (show)

     string :: String -> Doc
     string str = undefined

     text :: String -> Doc
     text str = undefined

     double :: Double -> Doc
     double num = undefined
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8163>
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