[GHC] #4893: panic! the 'impossible' happened: initC: srt_lbl

[GHC]

#4893: panic! the 'impossible' happened: initC: srt_lbl
---------------------------------------+------------------------------------
    Reporter:  plc                     |        Owner:                           
        Type:  bug                     |       Status:  infoneeded               
    Priority:  normal                  |    Milestone:  7.0.2                    
   Component:  Compiler                |      Version:  7.0.1                    
    Keywords:  impossible, dcore-lint  |     Testcase:                           
   Blockedby:                          |   Difficulty:                           
          Os:  Linux                   |     Blocking:                           
Architecture:  x86                     |      Failure:  GHC rejects valid program
---------------------------------------+------------------------------------

Comment(by aleator):

 {{{
 {-# LANGUAGE TransformListComp #-}
 module Main where

 import GHC.Exts

 main = return [show a | a@(c,i,f) <- [(1,2,3)],then sortWith by i, then
 group by c]
 }}}

 Will give the same error on compiling and when invoked from ghci it gives:
 *Main> main
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.0.1 for i386-apple-darwin):
         nameModule i{v ac7}

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

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4893#comment:9>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler