[GHC] #930: ghc-6.6: panic! (the 'impossible' happened) mkWWcpr: not a product GHC-Brian-6.5.1:IdInfo.IdInfo{tc rfD}

[GHC]

#930: ghc-6.6: panic! (the 'impossible' happened) mkWWcpr: not a product GHC-
Brian-6.5.1:IdInfo.IdInfo{tc rfD}
-------------------------+--------------------------------------------------
  Reporter:  briansmith  |          Owner:         
      Type:  bug         |         Status:  new    
  Priority:  normal      |      Milestone:         
 Component:  Compiler    |        Version:  6.5    
  Severity:  normal      |     Resolution:         
  Keywords:              |             Os:  Unknown
Difficulty:  Unknown     |   Architecture:  Unknown
-------------------------+--------------------------------------------------
Comment (by briansmith):

 If you remove the -O2 to compile TidyPgm, then it happens again in
 TcIface:
 {{{
 iface/TcIface.lhs:63:29:
     Warning: Imported from `Util' but not used: `equalLength'
 ghc-6.6: panic! (the 'impossible' happened)
   (GHC version 6.6 for i386-unknown-linux):
         mkWWcpr: not a product GHC-Brian-6.5.1:IdInfo.IdInfo{tc rfD}
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/930>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler