[GHC] #4892: panic building darcs

[GHC]

#4892: panic building darcs
-------------------------------+--------------------------------------------
    Reporter:  ksf             |       Owner:              
        Type:  bug             |      Status:  new         
    Priority:  normal          |   Component:  Compiler    
     Version:  7.0.1           |    Keywords:              
    Testcase:                  |   Blockedby:              
          Os:  Linux           |    Blocking:              
Architecture:  x86_64 (amd64)  |     Failure:  None/Unknown
-------------------------------+--------------------------------------------
 {{{
 [ 66 of 154] Compiling Darcs.Patch.V1.Commute (
 src/Darcs/Patch/V1/Commute.lhs, dist/build/Darcs/Patch/V1/Commute.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.0.1 for x86_64-unknown-linux):
         Template variable unbound in rewrite rule
     sg_s1lfe{tv} [co]
     [x{tv a1ktU} [sk], y{tv a1ktV} [sk], sg_s1lfe{tv} [co],
      sc_s1lff{v} [lid], sc_s1lfg{v} [lid]]
     [x{tv X1kxx} [sk], y{tv X1kxz} [sk], sg_s1lfe{tv} [co],
      sc_s1lff{v} [lid], sc_s1lfg{v} [lid]]
     [TYPE y{tv a1ktV} [sk], TYPE y{tv a1ktV} [sk],
      TYPE x{tv a1ktU} [sk], TYPE x{tv a1ktU} [sk],
      TYPE x{tv a1ktU} [sk], sc_s1lfg{v} [lid], sc_s1lff{v} [lid],
      darcs-2.5:Darcs.Witnesses.Ordered.NilRL{v r2L4} [gid[DataCon]]
        @ darcs-2.5:Darcs.Patch.V1.Core.Patch{tc rI0h}
        @ x{tv a1ktU} [sk]
        @ x{tv a1ktU} [sk]
        @ x{tv a1ktU} [sk]]
     [TYPE y{tv a1ktV} [sk], TYPE y{tv a1ktV} [sk],
      TYPE x{tv a1ktU} [sk], TYPE x{tv a1ktU} [sk],
      TYPE x{tv a1ktU} [sk], wild_s1lcg{v} [lid], sc_s1leC{v} [lid],
      darcs-2.5:Darcs.Witnesses.Ordered.NilRL{v r2L4} [gid[DataCon]]
        @ darcs-2.5:Darcs.Patch.V1.Core.Patch{tc rI0h}
        @ x{tv a1ktU} [sk]
        @ x{tv a1ktU} [sk]
        @ x{tv a1ktU} [sk]]
 }}}


 , from darcs screened as of Wed, 12 Jan 2011 20:00:00 +0000 amended with

 {{{
  if impl(ghc >= 7)
     ghc-options: -fwarn-missing-local-sigs
     extensions: NoMonoLocalBinds
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4892>
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