panic building darcs

[ 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

Trac metadata

Trac field	Value
Version	7.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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