ASSERT failed! file compiler/types/FamInstEnv.lhs

Building the current HEAD (darcs pull -a; ./darcs-all pull -a today) failed with the error

"inplace/bin/ghc-stage2"   -H32m -O -fasm [...snip...]
 -c libraries/vector/./Data/Vector/Unboxed.hs
 -o libraries/vector/dist-install/build/Data/Vector/Unboxed.o
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.1.20100928 for i386-unknown-linux):
        ASSERT failed! file compiler/types/FamInstEnv.lhs, line 321

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

Before that it spat out a lot of warnings.

Trac metadata

Trac field	Value
Version	7.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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