Core lint panic

Steps to reproduce:

• compile current HEAD
• cd libraries/dph/examples/quickhull && make

This eventually fails with:

../../../../inplace/bin/ghc-stage2 -o seq/quickhullSVG --make vectSVG.hs -Odph -threaded -rtsopts -fsimplifier-phases=4 -fstrictness-before=3 -msse2 -fdph-seq -odir seq -hidir seq -package dph-bench -package-conf ../lib/dph-bench.conf -dcore-lint
[1 of 5] Compiling SVG              ( SVG.hs, seq/SVG.o )
[5 of 5] Compiling Main             ( vectSVG.hs, seq/Main.o )
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.1.20101116 for i386-apple-darwin):
	Iface Lint failure
    In interface for vector-0.7.0.1:Data.Vector.Generic
    Unfolding of step{v i3N4}
      <no location info>:
          [in body of lambda with binder s1{v i3N7} [lid] :: ghc-prim:GHC.Types.Int{(w) tc 3J}]
          a29{v i3My} [lid] is out of scope
      <no location info>:
          In the type `vector-0.7.0.1:Data.Vector.Fusion.Stream.Monadic.Step{tc r2kS}
                         ghc-prim:GHC.Types.Int{(w) tc 3J} a{tv i3Ms} [tv]'
          a{tv i3Ms} [tv] is out of scope

I can't find a smaller example and just make seq/quickhullSVG works fine. The panic really only happens if some of the files are already built.

Trac metadata

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