id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
4511	Core lint panic	rl		"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."	bug	closed	normal		Compiler	7.1	fixed			Unknown/Multiple	Unknown/Multiple	Compile-time crash