GHC 6.6 panics when compiling HSet from collections package

[Daniel McAllansmith]

Hi.

I just got the collections package from 
http://darcs.haskell.org/packages/collections-ghc6.6

When trying to build it with GHC 6.6 on an amd64 linux machine using Cabal I 
got the following:

[12 of 57] Compiling Data.Tree.AVL.IntMap.Internals.HSet ( 
Data.Tree.AVL.IntMap/Data/Tree/AVL/IntMap/Internals/HSet.hs, 
dist/build/Data/Tree/AVL/IntMap/Internals/HSet.o )
ghc-6.6: panic! (the 'impossible' happened)
  (GHC version 6.6 for x86_64-unknown-linux):
        cgPanic
    tpl{v s2zg} [lid]
    static binds for:
    collections-0.3:Data.Tree.AVL.IntMap.Internals.HSet.intersectionMaybeH{v 
rji} [gid]
    collections-0.3:Data.Tree.AVL.IntMap.Internals.HSet.$Lr2jfforkL{v r2jf} 
[gid]
    collections-0.3:Data.Tree.AVL.IntMap.Internals.HSet.$Lr2jhforkR{v r2jh} 
[gid]
    local binds for:
    SRT label 
collections-0.3:Data.Tree.AVL.IntMap.Internals.HSet.intersectionWithH'{v 
rjg}_srt



Anyone seen this before?  A real GHC bug, a problem with my GHC installation, 
or a problem with the collections package?


Cheers
Daniel