BUG: GHC compiler error for 6.6

When compiling programs (ghc --make) that use regex-parsec I trigger an error in GHC 6.6:

ghc-6.6: panic! (the 'impossible' happened) (GHC version 6.6 for powerpc-apple-darwin): simplCore/Simplify.lhs:(1772,0)-(1788,47): Non-exhaustive patterns in function bind_args

I don't have a simple test case yet, but will try to make one if requested. -- Chris