Strict Word64 Compiler Panic

[Mark B Shields]

Let Crash.hs be:

module Crash where
import Data.Word (Word64)
data S = S { a :: ! Word64 }
s :: S
s = S { a = 0 }

Then:

(mbs at emae) ghci-5.04 -fglasgow-exts
   ___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 5.04, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Loading package base ... linking ... done.
Loading package haskell98 ... linking ... done.
Prelude> :l Crash
Compiling Crash            ( Crash.hs, interpreted )
ghc-5.04: panic! (the `impossible' happened, GHC version 5.04):
        ByteCodeGen.mkUnpackCode LW_

Please report it as a compiler bug to glasgow-haskell-bugs at haskell.org,
or http://sourceforge.net/projects/ghc/.

Only happens with combination of Word64 and !

Regards,
Mark