Code breaks with '-O', any ideas.

[David Brown]

My program 'harchive' <http://www.davidb.org/darcs/harchive/> breaks
if compiled with '-O'.  Just wondering if anyone has suggestions on
how to figure out what might be causing this.

Is is possible to build some files with '-O' and others without?

I'm not using unsafePerformIO.

Thanks,
David