http://bugs.winehq.org/show_bug.cgi?id=16413
--- Comment #5 from Austin English austinenglish@gmail.com 2009-01-12 09:23:23 --- (In reply to comment #4)
I'd also suggest to file a bug with your distro. For most functions these warnings have way too many false positives to be enabled by default, especially since there's no easy way to turn the warning off.
Ubuntu Intrepid doesn't show this anymore, but I still see this on pretty much every other platform I compile on. Those aren't as often, so I've disabled -Werror for now on those.
It'd be nice to fix this properly though.