There are a few changes in glibc-2.10 that might make your software fail to build with it, please refer to my blog post  if you're not sure what the problem is.
And no I don't usually provide emerge --info with these bugs because they are caused by glibc-2.10!
Created attachment 193503 [details]
gbuf.c:43: error: conflicting types for 'strnlen'
/usr/include/string.h:404: note: previous declaration of 'strnlen' was here
emacs, any interest in this?
(In reply to comment #3)
> emacs, any interest in this?
We will take it.
We had a deeper look and decided that this package is not worth any further effort. There is a experimental fork which can enter Gentoo once there is a need for it.
Treecleaner, maybe mask it for 60 days, if any complaints arise, Emacs team will put a live ebuild for the experimental fork into our overlay and eventually provide a normal ebuild upon release.
# Ulrich Mueller <email@example.com> (09 Jun 2009)
# Masked for removal in 60 days. Doesn't build with glibc-2.10. Incompatible
# with current Emacs versions. No upstream release since more than five years.
# If you want us to keep this package, please contact <firstname.lastname@example.org>, or
# leave a comment at bug 272593.