Created attachment 509364 [details] emerge --info Exult fails to compile with gcc 6.4 due to std::abs() in imagewin/scale_xbr.h. Inserting sed -i "s/abs(/abs((long)/g" imagewin/scale_xbr.h in src_prepare() of the ebuild fixes this problem. Though I think it's not a good workaround.
Looks like they moved to Github. The SF svnserve is so slow.
OK, with that out of the way, I can't reproduce this with GCC 6.4.0 at all. Please attach the entire build log to this bug report.
It seems changing to the current repository (github), the error is gone. I, also, wasn't able to reproduce the error any more.