you're receiving this canned bug because the package in summary uses the flag -Werror during build, which transforms warnings in errors, and is prone to break software when new GCC releases are added to Gentoo.
Please make sure your package does not use -Werror during build, so that it can be more future-proof for the new GCC releases.
Missing the build log
Created attachment 184104 [details]
fixed in raincoat-0.11