Created attachment 511440 [details] build.log, environment, output of emerge --info and output of emerge -pqv python... I try to emerge sonnet. It builds to 100% and then says emake failed. In the log there is no reason why. I am using gentoo for like 10 years. I don't remember having seen a similar case. Other thing: I don't mess with the system config, I only manipulate through /etc/portage config files, and emerge commands. So this should not happen I guess.
Created attachment 511444 [details] build.log
This looks like some GCC ABI fallout, see https://gentoo.org/support/news-items/2015-10-22-gcc-5-new-c++11-abi.html. Specifically, please try rebuilding app-text/hunspell.