Created attachment 460890 [details] emerge --info '=app-text/texlive-core-2016::gentoo' Using >=dev-libs/ptexenc-1.3.4_p20160523 seems to solve the issue.
eptex-eptex0.o: In function `doextension': eptex0.c:(.text+0x35049): undefined reference to `setinfileenc'
commit eadd9d8d9e0365ae35f7db9f7818f57f65cb88ab Author: Alexis Ballier <aballier@gentoo.org> Date: Sun Jan 22 09:43:36 2017 +0100 app-text/texlive-core: Bump dep requirements for 2016 version, bug #606772. thx!