At the beginning of the ebuild a DEPEND is put on sys-apps/openrc. A reason for that ? Else is probably totally useless, I don't see the relationship between a script that selects a compiler version and the scripts used at system startup.
uhm??? % grep openrc /usr/portage/sys-devel/gcc-config/gcc-config-1.4.1.ebuild % (nothing) Closing for now, reopen with more details.
From /usr/bin/gcc-config, lines 8-12: argv0=${0##*/} source /etc/init.d/functions.sh || { echo "${argv0}: Could not source /etc/init.d/functions.sh!" exit 1 } This creates an implicit dependency from openrc, even if it is not explicitly stated in the ebuild. As far as I can see, gcc-config only uses the functions from functions.sh to use things like ewarn and eerror, but if openrc is not installed, gcc-config just fails at runtime.
Sorry the noise, I just found Bug #373219.