gentoo-overlay/gnome-base/gnome-shell/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
<maintainer type="project">
	<email>gnome@gentoo.org</email>
	<name>Gentoo GNOME Desktop</name>
</maintainer>
<use>
	<flag name="i18n">Enable support for enhanced input methods through
		<pkg>app-i18n/ibus</pkg></flag>
	<flag name="openrc-force">Skip systemd dependency (#480336),
		enabling this flag will become your setup to be fully
		unsupported by upstream and downstream Gnome team. Do not
		try to enable it unless completely needed</flag>
</use>
</pkgmetadata>