The following commit: https://github.com/gentoo/gentoo/commit/9b00135f4696e539a3cbee711ac687f4f9ded105 removed ability to build SuperClassic server, which was done by setting firebird USE flags to "-client -superserver -xinetd". You can see it in ebuild source that this is a valid setting: use client && return (..) # SuperServer if use superserver ; then dosbin bin/{fbguard,fbserver} # ClassicServer elif use xinetd ; then dosbin bin/fb_inet_server # SuperClassic else If I change REQUIRED_USE to "?? ( client superserver xinetd )" in ebuild SuperClassic server builds fine again. Note this is not a duplicate of bug 420939, since that bug is about inability to build ClassicServer with "xinetd" USE flag being set (due to SuperClassic patch being wrongly applied).
Created Github PR 3357 that includes fix for this bug.
Thanks for your work, fixed by commit 06590bfb0f7ec387135e4c00935c52dcef5d00ef