dev-python/xapp currently has DEPEND="x11-libs/xapps" However, if x11-libs/xapps is built with USE='-introspection', dev-python/xapp will stop working, and break anything that depends on it (in my case, cinnamon-screensaver stopped working). As such, the depend line should instead be: DEPEND="x11-libs/xapps[introspection]"
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=6d11aa141259c04645bf015a8145a86503b8d53c commit 6d11aa141259c04645bf015a8145a86503b8d53c Author: Kristian Fiskerstrand <k_f@gentoo.org> AuthorDate: 2017-11-26 14:26:02 +0000 Commit: Kristian Fiskerstrand <k_f@gentoo.org> CommitDate: 2017-11-26 15:10:52 +0000 dev-python/xapp: Add explicit introspection dep Bug: https://bugs.gentoo.org/636162 Package-Manager: Portage-2.3.13, Repoman-2.3.3 dev-python/xapp/xapp-1.0.1-r2.ebuild | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)}