Since builder is optional and it's the only thing depending on gtk-3 it should be exposed as an USE flag. I built it with -Dbuilder=false and it seems to provide everyting flatpack needs.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=269e1e05ed7ed6dbb42074cedf2c97b50050e577 commit 269e1e05ed7ed6dbb42074cedf2c97b50050e577 Author: Mart Raudsepp <leio@gentoo.org> AuthorDate: 2019-03-31 08:02:38 +0000 Commit: Mart Raudsepp <leio@gentoo.org> CommitDate: 2019-03-31 08:10:21 +0000 dev-libs/appstream-glib: bump to 0.7.15, optional fonts support Closes: https://bugs.gentoo.org/673284 Package-Manager: Portage-2.3.52, Repoman-2.3.12 Signed-off-by: Mart Raudsepp <leio@gentoo.org> dev-libs/appstream-glib/Manifest | 1 + .../appstream-glib/appstream-glib-0.7.15.ebuild | 64 ++++++++++++++++++++++ dev-libs/appstream-glib/metadata.xml | 3 +- 3 files changed, 67 insertions(+), 1 deletion(-)