I'm firefox user, I'm using default flags that instruct emerge to build ff against system libvpx. Nobody else depends on libvpx yet on emerge -auDN world I get: !!! Multiple package instances within a single package slot have been pulled !!! into the dependency graph, resulting in a slot conflict: media-libs/libvpx:0 (media-libs/libvpx-1.8.0-r1:0/6::gentoo, ebuild scheduled for merge) pulled in by (no parents that aren't satisfied by other packages in this slot) (media-libs/libvpx-1.7.0:0/5::gentoo, ebuild scheduled for merge) pulled in by =media-libs/libvpx-1.7*:0=[postproc] required by (www-client/firefox-69.0:0/0::gentoo, installed) ^ ^^^^^^^ =media-libs/libvpx-1.7*:0/5=[postproc] required by (www-client/firefox-69.0:0/0::gentoo, installed) ^ ^^^^^^^^^ Reproducible: Always
Ok so my bad actually dev-qt/qtwebengine is using libvpx unconditionally (WTF?) and it is what is causing problems. Yet it's unclear why * These packages depend on media-libs/libvpx: dev-qt/qtwebengine-5.12.5 (>=media-libs/libvpx-1.5[svc]) .... www-client/firefox-69.0 (system-libvpx ? =media-libs/libvpx-1.7*:0[postproc]) mandates 1.8 breaking ff while qtwebengine should be happy with 1.7
