mpv will attempt to use an installed libplacebo even if USE="-vulkan" is specified: >>> package: media-libs/libplacebo-1.29.1 * - /usr/lib64/libplacebo.so.29 * used by /usr/bin/mpv (media-video/mpv-0.32.0-r1) media-video/mpv-0.32.0-r1::gentoo was built with the following: USE="X alsa cli dvb egl iconv lcms libass lua opengl pulseaudio uchardet vaapi vdpau wayland xv zlib (-aqua) -archive -bluray -cdda (-coreaudio) -cplugins -cuda -debug -doc -drm -dvd -gamepad -gbm -jack -javascript -jpeg -libcaca -libmpv -luajit -openal -oss (-raspberry-pi) -rubberband -samba -sdl (-selinux) -test -tools -vulkan -zimg" ABI_X86="(64)" PYTHON_TARGETS="python3_7 -python3_6"
Yeah, looking at the wscript the only option depending on libplacebo is vulkan (does indeed seem to be the case looking at the source). But it doesn't automatically use --disable-libplacebo if vulkan is unused so I guess the ebuild has to do it when USE=-vulkan for now (I don't think placebo needs its own USE).
Please also submit the full build.log
Created attachment 618088 [details] build log after `emerge -1 libplacebo; USE=-vulkan FEATURES=keeptemp emerge -1 mpv` Oh, of course.
Seems like libplacebo could just be bind to the vulkan use flag.
fixed.