mictlan ~ # emerge -vauDN --tree @world 

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!

emerge: there are no ebuilds to satisfy "media-gfx/potrace".
(dependency required by "media-gfx/imagemagick-7.1.0.17::media-kit[svg]" [ebuild])
(dependency required by "x11-wm/awesome-4.3::desktop-kit" [ebuild])(dependency required by "@selected" [set])
(dependency required by "@world" [argument])