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

Calculating dependencies ... done!
Dependency resolution took 1.02 s (backtrack: 0/20).

[ebuild  N     ] x11-misc/clipnotify-1.0.2::gentoo  2 KiB
[ebuild  N     ] x11-misc/xsel-1.2.1::gentoo  51 KiB
[ebuild  N     ] x11-misc/dmenu-5.4::gentoo  USE="-savedconfig -xinerama" 17 KiB
[ebuild  N     ] x11-misc/clipmenu-6.2.0-r1::gentoo  USE="dmenu -fzf -rofi" 9 KiB

Total: 4 packages (4 new), Size of downloads: 78 KiB