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

Calculating dependencies ... done!
Dependency resolution took 1.01 s (backtrack: 0/20).

[ebuild  N     ] x11-misc/dmenu-5.4::gentoo  USE="-savedconfig -xinerama" 17 KiB
[ebuild  N     ] x11-misc/j4-dmenu-desktop-3.2::gentoo  USE="dmenu -test" 123 KiB

Total: 2 packages (2 new), Size of downloads: 139 KiB