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

Calculating dependencies ... done!
Dependency resolution took 1.49 s (backtrack: 0/20).

[ebuild     U  ] virtual/libudev-257:0/1::gentoo [251-r2:0/1::gentoo] USE="(-systemd)" 0 KiB

Total: 1 package (1 upgrade), Size of downloads: 0 KiB