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

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

[ebuild  N     ] app-arch/cpio-2.15::gentoo  USE="nls" 1613 KiB
[ebuild  N     ] app-alternatives/cpio-0::gentoo  USE="gnu (split-usr) -libarchive" 0 KiB
[ebuild  N     ] sys-kernel/vanilla-sources-7.3.0:7.3.0::gentoo  USE="-build -symlink -vanilla" 158594 KiB

Total: 3 packages (3 new), Size of downloads: 160206 KiB