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

Calculating dependencies ... done!
Dependency resolution took 1.54 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/luajit-2.1.1787165859:2/2.1.1787165859::gentoo  USE="-lua52compat -static-libs" 1078 KiB
[ebuild     U  ] dev-libs/libuv-1.53.0:0/1::gentoo [1.51.0-r1:0/1::gentoo] USE="-verify-sig" 1359 KiB
[ebuild  N     ] dev-lua/luv-1.52.1.0::gentoo  USE="-test" LUA_SINGLE_TARGET="luajit -lua5-1 -lua5-3 -lua5-4" 269 KiB

Total: 3 packages (1 upgrade, 2 new), Size of downloads: 2706 KiB