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

Calculating dependencies ... done!
Dependency resolution took 0.97 s (backtrack: 0/20).

[ebuild  N     ] games-engines/box2d-2.4.2::gentoo  USE="-doc -test" 1208 KiB

Total: 1 package (1 new), Size of downloads: 1208 KiB