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-libs/libXcomposite-0.4.7::gentoo  USE="-doc" 267 KiB
[ebuild  N     ] x11-libs/libXtst-1.2.5::gentoo  USE="-doc" 285 KiB
[ebuild  N     ] x11-apps/xdpyinfo-1.3.4::gentoo  USE="-dga (-dmx) -xinerama" 134 KiB

Total: 3 packages (3 new), Size of downloads: 685 KiB