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

Calculating dependencies ... done!
Dependency resolution took 1.06 s (backtrack: 0/20).

[ebuild  N     ] acct-group/apt-cacher-ng-0-r2::gentoo  0 KiB
[ebuild  N     ] acct-user/apt-cacher-ng-0-r2::gentoo  0 KiB
[ebuild  N     ] net-misc/apt-cacher-ng-3.7.4_p1-r2::gentoo  USE="-doc -fuse (-selinux) (-systemd) -tcpd" 513 KiB

Total: 3 packages (3 new), Size of downloads: 513 KiB