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

Calculating dependencies ... done!
Dependency resolution took 1.02 s (backtrack: 0/20).

[ebuild  N     ] acct-group/postgres-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/pgbouncer-0-r2::gentoo  0 KiB
[ebuild  N     ] dev-db/pgbouncer-1.23.1::gentoo  USE="c-ares pam ssl -debug -doc (-systemd)" 684 KiB

Total: 3 packages (3 new), Size of downloads: 684 KiB