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

Calculating dependencies ... done!
Dependency resolution took 1.03 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/cJSON-1.7.19::gentoo  USE="-test" 348 KiB
[ebuild  N     ] net-misc/iperf-3.21:3::gentoo  USE="-sctp" 695 KiB

Total: 2 packages (2 new), Size of downloads: 1043 KiB