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

Calculating dependencies ... done!
Dependency resolution took 1.08 s (backtrack: 0/20).

[ebuild  N     ] acct-group/epmd-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/epmd-0-r3::gentoo  0 KiB
[ebuild  N     ] dev-lang/erlang-29.0:0/29.0::gentoo  USE="kpoll ssl -doc -java -odbc -sctp (-systemd) -tk -wxwidgets" 65437 KiB
[ebuild  N     ] dev-util/rebar-2.6.4-r1::gentoo  209 KiB
[ebuild  N     ] dev-erlang/hamcrest-0.1.0_p20160709::gentoo  USE="-test" 157 KiB

Total: 5 packages (5 new), Size of downloads: 65802 KiB