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

Calculating dependencies ... done!
Dependency resolution took 0.99 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/ocaml-4.14.2:0/4.14.2::gentoo  USE="ocamlopt -emacs -flambda -latex -xemacs" 5377 KiB
[ebuild  N     ] dev-ml/dune-3.23.1:0/3.23.1::gentoo  USE="-emacs -test" 3624 KiB
[ebuild  N     ] dev-ml/ocaml-migrate-parsetree-2.4.0-r1:0/2.4.0::gentoo  USE="ocamlopt -test" 203 KiB

Total: 3 packages (3 new), Size of downloads: 9203 KiB