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

Calculating dependencies ... done!
Dependency resolution took 1.04 s (backtrack: 0/20).

[ebuild  N     ] net-libs/libslirp-4.9.3::gentoo  USE="-static-libs -valgrind" 131 KiB
[ebuild  N     ] app-containers/slirp4netns-1.3.5::gentoo  64 KiB

Total: 2 packages (2 new), Size of downloads: 195 KiB