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

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

[ebuild  N     ] dev-libs/nspr-4.40::gentoo  USE="-debug" 986 KiB
[ebuild  N     ] dev-libs/nss-3.125::gentoo  USE="utils -cacert -test -test-full" CPU_FLAGS_X86="avx2 sse3" 76727 KiB

Total: 2 packages (2 new), Size of downloads: 77712 KiB