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/nspr-4.40::gentoo  USE="-debug" 986 KiB
[ebuild  N     ] dev-libs/nss-3.131::gentoo  USE="utils -cacert -test -test-full" CPU_FLAGS_X86="avx2 sse3" 85996 KiB
[ebuild  N     ] dev-libs/nss-pem-1.1.1::gentoo  41 KiB

Total: 3 packages (3 new), Size of downloads: 87023 KiB