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

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

[ebuild  N     ] dev-libs/jansson-2.15.1:0/4::gentoo  USE="-doc -static-libs" 478 KiB
[ebuild  N     ] app-arch/snappy-1.2.2-r1:0/1.1::gentoo  USE="-test" CPU_FLAGS_X86="avx avx2" 1083 KiB
[ebuild  N     ] dev-libs/avro-c-1.12.0-r1::gentoo  214 KiB
[ebuild  N     ] dev-libs/libserdes-5.4.0-r2::gentoo  61 KiB

Total: 4 packages (4 new), Size of downloads: 1835 KiB