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-libs/stb-20260415-r1::gentoo  1481 KiB
[ebuild  N     ] media-libs/zint-2.16.0:0/2.16::gentoo  USE="png -gui -test" 6273 KiB
[ebuild  N     ] media-libs/zxing-cpp-3.1.1:0/4::gentoo  USE="-test -tools" 1591 KiB

Total: 3 packages (3 new), Size of downloads: 9344 KiB