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/libatomic_ops-7.10.0::gentoo  531 KiB
[ebuild  N     ] dev-libs/boehm-gc-8.2.12::gentoo  USE="large threads -cxx -static-libs" 1204 KiB
[ebuild  N     ] dev-scheme/stklos-2.10::gentoo  USE="threads" 10040 KiB

Total: 3 packages (3 new), Size of downloads: 11774 KiB