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

Calculating dependencies ... done!
Dependency resolution took 0.97 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/jthread-1.3.3-r1:0/1.3.3::gentoo  9 KiB

Total: 1 package (1 new), Size of downloads: 9 KiB