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

Calculating dependencies ... done!
Dependency resolution took 1.00 s (backtrack: 0/20).

[ebuild  N     ] dev-cpp/xsimd-14.0.0::gentoo  USE="-doc -test" 300 KiB

Total: 1 package (1 new), Size of downloads: 300 KiB