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-cpp/catch-1.12.2-r3:1::gentoo  USE="-test" 369 KiB

Total: 1 package (1 new), Size of downloads: 369 KiB