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

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

[ebuild  N     ] sci-physics/clhep-2.4.7.1-r1:2/2.4.7.1::gentoo  USE="threads -doc -static-libs -test" 1201 KiB

Total: 1 package (1 new), Size of downloads: 1201 KiB