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-debug/valgrind-3.27.0::gentoo  USE="-mpi -verify-sig" 16889 KiB

Total: 1 package (1 new), Size of downloads: 16889 KiB