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

Calculating dependencies ... done!
Dependency resolution took 0.96 s (backtrack: 0/20).

[ebuild  N     ] dev-perl/perl-headers-0.0.2::gentoo  USE="debug sizeof-warning" 3 KiB

Total: 1 package (1 new), Size of downloads: 3 KiB