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

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

[ebuild  N     ] dev-perl/Symbol-Util-0.20.300-r2::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 28 KiB
[ebuild  N     ] dev-perl/constant-boolean-0.20.0-r2::gentoo  PERL_FEATURES="ithreads (-debug) -quadmath" 14 KiB

Total: 2 packages (2 new), Size of downloads: 41 KiB