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

Calculating dependencies ... done!
Dependency resolution took 1.03 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/libconfig-1.8.2:0/15::gentoo  USE="cxx -debug -static-libs -test" 3262 KiB
[ebuild  N     ] dev-perl/ExtUtils-PkgConfig-1.160.0-r1::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 10 KiB
[ebuild  N     ] dev-perl/Conf-Libconfig-1.0.3::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 50 KiB

Total: 3 packages (3 new), Size of downloads: 3321 KiB