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

Calculating dependencies ... done!
Dependency resolution took 1.00 s (backtrack: 0/20).

[ebuild  N     ] dev-perl/ExtUtils-CppGuess-0.270.0::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 16 KiB
[ebuild  N     ] dev-perl/ExtUtils-XSpp-0.190.0::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 184 KiB
[ebuild  N     ] dev-perl/Module-Build-WithXSpp-0.140.0-r1::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 14 KiB

Total: 3 packages (3 new), Size of downloads: 213 KiB