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

Calculating dependencies ... done!
Dependency resolution took 1.04 s (backtrack: 0/20).

[ebuild  N     ] dev-perl/IO-All-0.870.0-r1::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 76 KiB
[ebuild  N     ] virtual/jpeg-100-r1::gentoo  USE="-static-libs" 0 KiB
[ebuild  N     ] sci-libs/hdf-4.2.15-r2::gentoo  USE="-examples -fortran -static-libs -szip -test" 3570 KiB
[ebuild  N     ] dev-perl/ExtUtils-Depends-0.800.200::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 17 KiB
[ebuild  N     ] dev-perl/Alien-HDF4-0.60.0::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 4 KiB

Total: 5 packages (5 new), Size of downloads: 3666 KiB