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

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] sci-libs/dmlc-core-0_p20170719-r1::gentoo  USE="openmp -doc -s3 -test" 157 KiB

Total: 1 package (1 new), Size of downloads: 157 KiB