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

Calculating dependencies ... done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! All ebuilds that could satisfy "=dev-lang/mmix-20160804-r1" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-lang/mmix-20160804-r1::gentoo (masked by: mmix license(s))
A copy of the 'mmix' license is located at '/Volumes/Disk 1/Repository/portage-git/licenses/mmix'.


For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.