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

Calculating dependencies ... done!
Dependency resolution took 0.85 s (backtrack: 0/20).


!!! All ebuilds that could satisfy "=dev-cpp/eigen-5.0.9999" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-cpp/eigen-5.0.9999::gentoo (masked by: package.mask, missing keyword)
/Volumes/Disk 1/Repository/portage-git/profiles/package.mask:
# Paul Zander <negril.nx+gentoo@gmail.com> (2025-10-17)
# to many breakages


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