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 "=sys-libs/musl-9999" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-libs/musl-9999::gentoo (masked by: package.mask, missing keyword)
/Volumes/Disk 1/Repository/portage-git/profiles/base/package.mask:
# Sam James <sam@gentoo.org> (2022-09-10)
# Mask in general and unmask on specific profiles


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