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-devel/gcc-9.5.0" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-devel/gcc-9.5.0::gentoo (masked by: package.mask)
/Volumes/Disk 1/Repository/portage-git/profiles/package.mask:
# Sam James <sam@gentoo.org> (2024-09-30)
# GCC 12 and older no longer receive upstream support or fixes for
# bugs. Please switch to a newer GCC version using gcc-config.
#
# The earliest supported version of GCC is GCC 13, but 11/12 remain unmasked
# for now to ease sys-devel/gcc[d] bootstrapping.


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