As pointed out in Bug 98465, the missing functionality to use.mask single packages on single architectures leads to unreasonable use flag additions, limiting the usability of portage.
Since geoman mentioned it would be unclear what I want to propose... I assumed it would be natural to extend the use.mask files in the following way: foo would still mean to mask use flag foo for the specific profile foo:cat1/pkg1,cat2,pkg2,... would mask single flag|pkg combinations
I'd rather see a package.use.mask rather than use.mask for this, although any support would be good ;) package.use.mask compliments package.use IMHO.
we're talking about profiles here, not local /etc/portage/ ... considering we already use the 'use.mask' name in profiles, no point in changing it now
Putting a hold on feature requests for portage as they are drowning out the bugs. Most of these features should be available in the next major version of portage. But for the time being, they are just drowning out the major bugs and delaying the next version's progress. Any bugs that contain patches and any bugs for etc-update or dispatch-conf can be reopened. Sorry, I'm just not good enough with bugzilla. ;)
Fixed by now
>=portage-2.1.1 has support for use.force, package.use.force, and package.use.mask. The behavior has changed slightly in 2.1.2 for bug #151586.