I was doing a @world update and after I came back to it virtualbox-modules failed because the kernel config had incompatible option (TRIM_UNUSED_KSYMS) set. It would be nice to have known this upfront so I could have fixed it before it was halfway through the update. Could you also check for the incompatible options in pkg_pretend?
This comes from linux-mod.eclass which I cannot change. Reassigning to eclass maintainers...
This is an impactfull change for which the discussion resulted in the decision not to move forward with this. https://archives.gentoo.org/gentoo-dev/message/f545d1f6aa4cfb5852aaff2b1c441e3c