https://archives.gentoo.org/gentoo-pms/message/8f6bc33166d958ea760ebac4e220c7fd > If it should turn out that information about applied user's patches > will be needed, a query function (that could even show a list of > applied patches, like perl -V does) can be added later. This will be > something for EAPI 7, though. I am not aware of any current requests for including such a feature in the next EAPI. This bug is merely a placeholder so it won't be forgotten.
There appears to be no interest in such a feature. Closing.