It's not required for eclasses to use guards to die on unknown EAPIs, so we should compare the @SUPPORTED_EAPIS eclassdoc with the current EAPI used in an inheriting ebuild.
I think this is already implemented as UnsupportedEclassEapi under EapiCheck? https://pkgcore.github.io/pkgcheck/man/pkgcheck.html#unsupportedeclasseapi
(In reply to Arthur Zamarin from comment #1) > I think this is already implemented as UnsupportedEclassEapi under EapiCheck? > > https://pkgcore.github.io/pkgcheck/man/pkgcheck.html#unsupportedeclasseapi Oh my, yes!