It appears that dev-java/xsd2jibx required xsdlib (at least for building) but does not depend on it. The package dev-java/relaxng-datatype is also required, but that's a dependency of xsdlib so I don't think it should be added to xsd2jibx.
Please provide a failing build.log. Works fine here.
While reproducing I found out that xsd2jibx depends on xsdlib indirectly through dev-java/jibx, so this shouldn't happen. Dunno why it happened here. Anyway, the failure is reproducible on my system (when xsdlib is not around) so I can provide a build.log if still needed.
(In reply to comment #2) > While reproducing I found out that xsd2jibx depends on xsdlib indirectly > through dev-java/jibx, so this shouldn't happen. Dunno why it happened here. > > Anyway, the failure is reproducible on my system (when xsdlib is not around) so > I can provide a build.log if still needed. > Of course stuff breaks when you remove something from the dep chain. Portage does not do a deep scan to the dependencies by default so it won't warn you.