[native-image] @Deleted classes

[Vinche59]

Hello,

I use an old library who heavily use java.util.Calendar$Builder.build making java.util.JapaneseImperialCalendar type reacheable during compilation and this class is marked @deleted by GraalVM in CalendarSubstitutions.java

I'd want to know if there's a mechanism to "Undelete" a @deleted class when building a native image with GraalVM (without using --report-unsupported-elements-at-runtime option) ?

[zakkak]

HI @Vinche59, my understanding is that those are marked as @deleted because they are essentially not supported. Even if there was a way to "Undelete" them your application would probably fail if they ever got reached, that said using --report-unsupported-elements-at-runtime is probably a safer way to handle this, since it will throw an exception if the corresponding classes get reached.

Unfortunately though --report-unsupported-elements-at-runtime is discouraged in production code, and also makes it harder to detect other issues in your native-image.

[Vinche59]

Hello @zakkak
Thanks for the answer.

Yes it's what I was afraid of... So I will refactor and try to drop that library.

Just for info (as I see you quite active in Quarkus project also), I don't succeed to compile with --report-unsupported-elements-at-runtime option under Quarkus. As soon as I add this option, I've got compile errors in native (mostly NoClassDefFound errors) and as you said this option is discourage in production code :-)

[zakkak]

@Vinche59 that sounds a lot like #1725
So the work around would be to manually add the missing dependencies like in quarkusio/quarkus#6327 (comment)

As you can see it's a bit of a slippery slope so if you can avoid the said library it would be best :)

Please open an issue at https://github.com/quarkusio/quarkus or start a discuss at quarkusio.zulipchat.com/ if you need more help.