HHH-18489 Lazy, unowned one-to-one associations get loaded eagerly in queries - even with bytecode enhancement

[dreab8]

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https://hibernate.atlassian.net/browse/HHH-18489

[yrodiere]

Thanks. LGTM as long as this passes the test, but I noticed what could be a bug; see below.

[dreab8]

@yrodiere I applied your suggestions. What do you think?

[yrodiere]

I'm not familiar with that area of the code, but as far as I can tell it makes sense, thank you.

Do you think this can reasonably be backported to 6.6? ("no" is fine by me, I'm just asking)

[dreab8]

@yrodiere this is the 6.6 bakport

[yrodiere]

Thanks!

So we would be good to merge, but... s390x tests are failing, which may be caused by this PR since the failures on main are different:

• main: https://github.com/hibernate/hibernate-orm/runs/30073259548
• This PR: https://github.com/hibernate/hibernate-orm/pull/8812/checks?check_run_id=29606108080

[dreab8]

not sure how the changes in this PR may affect the failing test, trying to re-run the job

[sebersole]

lgtm. thanks!

[jimsimon-wk]

@dreab8 I think I may have found a regression with lazy loaded one-to-one associations. I was able to see some test failures by running the tests in this PR with @BytecodeEnhanced(runNotEnhancedAsWell = true). I put up a branch here to demonstrate that

I encountered these failures when upgrading to Hibernate 6.6 (coming from 6.5) when trying to load models that had lazy one-to-one relationships defined. Additionally, I noticed that the failures were still happening even when I eager-fetched those relations.

The exception I hit my application was

hibernate-orm/hibernate-core/src/main/java/org/hibernate/engine/internal/ManagedTypeHelper.java

Line 285 in f0f9691

throw new ClassCastException( "Object of type '" + entity.getClass() + "' can't be cast to PersistentAttributeInterceptable" );

I confirmed that enabling bytecode enhancements fixes the exception in my application when using Hibernate 6.6

Please let me know if you'd like to see this issue created as a ticket

[jimsimon-wk]

@sebersole @yrodiere forgot to ping some other members of the Hibernate team on the comment above

[yrodiere]

@jimsimon-wk Tests in this PR would be expected to fail if bytecode enhancement is disabled, because lazy-loaded one-to-one associations can only work with bytecode enhancement.

Now, lazy-loaded one-to-one associations should not make you application fail if you don't have bytecode enhancement -- these associations should just degrade gracefully into being loaded eagerly.

If you can write a reproducer based on https://github.com/hibernate/hibernate-test-case-templates/blob/main/orm/hibernate-orm-6/ where having a lazy-loaded one-to-one association in your model makes Hibernate ORM throw a ClassCastException, then yes, please create an issue and provide that reproducer.

[jimsimon-wk]

@yrodiere This should do the trick: #9560