@nicolas-grekas Thanks for your review, I’ll try to open the corresponding Doctrine bundle PR later today or this week; it’s mostly extension configuration and injecting the right config into the added array here. Depending on the feedback here I can expand either PR.

I don't think repurposing the target_entities configuration is a good thing. In the ORM, target entities work only in the mapping configuration for the targetEntity setting of relations. It does not work anywhere else. You cannot do $em->find(MyInterface::class, $id) and expect the interface to be resolved.
This PR is about emulating such find usage though.

Making the EntityValueResolver diverge from the behavior of the ORM while reusing the ORM configuration setting for that is likely to become a maintenance nightmare (as it ties this feature to the ORM feature, which could break it if the ORM changes things in its own feature)

I still think this makes sense. The diff is small enough and the linked issue explains the benefits quite well.
Attributes are about allowing more descriptive code, improving the DX, and here, I can see where the DX is improved.

You cannot do $em->find(MyInterface::class, $id)

Well, maybe that could be a feature request to the ORM?

As far as this PR is concerned, this is still very much decoupled from the ORM, so I don't think there is any risk (not to say the ORM won't remove a feature without extensive warnings / deprecations so again, no risk here).

Still 👍 to me.

@nicolas-grekas I agree! In my opinion resolve_target_entities and support for interfaces is not complete in Doctrine. We can define interfaces in relations, but we cannot use them in perfectly valid scenarios like MapEntity or AsEntityListener.

@stof Do you have any ideas or preferences on how to make entity interfaces in Doctrine and DoctrineBridge easier to work with?

Friendly ping @symfony/mergers

Thank you @NanoSector.