BC break: 2.7.2 => v2.8.0: Proxy generation: embedded documents can no longer be marked final

[Bilge]

⚠️ Full disclosure: I use doctrine/mongodb, not the One True Reference Implementation, ORM; in case that makes a difference.

Although it has never been possible to mark "root" documents final, embedded documents may be marked final since they are embedded inside other classes when generating proxies. Since 2.8.0, however, the following error is thrown where Foo is an @ODM\EmbeddedDocument class.

[Doctrine\Common\Proxy\Exception\InvalidArgumentException]
Unable to create a proxy for a final class "Foo".

[alcaeus]

Are you sure this worked for doctrine/common 2.7? ODM has always generated proxies for embedded documents (which I'm not sure makes sense), so I'd expect this would fail for 2.7 as well?

[Bilge]

@alcaeus The only thing I'm sure of is that it worked before this composer install (non-Doctrine projects omitted for brevity):

  - Updating doctrine/cache (v1.6.1 => v1.7.0): Downloading (100%)
  - Updating doctrine/collections (v1.4.0 => v1.5.0): Downloading (100%)
  - Updating doctrine/inflector (v1.1.0 => v1.2.0): Downloading (100%)
  - Updating alcaeus/mongo-php-adapter (1.1.1 => 1.1.2): Downloading (100%)
  - Updating doctrine/annotations (v1.4.0 => v1.5.0): Downloading (100%)
  - Updating doctrine/common (v2.7.2 => v2.8.0): Downloading (100%)
  - Updating doctrine/mongodb (1.5.0 => 1.6.0): Downloading (100%)

[alcaeus]

That's very strange. Could you provide a trace to the error above? I'd like to see what's responsible for trying to create a proxy for an embedded document. Couldn't find anything at first try.

[Bilge]

Sorry but an image is the best I can do...

[alcaeus]

Thanks for the trace I now see what's going on.

#771 introduced a sanity check to ensure no invalid classes will be generated. I wouldn't call that a BC break, since instantiating such a proxy object would always cause a fatal error.

The fix should be ODM not generating proxy objects for embedded documents, since they won't be needed, ever. I wouldn't revert the change here, as the issue is purely within ODM. I've created doctrine/mongodb-odm#1627 to track this, which will be fixed in 1.1.6. Until then I'd have to ask you to make your embedded documents non-final until we properly fix the issue.

Closing to move discussion to ODM where the bug has its roots.

[Bilge]

Thanks @alcaeus! We've already made those documents non-final, since we've learned it's usually impractical to wait for the next Doctrine release ;)

[alcaeus]

I'll only take slight offence at that ;)