#[AsMessageHandler] on abstract classes produces untagged services

[possi]

Example:

abstract class AbstractHandler implements MessageHandlerInterface {

}
class ExampleHandler extends AbstractHandler {
  // ...
}

Thanks to symfony-frameworks registerForAutoconfiguration the ExampleHandler is tagged as messenger.message_handler, as the class (indirect) implements the interface.

---

Result after rector:

#[AsMessageHandler]
abstract class AbstractHandler {
  // ...
}
class ExampleHandler extends AbstractHandler {
  // ...
}

No service gets tagged:

• abstract classes aren't considered a service, and therefore no tagging is happening
• the ExampleHandler has no attribute to it and doesn't get the tag added.

---

Possible solution:

I would recommend to add final to all modified classes. This prevents extending a message handler service and expecting to automaticly get tagged. Any wrong usages are instantly visible.
Just skipping abstract classes wouldn't be sufficient, as some may also extend a non abstract service.