I see one inconsistency here which might be confusing: Imagine having two definitions, one being autowired that triggers the auto registration of another service. The second definition is not autowired, but its constructor requires an argument whose type hint matches the note automatically registered definition. Do everything seems to work. But once you remove the autowired definition, the previously registered definition does not exist anymore. Thus letting the container build fail (that's no issue if we don't merge #21871).

Is this really related to #21871? I mean: autoregistered services are still valid by-type candidates, thus will trigger the behavior you describe with or without #21871. In fact, is there anything new here? Can't this happen already, with type hints instead of refs?

To me, that looks like an acceptable (and already accepted) edge case of autowiring - one situation where you need to make things explicit. Or is there something new I'm missing?

I'm working today on a better way to provide the target experience - at the loader level.
This PR is still usefull, but should be restricted to typed references as introduced in #21770
Thus, I'm closing here, and merging this one (after a few tweaks), within #21770.
@xabbuh let's continue this discussion on #21770 once I finish updating it, if they still apply there :)