👍 LGTM

@nicolasgrekas This change together with #21873 could lead to confusing behaviour (see my comment there), couldn't it?

@xabbuh to me, this change doesn't introduce any new behavior, thus can't lead to anything new in #21873: even without this PR, autoregistered services have always been valid by-type candidates for autowiring.

The difference is that you may want to register a service named Foo\Bar explicitly now that the id defaults to the class name. So you will get an error when you forget to register it. But with this change Foo\Bar could be created implicitly depending on whether another autowired service triggered the auto registration.

OK - and since this change now misses a purpose (I don't think I need it anymore now that I'm working on another approach) - I'm closing. Thanks for the feedback.

The behaviour is:

• If you have a Foo\Bar service already registered, then the PSR-4 loading won't auto-register a new Foo\Bar service
• If a Foo\Bar service has been auto-registered by a PSR-4 loading and you re-declare a new Foo\Bar later on, you override the service as expected

@nicolas-grekas could you confirm that this is correct or I misunderstood the change? (And if that's correct then @xabbuh I'm not sure to see what's confusing)

@theofidry this is not related to psr4, but to autoregistration of type-hints as services - @xabbuh is correct :)