Let's not revert before we understand.

@fabpot a stacktrace from the original issue would be helpful :) there are a few possible known suspects:https://github.com/symfony/symfony/search?l=PHP&q=%22Class+%25s+used+for+service+%25s+cannot+be+found.%22

the rationale isnt 100% clear to me, i.e. why exactly didnt we detect\Foo\Bar vs.Foo\Bar at an early stage? We had some discussion about it when introducingResolveClassPass i believe.

Now, some passes will benefit from#33111 when running "before removing" (e.g.AddConsoleCommandPass) whereas others will benefit from#33092 (e.g.RegisterEnvVarProcessorsPass).

So we may have somewhat of a chicken/egg situation, nevertheless the behavior change is real.

I guess the user may process such service IDs themselves (so we are as preservative as possible). For reproducible builds we don't involve class_exists (correct me if im wrong), as such we would make a big assumption on service IDs. Hence we provide an error as late as possible.

why we dont consider \Foo\Bar vs. Foo\Bar equal. We had some discussion about it when introducing ResolveClassPass i believe

I can answer that: because we do not want any normalization logic around ids. We got rid of any when making them case sensitive and that reduced the complexity by a nice margin. We do not want to introduce it again in a different flavor.

sorry, ive updated my comment :) basically, why didnt we do#33092 when introducing ResolveClassPass

the discussion im recalling is#28006, same topic really 😅