[Udo]

It would be trivial to write a command line tool to check (and maybe automatically fix) those typos. Incorporating it into a major new version also ensures everybody has enough time to prepare - and in case of hopeless and unfixable legacy apps: there is always the option not to upgrade.

Breaking changes in programming languages are not that uncommon, C# and Perl spring to mind from personal experience, but also to a lesser degree such things have happened with PHP itself (and it became better for it). In this case, it's actually a change that moves the runtime's behavior closer to what's expected. It's a change that improves internal consistency while also eliminating silly bugs like the one discussed here.

[Xylakant]

I'm not against changing that behavior since it's arguably stupid and inconsistent [1], but I'm wary of "trivial" changes. It's not only apps that need fixing, pretty much every library needs checking (and maybe fixing). This cannot be done with a commandline check, since classnames can be constructed on the fly, called via eval() or call_user_func() etc. Class names may be loaded or even defined on the fly (the SOAP Pear Extension does this to create proxies). All those cases can only be checked by executing the program. It's probably a good change, but this is anything but trivial.

[1] actually, I don't care at all since I moved on to greener pastures.