Fix bug in classExists when using multiple autoloaders (i.e. ZF2)

[bramstroker]

The autoloading routine in the classExists method makes the assumption the autoload method always returns a value (i.e. no void) when the autoloading of a class is succesfull. When you have multiple autoloaders registered to the spl stack this can lead to problems. In my case I'm using ZF2 ClassmapAutoloader and StandardAutoloader as fallback. The classmapAutoloader returns nothing so the autoload method in the StandardAutoloader is called as well, because the for loop is continued. This results in a second include, and a fatal error "Cannot redeclare class" is triggered.

[schmittjoh]

Loaders that you pass to the AnnotationRegistry must return a boolean.

However, you can easily wrap the Zend autoloader instead of passing it directly:

AnnotationRegistry::registerLoader(function($name) use ($zendLoader) { 
    $zendLoader->autoload();

    return class_exists($name, false);
});

[Fgruntjes]

The problem has nothing to do with the AnnotationRegistry. Its the fact that Doctrine\Common\ClassLoader::classExists() uses spl_autoload_functions() to see if it can load a class. In my application we have multiple ZF2 autoloaders registered with spl_autoload_register(). This function does not dictate a return value however the Doctrine\Common\ClassLoader::classExists() does not work properly if there are auto load methods / functions registered without a return value.

[schmittjoh]

Ups, I was too fast here!

Sorry :)

[Ocramius]

This was handled in #216