I wonder if when touching the code anyway it would make sense to actually implement __debugInfo(), like it is done for e.g. all the random engines, or HashContext (#14644). This would make internal classes behave more similar to userland classes.

Maybe we should add something to php/php-tasks for going through and adding that to every internal class? Right now I just want to get the subclasses to work, I'm not entirely sure what each parent class (SplFixedArray, in this case) should be returning

I think the "issue" is that there exists an object handler when it probably should not even be called and a proper __debugInfo() method be implemented which does the same thing.

And this would align the behaviour of internal and userland classes more like @TimWolla already mentionned.