just curious, as I was always told, would this cause another array copy operation (next to the one done by array_filter)?

would this cause another array copy operation (next to the one done by array_filter)?

I think so. array_values uses zend_array_to_list. It creates a new array and adds all values in a loop.

But without array_values we don't have a list. And we pass the array to methods requiring a list. The methods also work with non-list array, but phpdoc says they want a list.

So I think we should either actually passing lists or relaxing the param type to array. I think it is ok to use array_values in the given cases.

I think so. array_values uses zend_array_to_list. And it creates a new array and adds all values in a loop.

But note that zend_array_to_list is only called if it is not already a list.

Thank you for the detailed explanation and reasoning.