[php-src] Issue #7952: `CallbackFilterIterator` is not rewound by default/initialized

Issue: https://github.com/php/php-src/issues/7952 Comment Author: damianwadley This is correct as far as I know: iterators do not promise that they are rewound and valid when constructed, and are generally in an undefined state (though individual iterator classes may decide otherwise). If they did, ones that invoke code like CallbackIterator or Generator would have to immediately execute on construction. ArrayIterator doesn't have side effects like that so it could start in a valid state, but it could just as easily have not been implemented that way. Standard pattern has always been that if you want to use an iterator then you use it the same way that foreach does: rewind() to start, valid() to check the iterator is in a valid state, next() to advance, and repeat until no longer valid. How do you feel about making this a documentation bug? This "you are supposed to rewind before using an iterator" issue has been raised before but AFAIK never really been spelled out in the docs.