--TEST-- Non-ref generators cannot be iterated by-ref --FILE-- <?php function gen() { yield; } $gen = gen(); foreach ($gen as &$value) { } ?> --EXPECTF-- Fatal error: Uncaught exception 'Exception' with message 'You can only iterate a generator by-reference if it declared that it yields by-reference' in %s:%d Stack trace: #0 %s(%d): unknown() #1 {main} thrown in %s on line %d