Make sure empty cases work fine

Author: ndossche

ext/spl/spl_iterators.c

@@ -3064,7 +3064,8 @@ static zend_result spl_iterator_zip_valid(zend_object_iterator *iter)
 {
 	spl_zip_iterator *zip_iterator = (spl_zip_iterator *) iter;
 
-	for (uint32_t i = 0; i < zip_iterator->iterator_count; i++) {
+	uint32_t i = 0;
+	for (; i < zip_iterator->iterator_count; i++) {
 		spl_zip_iterator_entry *current = &zip_iterator->iterators[i];
 		if (spl_zip_iterator_is_obj_entry(current)) {
 			if (current->obj_iter->funcs->valid(current->obj_iter) != SUCCESS) {
@@ -3078,7 +3079,7 @@ static zend_result spl_iterator_zip_valid(zend_object_iterator *iter)
 		}
 	}
 
-	return SUCCESS;
+	return i > 0 ? SUCCESS : FAILURE;
 }
 
 /* Invariant: returned array is packed and has all UNDEF elements. */

ext/spl/tests/iterator_zip.phpt

@@ -3,6 +3,12 @@ iterator_zip
 --FILE--
 <?php
 
+foreach (iterator_zip() as $_) {} // FIXME
+
+foreach (iterator_zip([]) as $x) {
+    var_dump($x);
+}
+
 $a = [1, 2, 3];
 $b = [4, 5, 6];