Fix generator being a cycle to itself

Author: bwoebi

Zend/tests/generators/gc_with_yield_from.phpt

@@ -0,0 +1,45 @@
+--TEST--
+Verify yield from on generators being properly cycle collected
+--FILE--
+<?php
+
+function root() {
+	global $gens; // create cyclic reference to root
+	try {
+		yield 1;
+	} finally {
+		var_dump($gens);
+	}
+}
+
+function gen($x) {
+	global $gens;
+	yield from $gens[] = $x ? gen(--$x) : root();
+}
+
+$gen = $gens[] = gen(2);
+var_dump($gen->current());
+unset($gen, $gens);
+print "collect\n";
+gc_collect_cycles();
+print "end\n";
+
+?>
+--EXPECT--
+int(1)
+collect
+array(4) {
+  [0]=>
+  object(Generator)#1 (0) {
+  }
+  [1]=>
+  object(Generator)#2 (0) {
+  }
+  [2]=>
+  object(Generator)#3 (0) {
+  }
+  [3]=>
+  object(Generator)#4 (0) {
+  }
+}
+end

Zend/zend_generators.c

@@ -220,10 +220,10 @@ static uint32_t calc_gc_buffer_size(zend_generator *generator) /* {{{ */
 
 		/* Yield from root references */
 		if (generator->node.children == 0) {
-			zend_generator *root = generator->node.ptr.root;
-			while (root != generator) {
+			zend_generator *child = generator, *root = generator->node.ptr.root;
+			while (root != child) {
+				child = child->node.parent;
 				size++;
-				root = zend_generator_get_child(&root->node, generator);
 			}
 		}
 	}
@@ -287,8 +287,8 @@ static HashTable *zend_generator_get_gc(zval *object, zval **table, int *n) /* {
 	if (generator->node.children == 0) {
 		zend_generator *child = generator, *root = generator->node.ptr.root;
 		while (root != child) {
-			ZVAL_OBJ(gc_buffer++, &child->std);
 			child = child->node.parent;
+			ZVAL_OBJ(gc_buffer++, &child->std);
 		}
 	}