Fix GH-21583: SimpleXML empty element incorrectly casts to true.

Author: devnexen

ext/simplexml/simplexml.c

@@ -1843,12 +1843,7 @@ static zend_result sxe_object_cast_ex(zend_object *readobj, zval *writeobj, int
 	sxe = php_sxe_fetch_object(readobj);
 
 	if (type == _IS_BOOL) {
-		node = php_sxe_get_first_node_non_destructive(sxe, NULL);
-		if (node) {
-			ZVAL_TRUE(writeobj);
-		} else {
-			ZVAL_BOOL(writeobj, !sxe_prop_is_empty(readobj));
-		}
+		ZVAL_BOOL(writeobj, !sxe_prop_is_empty(readobj));
 		return SUCCESS;
 	}
 

ext/simplexml/tests/000.phpt

@@ -221,7 +221,7 @@ object(SimpleXMLElement)#%d (1) {
 }
 ===sxe->elem11->elem111->elem1111
 bool(true)
-bool(true)
+bool(false)
 int(1)
 object(SimpleXMLElement)#%d (0) {
 }

ext/simplexml/tests/gh21583.phpt

@@ -0,0 +1,18 @@
+--TEST--
+GH-21583 (SimpleXML empty element incorrectly casts to true)
+--EXTENSIONS--
+simplexml
+--FILE--
+<?php
+$xml = new SimpleXMLElement('<foo><bar/><baz attr="val"/><qux>text</qux></foo>');
+
+var_dump((bool) $xml->bar);
+var_dump((bool) $xml->baz);
+var_dump((bool) $xml->qux);
+var_dump((bool) $xml->nonexistent);
+?>
+--EXPECT--
+bool(false)
+bool(true)
+bool(true)
+bool(false)