[pull] master from php:master

Zend/tests/gh21504.inc

@@ -0,0 +1,3 @@
+<?php
+
+'1234' |> var_dump(...);

Zend/tests/gh21504.phpt

@@ -0,0 +1,12 @@
+--TEST--
+GH-21504: Incorrect RC-handling for ZEND_EXT_STMT op1
+--FILE--
+<?php
+
+$php_escaped = getenv('TEST_PHP_EXECUTABLE_ESCAPED');
+$cmd = $php_escaped . ' -n -e ' . escapeshellarg(__DIR__ . '/gh21504.inc');
+echo shell_exec($cmd);
+
+?>
+--EXPECT--
+string(4) "1234"

Zend/zend_compile.c

@@ -1950,6 +1950,9 @@ static void zend_do_extended_stmt(znode* result) /* {{{ */
 
 	opline->opcode = ZEND_EXT_STMT;
 	if (result) {
+		if (result->op_type == IS_CONST) {
+			Z_TRY_ADDREF(result->u.constant);
+		}
 		SET_NODE(opline->op1, result);
 	}
 }

ext/dom/node.c

@@ -2132,7 +2132,7 @@ static void dom_relink_ns_decls_element(HashTable *links, xmlNodePtr node)
 
 				ns->_private = attr;
 				if (attr->prev) {
-					attr->prev = attr->next;
+					attr->prev->next = attr->next;
 				} else {
 					node->properties = attr->next;
 				}

ext/dom/tests/modern/xml/gh21548.phpt

@@ -0,0 +1,17 @@
+--TEST--
+GH-21548 (Dom\XMLDocument::C14N() emits duplicate xmlns declarations after setAttributeNS())
+--CREDITS--
+Toon Verwerft (veewee)
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$doc = Dom\XMLDocument::createFromString('<root xmlns="urn:a" attr="val"/>');
+$doc->documentElement->setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:ns1", "urn:a");
+
+echo $doc->C14N() . PHP_EOL;
+
+?>
+--EXPECT--
+<root xmlns="urn:a" xmlns:ns1="urn:a" attr="val"></root>