Update Twig to v2.15.4

system/libs/Twig/NodeTraverser.php

@@ -11,6 +11,7 @@
 
 namespace Twig;
 
+use Twig\Node\Node;
 use Twig\NodeVisitor\NodeVisitorInterface;
 
 /**
@@ -18,14 +19,12 @@ use Twig\NodeVisitor\NodeVisitorInterface;
  *
  * It visits all nodes and their children and calls the given visitor for each.
  *
- * @final
- *
  * @author Fabien Potencier <fabien@symfony.com>
  */
-class NodeTraverser
+final class NodeTraverser
 {
-    protected $env;
-    protected $visitors = [];
+    private $env;
+    private $visitors = [];
 
     /**
      * @param NodeVisitorInterface[] $visitors
@@ -45,10 +44,8 @@ class NodeTraverser
 
     /**
      * Traverses a node and calls the registered visitors.
-     *
-     * @return \Twig_NodeInterface
      */
-    public function traverse(\Twig_NodeInterface $node)
+    public function traverse(Node $node): Node
     {
         ksort($this->visitors);
         foreach ($this->visitors as $visitors) {
@@ -60,24 +57,23 @@ class NodeTraverser
         return $node;
     }
 
-    protected function traverseForVisitor(NodeVisitorInterface $visitor, \Twig_NodeInterface $node = null)
+    /**
+     * @return Node|null
+     */
+    private function traverseForVisitor(NodeVisitorInterface $visitor, Node $node)
     {
-        if (null === $node) {
-            return;
-        }
-
         $node = $visitor->enterNode($node, $this->env);
 
         foreach ($node as $k => $n) {
-            if (null === $n) {
-                continue;
-            }
-
             if (false !== ($m = $this->traverseForVisitor($visitor, $n)) && null !== $m) {
                 if ($m !== $n) {
                     $node->setNode($k, $m);
                 }
             } else {
+                if (false === $m) {
+                    @trigger_error('Returning "false" to remove a Node from NodeVisitorInterface::leaveNode() is deprecated since Twig version 2.9; return "null" instead.', \E_USER_DEPRECATED);
+                }
+
                 $node->removeNode($k);
             }
         }