Prevent infinite loops

src/Runtime/LoopContext.php

@@ -105,6 +105,10 @@ final class LoopContext
 
     public function __invoke($iterator): \Generator
     {
+        if ($this->depth > 50) {
+            throw new \RuntimeException('Nesting level too deep.');
+        }
+
         yield from ($this->recurseFunc)(new LoopIterator($iterator), $this->parent, $this->blocks, $this->recurseFunc, $this->depth + 1);
     }
 

tests/Fixtures/tags/for/infinite_resursion.test

@@ -0,0 +1,15 @@
+--TEST--
+"for" tags prevents infinite recursions
+--TEMPLATE--
+{% for item in sitemap %}
+    {{ loop(sitemap) }}
+{% endfor %}
+--DATA--
+return [
+    'sitemap' => [
+        [ 'title' => 'foo' ],
+        [ 'title' => 'bar' ],
+    ],
+]
+--EXCEPTION--
+Twig\Error\RuntimeError: An exception has been thrown during the rendering of a template ("Nesting level too deep.") in "index.twig" at line 3.