Merge branch '1.x' into 2.x

* 1.x:
  updated CHANGELOG
  Throw exception on circular reference detection

CHANGELOG

@@ -75,7 +75,7 @@
 
 * 1.34.5 (2017-XX-XX)
 
- * n/a
+ * added circular reference detection when loading templates
 
 * 1.34.4 (2017-07-04)
 

lib/Twig/Environment.php

@@ -42,6 +42,7 @@ class Twig_Environment
     private $runtimeLoaders = array();
     private $runtimes = array();
     private $optionsHash;
+    private $loading = array();
 
     /**
      * Constructor.
@@ -382,7 +383,19 @@ class Twig_Environment
         // to be removed in 3.0
         $this->extensionSet->initRuntime($this);
 
-        return $this->loadedTemplates[$cls] = new $cls($this);
+        if (isset($this->loading[$cls])) {
+            throw new Twig_Error_Runtime(sprintf('Circular reference detected for Twig template "%s", path: %s.', $name, implode(' -> ', array_merge($this->loading, array($name)))));
+        }
+
+        $this->loading[$cls] = $name;
+
+        try {
+            $this->loadedTemplates[$cls] = new $cls($this);
+        } finally {
+            unset($this->loading[$cls]);
+        }
+
+        return $this->loadedTemplates[$cls];
     }
 
     /**

test/Twig/Tests/EnvironmentTest.php

@@ -352,6 +352,33 @@ class Twig_Tests_EnvironmentTest extends PHPUnit_Framework_TestCase
         $twig->loadTemplate($template, 'abc');
     }
 
+    /**
+     * @expectedException Twig_Error_Runtime
+     * @expectedExceptionMessage Circular reference detected for Twig template "base.html.twig", path: base.html.twig -> base.html.twig in "base.html.twig" at line 1
+     */
+    public function testFailLoadTemplateOnCircularReference()
+    {
+        $twig = new Twig_Environment(new Twig_Loader_Array(array(
+            'base.html.twig' => '{% extends "base.html.twig" %}',
+        )));
+
+        $twig->loadTemplate('base.html.twig');
+    }
+
+    /**
+     * @expectedException Twig_Error_Runtime
+     * @expectedExceptionMessage Circular reference detected for Twig template "base1.html.twig", path: base1.html.twig -> base2.html.twig -> base1.html.twig in "base1.html.twig" at line 1
+     */
+    public function testFailLoadTemplateOnComplexCircularReference()
+    {
+        $twig = new Twig_Environment(new Twig_Loader_Array(array(
+            'base1.html.twig' => '{% extends "base2.html.twig" %}',
+            'base2.html.twig' => '{% extends "base1.html.twig" %}',
+        )));
+
+        $twig->loadTemplate('base1.html.twig');
+    }
+
     protected function getMockLoader($templateName, $templateContent)
     {
         $loader = $this->getMockBuilder('Twig_LoaderInterface')->getMock();