Deprecate usage of undefined blocks

lib/Twig/Template.php

@@ -197,12 +197,16 @@ abstract class Twig_Template implements Twig_TemplateInterface
             $block = null;
         }
 
-        if (null !== $template) {
+        // avoid RCEs when sandbox is enabled
-            // avoid RCEs when sandbox is enabled
+        if (null !== $template && !$template instanceof self) {
-            if (!$template instanceof self) {
+            throw new LogicException('A block must be a method on a Twig_Template instance.');
-                throw new LogicException('A block must be a method on a Twig_Template instance.');
+        }
-            }
 
+        if (!$this->hasBlock($name, $context, $blocks)) {
+            @trigger_error(sprintf('Displaying undefined block "%s" in template "%s" is deprecated since version 1.29 and will throw an exception in 2.0.', $name, $this->getTemplateName()), E_USER_DEPRECATED);
+        }
+
+        if (null !== $template) {
             try {
                 $template->$block($context, $blocks);
             } catch (Twig_Error $e) {

test/Twig/Tests/Fixtures/functions/recursive_block_with_inheritance.test

@@ -12,7 +12,7 @@
 {% block list %}<ul>{{ block('children') }}</ul>{% endblock %}
 {% block children %}{% set currentItem = item %}{% for item in currentItem %}{{ block('item') }}{% endfor %}{% set item = currentItem %}{% endblock %}
 {% block item %}<li>{% if item is not iterable %}{{ block('label') }}{% else %}{{ block('list') }}{% endif %}</li>{% endblock %}
-{% block label %}{{ item }}{{ block('unknown') }}{% endblock %}
+{% block label %}{{ item }}{% endblock %}
 --TEMPLATE(base.twig)--
 {{ block('list') }}
 --DATA--

test/Twig/Tests/LegacyFixtures/functions/undefined_block.legacy.test

@@ -0,0 +1,12 @@
+--TEST--
+"block" function with undefined block
+--TEMPLATE--
+{% extends "base.twig" %}
+{% block foo %}{{ parent() }}{{ block('unknown') }}{{ block('bar') }}{% endblock %}
+--TEMPLATE(base.twig)--
+{% block foo %}Foo{% endblock %}
+{% block bar %}Bar{% endblock %}
+--DATA--
+return array()
+--EXPECT--
+FooBarBar

test/Twig/Tests/TemplateTest.php

@@ -214,15 +214,17 @@ class Twig_Tests_TemplateTest extends PHPUnit_Framework_TestCase
         $this->assertNotInstanceof('Twig_Markup', $template->getAttribute($template1, 'empty'));
         $this->assertSame('', $template->getAttribute($template1, 'empty'));
 
+        $blocks = array('name' => array($template1, 'block_name'));
+
         // trigger some deprecation notice messages to check them with @expectedDeprecation
-        $template->getAttribute($template, 'renderBlock', array('name', array()));
+        $template->getAttribute($template, 'renderBlock', array('name', array(), $blocks));
-        $template->getAttribute($template, 'displayBlock', array('name', array()));
+        $template->getAttribute($template, 'displayBlock', array('name', array(), $blocks));
         $template->getAttribute($template, 'hasBlock', array('name', array()));
         $template->getAttribute($template, 'render', array(array()));
         $template->getAttribute($template, 'display', array(array()));
 
-        $template->getAttribute($template1, 'renderBlock', array('name', array()));
+        $template->getAttribute($template1, 'renderBlock', array('name', array(), $blocks));
-        $template->getAttribute($template1, 'displayBlock', array('name', array()));
+        $template->getAttribute($template1, 'displayBlock', array('name', array(), $blocks));
         $template->getAttribute($template1, 'hasBlock', array('name', array()));
         $template->getAttribute($template1, 'render', array(array()));
         $template->getAttribute($template1, 'display', array(array()));
@@ -233,6 +235,20 @@ class Twig_Tests_TemplateTest extends PHPUnit_Framework_TestCase
         $this->assertFalse($template->getAttribute($template1, 'displayWithErrorHandling', array(), Twig_Template::METHOD_CALL, true));
     }
 
+    /**
+     * @group legacy
+     * @expectedDeprecation Displaying undefined block "unknown" in template "index.twig" is deprecated since version 1.29 and will throw an exception in 2.0.
+     * @expectedDeprecation Displaying undefined block "unknown" in template "index.twig" is deprecated since version 1.29 and will throw an exception in 2.0.
+     */
+    public function testRenderBlockWithUndefinedBlock()
+    {
+        $twig = new Twig_Environment($this->getMockBuilder('Twig_TemplateTestLoaderInterface')->getMock());
+
+        $template = new Twig_TemplateTest($twig, false, 'index.twig');
+        $template->renderBlock('unknown', array());
+        $template->displayBlock('unknown', array());
+    }
+
     /**
      * @dataProvider getTestsDependingOnExtensionAvailability
      */
@@ -534,6 +550,10 @@ class Twig_TemplateTest extends Twig_Template
             return parent::getAttribute($object, $item, $arguments, $type, $isDefinedTest, $ignoreStrictCheck);
         }
     }
+
+    public function block_name($context, array $blocks = array())
+    {
+    }
 }
 
 class Twig_TemplateArrayAccessObject implements ArrayAccess