[DependencyInjection] Fix missing ExpressionLanguageProviders on extension bild

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | ~
| License       | MIT
| Doc PR        | ~

src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php

@@ -29,6 +29,7 @@ class MergeExtensionConfigurationPass implements CompilerPassInterface
         $parameters = $container->getParameterBag()->all();
         $definitions = $container->getDefinitions();
         $aliases = $container->getAliases();
+        $exprLangProviders = $container->getExpressionLanguageProviders();
 
         foreach ($container->getExtensions() as $extension) {
             if ($extension instanceof PrependExtensionInterface) {
@@ -47,6 +48,10 @@ class MergeExtensionConfigurationPass implements CompilerPassInterface
             $tmpContainer->setResourceTracking($container->isTrackingResources());
             $tmpContainer->addObjectResource($extension);
 
+            foreach ($exprLangProviders as $provider) {
+                $tmpContainer->addExpressionLanguageProvider($provider);
+            }
+
             $extension->load($config, $tmpContainer);
 
             $container->merge($tmpContainer);

src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php

@@ -0,0 +1,47 @@
+<?php
+
+
+namespace Symfony\Component\DependencyInjection\Tests\Compiler;
+
+use Symfony\Component\DependencyInjection\Compiler\MergeExtensionConfigurationPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
+
+class MergeExtensionConfigurationPassTest extends \PHPUnit_Framework_TestCase
+{
+    public function testExpressionLanguageProviderForwarding()
+    {
+        if (true !== class_exists('Symfony\\Component\\ExpressionLanguage\\ExpressionLanguage')) {
+            $this->markTestSkipped('The ExpressionLanguage component isn\'t available!');
+        }
+
+        $tmpProviders = array();
+
+        $extension = $this->getMock('Symfony\\Component\\DependencyInjection\\Extension\\ExtensionInterface');
+        $extension->expects($this->any())
+            ->method('getXsdValidationBasePath')
+            ->will($this->returnValue(false));
+        $extension->expects($this->any())
+            ->method('getNamespace')
+            ->will($this->returnValue('http://example.org/schema/dic/foo'));
+        $extension->expects($this->any())
+            ->method('getAlias')
+            ->will($this->returnValue('foo'));
+        $extension->expects($this->once())
+            ->method('load')
+            ->will($this->returnCallback(function (array $config, ContainerBuilder $container) use (&$tmpProviders) {
+                $tmpProviders = $container->getExpressionLanguageProviders();
+            }));
+
+        $provider = $this->getMock('Symfony\\Component\\ExpressionLanguage\\ExpressionFunctionProviderInterface');
+        $container = new ContainerBuilder(new ParameterBag());
+        $container->registerExtension($extension);
+        $container->prependExtensionConfig('foo', array('bar' => true ));
+        $container->addExpressionLanguageProvider($provider);
+
+        $pass = new MergeExtensionConfigurationPass();
+        $pass->process($container);
+
+        $this->assertEquals(array($provider), $tmpProviders);
+    }
+}