Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/language/src/EventSubscriber/ConfigSubscriber.php

@@ -0,0 +1,79 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\language\EventSubscriber\ConfigSubscriber.
+ */
+
+namespace Drupal\language\EventSubscriber;
+
+use Drupal\Core\Language\LanguageDefault;
+use Drupal\Core\Language\LanguageManagerInterface;
+use Drupal\Core\PhpStorage\PhpStorageFactory;
+use Drupal\Core\Config\ConfigCrudEvent;
+use Drupal\Core\Config\ConfigEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Deletes the container if default language has changed.
+ */
+class ConfigSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The language manager.
+   *
+   * @var \Drupal\Core\Language\LanguageManagerInterface
+   */
+  protected $languageManager;
+
+  /**
+   * The default language.
+   *
+   * @var \Drupal\Core\Language\LanguageDefault
+   */
+  protected $languageDefault;
+
+  /**
+   * Constructs a new class object.
+   *
+   * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
+   *   The language manager.
+   * @param \Drupal\Core\Language\LanguageDefault $language_default
+   *   The default language.
+   */
+  public function __construct(LanguageManagerInterface $language_manager, LanguageDefault $language_default) {
+    $this->languageManager = $language_manager;
+    $this->languageDefault = $language_default;
+  }
+
+  /**
+   * Causes the container to be rebuilt on the next request.
+   *
+   * @param ConfigCrudEvent $event
+   *   The configuration event.
+   */
+  public function onConfigSave(ConfigCrudEvent $event) {
+    $saved_config = $event->getConfig();
+    if ($saved_config->getName() == 'system.site' && $event->isChanged('default_langcode')) {
+      $language = $this->languageManager->getLanguage($saved_config->get('default_langcode'));
+      // During an import the language might not exist yet.
+      if ($language) {
+        $this->languageDefault->set($language);
+        $this->languageManager->reset();
+        language_negotiation_url_prefixes_update();
+      }
+      // Trigger a container rebuild on the next request by deleting compiled
+      // from PHP storage.
+      PhpStorageFactory::get('service_container')->deleteAll();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  static function getSubscribedEvents() {
+    $events[ConfigEvents::SAVE][] = array('onConfigSave', 0);
+    return $events;
+  }
+
+}