Update to Drupal 8.2.0. For more information, see https://www.drupal.org/project/drupal/releases/8.2.0

core/lib/Drupal/Core/Render/Element/Checkboxes.php

@@ -122,4 +122,40 @@ class Checkboxes extends FormElement {
     }
   }
 
+  /**
+   * Determines which checkboxes were checked when a form is submitted.
+   *
+   * @param array $input
+   *   An array returned by the FormAPI for a set of checkboxes.
+   *
+   * @return array
+   *   An array of keys that were checked.
+   */
+  public static function getCheckedCheckboxes(array $input) {
+    // Browsers do not include unchecked options in a form submission. The
+    // FormAPI tries to normalize this to keep checkboxes consistent with other
+    // form elements. Checkboxes show up as an array in the form of option_id =>
+    // option_id|0, where integer 0 is an unchecked option.
+    //
+    // @see \Drupal\Core\Render\Element\Checkboxes::valueCallback()
+    // @see https://www.w3.org/TR/html401/interact/forms.html#checkbox
+    $checked = array_filter($input, function($value) {
+      return $value !== 0;
+    });
+    return array_keys($checked);
+  }
+
+  /**
+   * Determines if all checkboxes in a set are unchecked.
+   *
+   * @param array $input
+   *   An array returned by the FormAPI for a set of checkboxes.
+   *
+   * @return bool
+   *   TRUE if all options are unchecked. FALSE otherwise.
+   */
+  public static function detectEmptyCheckboxes(array $input) {
+    return empty(static::getCheckedCheckboxes($input));
+  }
+
 }

core/lib/Drupal/Core/Render/Element/Range.php

@@ -18,7 +18,7 @@ use Drupal\Core\Render\Element;
  * Usage example:
  * @code
  * $form['quantity'] = array(
- *   '#type' => 'number',
+ *   '#type' => 'range',
  *   '#title' => $this->t('Quantity'),
  * );
  * @endcode

core/lib/Drupal/Core/Render/Element/StatusMessages.php

@@ -45,12 +45,15 @@ class StatusMessages extends RenderElement {
    *   The updated renderable array containing the placeholder.
    */
   public static function generatePlaceholder(array $element) {
-    $element['messages_placeholder'] = [
+    $element = [
       '#lazy_builder' => [get_class() . '::renderMessages', [$element['#display']]],
       '#create_placeholder' => TRUE,
     ];
 
-    return $element;
+    // Directly create a placeholder as we need this to be placeholdered
+    // regardless if this is a POST or GET request.
+    // @todo remove this when https://www.drupal.org/node/2367555 lands.
+    return \Drupal::service('render_placeholder_generator')->createPlaceholder($element);
   }
 
   /**

core/lib/Drupal/Core/Render/PageDisplayVariantSelectionEvent.php

@@ -54,7 +54,7 @@ class PageDisplayVariantSelectionEvent extends Event implements RefinableCacheab
   /**
    * Constructs the page display variant plugin selection event.
    *
-   * @param string
+   * @param string $plugin_id
    *   The ID of the page display variant plugin to use by default.
    * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
    *   The current route match, for context.

core/lib/Drupal/Core/Render/RenderContext.php

@@ -10,8 +10,6 @@ namespace Drupal\Core\Render;
  * @see \Drupal\Core\Render\RendererInterface
  * @see \Drupal\Core\Render\Renderer
  * @see \Drupal\Core\Render\BubbleableMetadata
- *
- * @internal
  */
 class RenderContext extends \SplStack {
 

core/lib/Drupal/Core/Render/Renderer.php

@@ -365,11 +365,6 @@ class Renderer implements RendererInterface {
       $elements['#lazy_builder_built'] = TRUE;
     }
 
-    // All render elements support #markup and #plain_text.
-    if (!empty($elements['#markup']) || !empty($elements['#plain_text'])) {
-      $elements = $this->ensureMarkupIsSafe($elements);
-    }
-
     // Make any final changes to the element before it is rendered. This means
     // that the $element or the children can be altered or corrected before the
     // element is rendered into the final text.
@@ -382,6 +377,11 @@ class Renderer implements RendererInterface {
       }
     }
 
+    // All render elements support #markup and #plain_text.
+    if (!empty($elements['#markup']) || !empty($elements['#plain_text'])) {
+      $elements = $this->ensureMarkupIsSafe($elements);
+    }
+
     // Defaults for bubbleable rendering metadata.
     $elements['#cache']['tags'] = isset($elements['#cache']['tags']) ? $elements['#cache']['tags'] : array();
     $elements['#cache']['max-age'] = isset($elements['#cache']['max-age']) ? $elements['#cache']['max-age'] : Cache::PERMANENT;
@@ -733,7 +733,7 @@ class Renderer implements RendererInterface {
    *
    * @see \Drupal\Component\Utility\Html::escape()
    * @see \Drupal\Component\Utility\Xss::filter()
-   * @see \Drupal\Component\Utility\Xss::adminFilter()
+   * @see \Drupal\Component\Utility\Xss::filterAdmin()
    */
   protected function ensureMarkupIsSafe(array $elements) {
     if (empty($elements['#markup']) && empty($elements['#plain_text'])) {

core/lib/Drupal/Core/Render/theme.api.php

@@ -555,7 +555,7 @@ function hook_form_system_theme_settings_alter(&$form, \Drupal\Core\Form\FormSta
  *   The name of the theme hook.
  */
 function hook_preprocess(&$variables, $hook) {
- static $hooks;
+  static $hooks;
 
   // Add contextual links to the variables, if the user has permission.