Issue #1283892 by tim.plunkett, chx: Let Render API fail in a tale-telling way on invalid element.

includes/common.inc

@@ -6145,11 +6145,18 @@ function element_children(&$elements, $sort = FALSE) {
   $sortable = FALSE;
   foreach ($elements as $key => $value) {
     if ($key === '' || $key[0] !== '#') {
+      if (is_array($value)) {
         $children[$key] = $value;
-      if (is_array($value) && isset($value['#weight'])) {
+        if (isset($value['#weight'])) {
           $sortable = TRUE;
         }
       }
+      // Only trigger an error if the value is not null.
+      // @see http://drupal.org/node/1283892
+      elseif (isset($value)) {
+        trigger_error(t('"@key" is an invalid render array key', array('@key' => $key)), E_USER_ERROR);
+      }
+    }
   }
   // Sort the children if necessary.
   if ($sort && $sortable) {

modules/menu/menu.admin.inc

@@ -158,7 +158,7 @@ function menu_overview_form_submit($form, &$form_state) {
   // are sent by $_POST, ensuring parents are saved first, then their children.
   // See http://drupal.org/node/181126#comment-632270
   $order = array_flip(array_keys($form_state['input'])); // Get the $_POST order.
-  $form = array_merge($order, $form); // Update our original form with the new order.
+  $form = array_intersect_key(array_merge($order, $form), $form); // Update our original form with the new order.
 
   $updated_items = array();
   $fields = array('weight', 'plid');

modules/simpletest/tests/common.test

@@ -1724,6 +1724,23 @@ class DrupalRenderTestCase extends DrupalWebTestCase {
     ));
   }
 
+  /**
+   * Test rendering elements with invalid keys.
+   */
+  function testDrupalRenderInvalidKeys() {
+    $error = array(
+      '%type' => 'User error',
+      '!message' => '"child" is an invalid render array key',
+      '%function' => 'element_children()',
+    );
+    $message = t('%type: !message in %function (line ', $error);
+
+    variable_set('error_level', ERROR_REPORTING_DISPLAY_ALL);
+    $this->drupalGet('common-test/drupal-render-invalid-keys');
+    $this->assertResponse(200, t('Received expected HTTP status code.'));
+    $this->assertRaw($message, t('Found error message: !message.', array('!message' => $message)));
+  }
+
   protected function assertRenderedElement(array $element, $xpath, array $xpath_args = array()) {
     $original_element = $element;
     $this->drupalSetContent(drupal_render($element));

modules/simpletest/tests/common_test.module

@@ -52,6 +52,12 @@ function common_test_menu() {
     'access arguments' => array('access content'),
     'type' => MENU_CALLBACK,
   );
+  $items['common-test/drupal-render-invalid-keys'] = array(
+    'title' => 'Drupal Render',
+    'page callback' => 'common_test_drupal_render_invalid_keys',
+    'access arguments' => array('access content'),
+    'type' => MENU_CALLBACK,
+  );
   return $items;
 }
 
@@ -100,6 +106,22 @@ function common_test_destination() {
   print "The destination: " . check_plain($destination['destination']);
 }
 
+/**
+ * Render an element with an invalid render array key.
+ */
+function common_test_drupal_render_invalid_keys() {
+  define('SIMPLETEST_COLLECT_ERRORS', FALSE);
+
+  // Keys that begin with # may contain a value of any type, otherwise they must
+  // contain arrays.
+  $key = 'child';
+  $value = 'This should be an array.';
+  $element = array(
+    $key => $value,
+  );
+  return drupal_render($element);
+}
+
 /**
  * Implements hook_TYPE_alter().
  */