Issue #2260059 by er.pushpinderrana, joelpittet, LinL, SebCorbin | Mark Carver: Fixed Title in template_preprocess_item_list() is typecasted as string.

core/includes/theme.inc

@@ -1755,8 +1755,6 @@ function template_preprocess_tablesort_indicator(&$variables) {
  * @see http://drupal.org/node/1842756
  */
 function template_preprocess_item_list(&$variables) {
-  $variables['title'] = (string) $variables['title'];
-
   foreach ($variables['items'] as &$item) {
     $attributes = array();
     // If the item value is an array, then it is a render array.

core/modules/system/src/Tests/Theme/FunctionsTest.php

@@ -55,6 +55,23 @@ class FunctionsTest extends WebTestBase {
     $expected = '<div class="item-list"><h3>Some title</h3>No items found.</div>';
     $this->assertThemeOutput('item_list', $variables, $expected, 'Empty %callback generates empty string with title.');
 
+    // Verify that title set to 0 is output.
+    $variables = array();
+    $variables['title'] = 0;
+    $variables['empty'] = 'No items found.';
+    $expected = '<div class="item-list"><h3>0</h3>No items found.</div>';
+    $this->assertThemeOutput('item_list', $variables, $expected, '%callback with title set to 0 generates a title.');
+
+    // Verify that title set to a render array is output.
+    $variables = array();
+    $variables['title'] = array(
+      '#theme' => 'markup',
+      '#markup' => '<span>Render array</span>',
+    );
+    $variables['empty'] = 'No items found.';
+    $expected = '<div class="item-list"><h3><span>Render array</span></h3>No items found.</div>';
+    $this->assertThemeOutput('item_list', $variables, $expected, '%callback with title set to a render array generates a title.');
+
     // Verify that empty text is not displayed when there are list items.
     $variables = array();
     $variables['title'] = 'Some title';

core/modules/system/templates/item-list.html.twig

@@ -20,7 +20,7 @@
 #}
 {%- if items or empty -%}
   <div class="item-list">
-    {%- if title -%}
+    {%- if title is not empty -%}
       <h3>{{ title }}</h3>
     {%- endif -%}
     {%- if items -%}