Issue #2941208 by AdamPS, dpi, sja112, aleevas, andypost, anmolgoyal74,...

  /**

   * Pre-render callback to build the page title.

   *

   * There are two possibilities, depending on the value of the additional

   * entity type property 'enable_page_title_template'.

   * - FALSE (default): use the output of the related field formatter if it

   *   exists. This approach only works correctly for the node entity type and

   *   with the 'string' formatter. In other cases it likely produces illegal

   *   markup and possibly incorrect display. This option has been retained for

   *   backward-compatibility to support sites that expect attributes set on

   *   the field to propagate to the page title.

   * - TRUE: use the output from the entity_page_title template. This approach

   *   works correctly in all cases, without relying on a particular field

   *   formatter or special templates and is the preferred option for the

   *   future.

   *

   * @param array $page

   *   A page render array.

   *

  public function buildTitle(array $page) {

    $entity_type = $page['#entity_type'];

    $entity = $page['#' . $entity_type];

    // If the entity's label is rendered using a field formatter, set the

    // rendered title field formatter as the page title instead of the default

    // plain text title. This allows attributes set on the field to propagate

    // correctly (e.g. in-place editing).

    // If the entity has a label field, build the page title based on it.

    if ($entity instanceof FieldableEntityInterface) {

      $label_field = $entity->getEntityType()->getKey('label');

      $template_enabled = $entity->getEntityType()->get('enable_page_title_template');

      if ($label_field && $template_enabled) {

        // Set page title to the output from the entity_page_title template.

        $page_title = [

          '#theme' => 'entity_page_title',

          '#title' => $entity->label(),

          '#entity' => $entity,

          '#view_mode' => $page['#view_mode'],

        ];

        $page['#title'] = $this->renderer->render($page_title);

        // Prevent output of the label field in the main content.

        $page[$label_field]['#access'] = FALSE;

        return $page;

      }

      // Set page title to the rendered title field formatter instead of

      // the default plain text title.

      //

      // @todo https://www.drupal.org/project/drupal/issues/3015623

      //   Eventually delete this code and always use the first approach.

      if (isset($page[$label_field])) {

        // Allow templates and theme functions to generate different markup

        // for the page title, which must be inline markup as it will be placed

function node_display_configurable_test_entity_type_build(array &$entity_types) {

  // Allow skipping of extra preprocessing for configurable display.

  $entity_types['node']->set('enable_base_field_custom_preprocess_skipping', TRUE);

  $entity_types['node']->set('enable_page_title_template', TRUE);

}

    // Check the node with Drupal default non-configurable display.

    $this->drupalGet($node->toUrl());

    $this->assertNodeHtml($node, $user, TRUE, $metadata_region, $field_classes);

    $this->assertNodeHtml($node, $user, TRUE, $metadata_region, $field_classes, $field_classes);

    // Enable module to make base fields' displays configurable.

    \Drupal::service('module_installer')->install(['node_display_configurable_test']);

        'label' => 'above',

        'settings' => ['link' => FALSE],

      ])

      ->removeComponent('title')

      ->save();

    // Recheck the node with configurable display.

    $this->drupalGet($node->toUrl());

    $this->assertNodeHtml($node, $user, FALSE, $metadata_region, $field_classes);

    $this->assertNodeHtml($node, $user, FALSE, $metadata_region, $field_classes, FALSE);

    $assert->elementExists('css', 'div[rel="schema:author"]');

   * @param string $metadata_region

   *   The region of the node html content where meta data is expected.

   * @param bool $field_classes

   *   If TRUE, check for field--name-XXX classes.

   *   If TRUE, check for field--name-XXX classes on created/uid fields.

   * @param bool $title_classes

   *   If TRUE, check for field--name-XXX classes on title field.

   *

   * @internal

   */

  protected function assertNodeHtml(NodeInterface $node, UserInterface $user, bool $is_inline, string $metadata_region, bool $field_classes): void {

  protected function assertNodeHtml(NodeInterface $node, UserInterface $user, bool $is_inline, string $metadata_region, bool $field_classes, bool $title_classes): void {

    $assert = $this->assertSession();

    $html_element = $is_inline ? 'span' : 'div';

    $title_selector = 'h1 span' . ($field_classes ? '.field--name-title' : '');

    $title_selector = 'h1 span' . ($title_classes ? '.field--name-title' : '');

    $assert->elementTextContains('css', $title_selector, $node->getTitle());

    // With field classes, the selector can be very specific.

  }

}

/**

 * Implements hook_preprocess_entity_page_title().

 */

function quickedit_preprocess_entity_page_title(&$variables) {

  $variables['#cache']['contexts'][] = 'user.permissions';

  $entity = $variables['entity'];

  if (!\Drupal::currentUser()->hasPermission('access in-place editing')) {

    return;

  }

  if (($entity instanceof RevisionableInterface) && !$entity->isLatestRevision()) {

    return;

  }

  $label_field = $entity->getEntityType()->getKey('label');

  $variables['attributes']['data-quickedit-field-id'] = $entity->getEntityTypeId() . '/' . $entity->id() . '/' . $label_field . '/' . $entity->language()->getId() . '/' . $variables['view_mode'];

}

/**

 * Implements hook_preprocess_HOOK() for field templates.

 */

      'file' => 'system.theme.inc',

      'variables' => ['error_message' => []],

    ],

    'entity_page_title' => [

      'variables' => [

        'attributes' => [],

        'title' => NULL,

        'entity' => NULL,

        'view_mode' => NULL,

      ],

    ],

  ]);

}