Replace all implementations of hook_menu_alter with appropriate uses of the new routing system

Forgive me for not knowing enough about the issue, but is there a place to find out how the alters should work?

I assume it should handle the way it does now, just alter with new new menu system setup? Example

<?php
/**
 * Implements hook_menu_alter().
 */
function comment_menu_alter(&$items) {
  if (isset($items['admin/content'])) {
    // Add comments to the description for admin/content if any.
    $items['admin/content']['description'] = 'Administer content and comments.';
  }
}

becomes....

<?php
/**
 * Implements hook_menu_alter().
 */
function comment_menu_alter(&$items) {
  if (isset($items['admin.content'])) {
    // Add comments to the description for admin/content if any.
    $items['admin.content']['description'] = 'Administer content and comments.';
  }
}

@kylebrowning I think the change would be much more drastic. If I'm not mistaken the hook_menu_alter() implementations would be replaced with route subscribers, likely extending RouteSubscriberBase.

I'd say \Drupal\field_ui\Routing\RouteSubscriber is probably the best example currently in core.

Here is a list of places where we still use hook_menu_alter():

• comment: This just changes a link description [x] proper usecase
• content_translation: Change some title and weights [x] proper usecase
• editor: Rename title/description [x] proper usecase
• views: add menu links [x] proper usecase

Considering this I will mark the issue as fixed. All actual usecases already use route subscribers.