Grant global discussion permissions so that unrestricted tag permissions work

Say you have limited viewing/starting discussions globally to admins, and then have a single tag which allows everyone to view/start discussions. Previously this wouldn't work as expected because the non-admin would be stopped because when the core command checks for the global permission.

extensions/tags/bootstrap.php

@@ -11,7 +11,6 @@
 
 use Flarum\Tags\Access;
 use Flarum\Tags\Listener;
-use Flarum\Tags\Tag;
 use Illuminate\Contracts\Events\Dispatcher;
 
 return function (Dispatcher $events) {
@@ -24,6 +23,7 @@ return function (Dispatcher $events) {
     $events->subscribe(Listener\SaveTagsToDatabase::class);
     $events->subscribe(Listener\UpdateTagMetadata::class);
 
+    $events->subscribe(Access\GlobalPolicy::class);
     $events->subscribe(Access\DiscussionPolicy::class);
     $events->subscribe(Access\TagPolicy::class);
     $events->subscribe(Access\FlagPolicy::class);

extensions/tags/src/Access/DiscussionPolicy.php

@@ -36,7 +36,6 @@ class DiscussionPolicy extends AbstractPolicy
 
     /**
      * @param SettingsRepositoryInterface $settings
-     * @param Gate $gate
      */
     public function __construct(SettingsRepositoryInterface $settings)
     {
@@ -101,6 +100,12 @@ class DiscussionPolicy extends AbstractPolicy
                 ->whereIn('tag_id', Tag::getIdsWhereCannot($actor, 'viewDiscussions'))
                 ->where('discussions.id', new Expression('discussion_id'));
         });
+
+        // Hide discussions with no tags if the user doesn't have that global
+        // permission.
+        if (! $actor->hasPermission('viewDiscussions')) {
+            $query->has('tags');
+        }
     }
 
     /**
@@ -123,7 +128,8 @@ class DiscussionPolicy extends AbstractPolicy
 
     /**
      * This method checks, if the user is still allowed to edit the tags
-     * based on the configuration item
+     * based on the configuration item.
+     *
      * @param User $actor
      * @param Discussion $discussion
      * @return bool

extensions/tags/src/Access/GlobalPolicy.php

@@ -0,0 +1,36 @@
+<?php
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Tags\Access;
+
+use Flarum\Event\GetPermission;
+use Illuminate\Contracts\Events\Dispatcher;
+
+class GlobalPolicy
+{
+    /**
+     * @param Dispatcher $events
+     */
+    public function subscribe(Dispatcher $events)
+    {
+        $events->listen(GetPermission::class, [$this, 'grantGlobalDiscussionPermissions']);
+    }
+
+    /**
+     * @param GetPermission $event
+     * @return bool
+     */
+    public function grantGlobalDiscussionPermissions(GetPermission $event)
+    {
+        if (in_array($event->ability, ['viewDiscussions', 'startDiscussion']) && empty($event->arguments)) {
+            return $event->actor->hasPermissionLike($event->ability);
+        }
+    }
+}