Only allow OP to add tags that they can start discussions without approval in

closes flarum/core#904

extensions/approval/bootstrap.php

@@ -10,6 +10,7 @@
  */
 
 use Flarum\Approval\Listener;
+use Flarum\Approval\Access;
 use Illuminate\Contracts\Events\Dispatcher;
 
 return function (Dispatcher $events) {
@@ -18,4 +19,6 @@ return function (Dispatcher $events) {
     $events->subscribe(Listener\ApproveContent::class);
     $events->subscribe(Listener\HideUnapprovedContent::class);
     $events->subscribe(Listener\UnapproveNewContent::class);
+
+    $events->subscribe(Access\TagPolicy::class);
 };

extensions/approval/src/Access/TagPolicy.php

@@ -0,0 +1,37 @@
+<?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\Approval\Access;
+
+use Flarum\Core\Access\AbstractPolicy;
+use Flarum\Core\User;
+use Flarum\Tags\Tag;
+
+class TagPolicy extends AbstractPolicy
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected $model = Tag::class;
+
+    /**
+     * @param User $actor
+     * @param Tag $tag
+     * @return bool|null
+     */
+    public function addToDiscussion(User $actor, Tag $tag)
+    {
+        $disallowedTags = Tag::getIdsWhereCannot($actor, 'discussion.startWithoutApproval');
+
+        if (in_array($tag->id, $disallowedTags)) {
+            return false;
+        }
+    }
+}