FEATURE: allow moderators to convert a private message to public topic or vice versa

app/assets/javascripts/discourse/templates/topic.hbs

@@ -256,7 +256,7 @@
       {{/if}}
     </li>
 
-    {{#if currentUser.admin}}
+    {{#if currentUser.staff}}
       <li class="topic-admin-convert">
         {{#if model.isPrivateMessage}}
           {{d-button action="convertToPublicTopic" icon="comment" label="topic.actions.make_public"}}

lib/guardian/topic_guardian.rb

@@ -59,7 +59,9 @@ module TopicGuardian
   end
 
   def can_convert_topic?(topic)
-    topic && !topic.trashed? && is_admin?
+    return false if topic && topic.trashed?
+    return true if is_admin?
+    is_moderator? && can_create_post?(topic)
   end
 
   def can_reply_as_new_topic?(topic)

spec/components/guardian_spec.rb

@@ -881,8 +881,12 @@ describe Guardian do
       expect(Guardian.new.can_convert_topic?(topic)).to be_falsey
     end
 
-    it 'returns false when not admin' do
-      expect(Guardian.new(moderator).can_convert_topic?(topic)).to be_falsey
+    it 'returns false when not staff' do
+      expect(Guardian.new(trust_level_4).can_convert_topic?(topic)).to be_falsey
+    end
+
+    it 'returns true when a moderator' do
+      expect(Guardian.new(moderator).can_convert_topic?(topic)).to be_truthy
     end
 
     it 'returns true when an admin' do