1 files changed, 19 insertions, 13 deletions

diff --git a/app/models/concerns/participable.rb b/app/models/concerns/participable.rb
index ffc874357fd..85367f89f4f 100644
--- a/app/models/concerns/participable.rb
+++ b/app/models/concerns/participable.rb
@@ -12,7 +12,7 @@
 #
 #       # ...
 #
-#       participant :author, :assignee, :mentioned_users, :notes
+#       participant :author, :assignee, :notes, ->(current_user) { mentioned_users(current_user) }
 #     end
 #
 #     issue = Issue.last
@@ -27,7 +27,7 @@ module Participable
 
   module ClassMethods
     def participant(*attrs)
-      participant_attrs.concat(attrs.map(&:to_s))
+      participant_attrs.concat(attrs)
     end
 
     def participant_attrs
@@ -37,33 +37,39 @@ module Participable
 
   # Be aware that this method makes a lot of sql queries.
   # Save result into variable if you are going to reuse it inside same request
-  def participants(current_user = self.author)
-    self.class.participant_attrs.flat_map do |attr|
-      meth = method(attr)
-
+  def participants(current_user = self.author, load_lazy_references: true)
+    participants = self.class.participant_attrs.flat_map do |attr|
       value =
-        if meth.arity == 1 || meth.arity == -1
-          meth.call(current_user)
+        if attr.respond_to?(:call)
+          instance_exec(current_user, &attr)
         else
-          meth.call
+          send(attr)
         end
 
       participants_for(value, current_user)
-    end.compact.uniq.select do |user|
-      user.can?(:read_project, self.project)
+    end.compact.uniq
+
+    if load_lazy_references
+      participants = Gitlab::Markdown::ReferenceFilter::LazyReference.load(participants).uniq
+
+      participants.select! do |user|
+        user.can?(:read_project, project)
+      end
     end
+
+    participants
   end
 
   private
 
   def participants_for(value, current_user = nil)
     case value
-    when User
+    when User, Gitlab::Markdown::ReferenceFilter::LazyReference
       [value]
     when Enumerable, ActiveRecord::Relation
       value.flat_map { |v| participants_for(v, current_user) }
     when Participable
-      value.participants(current_user)
+      value.participants(current_user, load_lazy_references: false)
     end
   end
 end