Participable doesn't need to know about Mentionable

app/models/commit.rb

@@ -2,13 +2,13 @@ class Commit
   extend ActiveModel::Naming
 
   include ActiveModel::Conversion
-  include Mentionable
   include Participable
+  include Mentionable
   include Referable
   include StaticModel
 
   attr_mentionable :safe_message
-  participant :author, :committer, :notes, :mentioned_users
+  participant :author, :committer, :notes
 
   attr_accessor :project
 

app/models/concerns/issuable.rb

@@ -6,8 +6,8 @@
 #
 module Issuable
   extend ActiveSupport::Concern
-  include Mentionable
   include Participable
+  include Mentionable
 
   included do
     belongs_to :author, class_name: "User"
@@ -47,7 +47,7 @@ module Issuable
              prefix: true
 
     attr_mentionable :title, :description
-    participant :author, :assignee, :notes, :mentioned_users
+    participant :author, :assignee, :notes
   end
 
   module ClassMethods

app/models/concerns/mentionable.rb

@@ -20,6 +20,12 @@ module Mentionable
     end
   end
 
+  included do
+    if self < Participable
+      participant ->(current_user) { mentioned_users(current_user, load_lazy_references: false) }
+    end
+  end
+
   # Returns the text used as the body of a Note when this object is referenced
   #
   # By default this will be the class name and the result of calling

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
@@ -39,12 +39,11 @@ module Participable
   # Save result into variable if you are going to reuse it inside same request
   def participants(current_user = self.author, project = self.project, load_lazy_references: true)
     participants = self.class.participant_attrs.flat_map do |attr|
-      meth = method(attr)
       value =
-        if attr == :mentioned_users
-          meth.call(current_user, load_lazy_references: false)
+        if attr.respond_to?(:call)
+          instance_exec(current_user, &attr)
         else
-          meth.call
+          send(attr)
         end
 
       participants_for(value, current_user, project)

app/models/note.rb

@@ -22,14 +22,14 @@ require 'carrierwave/orm/activerecord'
 require 'file_size_validator'
 
 class Note < ActiveRecord::Base
-  include Mentionable
   include Gitlab::CurrentSettings
   include Participable
+  include Mentionable
 
   default_value_for :system, false
 
   attr_mentionable :note
-  participant :author, :mentioned_users
+  participant :author
 
   belongs_to :project
   belongs_to :noteable, polymorphic: true