Fix #3890. (Calling proxy_association in scope chain.)

activerecord/lib/active_record/associations/collection_proxy.rb

@@ -41,8 +41,7 @@ module ActiveRecord
       delegate :group, :order, :limit, :joins, :where, :preload, :eager_load, :includes, :from,
                :lock, :readonly, :having, :pluck, :to => :scoped
 
-      delegate :target, :load_target, :loaded?, :scoped,
-               :to => :@association
+      delegate :target, :load_target, :loaded?, :to => :@association
 
       delegate :select, :find, :first, :last,
                :build, :create, :create!,
@@ -62,6 +61,13 @@ module ActiveRecord
         @association
       end
 
+      def scoped
+        association = @association
+        association.scoped.extending do
+          define_method(:proxy_association) { association }
+        end
+      end
+
       def respond_to?(name, include_private = false)
         super ||
         (load_target && target.respond_to?(name, include_private)) ||

activerecord/test/cases/associations/extension_test.rb

@@ -71,6 +71,12 @@ class AssociationsExtensionsTest < ActiveRecord::TestCase
     assert_equal 'MyApplication::Business::DeveloperAssociationNameAssociationExtension', extension_name(MyApplication::Business::Developer)
   end
 
+  def test_proxy_association_after_scoped
+    post = posts(:welcome)
+    assert_equal post.association(:comments), post.comments.the_association
+    assert_equal post.association(:comments), post.comments.scoped.the_association
+  end
+
   private
 
     def extension_name(model)

activerecord/test/models/post.rb

@@ -44,6 +44,10 @@ class Post < ActiveRecord::Base
     def newest
       created.last
     end
+
+    def the_association
+      proxy_association
+    end
   end
 
   has_many :author_favorites, :through => :author
@@ -185,4 +189,4 @@ end
 class SpecialPostWithDefaultScope < ActiveRecord::Base
   self.table_name = 'posts'
   default_scope where(:id => [1, 5,6])
-end
+end