Make default_scope work with Relations

activerecord/lib/active_record/base.rb

@@ -1236,7 +1236,7 @@ module ActiveRecord #:nodoc:
         end
 
         def construct_finder_arel(options = {}, scope = nil)
-          relation = unscoped.apply_finder_options(options)
+          relation = options.is_a?(Hash) ? unscoped.apply_finder_options(options) : unscoped.merge(options)
           relation = scope.merge(relation) if scope
           relation
         end
@@ -1450,7 +1450,8 @@ module ActiveRecord #:nodoc:
         end
 
         def scoped_methods #:nodoc:
-          Thread.current[:"#{self}_scoped_methods"] ||= self.default_scoping.dup
+          key = :"#{self}_scoped_methods"
+          Thread.current[key] = Thread.current[key].presence || self.default_scoping.dup
         end
 
         def current_scoped_methods #:nodoc:

activerecord/test/cases/method_scoping_test.rb

@@ -588,7 +588,7 @@ class HasAndBelongsToManyScopingTest< ActiveRecord::TestCase
 end
 
 class DefaultScopingTest < ActiveRecord::TestCase
-  fixtures :developers
+  fixtures :developers, :posts
 
   def test_default_scope
     expected = Developer.find(:all, :order => 'salary DESC').collect { |dev| dev.salary }
@@ -657,6 +657,12 @@ class DefaultScopingTest < ActiveRecord::TestCase
     received = DeveloperOrderedBySalary.find(:all, :order => 'salary').collect { |dev| dev.salary }
     assert_equal expected, received
   end
+
+  def test_default_scope_using_relation
+    posts = PostWithComment.scoped
+    assert_equal 2, posts.count
+    assert_equal posts(:thinking), posts.first
+  end
 end
 
 =begin

activerecord/test/models/post.rb

@@ -100,3 +100,8 @@ end
 class SubStiPost < StiPost
   self.table_name = Post.table_name
 end
+
+class PostWithComment < ActiveRecord::Base
+  self.table_name = 'posts'
+  default_scope where("posts.comments_count > 0").order("posts.comments_count ASC")
+end