STI should not ignore type condition while applying scopes from paren…

…t class scopes

[#4507 state:resolved]

Signed-off-by: José Valim <jose.valim@gmail.com>

activerecord/lib/active_record/named_scope.rb

@@ -99,11 +99,7 @@ def scope(name, scope_options = {}, &block)
           block_given? ? relation.extending(Module.new(&block)) : relation
         end
 
-        singleton_class.instance_eval do
-          define_method name do |*args|
-            scopes[name].call(*args)
-          end
-        end
+        singleton_class.send :define_method, name, &scopes[name]
       end
 
       def named_scope(*args, &block)

activerecord/test/cases/named_scope_test.rb

@@ -142,6 +142,11 @@ def test_has_many_associations_have_access_to_named_scopes
     assert_equal authors(:david).posts & Post.containing_the_letter_a, authors(:david).posts.containing_the_letter_a
   end
 
+  def test_named_scope_with_STI
+    assert_equal 3,Post.containing_the_letter_a.count
+    assert_equal 1,SpecialPost.containing_the_letter_a.count
+  end
+
   def test_has_many_through_associations_have_access_to_named_scopes
     assert_not_equal Comment.containing_the_letter_e, authors(:david).comments
     assert !Comment.containing_the_letter_e.empty?