Fix instance_eval calls to association proxies

In the current stable, ActiveRecord::Associations::AssociationProxy#method_missing calls yield() if a block is given, causing the block to always be evaluated in its calling context. However, in the case of instance_eval, correct behavior requires that the block be passed directly to the @target, rather than being evaluated inside a different block. Incidentally, this also simplifies the code slightly.

[#3412 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activerecord/lib/active_record/associations/association_proxy.rb

@@ -200,18 +200,14 @@ def with_scope(*args, &block)
 
       private
         # Forwards any missing method call to the \target.
-        def method_missing(method, *args)
+        def method_missing(method, *args, &block)
           if load_target
             unless @target.respond_to?(method)
               message = "undefined method `#{method.to_s}' for \"#{@target}\":#{@target.class.to_s}"
               raise NoMethodError, message
             end
 
-            if block_given?
-              @target.send(method, *args)  { |*block_args| yield(*block_args) }
-            else
-              @target.send(method, *args)
-            end
+            @target.send(method, *args, &block)
           end
         end
 

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -1178,5 +1178,13 @@ def test_creating_using_primary_key
     client = firm.clients_using_primary_key.create!(:name => 'test')
     assert_equal firm.name, client.firm_name
   end
+
+  def test_normal_method_call_in_association_proxy
+    assert_equal 'Welcome to the weblog', Comment.all.map { |comment| comment.post }.first.title
+  end
+
+  def test_instance_eval_in_association_proxy
+    assert_equal 'Welcome to the weblog', Comment.all.map { |comment| comment.post }.first.instance_eval{title}
+  end
 end