Don't call attr_readonly on polymorphic belongs_to associations, in case it...

Don't call attr_readonly on polymorphic belongs_to associations, in case it matches the name of some other non-ActiveRecord class/module.  [Rick]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7748 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Don't call attr_readonly on polymorphic belongs_to associations, in case it matches the name of some other non-ActiveRecord class/module.  [Rick]
+
 * Try loading activerecord-<adaptername>-adapter gem before trying a plain require so you can use custom gems for the bundled adapters. Also stops gems from requiring an adapter from an old Active Record gem.  [Jeremy Kemper, Derrick Spell]
 
 

activerecord/lib/active_record/associations.rb

@@ -844,7 +844,7 @@ def belongs_to(association_id, options = {})
           )
           
           module_eval(
-            "#{reflection.class_name}.send(:attr_readonly,\"#{cache_column}\".intern) if defined?(#{reflection.class_name})"
+            "#{reflection.class_name}.send(:attr_readonly,\"#{cache_column}\".intern) if defined?(#{reflection.class_name}) && #{reflection.class_name}.respond_to?(:attr_readonly)"
           )
         end
       end

activerecord/test/fixtures/tagging.rb

+# test that attr_readonly isn't called on the :taggable polymorphic association
+module Taggable
+end
+
 class Tagging < ActiveRecord::Base
   belongs_to :tag, :include => :tagging
   belongs_to :super_tag,   :class_name => 'Tag', :foreign_key => 'super_tag_id'