2 files changed, 10 insertions, 54 deletions
diff --git a/activesupport/lib/active_support/core_ext/class/attribute.rb b/activesupport/lib/active_support/core_ext/class/attribute.rb
index f2a221c396..802d988af2 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute.rb
@@ -75,11 +75,15 @@ class Class
     instance_predicate = options.fetch(:instance_predicate, true)
 
     attrs.each do |name|
+      remove_possible_singleton_method(name)
       define_singleton_method(name) { nil }
+
+      remove_possible_singleton_method("#{name}?")
       define_singleton_method("#{name}?") { !!public_send(name) } if instance_predicate
 
       ivar = "@#{name}"
 
+      remove_possible_singleton_method("#{name}=")
       define_singleton_method("#{name}=") do |val|
         singleton_class.class_eval do
           remove_possible_method(name)
@@ -110,18 +114,15 @@ class Class
             self.class.public_send name
           end
         end
+
+        remove_possible_method "#{name}?"
         define_method("#{name}?") { !!public_send(name) } if instance_predicate
       end
 
-      attr_writer name if instance_writer
-    end
-  end
-
-  private
-
-    unless respond_to?(:singleton_class?)
-      def singleton_class?
-        ancestors.first != self
+      if instance_writer
+        remove_possible_method "#{name}="
+        attr_writer name
       end
     end
+  end
 end
diff --git a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb b/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
deleted file mode 100644
index 1c305c5970..0000000000
--- a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-require 'active_support/core_ext/kernel/singleton_class'
-require 'active_support/core_ext/module/remove_method'
-require 'active_support/core_ext/module/deprecation'
-
-
-class Class
-  def superclass_delegating_accessor(name, options = {})
-    # Create private _name and _name= methods that can still be used if the public
-    # methods are overridden.
-    _superclass_delegating_accessor("_#{name}", options)
-
-    # Generate the public methods name, name=, and name?.
-    # These methods dispatch to the private _name, and _name= methods, making them
-    # overridable.
-    singleton_class.send(:define_method, name) { send("_#{name}") }
-    singleton_class.send(:define_method, "#{name}?") { !!send("_#{name}") }
-    singleton_class.send(:define_method, "#{name}=") { |value| send("_#{name}=", value) }
-
-    # If an instance_reader is needed, generate public instance methods name and name?.
-    if options[:instance_reader] != false
-      define_method(name) { send("_#{name}") }
-      define_method("#{name}?") { !!send("#{name}") }
-    end
-  end
-
-  deprecate superclass_delegating_accessor: :class_attribute
-
-  private
-    # Take the object being set and store it in a method. This gives us automatic
-    # inheritance behavior, without having to store the object in an instance
-    # variable and look up the superclass chain manually.
-    def _stash_object_in_method(object, method, instance_reader = true)
-      singleton_class.remove_possible_method(method)
-      singleton_class.send(:define_method, method) { object }
-      remove_possible_method(method)
-      define_method(method) { object } if instance_reader
-    end
-
-    def _superclass_delegating_accessor(name, options = {})
-      singleton_class.send(:define_method, "#{name}=") do |value|
-        _stash_object_in_method(value, name, options[:instance_reader] != false)
-      end
-      send("#{name}=", nil)
-    end
-end