Fix some backward incompatible behavior on AM.

actionmailer/lib/action_mailer/base.rb

@@ -250,6 +250,7 @@ class Base < AbstractController::Base
     include AbstractController::Layouts
     include AbstractController::Helpers
     include AbstractController::Translation
+    include AbstractController::Compatibility
 
     helper  ActionMailer::MailHelper
 

actionpack/lib/abstract_controller.rb

@@ -12,6 +12,7 @@ module AbstractController
   autoload :Base
   autoload :Callbacks
   autoload :Collector
+  autoload :Compatibility
   autoload :Helpers
   autoload :Layouts
   autoload :LocalizedCache

actionpack/lib/abstract_controller/compatibility.rb

+module AbstractController
+  module Compatibility
+    extend ActiveSupport::Concern
+
+    def _find_layout(name, details)
+      details[:prefix] = nil if name =~ /\blayouts/
+      super
+    end
+
+    # Move this into a "don't run in production" module
+    def _default_layout(details, require_layout = false)
+      super
+    rescue ActionView::MissingTemplate
+      _find_layout(_layout({}), {})
+      nil
+    end
+  end
+end

actionpack/lib/abstract_controller/helpers.rb

@@ -25,7 +25,7 @@ module ClassMethods
       def inherited(klass)
         helpers = _helpers
         klass._helpers = Module.new { include helpers }
-
+        klass.class_eval { default_helper_module! unless name.blank? }
         super
       end
 
@@ -146,6 +146,16 @@ def _modules_for_helpers(args)
           end
         end
       end
+
+      def default_helper_module!
+        module_name = name.sub(/Controller$/, '')
+        module_path = module_name.underscore
+        helper module_path
+      rescue MissingSourceFile => e
+        raise e unless e.is_missing? "helpers/#{module_path}_helper"
+      rescue NameError => e
+        raise e unless e.missing_name? "#{module_name}Helper"
+      end
     end
   end
 end

actionpack/lib/action_controller/metal/compatibility.rb

@@ -2,6 +2,8 @@ module ActionController
   module Compatibility
     extend ActiveSupport::Concern
 
+    include AbstractController::Compatibility
+
     class ::ActionController::ActionControllerError < StandardError #:nodoc:
     end
 
@@ -103,19 +105,6 @@ def method_for_action(action_name)
       super || (respond_to?(:method_missing) && "_handle_method_missing")
     end
 
-    def _find_layout(name, details)
-      details[:prefix] = nil if name =~ /\blayouts/
-      super
-    end
-
-    # Move this into a "don't run in production" module
-    def _default_layout(details, require_layout = false)
-      super
-    rescue ActionView::MissingTemplate
-      _find_layout(_layout({}), {})
-      nil
-    end
-
     def performed?
       response_body
     end

actionpack/lib/action_controller/metal/helpers.rb

@@ -63,11 +63,6 @@ def helpers_dir=(value)
         self.helpers_path = Array(value)
       end
 
-      def inherited(klass)
-        klass.class_eval { default_helper_module! unless name.blank? }
-        super
-      end
-
       # Declares helper accessors for controller attributes. For example, the
       # following adds new +name+ and <tt>name=</tt> instance methods to a
       # controller and makes them available to the view:
@@ -101,16 +96,6 @@ def _modules_for_helpers(args)
           super(args)
         end
 
-        def default_helper_module!
-          module_name = name.sub(/Controller$/, '')
-          module_path = module_name.underscore
-          helper module_path
-        rescue MissingSourceFile => e
-          raise e unless e.is_missing? "helpers/#{module_path}_helper"
-        rescue NameError => e
-          raise e unless e.missing_name? "#{module_name}Helper"
-        end
-
         # Extract helper names from files in app/helpers/**/*_helper.rb
         def all_application_helpers
           helpers = []