1 files changed, 28 insertions, 10 deletions

diff --git a/actionpack/lib/action_controller/layout.rb b/actionpack/lib/action_controller/layout.rb
index 54108df06d..3631ce86af 100644
--- a/actionpack/lib/action_controller/layout.rb
+++ b/actionpack/lib/action_controller/layout.rb
@@ -175,12 +175,13 @@ module ActionController #:nodoc:
       def default_layout(format) #:nodoc:
         layout = read_inheritable_attribute(:layout)
         return layout unless read_inheritable_attribute(:auto_layout)
-        find_layout(layout, format)
+        @default_layout ||= {}
+        @default_layout[format] ||= default_layout_with_format(format, layout)
+        @default_layout[format]
       end
 
-      def find_layout(layout, *formats) #:nodoc:
-        return layout if layout.respond_to?(:render)
-        view_paths.find_template(layout.to_s =~ /layouts\// ? layout : "layouts/#{layout}", *formats)
+      def layout_list #:nodoc:
+        Array(view_paths).sum([]) { |path| Dir["#{path}/layouts/**/*"] }
       end
 
       private
@@ -188,7 +189,7 @@ module ActionController #:nodoc:
           inherited_without_layout(child)
           unless child.name.blank?
             layout_match = child.name.underscore.sub(/_controller$/, '').sub(/^controllers\//, '')
-            child.layout(layout_match, {}, true) if child.find_layout(layout_match, :all)
+            child.layout(layout_match, {}, true) unless child.layout_list.grep(%r{layouts/#{layout_match}(\.[a-z][0-9a-z]*)+$}).empty?
           end
         end
 
@@ -199,6 +200,15 @@ module ActionController #:nodoc:
         def normalize_conditions(conditions)
           conditions.inject({}) {|hash, (key, value)| hash.merge(key => [value].flatten.map {|action| action.to_s})}
         end
+
+        def default_layout_with_format(format, layout)
+          list = layout_list
+          if list.grep(%r{layouts/#{layout}\.#{format}(\.[a-z][0-9a-z]*)+$}).empty?
+            (!list.grep(%r{layouts/#{layout}\.([a-z][0-9a-z]*)+$}).empty? && format == :html) ? layout : nil
+          else
+            layout
+          end
+        end
     end
 
     # Returns the name of the active layout. If the layout was specified as a method reference (through a symbol), this method
@@ -207,18 +217,20 @@ module ActionController #:nodoc:
     # weblog/standard, but <tt>layout "standard"</tt> will return layouts/standard.
     def active_layout(passed_layout = nil)
       layout = passed_layout || self.class.default_layout(default_template_format)
-
       active_layout = case layout
+        when String then layout
         when Symbol then __send__(layout)
         when Proc   then layout.call(self)
-        else layout
       end
 
+      # Explicitly passed layout names with slashes are looked up relative to the template root,
+      # but auto-discovered layouts derived from a nested controller will contain a slash, though be relative
+      # to the 'layouts' directory so we have to check the file system to infer which case the layout name came from.
       if active_layout
-        if layout = self.class.find_layout(active_layout, @template.template_format)
-          layout
+        if active_layout.include?('/') && ! layout_directory?(active_layout)
+          active_layout
         else
-          raise ActionView::MissingTemplate.new(self.class.view_paths, active_layout)
+          "layouts/#{active_layout}"
         end
       end
     end
@@ -259,6 +271,12 @@ module ActionController #:nodoc:
         end
       end
 
+      def layout_directory?(layout_name)
+        @template.__send__(:_pick_template, "#{File.join('layouts', layout_name)}.#{@template.template_format}") ? true : false
+      rescue ActionView::MissingTemplate
+        false
+      end
+
       def default_template_format
         response.template.template_format
       end