remove LookupContext#with_layout_format by passing formats for layouts explicitely.

actionview/lib/action_view/lookup_context.rb

@@ -229,21 +229,5 @@ def locale=(value)
 
       super(default_locale)
     end
-
-    # Uses the first format in the formats array for layout lookup.
-    def with_layout_format
-      if formats.size == 1
-        yield
-      else
-        old_formats = formats
-        _set_detail(:formats, formats[0,1])
-
-        begin
-          yield
-        ensure
-          _set_detail(:formats, old_formats)
-        end
-      end
-    end
   end
 end

actionview/lib/action_view/renderer/streaming_template_renderer.rb

@@ -47,7 +47,7 @@ def render_template(template, layout_name = nil, locals = {}) #:nodoc:
       return [super] unless layout_name && template.supports_streaming?
 
       locals ||= {}
-      layout   = layout_name && find_layout(layout_name, locals.keys)
+      layout   = layout_name && find_layout(layout_name, locals.keys, [formats.first])
 
       Body.new do |buffer|
         delayed_render(buffer, template, layout, @view, locals)

actionview/lib/action_view/renderer/template_renderer.rb

@@ -57,7 +57,7 @@ def render_template(template, layout_name = nil, locals = nil) #:nodoc:
     end
 
     def render_with_layout(path, locals) #:nodoc:
-      layout  = path && find_layout(path, locals.keys)
+      layout  = path && find_layout(path, locals.keys, [formats.first])
       content = yield(layout)
 
       if layout
@@ -72,25 +72,28 @@ def render_with_layout(path, locals) #:nodoc:
     # This is the method which actually finds the layout using details in the lookup
     # context object. If no layout is found, it checks if at least a layout with
     # the given name exists across all details before raising the error.
-    def find_layout(layout, keys)
-      with_layout_format { resolve_layout(layout, keys) }
+    def find_layout(layout, keys, formats)
+      resolve_layout(layout, keys, formats)
     end
 
-    def resolve_layout(layout, keys)
+    def resolve_layout(layout, keys, formats)
+      details = @details.dup
+      details[:formats] = formats
+
       case layout
       when String
         begin
           if layout =~ /^\//
-            with_fallbacks { find_template(layout, nil, false, keys, @details) }
+            with_fallbacks { find_template(layout, nil, false, keys, details) }
           else
-            find_template(layout, nil, false, keys, @details)
+            find_template(layout, nil, false, keys, details)
           end
         rescue ActionView::MissingTemplate
           all_details = @details.merge(:formats => @lookup_context.default_formats)
           raise unless template_exists?(layout, nil, false, keys, all_details)
         end
       when Proc
-        resolve_layout(layout.call, keys)
+        resolve_layout(layout.call, keys, formats)
       when FalseClass
         nil
       else