From cecbf5dd4d814f0bbd6a7c77a7c550c90a75cf47 Mon Sep 17 00:00:00 2001
From: Juan Barreneche <snipperme@gmail.com>
Date: Thu, 14 Mar 2013 18:02:20 -0300
Subject: [PATCH] Include I18n fallbacks in :locale lookup context

---
 actionpack/CHANGELOG.md                                | 5 +++++
 actionpack/lib/action_view/lookup_context.rb           | 8 +++++++-
 actionpack/test/controller/localized_templates_test.rb | 9 +++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index b23d0668d37f..69096443fea9 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,5 +1,10 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Include I18n locale fallbacks in view lookup.
+    Fixes GH#3512.
+
+    *Juan Barreneche*
+
 *   Integration and functional tests allow headers and rack env
     variables to be passed when performing requests.
     Fixes #6513.
diff --git a/actionpack/lib/action_view/lookup_context.rb b/actionpack/lib/action_view/lookup_context.rb
index 4e4816d98324..d61cc0f304bb 100644
--- a/actionpack/lib/action_view/lookup_context.rb
+++ b/actionpack/lib/action_view/lookup_context.rb
@@ -43,7 +43,13 @@ def initialize_details(details)
     module Accessors #:nodoc:
     end
 
-    register_detail(:locale)  { [I18n.locale, I18n.default_locale].uniq }
+    register_detail(:locale) do
+      locales = [I18n.locale]
+      locales.concat(I18n.fallbacks[I18n.locale]) if I18n.respond_to? :fallbacks
+      locales << I18n.default_locale
+      locales.uniq!
+      locales
+    end
     register_detail(:formats) { ActionView::Base.default_formats || [:html, :text, :js, :css,  :xml, :json] }
     register_detail(:handlers){ Template::Handlers.extensions }
 
diff --git a/actionpack/test/controller/localized_templates_test.rb b/actionpack/test/controller/localized_templates_test.rb
index bac1d0297776..6b02eedaed57 100644
--- a/actionpack/test/controller/localized_templates_test.rb
+++ b/actionpack/test/controller/localized_templates_test.rb
@@ -25,4 +25,13 @@ def test_default_locale_template_is_used_when_locale_is_missing
   ensure
     I18n.locale = old_locale
   end
+
+  def test_use_fallback_locales
+    I18n.locale = :"de-AT"
+    I18n.backend.class.send(:include, I18n::Backend::Fallbacks)
+    I18n.fallbacks[:"de-AT"] = [:de]
+
+    get :hello_world
+    assert_equal "Gutten Tag", @response.body
+  end
 end