Raise an ArgumentError when a clashing named route is defined

1 files changed, 8 insertions, 1 deletions

diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 619dd22ec1..38e9288572 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -403,11 +403,18 @@ module ActionDispatch
       def add_route(app, conditions = {}, requirements = {}, defaults = {}, name = nil, anchor = true)
         raise ArgumentError, "Invalid route name: '#{name}'" unless name.blank? || name.to_s.match(/^[_a-z]\w*$/i)
 
+        if name && named_routes[name]
+          raise ArgumentError, "Invalid route name, already in use: '#{name}' \n" \
+            "This conflict might arise if your routes contain `resources :#{name.pluralize}`. " \
+            "If so, you can restrict the routes created with `resources` as explained here: \n" \
+            "http://guides.rubyonrails.org/routing.html#restricting-the-routes-created"
+        end
+
         path = build_path(conditions.delete(:path_info), requirements, SEPARATORS, anchor)
         conditions = build_conditions(conditions, path.names.map { |x| x.to_sym })
 
         route = @set.add_route(app, path, conditions, defaults, name)
-        named_routes[name] = route if name && !named_routes[name]
+        named_routes[name] = route if name
         route
       end