use raise to create exceptions and to set the backtrace

actionpack/lib/action_dispatch/middleware/show_exceptions.rb

@@ -50,7 +50,7 @@ def call(env)
         # Only this middleware cares about RoutingError. So, let's just raise
         # it here.
         if headers['X-Cascade'] == 'pass'
-           exception = ActionController::RoutingError.new("No route matches #{env['PATH_INFO'].inspect}")
+           raise ActionController::RoutingError, "No route matches #{env['PATH_INFO'].inspect}"
         end
       rescue Exception => exception
         raise exception if env['action_dispatch.show_exceptions'] == false

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -450,7 +450,7 @@ def generate
         end
 
         def raise_routing_error
-          raise ActionController::RoutingError.new("No route matches #{options.inspect}")
+          raise ActionController::RoutingError, "No route matches #{options.inspect}"
         end
 
         def different_controller?