Don't show the warning if we're already raising the error anyway

If the route set is empty, or if none of the routes matches with a score > 0,
there is no point showing the deprecation message because we are already be
raising the `ActionController::UrlGenerationError` mentioned in the warning.

In this case it is the expected behavior and the user wouldn't have to take any
actions.

1 files changed, 13 insertions, 8 deletions

diff --git a/actionpack/lib/action_dispatch/journey/formatter.rb b/actionpack/lib/action_dispatch/journey/formatter.rb
index 62bd4a33f2..177f586c0e 100644
--- a/actionpack/lib/action_dispatch/journey/formatter.rb
+++ b/actionpack/lib/action_dispatch/journey/formatter.rb
@@ -81,14 +81,8 @@ module ActionDispatch
           if named_routes.key?(name)
             yield named_routes[name]
           else
-            if name
-              ActiveSupport::Deprecation.warn <<-MSG.squish
-                You are trying to generate the URL for a named route called
-                #{name.inspect} but no such route was found. In the future,
-                this will result in an `ActionController::UrlGenerationError`
-                exception.
-              MSG
-            end
+            # Make sure we don't show the deprecation warning more than once
+            warned = false
 
             routes = non_recursive(cache, options)
 
@@ -98,6 +92,17 @@ module ActionDispatch
               break if score < 0
 
               hash[score].sort_by { |i, _| i }.each do |_, route|
+                if name && !warned
+                  ActiveSupport::Deprecation.warn <<-MSG.squish
+                    You are trying to generate the URL for a named route called
+                    #{name.inspect} but no such route was found. In the future,
+                    this will result in an `ActionController::UrlGenerationError`
+                    exception.
+                  MSG
+
+                  warned = true
+                end
+
                 yield route
               end
             end