Show an "unmatched constraints" error for mismatching and present params

Currently a misleading "missing required keys" error is thrown when a param
fails to match the constraints of a particular route. This commit ensures that
these params are recognised as unmatching rather than missing.

Note: this means that a different error message will be provided between
optimized and non-optimized path helpers, due to the fact that the former does
not check constraints when matching routes.

Fixes #26470.

2 files changed, 6 insertions, 2 deletions

diff --git a/actionpack/lib/action_dispatch/journey/formatter.rb b/actionpack/lib/action_dispatch/journey/formatter.rb
index a289c34e8b..dc8b24b089 100644
--- a/actionpack/lib/action_dispatch/journey/formatter.rb
+++ b/actionpack/lib/action_dispatch/journey/formatter.rb
@@ -44,8 +44,12 @@ module ActionDispatch
           return [route.format(parameterized_parts), params]
         end
 
+        unmatched_keys = (missing_keys || []) & constraints.keys
+        missing_keys = (missing_keys || []) - unmatched_keys
+
         message = "No route matches #{Hash[constraints.sort_by { |k,v| k.to_s }].inspect}"
-        message << " missing required keys: #{missing_keys.sort.inspect}" if missing_keys && !missing_keys.empty?
+        message << ", missing required keys: #{missing_keys.sort.inspect}" if missing_keys && !missing_keys.empty?
+        message << ", possible unmatched constraints: #{unmatched_keys.sort.inspect}" if unmatched_keys && !unmatched_keys.empty?
 
         raise ActionController::UrlGenerationError, message
       end
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 5abf59402d..a1bc357c8b 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -210,7 +210,7 @@ module ActionDispatch
                 }
                 constraints = Hash[@route.requirements.merge(params).sort_by { |k,v| k.to_s }]
                 message = "No route matches #{constraints.inspect}"
-                message << " missing required keys: #{missing_keys.sort.inspect}"
+                message << ", missing required keys: #{missing_keys.sort.inspect}"
 
                 raise ActionController::UrlGenerationError, message
               end