1 files changed, 14 insertions, 2 deletions
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index b618b9c400..8b5a39dcaf 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -50,7 +50,19 @@ module ActionDispatch
 
         private
           def constraint_args(constraint, request)
-            constraint.arity == 1 ? [request] : [request.path_parameters, request]
+            arity = if constraint.respond_to?(:arity)
+              constraint.arity
+            else
+              constraint.method(:call).arity
+            end
+
+            if arity < 1
+              []
+            elsif arity == 1
+              [request]
+            else
+              [request.path_parameters, request]
+            end
           end
       end
 
@@ -390,7 +402,7 @@ module ActionDispatch
       # for root cases, where the latter is the correct one.
       def self.normalize_path(path)
         path = Journey::Router::Utils.normalize_path(path)
-        path.gsub!(%r{/(\(+)/?}, '\1/') unless path =~ %r{^/\(+[^)]+\)$}
+        path.gsub!(%r{/(\(+)/?}, '\1/') unless path =~ %r{^/(\(+[^)]+\)){1,}$}
         path
       end