Merge pull request rails#54646 from Edouard-chin/ec-current-attribute-fix

Fix CurrentAttributes not setting an attribute's default:

Author: byroot

activesupport/lib/active_support/current_attributes.rb

@@ -187,7 +187,7 @@ def method_added(name)
           super
           return if name == :initialize
           return unless public_method_defined?(name)
-          return if respond_to?(name, true)
+          return if singleton_class.method_defined?(name) || singleton_class.private_method_defined?(name)
           Delegation.generate(singleton_class, [name], to: :instance, as: self, nilable: false)
         end
     end

activesupport/test/current_attributes_test.rb

@@ -262,4 +262,18 @@ class InvalidAttributeNames < ActiveSupport::CurrentAttributes
       end
     end
   end
+
+  test "method_added hook doesn't reach the instance. Fix for #54646" do
+    current = Class.new(ActiveSupport::CurrentAttributes) do
+      def self.name
+        "MyCurrent"
+      end
+
+      def foo; end # Sets the cache because of a `method_added` hook
+
+      attribute :bar, default: {}
+    end
+
+    assert_instance_of(Hash, current.bar)
+  end
 end