Fixed issue w/custom accessors + reserved name + inheritance

Fixed an issue where custom accessor methods (such as those generated by
`enum`) with the same name as a global method are incorrectly overridden
when subclassing.

This was partially fixed in 4155431 then broken again by e5f15a8.

Fixes #16288.

1 files changed, 8 insertions, 5 deletions

diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index a2bb78dfcc..82f1682b33 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -57,6 +57,8 @@ module ActiveRecord
       end
     end
 
+    class GeneratedAttributeMethods < Module; end # :nodoc:
+
     module ClassMethods
       def inherited(child_class) #:nodoc:
         child_class.initialize_generated_modules
@@ -64,7 +66,7 @@ module ActiveRecord
       end
 
       def initialize_generated_modules # :nodoc:
-        @generated_attribute_methods = Module.new { extend Mutex_m }
+        @generated_attribute_methods = GeneratedAttributeMethods.new { extend Mutex_m }
         @attribute_methods_generated = false
         include @generated_attribute_methods
       end
@@ -113,10 +115,11 @@ module ActiveRecord
         if superclass == Base
           super
         else
-          # If B < A and A defines its own attribute method, then we don't want to overwrite that.
-          defined = method_defined_within?(method_name, superclass, superclass.generated_attribute_methods)
-          base_defined = Base.method_defined?(method_name) || Base.private_method_defined?(method_name)
-          defined && !base_defined || super
+          # If ThisClass < ... < SomeSuperClass < ... < Base and SomeSuperClass
+          # defines its own attribute method, then we don't want to overwrite that.
+          defined = method_defined_within?(method_name, superclass, Base) &&
+            ! superclass.instance_method(method_name).owner.is_a?(GeneratedAttributeMethods)
+          defined || super
         end
       end