Merge pull request rails#48996 from Shopify/check-for-parent-being-an-owner-of-the-target-method

Allow parent being the owner of an alias attribute method

Author: byroot

activerecord/lib/active_record/attribute_methods.rb

@@ -87,7 +87,8 @@ def alias_attribute_method_definition(code_generator, pattern, new_name, old_nam
         old_name = old_name.to_s
 
         method_defined = method_defined?(target_name) || private_method_defined?(target_name)
-        manually_defined = method_defined && self.instance_method(target_name).owner != generated_attribute_methods
+        manually_defined = method_defined &&
+          !self.instance_method(target_name).owner.is_a?(GeneratedAttributeMethods)
         reserved_method_name = ::ActiveRecord::AttributeMethods.dangerous_attribute_methods.include?(target_name)
 
         if manually_defined && !reserved_method_name

activerecord/test/cases/attribute_methods_test.rb

@@ -1266,6 +1266,28 @@ class ChildWithDeprecatedBehaviorResolved < ClassWithDeprecatedAliasAttributeBeh
     assert_equal("overridden_subject_was", obj.subject_was)
   end
 
+  ParentWithAlias = Class.new(ActiveRecord::Base) do
+    self.table_name = "topics"
+    alias_attribute :parents_subject, :title
+  end
+
+  AbstractClassInBetween = Class.new(ParentWithAlias) do
+    self.abstract_class = true
+    alias_attribute :parents_subject, :title
+  end
+
+  ChildWithAnAliasFromAbstractClass = Class.new(AbstractClassInBetween) do
+  end
+
+  test "#alias_attribute with the same alias as parent doesn't issue a deprecation" do
+    ParentWithAlias.new # eagerly generate parents alias methods
+    obj = assert_not_deprecated(ActiveRecord.deprecator) do
+      ChildWithAnAliasFromAbstractClass.new
+    end
+    obj.title = "hey"
+    assert_equal("hey", obj.parents_subject)
+  end
+
   test "#alias_attribute method on an abstract class is available on subclasses" do
     superclass = Class.new(ActiveRecord::Base) do
       self.abstract_class = true