Fix defect where aliased attribute methods on abstract classes were b…

…eing not defined

rails/rails@a88f47d fixed an issue where subclasses were regenerating aliased attribute methods defined on parent classes. Part of the solution was to call #generate_alias_attributes recursively on a class's superclass to generate all the alias attributes in the inheritance hierarchy. However, the implementation relies on #base_class to determine if we should call #generate_alias_attributes on the superclass. Since all models that inherit from abstract classes are base classes, this means that #generate_alias_attributes will never be called on abstract classes, meaning no method will be generated for any alias attributes defined on them.

To fix this issue, we should always call #generate_alias_attributes on the superclass unless the superclass is ActiveRecord::Base.

activerecord/lib/active_record/attribute_methods.rb

@@ -65,7 +65,7 @@ def eagerly_generate_alias_attribute_methods(_new_name, _old_name) # :nodoc:
       end
 
       def generate_alias_attributes # :nodoc:
-        superclass.generate_alias_attributes unless base_class?
+        superclass.generate_alias_attributes unless superclass == Base
         return if @alias_attributes_mass_generated
 
         generated_attribute_methods.synchronize do

activerecord/test/cases/attribute_methods_test.rb

@@ -1246,6 +1246,18 @@ class ChildWithDeprecatedBehaviorResolved < ClassWithDeprecatedAliasAttributeBeh
     assert_equal("overridden_subject_was", obj.subject_was)
   end
 
+  test "#alias_attribute method on an abstract class is available on subclasses" do
+    superclass = Class.new(ActiveRecord::Base) do
+      self.abstract_class = true
+      alias_attribute :id_value, :id
+    end
+    subclass = Class.new(superclass) { self.table_name = "topics" }
+
+    object = subclass.build(id: 123_456)
+
+    assert_equal 123_456, object.id_value
+  end
+
   private
     def new_topic_like_ar_class(&block)
       klass = Class.new(ActiveRecord::Base) do