Allow serialize attribute on alias_attribute

Related to #25998.

activerecord/lib/active_record/attributes.rb

@@ -207,6 +207,8 @@ module ClassMethods
       # methods in ActiveModel::Type::Value for more details.
       def attribute(name, cast_type = nil, default: NO_DEFAULT_PROVIDED, **options)
         name = name.to_s
+        name = attribute_aliases[name] || name
+
         reload_schema_from_cache
 
         case cast_type

activerecord/lib/active_record/enum.rb

@@ -186,11 +186,9 @@ def _enum(name, values, prefix: nil, suffix: nil, scopes: true, **options)
         detect_enum_conflict!(name, name)
         detect_enum_conflict!(name, "#{name}=")
 
-        attr = attribute_alias?(name) ? attribute_alias(name) : name
-
-        attribute(attr, **options) do |subtype|
+        attribute(name, **options) do |subtype|
           subtype = subtype.subtype if EnumType === subtype
-          EnumType.new(attr, enum_values, subtype)
+          EnumType.new(name, enum_values, subtype)
         end
 
         value_method_names = []

activerecord/test/cases/serialized_attribute_test.rb

@@ -41,6 +41,21 @@ def test_serialized_attribute
     assert_equal(myobj, topic.content)
   end
 
+  def test_serialized_attribute_on_alias_attribute
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = Topic.table_name
+      alias_attribute :object, :content
+      serialize :object, MyObject
+    end
+
+    myobj = MyObject.new("value1", "value2")
+    topic = klass.create!(object: myobj)
+    assert_equal(myobj, topic.object)
+
+    topic.reload
+    assert_equal(myobj, topic.object)
+  end
+
   def test_serialized_attribute_with_default
     klass = Class.new(ActiveRecord::Base) do
       self.table_name = Topic.table_name