Deprecate unused symbolized_base_class and symbolized_sti_name.

These methods were only used for the `IdentityMap` which was removed.
They are no longer used internally and should be removed without replacement.

As they were not `:nodoc:`'ed it's better to deprecate them before removal.

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Deprecate unused `ActiveRecord::Base.symbolized_base_class`
+    and `ActiveRecord::Base.symbolized_sti_name` without replacement.
+
+    *Yves Senn*
+
 *   Since the `test_help.rb` in Railties now automatically maintains
     your test schema, the `rake db:test:*` tasks are deprecated. This
     doesn't stop you manually running other tasks on your test database

activerecord/lib/active_record/inheritance.rb

@@ -45,10 +45,12 @@ module ActiveRecord
       end
 
       def symbolized_base_class
+        ActiveSupport::Deprecation.warn("ActiveRecord::Base.symbolized_base_class is deprecated and will be removed without replacement.")
         @symbolized_base_class ||= base_class.to_s.to_sym
       end
 
       def symbolized_sti_name
+        ActiveSupport::Deprecation.warn("ActiveRecord::Base.symbolized_sti_name is deprecated and will be removed without replacement.")
         @symbolized_sti_name ||= sti_name.present? ? sti_name.to_sym : symbolized_base_class
       end
 

guides/source/4_1_release_notes.md

@@ -432,6 +432,9 @@ for detailed changes.
   automatically maintained. See railties release notes. ([Pull
   Request](https://github.com/rails/rails/pull/13528))
 
+* Deprecate unused `ActiveRecord::Base.symbolized_base_class`
+  and `ActiveRecord::Base.symbolized_sti_name` without replacement.
+
 ### Notable changes
 
 * Added `ActiveRecord::Base.to_param` for convenient "pretty" URLs derived from