Merge PR rails#42538

Author: rafaelfranca

actionmailbox/test/dummy/config/initializers/application_controller_renderer.rb

@@ -1,3 +1,11 @@
+*   New and upgraded Rails apps no longer generate `config/initializers/application_controller_renderer.rb`
+    or `config/initializers/cookies_serializer.rb`
+
+    The default value for `cookies_serializer` (`:json`) has been moved to `config.load_defaults("7.0")`.
+    The new framework defaults file sets the serializer to `:marshal`.
+
+    *Alex Ghiculescu*
+
 *   New applications get a dependency on the new `debug` gem, replacing `byebug`.
 
     *Xavier Noria*

actionmailbox/test/dummy/config/initializers/cookies_serializer.rb

@@ -199,6 +199,7 @@ def load_defaults(target_version)
 
           if respond_to?(:action_dispatch)
             action_dispatch.return_only_request_media_type_on_content_type = false
+            action_dispatch.cookies_serializer = :json
           end
 
           if respond_to?(:action_controller)

actiontext/test/dummy/config/initializers/application_controller_renderer.rb

@@ -117,7 +117,6 @@ def config
     end
 
     def config_when_updating
-      cookie_serializer_config_exist  = File.exist?("config/initializers/cookies_serializer.rb")
       action_cable_config_exist       = File.exist?("config/cable.yml")
       active_storage_config_exist     = File.exist?("config/storage.yml")
       rack_cors_config_exist          = File.exist?("config/initializers/cors.rb")
@@ -131,10 +130,6 @@ def config_when_updating
 
       config
 
-      unless cookie_serializer_config_exist
-        gsub_file "config/initializers/cookies_serializer.rb", /json(?!,)/, "marshal"
-      end
-
       if !options[:skip_action_cable] && !action_cable_config_exist
         template "config/cable.yml"
       end
@@ -160,10 +155,6 @@ def config_when_updating
       end
 
       if options[:api]
-        unless cookie_serializer_config_exist
-          remove_file "config/initializers/cookies_serializer.rb"
-        end
-
         unless csp_config_exist
           remove_file "config/initializers/content_security_policy.rb"
         end
@@ -487,7 +478,6 @@ def delete_action_cable_files_skipping_action_cable
 
       def delete_non_api_initializers_if_api_option
         if options[:api]
-          remove_file "config/initializers/cookies_serializer.rb"
           remove_file "config/initializers/content_security_policy.rb"
           remove_file "config/initializers/permissions_policy.rb"
         end