Move plumbing to enable yjit to inside the framework

guides/source/configuring.md

@@ -65,6 +65,7 @@ Below are the default values associated with each target version. In cases of co
 - [`config.active_record.postgresql_adapter_decode_dates`](#config-active-record-postgresql-adapter-decode-dates): `true`
 - [`config.active_record.validate_migration_timestamps`](#config-active-record-validate-migration-timestamps): `true`
 - [`config.active_storage.web_image_content_types`](#config-active-storage-web-image-content-types): `%w[image/png image/jpeg image/gif image/webp]`
+- [`config.yjit`](#config-yjit): `true`
 
 #### Default Values for Target Version 7.1
 
@@ -613,6 +614,16 @@ Used to easily add nested custom configuration to the application config object
 
 See [Custom Configuration](#custom-configuration)
 
+#### `config.yjit`
+
+Enables YJIT as of Ruby 3.3, to bring sizeable performance improvements. If you are
+deploying to a memory constrained environment you may want to set this to `false`.
+
+| Starting with version | The default value is |
+| --------------------- | -------------------- |
+| (original)            | `false`              |
+| 7.2                   | `true`               |
+
 ### Configuring Assets
 
 #### `config.assets.css_compressor`

railties/lib/rails/application/configuration.rb

@@ -23,7 +23,7 @@ class Configuration < ::Rails::Engine::Configuration
                     :content_security_policy_nonce_generator, :content_security_policy_nonce_directives,
                     :require_master_key, :credentials, :disable_sandbox, :sandbox_by_default,
                     :add_autoload_paths_to_load_path, :rake_eager_load, :server_timing, :log_file_size,
-                    :dom_testing_default_html_version
+                    :dom_testing_default_html_version, :yjit
 
       attr_reader :encoding, :api_only, :loaded_config_version, :log_level
 
@@ -81,6 +81,7 @@ def initialize(*)
         @rake_eager_load                         = false
         @server_timing                           = false
         @dom_testing_default_html_version        = :html4
+        @yjit                                    = false
       end
 
       # Loads default configuration values for a target version. This includes
@@ -318,6 +319,8 @@ def load_defaults(target_version)
         when "7.2"
           load_defaults "7.1"
 
+          self.yjit = true
+
           if respond_to?(:active_job)
             active_job.enqueue_after_transaction_commit = :default
           end

railties/lib/rails/application/finisher.rb

@@ -231,6 +231,12 @@ def self.complete(_state)
           ActiveSupport::DescendantsTracker.disable_clear!
         end
       end
+
+      initializer :enable_yjit do
+        if config.yjit && defined?(RubyVM::YJIT.enable)
+          RubyVM::YJIT.enable
+        end
+      end
     end
   end
 end

railties/test/generators/app_generator_test.rb

@@ -55,7 +55,6 @@
   config/environments/test.rb
   config/initializers/assets.rb
   config/initializers/content_security_policy.rb
-  config/initializers/enable_yjit.rb
   config/initializers/filter_parameter_logging.rb
   config/initializers/inflections.rb
   config/initializers/permissions_policy.rb

railties/test/generators/plugin_generator_test.rb

@@ -54,7 +54,6 @@
   test/dummy/config/environments/production.rb
   test/dummy/config/environments/test.rb
   test/dummy/config/initializers/content_security_policy.rb
-  test/dummy/config/initializers/enable_yjit.rb
   test/dummy/config/initializers/filter_parameter_logging.rb
   test/dummy/config/initializers/inflections.rb
   test/dummy/config/initializers/permissions_policy.rb