From cbfe735c69a37446d0c5a9d448ad6d181abd1736 Mon Sep 17 00:00:00 2001
From: Xavier Noria <fxn@hashref.com>
Date: Thu, 14 Apr 2022 22:31:26 +0200
Subject: [PATCH] Deprecate config.enable_dependency_loading

---
 guides/source/configuring.md                   |  4 ----
 railties/CHANGELOG.md                          |  4 ++++
 .../lib/rails/application/configuration.rb     | 18 +++++++++++++++++-
 .../test/application/configuration_test.rb     |  7 +++++++
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 872881524b762..1b3cc7cfb8995 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -233,10 +233,6 @@ Registers namespaces that are eager loaded when `config.eager_load` is set to `t
 
 Accepts an array of paths from which Rails will eager load on boot if `config.eager_load` is true. Defaults to every folder in the `app` directory of the application.
 
-#### `config.enable_dependency_loading`
-
-When `true`, enables autoloading, even if the application is eager loaded and `config.enable_reloading` is set to `false`. Defaults to `false`.
-
 #### `config.encoding`
 
 Sets up the application-wide encoding. Defaults to UTF-8.
diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index 5e898223eb035..e9e75a5c43c03 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Deprecate `config.enable_dependency_loading`. This flag addressed a limitation of the `classic` autoloader and has no effect nowadays. To fix this deprecation, please just delete the reference.
+
+    *Xavier Noria*
+
 *   Define `config.enable_reloading` to be `!config.cache_classes` for a more intuitive name. While `config.enable_reloading` and `config.reloading_enabled?` are preferred from now on, `config.cache_classes` is supported for backwards compatibility.
 
     *Xavier Noria*
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 8df587dbff7fb..843ebe6238eef 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -17,7 +17,7 @@ class Configuration < ::Rails::Engine::Configuration
                     :log_tags, :railties_order, :relative_url_root, :secret_key_base,
                     :ssl_options, :public_file_server,
                     :session_options, :time_zone, :reload_classes_only_on_change,
-                    :beginning_of_week, :filter_redirect, :x, :enable_dependency_loading,
+                    :beginning_of_week, :filter_redirect, :x,
                     :read_encrypted_secrets, :log_level, :content_security_policy_report_only,
                     :content_security_policy_nonce_generator, :content_security_policy_nonce_directives,
                     :require_master_key, :credentials, :disable_sandbox, :add_autoload_paths_to_load_path,
@@ -297,6 +297,22 @@ def enable_reloading=(value)
         self.cache_classes = !value
       end
 
+      ENABLE_DEPENDENCY_LOADING_WARNING = <<~MSG
+        This flag addressed a limitation of the `classic` autoloader and has no effect nowadays.
+        To fix this deprecation, please just delete the reference.
+      MSG
+      private_constant :ENABLE_DEPENDENCY_LOADING_WARNING
+
+      def enable_dependency_loading
+        ActiveSupport::Deprecation.warn(ENABLE_DEPENDENCY_LOADING_WARNING)
+        @enable_dependency_loading
+      end
+
+      def enable_dependency_loading=(value)
+        ActiveSupport::Deprecation.warn(ENABLE_DEPENDENCY_LOADING_WARNING)
+        @enable_dependency_loading = value
+      end
+
       def encoding=(value)
         @encoding = value
         silence_warnings do
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index 5ee8593c610c5..627aaba3a7bc9 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -1343,6 +1343,13 @@ def index
       assert_equal false, ActionView::Resolver.caching?
     end
 
+    test "config.enable_dependency_loading is deprecated" do
+      app "development"
+
+      assert_deprecated { Rails.application.config.enable_dependency_loading }
+      assert_deprecated { Rails.application.config.enable_dependency_loading = true }
+    end
+
     test "ActionController::Base.raise_on_open_redirects is true by default for new apps" do
       app "development"