Ensure all initializers are collections.

railties/lib/rails/application.rb

@@ -90,10 +90,10 @@ def call(env)
     end
 
     def initializers
-      initializers = Bootstrap.initializers
+      initializers = Bootstrap.initializers_for(self)
       railties.all { |r| initializers += r.initializers }
       initializers += super
-      initializers += Finisher.initializers
+      initializers += Finisher.initializers_for(self)
       initializers
     end
 

railties/lib/rails/application/bootstrap.rb

@@ -3,28 +3,28 @@ class Application
     module Bootstrap
       include Initializable
 
-      initializer :load_environment_config do |app|
-        app.require_environment!
+      initializer :load_environment_config do
+        require_environment!
       end
 
-      initializer :load_all_active_support do |app|
-        require "active_support/all" unless app.config.active_support.bare
+      initializer :load_all_active_support do
+        require "active_support/all" unless config.active_support.bare
       end
 
       # Preload all frameworks specified by the Configuration#frameworks.
       # Used by Passenger to ensure everything's loaded before forking and
       # to avoid autoload race conditions in JRuby.
-      initializer :preload_frameworks do |app|
+      initializer :preload_frameworks do
         require 'active_support/dependencies'
-        ActiveSupport::Autoload.eager_autoload! if app.config.preload_frameworks
+        ActiveSupport::Autoload.eager_autoload! if config.preload_frameworks
       end
 
       # Initialize the logger early in the stack in case we need to log some deprecation.
-      initializer :initialize_logger do |app|
-        Rails.logger ||= app.config.logger || begin
-          path = app.config.paths.log.to_a.first
+      initializer :initialize_logger do
+        Rails.logger ||= config.logger || begin
+          path = config.paths.log.to_a.first
           logger = ActiveSupport::BufferedLogger.new(path)
-          logger.level = ActiveSupport::BufferedLogger.const_get(app.config.log_level.to_s.upcase)
+          logger.level = ActiveSupport::BufferedLogger.const_get(config.log_level.to_s.upcase)
           logger.auto_flushing = false if Rails.env.production?
           logger
         rescue StandardError => e
@@ -39,23 +39,23 @@ module Bootstrap
       end
 
       # Initialize cache early in the stack so railties can make use of it.
-      initializer :initialize_cache do |app|
+      initializer :initialize_cache do
         unless defined?(RAILS_CACHE)
-          silence_warnings { Object.const_set "RAILS_CACHE", ActiveSupport::Cache.lookup_store(app.config.cache_store) }
+          silence_warnings { Object.const_set "RAILS_CACHE", ActiveSupport::Cache.lookup_store(config.cache_store) }
 
           if RAILS_CACHE.respond_to?(:middleware)
-            app.config.middleware.insert_after(:"Rack::Lock", RAILS_CACHE.middleware)
+            config.middleware.insert_after(:"Rack::Lock", RAILS_CACHE.middleware)
           end
         end
       end
 
       # Initialize rails subscriber on top of notifications.
-      initializer :initialize_subscriber do |app|
+      initializer :initialize_subscriber do
         require 'active_support/notifications'
 
-        if app.config.colorize_logging == false
-          Rails::Subscriber.colorize_logging     = false
-          app.config.generators.colorize_logging = false
+        if config.colorize_logging == false
+          Rails::Subscriber.colorize_logging = false
+          config.generators.colorize_logging = false
         end
 
         ActiveSupport::Notifications.subscribe do |*args|
@@ -63,8 +63,8 @@ module Bootstrap
         end
       end
 
-      initializer :set_clear_dependencies_hook do |app|
-        unless app.config.cache_classes
+      initializer :set_clear_dependencies_hook do
+        unless config.cache_classes
           ActionDispatch::Callbacks.after do
             ActiveSupport::Dependencies.clear
           end
@@ -73,8 +73,8 @@ module Bootstrap
 
       # Sets the dependency loading mechanism.
       # TODO: Remove files from the $" and always use require.
-      initializer :initialize_dependency_mechanism do |app|
-        ActiveSupport::Dependencies.mechanism = app.config.cache_classes ? :require : :load
+      initializer :initialize_dependency_mechanism do
+        ActiveSupport::Dependencies.mechanism = config.cache_classes ? :require : :load
       end
 
       initializer :bootstrap_load_path do

railties/lib/rails/application/finisher.rb

@@ -15,26 +15,26 @@ module Finisher
         end
       end
 
-      initializer :add_builtin_route do |app|
+      initializer :add_builtin_route do
         if Rails.env.development?
           Rails::Application::RoutesReloader.paths << File.join(RAILTIES_PATH, 'builtin', 'routes.rb')
         end
       end
 
-      initializer :build_middleware_stack do |app|
-        app.app
+      initializer :build_middleware_stack do
+        app
       end
 
       # Fires the user-supplied after_initialize block (config#after_initialize)
-      initializer :after_initialize do |app|
-        app.config.after_initialize_blocks.each do |block|
-          block.call(app)
+      initializer :after_initialize do
+        config.after_initialize_blocks.each do |block|
+          block.call(self)
         end
       end
 
       # Disable dependency loading during request cycle
-      initializer :disable_dependency_loading do |app|
-        if app.config.cache_classes && !app.config.dependency_loading
+      initializer :disable_dependency_loading do
+        if config.cache_classes && !config.dependency_loading
           ActiveSupport::Dependencies.unhook!
         end
       end

railties/lib/rails/initializable.rb

@@ -64,10 +64,7 @@ def run_initializers(*args)
     end
 
     def initializers
-      @initializers ||= begin
-        initializers = self.class.initializers_chain
-        Collection.new(initializers.map { |i| i.bind(self) })
-      end
+      @initializers ||= self.class.initializers_for(self)
     end
 
     module ClassMethods
@@ -84,6 +81,10 @@ def initializers_chain
         initializers
       end
 
+      def initializers_for(binding)
+        Collection.new(initializers_chain.map { |i| i.bind(binding) })
+      end
+
       def initializer(name, opts = {}, &blk)
         raise ArgumentError, "A block must be passed when defining an initializer" unless blk
         initializers << Initializer.new(name, nil, opts, &blk)