bouncing_test.patch

diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index f71c7336fe..6edbe2ff65 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -612,7 +612,7 @@ def set_payload_for_mail(payload, mail)
         payload[:perform_deliveries] = mail.perform_deliveries
       end
 
-      def method_missing(method_name, *args)
+      ruby2_keywords def method_missing(method_name, *args)
         if action_methods.include?(method_name.to_s)
           MessageDelivery.new(self, method_name, *args)
         else
@@ -633,7 +633,7 @@ def initialize
       @_message = Mail.new
     end
 
-    def process(method_name, *args) #:nodoc:
+    ruby2_keywords def process(method_name, *args) #:nodoc:
       payload = {
         mailer: self.class.name,
         action: method_name,
@@ -654,7 +654,7 @@ def respond_to?(string, include_all = false)
         true
       end
 
-      def method_missing(*args)
+      ruby2_keywords def method_missing(*args)
         nil
       end
     end
diff --git a/actionmailer/lib/action_mailer/message_delivery.rb b/actionmailer/lib/action_mailer/message_delivery.rb
index 1e5cab6d47..f858c592c0 100644
--- a/actionmailer/lib/action_mailer/message_delivery.rb
+++ b/actionmailer/lib/action_mailer/message_delivery.rb
@@ -15,7 +15,7 @@ module ActionMailer
   #   Notifier.welcome(User.first).deliver_later # enqueue email delivery as a job through Active Job
   #   Notifier.welcome(User.first).message       # a Mail::Message object
   class MessageDelivery < Delegator
-    def initialize(mailer_class, action, *args) #:nodoc:
+    ruby2_keywords def initialize(mailer_class, action, *args) #:nodoc:
       @mailer_class, @action, @args = mailer_class, action, args
 
       # The mail is only processed if we try to call any methods on it.
diff --git a/actionmailer/lib/action_mailer/rescuable.rb b/actionmailer/lib/action_mailer/rescuable.rb
index 5b567eb500..0915b1f774 100644
--- a/actionmailer/lib/action_mailer/rescuable.rb
+++ b/actionmailer/lib/action_mailer/rescuable.rb
@@ -20,7 +20,7 @@ def handle_exceptions #:nodoc:
     end
 
     private
-      def process(*)
+      ruby2_keywords def process(*)
         handle_exceptions do
           super
         end
diff --git a/actionpack/lib/abstract_controller/base.rb b/actionpack/lib/abstract_controller/base.rb
index 3ff922029b..9db6b1ac03 100644
--- a/actionpack/lib/abstract_controller/base.rb
+++ b/actionpack/lib/abstract_controller/base.rb
@@ -124,7 +124,7 @@ def method_added(name)
     #
     # ==== Returns
     # * <tt>self</tt>
-    def process(action, *args)
+    ruby2_keywords def process(action, *args)
       @_action_name = action.to_s
 
       unless action_name = _find_action_name(@_action_name)
@@ -191,7 +191,7 @@ def action_method?(name)
       #
       # Notice that the first argument is the method to be dispatched
       # which is *not* necessarily the same as the action name.
-      def process_action(method_name, *args)
+      ruby2_keywords def process_action(method_name, *args)
         send_action(method_name, *args)
       end
 
diff --git a/actionview/lib/action_view/rendering.rb b/actionview/lib/action_view/rendering.rb
index 9ee6dabf31..a5f3083885 100644
--- a/actionview/lib/action_view/rendering.rb
+++ b/actionview/lib/action_view/rendering.rb
@@ -34,7 +34,7 @@ def initialize
     end
 
     # Overwrite process to setup I18n proxy.
-    def process(*) #:nodoc:
+    ruby2_keywords def process(*) #:nodoc:
       old_config, I18n.config = I18n.config, I18nProxy.new(I18n.config, lookup_context)
       super
     ensure
diff --git a/activejob/lib/active_job/arguments.rb b/activejob/lib/active_job/arguments.rb
index e08e30040b..a0bef12526 100644
--- a/activejob/lib/active_job/arguments.rb
+++ b/activejob/lib/active_job/arguments.rb
@@ -52,6 +52,8 @@ def deserialize(arguments)
       # :nodoc:
       SYMBOL_KEYS_KEY = "_aj_symbol_keys"
       # :nodoc:
+      RUBY2_KEYWORDS_KEY = "_aj_ruby2_keywords_keys"
+      # :nodoc:
       WITH_INDIFFERENT_ACCESS_KEY = "_aj_hash_with_indifferent_access"
       # :nodoc:
       OBJECT_SERIALIZER_KEY = "_aj_serialized"
@@ -60,10 +62,30 @@ def deserialize(arguments)
       RESERVED_KEYS = [
         GLOBALID_KEY, GLOBALID_KEY.to_sym,
         SYMBOL_KEYS_KEY, SYMBOL_KEYS_KEY.to_sym,
+        RUBY2_KEYWORDS_KEY, RUBY2_KEYWORDS_KEY.to_sym,
         OBJECT_SERIALIZER_KEY, OBJECT_SERIALIZER_KEY.to_sym,
         WITH_INDIFFERENT_ACCESS_KEY, WITH_INDIFFERENT_ACCESS_KEY.to_sym,
       ]
-      private_constant :PERMITTED_TYPES, :RESERVED_KEYS, :GLOBALID_KEY, :SYMBOL_KEYS_KEY, :WITH_INDIFFERENT_ACCESS_KEY
+      private_constant :PERMITTED_TYPES, :RESERVED_KEYS, :GLOBALID_KEY, :SYMBOL_KEYS_KEY, :RUBY2_KEYWORDS_KEY, :WITH_INDIFFERENT_ACCESS_KEY
+
+      class Ruby2KeywordsUtil
+        def initialize(*args)
+          @args = args
+        end
+        attr_reader :args
+
+        def self.flagged?(hash)
+          !self.new(*[hash]).args.last.equal?(hash)
+        end
+
+        ruby2_keywords def flag(*args)
+          args.last
+        end
+
+        def self.flag(hash)
+          self.new.flag(**hash)
+        end
+      end
 
       def serialize_argument(argument)
         case argument
@@ -79,6 +101,7 @@ def serialize_argument(argument)
           symbol_keys = argument.each_key.grep(Symbol).map(&:to_s)
           result = serialize_hash(argument)
           result[SYMBOL_KEYS_KEY] = symbol_keys
+          result[RUBY2_KEYWORDS_KEY] = Ruby2KeywordsUtil.flagged?(argument)
           result
         when -> (arg) { arg.respond_to?(:permitted?) }
           serialize_indifferent_hash(argument.to_h)
@@ -131,7 +154,9 @@ def deserialize_hash(serialized_hash)
         if result.delete(WITH_INDIFFERENT_ACCESS_KEY)
           result = result.with_indifferent_access
         elsif symbol_keys = result.delete(SYMBOL_KEYS_KEY)
+          ruby2_keywords_flag = result.delete(RUBY2_KEYWORDS_KEY)
           result = transform_symbol_keys(result, symbol_keys)
+          result = Ruby2KeywordsUtil.flag(**result) if ruby2_keywords_flag
         end
         result
       end

class Klass
attr_accessor :str
end
s1 = Klass.new #=> #Klass:0x401b3a38
s1.str = "Hello" #=> "Hello"
s2 = s1.clone #=> #<Klass:0x401b3998 @str="Hello">
s2.str[1,4] = "i" #=> "i"
s1.inspect #=> "#<Klass:0x401b3a38 @str="Hi">"
s2.inspect #=> "#<Klass:0x401b3998 @