Fix keyword arguments warnings in Active Job

Related #38053, #38187, #38105, #38260.

This is a reattempt to fix keyword arguments warnings in Active Job.

Now Ruby (master) has `Hash.ruby2_keywords_hash{?,}` and that will be
backported to 2.7.1.

https://github.com/ruby/ruby/pull/2818
https://bugs.ruby-lang.org/issues/16486

I've emulated that for 2.7.0 and older versions.

activejob/lib/active_job/arguments.rb

@@ -52,6 +52,8 @@ module ActiveJob
       # :nodoc:
       SYMBOL_KEYS_KEY = "_aj_symbol_keys"
       # :nodoc:
+      RUBY2_KEYWORDS_KEY = "_aj_ruby2_keywords"
+      # :nodoc:
       WITH_INDIFFERENT_ACCESS_KEY = "_aj_hash_with_indifferent_access"
       # :nodoc:
       OBJECT_SERIALIZER_KEY = "_aj_serialized"
@@ -60,10 +62,39 @@ module ActiveJob
       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
+
+      unless Hash.respond_to?(:ruby2_keywords_hash?) && Hash.respond_to?(:ruby2_keywords_hash)
+        using Module.new {
+          refine Hash do
+            class << Hash
+              if RUBY_VERSION >= "2.7"
+                def ruby2_keywords_hash?(hash)
+                  !new(*[hash]).default.equal?(hash)
+                end
+              else
+                def ruby2_keywords_hash?(hash)
+                  false
+                end
+              end
+
+              def ruby2_keywords_hash(hash)
+                _ruby2_keywords_hash(**hash)
+              end
+
+              private def _ruby2_keywords_hash(*args)
+                args.last
+              end
+              ruby2_keywords(:_ruby2_keywords_hash) if respond_to?(:ruby2_keywords, true)
+            end
+          end
+        }
+      end
 
       def serialize_argument(argument)
         case argument
@@ -76,9 +107,14 @@ module ActiveJob
         when ActiveSupport::HashWithIndifferentAccess
           serialize_indifferent_hash(argument)
         when Hash
-          symbol_keys = argument.each_key.grep(Symbol).map(&:to_s)
+          symbol_keys = argument.each_key.grep(Symbol).map!(&:to_s)
+          aj_hash_key = if Hash.ruby2_keywords_hash?(argument)
+            RUBY2_KEYWORDS_KEY
+          else
+            SYMBOL_KEYS_KEY
+          end
           result = serialize_hash(argument)
-          result[SYMBOL_KEYS_KEY] = symbol_keys
+          result[aj_hash_key] = symbol_keys
           result
         when -> (arg) { arg.respond_to?(:permitted?) }
           serialize_indifferent_hash(argument.to_h)
@@ -132,6 +168,9 @@ module ActiveJob
           result = result.with_indifferent_access
         elsif symbol_keys = result.delete(SYMBOL_KEYS_KEY)
           result = transform_symbol_keys(result, symbol_keys)
+        elsif symbol_keys = result.delete(RUBY2_KEYWORDS_KEY)
+          result = transform_symbol_keys(result, symbol_keys)
+          result = Hash.ruby2_keywords_hash(result)
         end
         result
       end

activejob/lib/active_job/core.rb

@@ -86,6 +86,7 @@ module ActiveJob
       @executions = 0
       @exception_executions = {}
     end
+    ruby2_keywords(:initialize) if respond_to?(:ruby2_keywords, true)
 
     # Returns a hash with the job data that can safely be passed to the
     # queuing adapter.

activejob/lib/active_job/enqueuing.rb

@@ -21,11 +21,13 @@ module ActiveJob
       def perform_later(*args)
         job_or_instantiate(*args).enqueue
       end
+      ruby2_keywords(:perform_later) if respond_to?(:ruby2_keywords, true)
 
       private
         def job_or_instantiate(*args) # :doc:
           args.first.is_a?(self) ? args.first : new(*args)
         end
+        ruby2_keywords(:job_or_instantiate) if respond_to?(:ruby2_keywords, true)
     end
 
     # Enqueues the job to be performed by the queue adapter.

activejob/lib/active_job/execution.rb

@@ -17,6 +17,7 @@ module ActiveJob
       def perform_now(*args)
         job_or_instantiate(*args).perform_now
       end
+      ruby2_keywords(:perform_now) if respond_to?(:ruby2_keywords, true)
 
       def execute(job_data) #:nodoc:
         ActiveJob::Callbacks.run_callbacks(:execute) do

activejob/test/cases/argument_serialization_test.rb

@@ -170,7 +170,7 @@ class ArgumentSerializationTest < ActiveSupport::TestCase
   end
 
   test "allows for keyword arguments" do
-    KwargsJob.perform_later(argument: 2)
+    KwargsJob.perform_now(argument: 2)
 
     assert_equal "Job with argument: 2", JobBuffer.last_value
   end