Bug when broadcasting TaggedLogging(without a block) loggers.

[tmimura39]

Steps to reproduce

require 'active_support'
main_logger = ActiveSupport::TaggedLogging.new(ActiveSupport::Logger.new('main_logger.log'))
broadcast_logger = ActiveSupport::TaggedLogging.new(ActiveSupport::Logger.new('broadcast_logger.log'))
main_logger.extend(ActiveSupport::Logger.broadcast(broadcast_logger))
main_logger.tagged('tag')
main_logger.info('text')

Expected behavior

$ tail main_logger.log broadcast_logger.log
==> main_logger.log <==
# Logfile created on 2022-08-19 18:53:04 +0900 by logger.rb/v1.5.0
text

==> broadcast_logger.log <==
# Logfile created on 2022-08-19 18:53:04 +0900 by logger.rb/v1.5.0
text

Actual behavior

$ tail main_logger.log broadcast_logger.log
==> main_logger.log <==
# Logfile created on 2022-08-19 18:53:04 +0900 by logger.rb/v1.5.0
text

==> broadcast_logger.log <==
# Logfile created on 2022-08-19 18:53:04 +0900 by logger.rb/v1.5.0
[tag] text

If #tagged is used without blocking, the tag is incorrectly referenced in the broadcast destination logger.

I think it is a bug related to #44695.

When the formatter of the logger that originated the broadcast is updated, the reference to the tag to which the broadcast is directed is switched.

rails/activesupport/lib/active_support/tagged_logging.rb

Lines 99 to 107 in 04972d9

	define_singleton_method(:formatter=) do |formatter|
	other_logger.formatter ||= formatter
	other_logger.formatter.singleton_class.redefine_method(:current_tags) do
	formatter.current_tags
	end
	super(formatter)
	end

without block #tagged creates a temporary logger, in which case the formatter is updated.

rails/activesupport/lib/active_support/tagged_logging.rb

Line 116 in 04972d9

logger = ActiveSupport::TaggedLogging.new(self)

rails/activesupport/lib/active_support/tagged_logging.rb

Lines 85 to 90 in 04972d9

	if logger.formatter
	logger.formatter = logger.formatter.dup
	else
	# Ensure we set a default formatter so we aren't extending nil!
	logger.formatter = ActiveSupport::Logger::SimpleFormatter.new
	end

As a result, it appears that tags applied to temporary loggers are subsequently referenced in the broadcast destination loggers.

supplementary information

The standard output of logs at rails server startup in the development environment is implemented in broadcast.
Therefore, there may be differences in log output between standard output and log/develooment.log.

rails/railties/lib/rails/commands/server/server_command.rb

Lines 75 to 85 in 3d84e12

	def log_to_stdout
	wrapped_app # touch the app so the logger is set up
	console = ActiveSupport::Logger.new(STDOUT)
	console.formatter = Rails.logger.formatter
	console.level = Rails.logger.level
	unless ActiveSupport::Logger.logger_outputs_to?(Rails.logger, STDOUT)
	Rails.logger.extend(ActiveSupport::Logger.broadcast(console))
	end
	end

System configuration

Rails version: 7.0.2.3

Ruby version: 3.1.1