module ActiveSupport::Deprecation::InstanceDelegator::ClassMethods

def _instance
  @_instance ||= MUTEX.synchronize { @_instance ||= new }
end

def include(included_module)
  included_module.instance_methods.each { |m| method_added(m) }
  super
end

def instance
  ActiveSupport.deprecator.warn("ActiveSupport::Deprecation.instance is deprecated (use your own Deprecation object)")
  _instance
end

def method_added(method_name)
  use_instead =
    case method_name
    when :silence, :behavior=, :disallowed_behavior=, :disallowed_warnings=, :silenced=, :debug=
      target = "(defined?(Rails.application.deprecators) ? Rails.application.deprecators : ActiveSupport::Deprecation._instance)"
      "Rails.application.deprecators.#{method_name}"
    when :warn, :deprecate_methods, :gem_name, :gem_name=, :deprecation_horizon, :deprecation_horizon=
      "your own Deprecation object"
    else
      "Rails.application.deprecators[framework].#{method_name} where framework is for example :active_record"
    end
  args = /[^\]]=\z/.match?(method_name) ? "arg" : "..."
  target ||= "ActiveSupport::Deprecation._instance"
  singleton_class.module_eval <<~RUBY, __FILE__, __LINE__ + 1
    def #{method_name}(#{args})
      #{target}.#{method_name}(#{args})
    ensure
      ActiveSupport.deprecator.warn("Calling #{method_name} on ActiveSupport::Deprecation is deprecated and will be removed from Rails (use #{use_instead} instead)")
    end
  RUBY
end