class RuboCop::CLI

def run_line_length_cop_auto_gen_config(paths)

on Metrics/LineLength:Max get the correct value for that parameter.
Do an initial run with only Metrics/LineLength so that cops that depend 
def run_line_length_cop_auto_gen_config(paths)
  puts Rainbow('Phase 1 of 2: run Metrics/LineLength cop').yellow
  @options[:only] = ['Metrics/LineLength']
  execute_runner(paths)
  @options.delete(:only)
  @config_store = ConfigStore.new
  # Save the todo configuration of the LineLength cop.
  IO.read(ConfigLoader::AUTO_GENERATED_FILE)
    .lines
    .drop_while { |line| line.start_with?('#') }
    .join
end