Metrics/ParameterLists ignores Max value generate by rubocop --auto-gen-config

[ShockwaveNN]

Steps to reproduce the problem

1. Create test.rb file with content:

# frozen_string_literal: true

def foo(param1, param2, param3 = true, param4 = false, param5 = false, param6 = false)
  puts param1
  puts param2
  puts param3
  puts param4
  puts param5
  puts param6
end

2. run rubocop --auto-gen-config and get this .rubocop_todo.yml

# This configuration was generated by
# `rubocop --auto-gen-config`
# on 2021-01-29 13:25:51 UTC using RuboCop version 1.9.0.
# The point is for the user to remove these configuration records
# one by one as the offenses are removed from the code base.
# Note that changes in the inspected code, or installation of new
# versions of RuboCop, may require this file to be generated again.

# Offense count: 2
# Configuration parameters: CountKeywordArgs, MaxOptionalParameters.
Metrics/ParameterLists:
  Max: 6

# Offense count: 4
# Configuration parameters: AllowedMethods.
# AllowedMethods: respond_to_missing?
Style/OptionalBooleanParameter:
  Exclude:
    - 'test.rb'

3. Metrics/ParameterLists max is 6, so it should be no warning for running rubocop now, but there is one:

rubocop
...
Offenses:

test.rb:3:1: C: Metrics/ParameterLists: Method has too many optional parameters. [4/3]
def foo(param1, param2, param3 = true, param4 = false, param5 = false, param6 = false) ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

1 file inspected, 1 offense detected

RuboCop version

1.9.0 (using Parser 3.0.0.0, rubocop-ast 1.4.1, running on ruby 2.7.2 x86_64-linux)

[dvandersluis]

Optional parameters have a separate configuration, MaxOptionalParameters, which is why you're seeing [4/3] and not [6/4]. You could add that config to the todo file in the meantime until this is fixed.

[ShockwaveNN]

Shouldn't --auto-gen-config generate config which will not result any warning on next rubocop run?

[dvandersluis]

Definitely, I'm opening a PR momentarily.