Style/NumberedParametersLimit incorrectly(?) counting largest parameter number instead of number of parameters used

[owst]

Added in #10111 , Style/NumberedParametersLimit reports that more than one numbered parameter is used, when there is only one parameter used but it is "higher" than _1 e.g. _2.

For example, .group_by { _2 } causes an offense of

Avoid using more than 1 numbered parameter; 2 detected.

(but group_by { _1 } does not)

I suspect that the intention of the cop was to avoid using more than one numbered parameter in a single block (e.g. { _1 + _2 + _3 }), rather than a single reference to a not-first numbered parameter (e.g. { _2 }).

---

Expected behavior

No offense - a single parameter is used

Actual behavior

An offense was raised.

Steps to reproduce the problem

TargetRubyVersion must be (at least) 2.7. Then the following repro.rb:

grouped = { a: 1, b: 1, c: 2 }.group_by { _2 }

gives:

$ rubocop --config =(echo -e "AllCops:\n  TargetRubyVersion: 2.7") --debug --cache false --only Style/NumberedParametersLimit re
pro.rb
configuration from /tmp/zshJPIBdI
Default configuration from /Users/owenstephens/.rbenv/versions/2.7.6/lib/ruby/gems/2.7.0/gems/rubocop-1.41.0/config/default.yml
Inspecting 1 file
Scanning /private/tmp/repro.rb
C

Offenses:

repro.rb:1:11: C: Style/NumberedParametersLimit: Avoid using more than 1 numbered parameter; 2 detected.
grouped = { a: 1, b: 1, c: 2 }.group_by { _2 }
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

1 file inspected, 1 offense detected

RuboCop version

$ [bundle exec] rubocop -V
1.44.1 (using Parser 3.2.0.0, rubocop-ast 1.24.1, running on ruby 3.1.3) [x86_64-darwin21]