Performance/RedundantStringChars: Does not detect string.chars.last

[DannyBen]

Expected behavior

Expected the cop to report string.chars.last and autocorrect it to string[-1].

Actual behavior

The cop only corrects string.chars.first and does not report string.chars.last as an offense.

Steps to reproduce the problem

Create this rubocop.yml:

require: rubocop-performance

AllCops:
  NewCops: enable
  TargetRubyVersion: 3.0

Create this test.rb file:

# frozen_string_literal: true

string = 'AZ'

p string.chars.first
p string.chars.last

Run rubocop or rubocop -A. The autocorrected output will be:

# frozen_string_literal: true

string = 'AZ'

p string[0]
p string.chars.last

RuboCop version

$ rubocop -V
1.39.0 (using Parser 3.1.2.1, rubocop-ast 1.23.0, running on ruby 3.1.0) [x86_64-linux]
  - rubocop-performance 1.15.1