Style/RedundantSelf doesn't consider pattern matching variables

[kotovalexarian]

Style/RedundantSelf doesn't consider pattern matching variables. It treats the following code as offense, while removing self would change the behavior:

case cdr
in Integer => bar
  self.bar + bar
end

Also I want to notice that this code will be automatically corrected by RuboCop, which is a serious issue.

---

Expected behavior

$ rubocop --debug main.rb
For /home/kotovalexarian: configuration from /home/kotovalexarian/.rubocop.yml
Default configuration from /home/kotovalexarian/.rvm/gems/ruby-3.0.2@arcamark/gems/rubocop-1.21.0/config/default.yml
Use parallel by default.
Running parallel inspection
Inspecting 1 file
Scanning /home/kotovalexarian/main.rb
Loading cache from /home/kotovalexarian/.cache/rubocop_cache/1659dbf77b85bb74d511f7d88e7efa9320f1354c/6d7a3b621ca1730e04accd938619e4bdab66cfb1/a12a29925874af02e20456d83e6d5b54d11f7cee
.

1 file inspected, no offenses detected
Finished in 0.15581881400066777 seconds

Actual behavior

$ rubocop --debug main.rb
For /home/kotovalexarian: configuration from /home/kotovalexarian/.rubocop.yml
Default configuration from /home/kotovalexarian/.rvm/gems/ruby-3.0.2@arcamark/gems/rubocop-1.21.0/config/default.yml
Use parallel by default.
Running parallel inspection
Loading cache from /home/kotovalexarian/.cache/rubocop_cache/1659dbf77b85bb74d511f7d88e7efa9320f1354c/6d7a3b621ca1730e04accd938619e4bdab66cfb1/9a472dafb77012ac390f31cfdb34eb67a85f31ab
Inspecting 1 file
Scanning /home/kotovalexarian/main.rb
Loading cache from /home/kotovalexarian/.cache/rubocop_cache/1659dbf77b85bb74d511f7d88e7efa9320f1354c/6d7a3b621ca1730e04accd938619e4bdab66cfb1/9a472dafb77012ac390f31cfdb34eb67a85f31ab
C

Offenses:

main.rb:14:7: C: [Correctable] Style/RedundantSelf: Redundant self detected.
      self.bar + bar
      ^^^^

1 file inspected, 1 offense detected, 1 offense auto-correctable
Finished in 0.10107574600078806 seconds

Steps to reproduce the problem

Install Ruby 3.0.2 and RuboCop 1.12.0.

Create file .rubocop.yml with the following content:

AllCops:
  TargetRubyVersion: 3.0
  NewCops: enable

Create file main.rb with the following content:

# frozen_string_literal: true

##
# Foo class.
#
class Foo
  def bar
    100
  end

  def car(cdr)
    case cdr
    in Integer => bar
      self.bar + bar
    end
  end
end

raise unless Foo.new.cdr(23) == 123

RuboCop version

$ rubocop -V 
1.21.0 (using Parser 3.0.2.0, rubocop-ast 1.11.0, running on ruby 3.0.2 x86_64-linux)