Style/ArgumentsForwarding incorrectly fixes a case where an argument is used elsewhere in the method

[davidenglishmusic]

The auto-correct for the cop can break code by replacing the arguments when one of them is referenced in another part of the method.

---

Expected behavior

The following should not elicit a correction:

def method_missing(m, *args, **kwargs, &block)
  if @template.respond_to?(m)
    @template.send(m, *args, **kwargs, &block)
  else
    super
  end
end

Actual behavior

It corrects to the following which throws an undefined variable error:

def method_missing(...)
  if @template.respond_to?(m)
    @template.send(...)
  else
    super
  end
end

Steps to reproduce the problem

Auto-correct the code listed under the expected behavior heading.

RuboCop version

1.55.1 (using Parser 3.2.2.3, rubocop-ast 1.29.0, running on ruby 3.1.1) [x86_64-linux]
  - rubocop-capybara 2.18.0
  - rubocop-factory_bot 2.23.1
  - rubocop-performance 1.18.0
  - rubocop-rails 2.20.2
  - rubocop-rspec 2.23.0

[mattbrictson]

I noticed a similar bug.

Original:

def post(*args, &block)
  future_on(executor, *args, &block)

Erroneously corrected by rubocop to:

def post(...)
  future_on(...)

Expected behavior:

def post(...)
  future_on(executor, ...)

[owst]

Thanks for the report - I'll take a look at fixing this. There's clearly some overlap/similarity with #12087 too.

[tmikoss]

Adding another similar example. Produced by rubocop -a, version 1.55.1. association_name is used in the fucntion body.

Edit: rubocop -V:

1.55.1 (using Parser 3.2.2.3, rubocop-ast 1.29.0, running on ruby 3.1.2) [arm64-darwin21]
  - rubocop-performance 1.18.0
  - rubocop-rails 2.20.2

[koic]

FYI, I've opened #12101 to fix due to many reports about this issue. Thank you.

[chulkilee]

1.56 included the fix (#12103) but it did not fix the issue.

Source

class Foo
  def bar(*args, &block)
    hello(*args, &block)
    world(*args)
  end
end

Script

bin/rubocop --version
1.56.0

bin/rubocop -a test.rb
Inspecting 1 file
C

Offenses:

test.rb:2:11: C: [Corrected] Style/ArgumentsForwarding: Use shorthand syntax ... for arguments forwarding.
  def bar(*args, &block)
          ^^^^^^^^^^^^^
test.rb:3:11: C: [Corrected] Style/ArgumentsForwarding: Use shorthand syntax ... for arguments forwarding.
    hello(*args, &block)
          ^^^^^^^^^^^^^

Output

class Foo
  def bar(...)
    hello(...)
    world(*args)
  end
end

Can we reopen this issue? Or let me know if opening a new issue is preferred.

[owst]

@chulkilee apologies that I've still not got the cop quite right - without looking at the code, your issue looks like a slightly different scenario/cause to me, so I think it should be a new issue. I'll try and take a look over the weekend.

[chulkilee]

@owst Got it - created #12117