Autocorrecting with Performance/BlockGivenWithExplicitBlock and Lint/UnusedMethodArgument breaks code

[ymap]

When both Performance/BlockGivenWithExplicitBlock and Lint/UnusedMethodArgument cops are enabled, there seem to be cases where the autocorrect introduces incorrect behavior. This specifically occurs in method definitions with the following characteristics:

• The block argument is explicitly declared.
• This argument remains unused within the method.
• The method invokes block_given?.

Here's a sample code to illustrate the issue:

def foo(&block)
  block_given?
end

---

Expected Behavior

Only one of the cop's autocorrects should be executed. Ideally, the code should be:

def foo
  block_given?
end

or

def foo(&block)
  block
end

Actual Behavior

The autocorrect results in:

def foo
  block
end

This leads to the code referencing an undefined variable block, thus deviating from the intended functionality.

Steps to Reproduce

1. Save the code snippet below as example.rb.

def foo(&block)
  block_given?
end

2. Run bundle exec rubocop -a example.rb.

RuboCop Version

$ bundle exec rubocop -V
1.56.1 (using Parser 3.2.2.3, rubocop-ast 1.29.0, running on ruby 3.0.2) [x86_64-linux]
  - rubocop-performance 1.19.0
  - rubocop-rspec 2.22.0