(thanks for working on Rubocop! 🙏 apologies if this has already been addressed.)

When a local variable is set using conditional assignment with the result from another module method, and safe-autocorrect with Style/RedundantSelf is run, then self is removed but the behaviour of the code changes completely.

I think it makes sense for the cop warning to be raised, but the safe auto-correct shouldn't break the code or change its behaviour. An unsafe autocorrect would be fine, of course.

I understand that conditional assignment would be pointless in the example below, but sometimes you have a lot of these issues to comb through. Having the safe-autocorrect changing the behaviour of the code wasn't expected.

Happy to try and put in a fix for this in case it's really a bug.

Expected behavior

Running bundle exec rubocop --only Style/RedundantSelf rubocop_redundant_self.rb -a should not change the behaviour of the code below.

module RubocopRedundantSelf
  def self.example
    foo ||= self.foo
  end

  def self.foo
    "hello"
  end
end

Actual behavior

The behaviour of the code changes - now foo is always nil:

module RubocopRedundantSelf
  def self.example
    foo ||= foo # <-- self is removed here
  end

  # (...)
end

Steps to reproduce the problem

Full sample code:

module RubocopRedundantSelf
  def self.example
    foo ||= self.foo

    if foo.nil?
      raise "foo must not be nil"
    end

    foo
  end

  def self.foo
    "hello"
  end
end

puts RubocopRedundantSelf.example

1. if you run the code, it works fine:

$ ruby rubocop_redundant_self.rb
#=> hello

2. Run safe autocorrect:

$ rubocop --only Style/RedundantSelf -a

C: [Corrected] Style/RedundantSelf: Redundant self detected.
    foo ||= self.foo
            ^^^^

1 file inspected, 2 offenses detected, 1 offense corrected

3. Resulting code:

module RubocopRedundantSelf
  def self.example
    foo ||= foo # <---- self is removed here

    if foo.nil?
      raise "foo must not be nil"
    end

    foo
  end

  def self.foo
    "hello"
  end
end

puts RubocopRedundantSelf.example

4. If you run the code, the behaviour changes:

rubocop_redundant_self.rb:6:in 'RubocopRedundantSelf.example': foo must not be nil (RuntimeError)
	from rubocop_redundant_self.rb:17:in '<main>'

RuboCop version

1.76.2 (using Parser 3.3.8.0, Prism 1.4.0, rubocop-ast 1.45.1, analyzing as Ruby 3.4, running on ruby 3.4.4) [arm64-darwin24]

Full debug output:

bundle exec rubocop --debug --only Style/RedundantSelf rubocop_redundant_self.rb -a --debug

For (...): configuration from .rubocop.yml
Inheriting configuration from .rubocop.project.yml
Default configuration from .bundle/ruby/3.4.0/gems/rubocop-1.76.2/config/default.yml
Use parallel by default.
Skipping parallel inspection: only a single file needs inspection
Inspecting 1 file
Scanning rubocop_redundant_self.rb
C

Offenses:

rubocop_redundant_self.rb:3:13: C: [Corrected] Style/RedundantSelf: Redundant self detected.
    foo ||= self.foo
            ^^^^