Bug #21446: StackOverflow when changing visibility in reopened refinement

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: 3.5.0
• Backport: 3.2: REQUIRED, 3.3: REQUIRED, 3.4: REQUIRED

[luke-gru (Luke Gruber)]

class A
  def a
    :a
  end
end
class B < A
end

module R
  refine B do
    private :a
  end
end
module R
  refine B do
    public :a
  end
end
using R
B.new.a # StackOverflow

I would expect it to change the visibility, not to overflow the stack.

[nobu (Nobuyoshi Nakada)]

It does not seem to need to reopen the refinement.

Reproduces just by changing visibility twice.

module R
  refine B do
    private :a
    public :a
  end
end

[nobu (Nobuyoshi Nakada)]

• Backport changed from 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.2: REQUIRED, 3.3: REQUIRED, 3.4: REQUIRED

[jeremyevans0 (Jeremy Evans)]

I found that you don't even need to change the visibility twice. This issue affects all refinement visibility change methods where the method whose visibility is changed by the refinement is in an ancestor of the refined class. Here's a simplified example:

class A
  private def a
    :a
  end
end
class B < A
end

module R
  refine B do
    public :a
  end
end
using R
p B.new.a

I've submitted a pull request that handles this case: https://github.com/ruby/ruby/pull/14817