From: "jeremyevans0 (Jeremy Evans) via ruby-core" <ruby-core@...>
Date: 2023-07-13T17:18:32+00:00
Subject: [ruby-core:114169] [Ruby master Bug#19749] Confirm correct behaviour when attaching private method with `#define_method`

Issue #19749 has been updated by jeremyevans0 (Jeremy Evans).


I don't think my discussion from comment #7 was considered during the dev meeting. Discussion focused on general `define_method` behavior, which I don't think is a bug. I should have been more clear in the dev meeting ticket exactly what I would like to fix.

Here's a reduced example showing the problem:

```ruby
class A
  def a; end
  private def b; end

  m = instance_method(:b)
  define_method(:c, m) # defines public method
  define_method(:b, m) # defines private method, should define public method

  private

  m = instance_method(:a)
  define_method(:d, m) # defines private method
  define_method(:a, m) # defines public method, should define private method

  p public_instance_methods(false)  # => [:c, :a] # should be [:c, :b]
  p private_instance_methods(false) # => [:b, :d] # should be [:a, :d]
end
```

I think this particular behavior of not changing visibility of a method when calling `define_method` with the same method body is a bug that should be fixed.

----------------------------------------
Bug #19749: Confirm correct behaviour when attaching private method with `#define_method`
https://bugs.ruby-lang.org/issues/19749#change-103855

* Author: itarato (Peter Arato)
* Status: Open
* Priority: Normal
* ruby -v: 3.3.0
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
This issue is a special case of https://bugs.ruby-lang.org/issues/19745:

Should dynamically added private methods via `.singleton_class.send(:define_method,...` at the top-level be accessible publicly?

See the following example:

```ruby
def bar; end

foo = Object.new
foo.singleton_class.define_method(:bar, method(:bar))

foo.bar # No error.
```

The script above runs fine on latest Ruby 3.3. Is this correct to ignore the fact that the visibility in the caller context is the default top-level private visibility?

This came up during a TruffleRuby investigation (https://github.com/oracle/truffleruby/issues/3134) where the result for the same script is: `private method 'bar' called for #<Object:0xc8> (NoMethodError)`




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