From: "mame (Yusuke Endoh)" <noreply@...>
Date: 2022-05-18T01:27:12+00:00
Subject: [ruby-core:108605] [Ruby master Bug#18751] Regression on master for Method#== when comparing public with private method

Issue #18751 has been updated by mame (Yusuke Endoh).


jeremyevans0 (Jeremy Evans) wrote in #note-10:
> you would have to make it so the `rb_method_entry_t*` points to the ZSUPER method.

Yes. I meant it by "we determined to allow a Method object for ZSUPER method entry".

> Lacking a detailed understanding of why the code is the way it is, I made the assumption that there is a reason the `rb_method_entry_t*` points to the original method,

I think the original author (matz? nobu? Or ko1? I don't know) wanted to hide ZSUPER method entry from users because it is an implementation detail. However, #18729 showed that the hiding was incomplete. At the previous dev meeting, we discussed whether the hiding is really needed, and agreed to stop hiding it (https://bugs.ruby-lang.org/issues/18729#note-6).

> and I took the conservative approach of just adding visibility information without changing other internals.

You are very thoughtful and wonderful! Thank you always.

----------------------------------------
Bug #18751: Regression on master for Method#== when comparing public with private method
https://bugs.ruby-lang.org/issues/18751#change-97642

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.2.0dev (2022-04-23T02:59:20Z master e142bea799) [x86_64-linux]
* Backport: 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED
----------------------------------------
This script repros:
```ruby
class C
  class << self
    alias_method :n, :new
    private :new
  end
end

p C.method(:n) == C.method(:new) # => true

puts
p C.method(:n) == Class.method(:new) # => false
p C.method(:n) == Class.method(:new).unbind.bind(C) # => true

puts
p C.method(:new) == Class.method(:new) # => false
p C.method(:new) == Class.method(:new).unbind.bind(C) # => true, BUT false on master
p C.method(:new) == Class.instance_method(:new).bind(C) # => true, BUT false on master
p [C.method(:new), Class.instance_method(:new).bind(C)] # => [#<Method: #<Class:C>(Class)#new(*)>, #<Method: #<Class:C>(Class)#new(*)>]
```

So this prints the expected results on 2.7.5, 3.0.3, 3.1.1 but not on master, which seems a regression.
Notably this breaks the pattern discussed in https://bugs.ruby-lang.org/issues/18729#note-5, and it means there is no way to find out if two methods share the same "definition/logic/def", which is a big limitation.



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