From: "nagachika (Tomoyuki Chikanaga)" <noreply@...>
Date: 2022-10-01T06:35:43+00:00
Subject: [ruby-core:110157] [Ruby master Bug#18435] Calling `protected` on ancestor method changes result of `instance_methods(false)`

Issue #18435 has been updated by nagachika (Tomoyuki Chikanaga).


ruby_3_1 9e739022ded433f189a575017d3936b79541f229 merged revision(s) 94cea3e4d0a60326bd95be762819eed8ccd59ca6,aa53d69aa21c4dfa2a78a1cec5cb34e9697b3d30,6b7d32a5e54088b6b4014529bbf2b4b8c1a96029,c6319026caa6c8f0f569f80011e8502349a04b14,aa490f9442c32cd0e1e449ac817f410bd5924c8b.

Thank you Eregon to point out the additional changesets!

----------------------------------------
Bug #18435: Calling `protected` on ancestor method changes result of `instance_methods(false)`
https://bugs.ruby-lang.org/issues/18435#change-99414

* Author: ufuk (Ufuk Kayserilioglu)
* Status: Closed
* Priority: Normal
* Assignee: Eregon (Benoit Daloze)
* ruby -v: ruby 2.7.5p203 (2021-11-24 revision f69aeb8314) [x86_64-darwin20]
* Backport: 2.6: DONTNEED, 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONE
----------------------------------------
As documented `instance_methods(false)` works as follows:

```ruby
module A
  def method1()  end
end

class B
  include A

  def method2()  end
end

p B.instance_methods(false) #=> [:method2]
```

However, calling `protected` on the method defined by `A`, unexpectedly changes the result of `instance_methods(false)` on `B`, even though the owner of the method is still `A`:
```ruby
module A
  def method1()  end
end

class B
  include A

  protected :method1

  def method2()  end
end

p B.instance_methods(false) #=> [:method1, :method2]
p B.instance_method(:method1).owner #=> A
```

In contrast, calling `private` or `public` on the same method does not cause any changes on the result of `B.instance_methods(false)`.

This feels like a bug in the implementation of `instance_methods(false)`, but, if it is by design, it should at least be documented on `Module#instance_methods`.

This reproduction script gives the same output all the way from Ruby 2.0 up to Ruby-HEAD:
https://wandbox.org/permlink/LqbXMBTYxURRZmDz



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