[ruby-core:102889] [Ruby master Bug#17519] set_visibility fails when a prepended module and a refinement both exist

[merch-redmine@jeremyevans.net]

Issue #17519 has been updated by jeremyevans0 (Jeremy Evans).

Backport changed from 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN to 2.5: UNKNOWN, 2.6: REQUIRED, 2.7: REQUIRED, 3.0: REQUIRED

fledman (David Feldman) wrote in #note-6:
> do you plan to backport the fix to any of the supported 2.x versions?

The choice of which patches to backport is up to the branch maintainer. I've marked this for backporting, but it is their decision.

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Bug #17519: set_visibility fails when a prepended module and a refinement both exist
https://bugs.ruby-lang.org/issues/17519#change-90950

* Author: fledman (David Feldman)
* Status: Closed
* Priority: Normal
* ruby -v: ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-darwin19]
* Backport: 2.5: UNKNOWN, 2.6: REQUIRED, 2.7: REQUIRED, 3.0: REQUIRED
----------------------------------------
the set_visibility functions (aka public/private/protected) fail with NameError when:
* called on a specific object's singleton class
* for a specific method
* and both of the following are true
 * any module has been prepended to the object's class
 * a refinement exists for the specific method

note that the refinement does not need to ever be used

I have reproduced this on 3.0.0, 2.7.2, and 2.6.6 (those were the only 3 version I tested)

``` ruby
def test_visibility(function)
  h1 = {x:1, y:1}
  h2 = {x:2, y:2}

  h1.singleton_class.send(:private, function)
  h2.singleton_class.send(:public, function)

  begin
    puts h1.public_send(function, :x)
  rescue NoMethodError => err
    puts "hit NoMethodError as expected: #{err.inspect}"
  end

  puts h2.public_send(function, :x)
end
```

succeeds without any prepended modules or refinements:
```ruby
irb> test_visibility :except
hit NoMethodError as expected: #<NoMethodError: private method `except' called for {:x=>1, :y=>1}:Hash>
{:y=>2}
=> nil
```

succeeds with only a prepended module:
```ruby
irb> module Nothing; end; Hash.prepend(Nothing); Hash.ancestors
=> [Nothing, Hash, Enumerable, Object, PP::ObjectMixin, Kernel, BasicObject]

irb> test_visibility :except
hit NoMethodError as expected: #<NoMethodError: private method `except' called for {:x=>1, :y=>1}:Hash>
{:y=>2}
=> nil
```

succeeds with only a refinement:
```ruby
irb> module NeverUsed
  refine Hash do
    def except(*keys)
      {never: 'used'}
    end
  end
end
=> #<refinement:Hash@NeverUsed>

irb> test_visibility :except
hit NoMethodError as expected: #<NoMethodError: private method `except' called for {:x=>1, :y=>1}:Hash>
{:y=>2}
=> nil
```

fails with both a refinement and a prepended module:
```ruby
irb> module Nothing; end; Hash.prepend(Nothing); Hash.ancestors
=> [Nothing, Hash, Enumerable, Object, PP::ObjectMixin, Kernel, BasicObject]

irb> module NeverUsed
  refine Hash do
    def except(*keys)
      {never: 'used'}
    end
  end
end
=> #<refinement:Hash@NeverUsed>

irb> test_visibility :except
Traceback (most recent call last):
        6: from .rubies/ruby-3.0.0/bin/irb:23:in `<main>'
        5: from .rubies/ruby-3.0.0/bin/irb:23:in `load'
        4: from .rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/irb-1.3.0/exe/irb:11:in `<top (required)>'
        3: from (irb):25:in `<main>'
        2: from (irb):5:in `test_visibility'
        1: from (irb):5:in `private'
NameError (undefined method `except' for class `#<Class:#<Hash:0x00007ffd6b176f18>>')
Did you mean?  exec

# non-refined method still works
irb> test_visibility :fetch
hit NoMethodError as expected: #<NoMethodError: private method `fetch' called for {:x=>1, :y=>1}:Hash>
2
=> nil
```



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