[ruby-core:120919] [Ruby master Bug#21125] Kernel is called first

9 Feb 2025

      Issue #21125 has been updated by jeremyevans0 (Jeremy Evans).

jeremyevans0 (Jeremy Evans) wrote in #note-3:
...
mikik0 (Hashino Mikiko) wrote in #note-2:
...
@jeremyevans0 san
It works with Ruby 3.3 series, but not from Ruby 3.4. Is it a specification?
You are correct.  It also works on Ruby 3.4 when using `--parser=parse.y`, so this appears to be related to prism.  I'll have to do more analysis to determine which behavior is correct, but it's certainly a bug that the behavior is not the same between prism and parse.y.
Sorry, that was me testing the wrong version.  The behavior is the same between prism and parse.y, so this is a difference in behavior between Ruby 3.3 and 3.4.  I still need to more analysis to determine which behavior is correct.

----------------------------------------
Bug #21125: Kernel is called first
https://bugs.ruby-lang.org/issues/21125#change-111801

* Author: mikik0 (Hashino Mikiko)
* Status: Open
* ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [arm64-darwin24]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Kernel#system is being called when there is a column or method name named system.
The other methods of Kernel reproduce the problem.
Ex.Rand returns a random value, and exit terminates the program.

## Reproducible script:

``` ruby
class ObjectifiedHash
  def initialize(hash)
    @hash = hash
  end

  private

  attr_reader :hash

  def method_missing(method_name, *args, &block)
    if hash.key?(method_name.to_sym)
      hash[method_name.to_sym]
    else
      super
    end
  end

  def respond_to_missing?(method_name, include_private = false)
    hash.key?(method_name.to_sym) || super
  end
end

class Foo
  def system(...)
    # Kernel#system is called
    raw.system(...)
    # (...) passes if there is no
    # raw.system
  end

  def initialize(raw)
    @raw = raw
  end

  def get_system
    system
  end

  private

  attr_reader :raw
end

class Test
  def self.run
    obj = ObjectifiedHash.new({
      system: 'system'
    })

    foo = Foo.new(obj)
    # foo.system would pass.
    # After executing foo.system, hoge.get_system also passes.
    # p foo.system
    p foo.get_system
  end
end

Test.run

```

## Execution Results
``` shell
hoge.rb:26:in 'Kernel#system': wrong number of arguments (given 0, expected 1+) (ArgumentError)

    raw.system(...)
               ^^^
        from ruby.rb:26:in 'Foo#system'
        from ruby.rb:36:in 'Foo#get_system'
        from ruby.rb:54:in 'Test.run'
        from ruby.rb:58:in '<main>'
```

## Expected results
``` shell
"system"
```

PR that may be relevant: https://github.com/ruby/ruby/pull/11028

-- 
https://bugs.ruby-lang.org/