Bug #16403: Unavailable protected methods through `Symbol#to_proc`

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 2.6.5p114 (2019-10-01 revision 67812) [x86_64-linux]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN

[AlexWayfer (Alexander Popov)]

Hello!

I've faced with a bug (I guess):

# protected.rb
# frozen_string_literal: true

class Foo
  def initialize(text, *children)
    @text = text
    @children = children
  end

  def via_each
    @children.reduce(text) do |result, child|
      result + child.text
    end
  end

  def via_map
    text + @children.map(&:text).reduce(:+)
  end

  protected

  attr_reader :text
end

child1 = Foo.new('Alexander ')
child2 = Foo.new('Popov')

foo = Foo.new('Hello ', child1, child2)

puts foo.via_each

puts foo.via_map

Output:

Hello Alexander Popov
Traceback (most recent call last):
	2: from protected.rb:31:in `<main>'
	1: from protected.rb:16:in `via_map'
protected.rb:16:in `map': protected method `text' called for #<Foo:0x000055db24b97710 @text="Alexander ", @children=[]> (NoMethodError)

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Rejected

Proc by Symbol#to_proc calls the method on its argument in an isolated context, so the receiver does not exist.