Bug #13145: Symbol#clone doesn't work correctly

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16]
• Backport: 2.2: DONTNEED, 2.3: DONTNEED, 2.4: DONE

[hiro4bbh (Tatsuhiro Aoshima)]

Ruby 2.4.0 has a bug that Symbol converted from String at first cannot be cloned:

user@mypc ~$ irb
irb(main):001:0> :abc.clone  # When :abc has not been created from String (e.g. 'abc'.to_s.to_sym), clone will work.
=> :abc
irb(main):002:0> 'abc'.to_s.to_sym
=> :abc
irb(main):003:0> :abc.clone  # This clone will also work.
=> :abc
irb(main):004:0> 'abcd'.to_s.to_sym
=> :abcd
irb(main):005:0> :abcd.clone  # This clone WON'T WORK!?
TypeError: allocator undefined for Symbol
	from (irb):5:in `clone'
	from (irb):5
	from /usr/local/bin/irb:11:in `<main>'
irb(main):006:0>

As written in Ruby 2.4.0 documentation (e.g. https://docs.ruby-lang.org/ja/latest/method/Object/i/clone.html),
Symbol#clone must return itself.

Currently, I define Symbol#clone as the following in order to fix this bug:

class Symbol
  def clone
    self
  end
end

I think something has gone wrong ...

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Backport changed from 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN to 2.2: DONTNEED, 2.3: DONTNEED, 2.4: REQUIRED

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r57407.

---

object.c: no TypeError at Symbol

• object.c (special_object_p): uninterned Symbol also should not
  raise a TypeError but return itself instead, as well as interned
  Symbols. [ruby-core:79216] [Bug #13145]

[naruse (Yui NARUSE)]

• Backport changed from 2.2: DONTNEED, 2.3: DONTNEED, 2.4: REQUIRED to 2.2: DONTNEED, 2.3: DONTNEED, 2.4: DONE

ruby_2_4 r57869 merged revision(s) 57407.