Bug #11086: Symbol#instance_eval gives 'TypeError: can't define singleton' when coerced with String#to_sym

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]
• Backport: 2.0.0: DONTNEED, 2.1: DONTNEED, 2.2: DONE

[ThijsWouters (Thijs Wouters)]

When I coerce a String into a Symbol with String#to_sym, a call to Symbol#instance_eval fails with 'TypeError: can't define singleton'. If I first define the Symbol, it works as expected.

Failure:

2.2.1 :001 > "test_symbol".to_sym.instance_eval{true}
TypeError: can't define singleton
	from (irb):1:in `instance_eval'
	from (irb):1
	from /home/xxx/.rvm/rubies/ruby-2.2.1/bin/irb:11:in `<main>'
2.2.1 :002 > :test_symbol.instance_eval{true}
TypeError: can't define singleton
	from (irb):2:in `instance_eval'
	from (irb):2
	from /home/xxx/.rvm/rubies/ruby-2.2.1/bin/irb:11:in `<main>'
2.2.1 :003 > exit

Other way around:

2.2.1 :001 > :test_symbol.instance_eval{true}
 => true 
2.2.1 :002 > "test_symbol".to_sym.instance_eval{true}
 => true 
2.2.1 :003 > exit 

This also fails in 2.2.0, but does not in 2.1.5.

[ThijsWouters (Thijs Wouters)]

• File test.patch test.patch added

I added a patch with a failing test.

[nobu (Nobuyoshi Nakada)]

• Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN to 2.0.0: DONTNEED, 2.1: DONTNEED, 2.2: REQUIRED

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

Applied in changeset r50372.

---

vm_eval.c: allow symbols to instance_eval/exec

• vm_eval.c (rb_obj_instance_eval, rb_obj_instance_exec): allow
  symbols to just instance_eval/exec, execept for definition of
  singletons. [ruby-core:68961] [Bug #11086]

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.0.0: DONTNEED, 2.1: DONTNEED, 2.2: REQUIRED to 2.0.0: DONTNEED, 2.1: DONTNEED, 2.2: DONE

Backported into ruby_2_2 branch at r50561.