Bug #11668: SEGV instead of SystemStackError when using the TracePoint API

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.3.0dev (2015-11-09 trunk 52499) [x86_64-linux
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

[deivid (David Rodríguez)]

fixnum_monkey.rb

class Fixnum
  define_method(:to_s) do |*args|
    to_default_s(*args)
  end

  alias_method :to_default_s, :to_s
end

If I use this code normally it gives me SystemStackError as expected

$ ruby -e "load('fixnum_monkey.rb');  5.to_s"
fixnum_monkey.rb:2:in `block in <class:Fixnum>': stack level too deep (SystemStackError)
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
    ... 5804 levels...
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from fixnum_monkey.rb:3:in `block in <class:Fixnum>'
   from -e:1:in `<main>'

But if I enable the return event of the TracePoint API before using it, I get a segfault

$ ruby -e "load('fixnum_monkey.rb'); TracePoint.trace(:return) { |_tp| }; 5.to_s"
Violación de segmento

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

It looks like this problem was fixed. While I can get this code to segfault on Ruby <2.5, I can no longer get a segfault for this code starting with Ruby 2.5:

class Fixnum
  define_method(:to_s) do |*args|
    to_default_s(*args)
  end

  alias_method :to_default_s, :to_s
end

TracePoint.trace(:return) { |_tp| }
1.to_s