Bug #17033: Infinite Traceback when encountering an Exception while catching an Exception

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-linux]
• Backport: 2.5: DONTNEED, 2.6: DONE, 2.7: DONE

[NickHackman (Nick Hackman)]

In Ruby 2.7.1 when an Exception occurs and another occurs when handling the first one it results in an infinite Traceback that doesn't mention the error.

class MyException < StandardError
  def initialize(obj)
    @obj = obj
  end

  def to_s
    @obj.to_strm
  end
end

begin
  raise MyException.new('test'), 'message'
rescue StandardError => e
  puts e.to_s
end

In the above instance, there's a typo to_strm doesn't exist for type String, but instead of a normal case of a typo saying that the method doesn't exist the output is

~ λ ruby ruby_traceback_hell.rb
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
...

it keeps going without printing any sort of message about the actual error.

It's expected that this would result in a message saying that the method is undefined, and this is the behavior on 2.5.1, and appears to be a regression in 2.7.1

[NickHackman (Nick Hackman)]

NickHackman (Nick Hackman) wrote:

In Ruby 2.7.1 when an Exception occurs and another occurs when handling the first one it results in an infinite Traceback that doesn't mention the error.

class MyException < StandardError
  def initialize(obj)
    @obj = obj
  end

  def to_s
    @obj.to_strm
  end
end

begin
  raise MyException.new('test'), 'message'
rescue StandardError => e
  puts e.to_s
end

In the above instance, there's a typo to_strm doesn't exist for type String, but instead of a normal case of a typo saying that the method doesn't exist the output is

~ λ ruby ruby_traceback_hell.rb
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
...

it keeps going without printing any sort of message about the actual error.

It's expected that this would result in a message saying that the method is undefined, and this is the behavior on 2.5.1, and appears to be a regression in 2.7.1

If this is an actual issue is it possible I could work on it?

[nobu (Nobuyoshi Nakada)]

• Backport changed from 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN to 2.5: DONTNEED, 2.6: REQUIRED, 2.7: REQUIRED

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset git|579645d9f870fa4116dcd3200bbbb6e2c0b7f400.

---

Fixed infinite loop at error in printing cause [Bug #17033]

[ujihisa (Tatsuhiro Ujihisa)]

(Oh I see, this and https://bugs.ruby-lang.org/issues/14566#change-71448 were independent)

[nobu (Nobuyoshi Nakada)]

Yes, it is similar however occurs while printing causes, which was added at 2.6.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.5: DONTNEED, 2.6: REQUIRED, 2.7: REQUIRED to 2.5: DONTNEED, 2.6: REQUIRED, 2.7: DONE

ruby_2_7 27fa1c61b78c1685ccf9ac203a95cfa9041d618f merged revision(s) 579645d9f870fa4116dcd3200bbbb6e2c0b7f400.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.5: DONTNEED, 2.6: REQUIRED, 2.7: DONE to 2.5: DONTNEED, 2.6: DONE, 2.7: DONE

backported into ruby_2_6 at r67913.