Stack Overflow results in crash instead of SystemStackError

[jherman3]

In pry, if I purposely overflow the stack with infinite recursion, the expected exception is raised:

[1] pry(main)> def crash;crash;end
=> :crash
[2] pry(main)> crash
SystemStackError: stack level too deep

However, if pry-rescue is installed, the following happens, and pry crashes to the shell

[1] pry(main)> def crash;crash;end
=> :crash
[2] pry(main)> crash
/home/user/.rvm/gems/ruby-2.1.0/gems/pry-0.9.12.6/lib/pry/pry_instance.rb:523:in `attr_accessor': can't modify frozen Class (RuntimeError)

[vincentwoo]

This one's interesting. Do you have any leads on why this might be the case?

[kyrylo]

This is fixed with the most recent Pry version: gem install pry -v 0.10.0.pre2. I don't know what exactly fixed it, because there was a lot of commits.

[vincentwoo]

This is happening for me again, now:

root@ac6fb7242f86:~# pry
[1] pry(main)> def crash;crash;end
=> :crash
[2] pry(main)> crash
/var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/last_exception.rb:54:in `bt_source_location_for': undefined method `[]' for nil:NilClass (NoMethodError)
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/last_exception.rb:15:in `initialize'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:494:in `new'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:494:in `last_exception='
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:331:in `rescue in handle_line'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:317:in `handle_line'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:243:in `block (2 levels) in eval'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:242:in `catch'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:242:in `block in eval'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:241:in `catch'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_instance.rb:241:in `eval'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/repl.rb:77:in `block in repl'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/repl.rb:67:in `loop'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/repl.rb:67:in `repl'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/repl.rb:38:in `block in start'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/input_lock.rb:61:in `__with_ownership'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/input_lock.rb:79:in `with_ownership'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/repl.rb:38:in `start'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/repl.rb:15:in `start'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/pry_class.rb:169:in `start'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/cli.rb:219:in `block in <top (required)>'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/cli.rb:83:in `block in parse_options'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/cli.rb:83:in `each'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/lib/pry/cli.rb:83:in `parse_options'
    from /var/lib/gems/2.3.0/gems/pry-0.10.3/bin/pry:16:in `<top (required)>'
    from /usr/local/bin/pry:23:in `load'
    from /usr/local/bin/pry:23:in `<main>'
root@ac6fb7242f86:~# pry --version
Pry version 0.10.3 on Ruby 2.3.0
root@ac6fb7242f86:~# gem list

*** LOCAL GEMS ***

awesome_print (1.6.1)
bigdecimal (1.2.8)
coderay (1.1.0)
diff-lcs (1.2.5)
interception (0.5)
io-console (0.4.5)
json (1.8.3)
method_source (0.8.2)
minitest (5.8.4)
pry (0.10.3)
pry-doc (0.8.0)
pry-rescue (1.4.2)
psych (2.0.17)
rdoc (4.2.1)
rspec (3.4.0)
rspec-core (3.4.1)
rspec-expectations (3.4.0)
rspec-mocks (3.4.1)
rspec-support (3.4.1)
slop (3.6.0)
yard (0.8.7.6)

[vincentwoo]

Also, trying to run pry-rescue against a file that has a stack overflow error causes some weird fatal reentry error:

vwoo:rescuetest vwoo$ bundle exec rescue test.rb
WARNING: Tried to inspect exception outside of Pry::rescue{ }
/Users/vwoo/pry-rescue/lib/pry-rescue/core_ext.rb:20:in `rescue in block (2 levels) in rescue': exception reentered (fatal)
    from /Users/vwoo/pry-rescue/lib/pry-rescue/core_ext.rb:15:in `block (2 levels) in rescue'
    from /Users/vwoo/pry-rescue/lib/pry-rescue/core_ext.rb:14:in `catch'
    from /Users/vwoo/pry-rescue/lib/pry-rescue/core_ext.rb:14:in `block in rescue'
    from /Users/vwoo/pry-rescue/lib/pry-rescue/core_ext.rb:13:in `loop'
    from /Users/vwoo/pry-rescue/lib/pry-rescue/core_ext.rb:13:in `rescue'
    from /Users/vwoo/pry-rescue/lib/pry-rescue.rb:75:in `load'
    from /Users/vwoo/pry-rescue/bin/rescue:49:in `<top (required)>'
    from /Users/vwoo/.gem/ruby/2.3.0/bin/rescue:23:in `load'
    from /Users/vwoo/.gem/ruby/2.3.0/bin/rescue:23:in `<main>'

test.rb:

def crash
  crash
end

crash

@ConradIrwin: any thoughts? this one is pretty tricky.

[ConradIrwin]

There used to be a guard in the code to avoid calling any methods if the exception was a stack overflow — someone should try and find that code and check whether it works ;)

[vincentwoo]

https://github.com/ConradIrwin/pry-rescue/blob/master/lib/pry-rescue/core_ext.rb#L42 tries to catch SystemStackError, but at that point it is already a fatal for me. I guess what you're saying is that post rescue if any method is executed at all, we'll fatal out?