Bug #7308: Infinite recursion on circular 'using'

• Status: Closed
• Assignee: shugo (Shugo Maeda)
• Target version: 2.0.0
• ruby -v: 2.0.0-preview1

This code causes infinite recursion:

module X; using X; end

Note that any circular 'using' will cause infinite recursion, not just a module using itself:

module A; end
module B; using A; end
module A; using B; end

This raises a SystemStackError on my OS X Lion machine, but it causes a segmentation fault on Ubuntu 10.04 i686 (running 2.6.32-38). I've attached a dump of an IRB session which finishes with a segfault.

[mame (Yusuke Endoh)]

• Status changed from Open to Assigned
• Assignee set to shugo (Shugo Maeda)
• Target version set to 2.0.0

• File prevent-circular-using.patch prevent-circular-using.patch added

I've attached a patch that does a simple DFS to make sure no circular using relationship is created.

[shugo (Shugo Maeda)]

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

This issue was solved with changeset r37646.
Charlie, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• eval.c (rb_mod_using): raise an ArgumentError if cyclic using is
  detected. based on the patch by Charlie Somerville.
  [ruby-core:49092] Bug #7308

• test/ruby/test_refinement.rb: related test.

[shugo (Shugo Maeda)]

charliesome (Charlie Somerville) wrote:

I've attached a patch that does a simple DFS to make sure no circular using relationship is created.

Thank you. I've changed it to raise an ArgumentError instead of TypeError for the consistency with the cyclic include detection.