Bug #15720: SystemStackError when referencing a refinement in a module that isn't used

• Status: Closed
• Assignee: ko1 (Koichi Sasada)
• Target version: -
• ruby -v: ruby 2.7.0dev (2019-03-21 trunk 67332) [x86_64-linux]
• Backport: 2.4: UNKNOWN, 2.5: DONE, 2.6: DONE

[chocolateboy (Chocolate Boy)]

module M1
  refine Kernel do
    def foo
      'foo called!'
    end
  end
end

module M2
  refine Kernel do
    def bar
      'bar called!'
    end
  end
end

using M1

puts foo
puts bar

Expected:

foo called!
Traceback (most recent call last):
bug.rb:20:in `<main>': undefined local variable or method `bar' for main:Object (NameError)

Actual:

foo called!
Traceback (most recent call last):
bug.rb:20:in `<main>': stack level too deep (SystemStackError)

Platform: Linux (Arch)

ruby -v:

• ruby 2.7.0dev (2019-03-21 trunk 67332) [x86_64-linux]
• ruby 2.6.2p47 (2019-03-13 revision 67232) [x86_64-linux]
• ruby 2.5.5p157 (2019-03-15 revision 67260) [x86_64-linux]

[chocolateboy (Chocolate Boy)]

• Description updated (diff)

[chocolateboy (Chocolate Boy)]

• Description updated (diff)

[chocolateboy (Chocolate Boy)]

• Description updated (diff)

[jeremyevans0 (Jeremy Evans)]

• File sse-unused-refinement.patch sse-unused-refinement.patch added
• Status changed from Open to Assigned
• Assignee set to ko1 (Koichi Sasada)

I can confirm this issue. I believe it stems from the fact that in vm_call_method_each_type, cc->me is getting overwritten by ref_me even if they already have the same def but a different defined_class, which results in infinite recursion. The attached patch should fix your example, but my understanding of this code is limited. ko1 or shugo should probably review this patch and determine if it is the proper way to fix this issue. This could possibly be related to #14068.

[nobu (Nobuyoshi Nakada)]

Seems fine.
Just rename test_refining_module_repeatedly which redefines an existing method.

• Status changed from Assigned to Closed

Applied in changeset git|5e018214e7435030727a97ac49db038d96438e74.

---

Fix SystemStackError when calling a method in an unused refinement

Fixes [Bug #15720]

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN to 2.4: UNKNOWN, 2.5: REQUIRED, 2.6: REQUIRED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.4: UNKNOWN, 2.5: REQUIRED, 2.6: REQUIRED to 2.4: UNKNOWN, 2.5: REQUIRED, 2.6: DONE

ruby_2_6 r67729 merged revision(s) 5e018214e7435030727a97ac49db038d96438e74.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.4: UNKNOWN, 2.5: REQUIRED, 2.6: DONE to 2.4: UNKNOWN, 2.5: DONE, 2.6: DONE

ruby_2_5 r67765 merged revision(s) 5e018214e7435030727a97ac49db038d96438e74.