From: "Eregon (Benoit Daloze) via ruby-core" <ruby-core@...>
Date: 2026-04-12T11:35:07+00:00
Subject: [ruby-core:125240] [Ruby Bug#21992] Defining BasicObject#initialize causes segmentation fault

Issue #21992 has been updated by Eregon (Benoit Daloze).


nobu (Nobuyoshi Nakada) wrote in #note-1:
> `BasicObject#initialize` is not defined, so "redefining" may be questionable.

It seems it is defined:
```
$ ruby -ve 'p Class.new.instance_method :initialize' 
ruby 3.4.9 (2026-03-11 revision 76cca827ab) +PRISM [x86_64-linux]
#<UnboundMethod: BasicObject#initialize()>
```

----------------------------------------
Bug #21992: Defining BasicObject#initialize causes segmentation fault
https://bugs.ruby-lang.org/issues/21992#change-116979

* Author: petercooper (Peter Cooper)
* Status: Open
* ruby -v: 4.0.2
* Backport: 3.2: REQUIRED, 3.3: REQUIRED, 3.4: REQUIRED, 4.0: REQUIRED
----------------------------------------
Simplest reproduction:

``` ruby
class BasicObject
  def initialize
  end
end
```

In Ruby HEAD, 4.0.2, 3.4.7, and 3.3.11 on macOS, this leads to an immediate segmentation fault. I also got this on Ruby 3.4.1 on Linux.

What I would expect, a warning similar to that raised if you do the same on `Object`.

I couldn't find a previous mention of this. It's not something you would ever write yourself, but I guess it could arise during metaprogramming or dynamic code generation with the right (wrong) constant name in play.



-- 
https://bugs.ruby-lang.org/
______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/