From: "Eregon (Benoit Daloze)" <noreply@...>
Date: 2022-06-17T10:45:24+00:00
Subject: [ruby-core:108981] [Ruby master Bug#18832] Suspicious superclass mismatch

Issue #18832 has been updated by Eregon (Benoit Daloze).


Yes, I think that's a great example why we should fix this.

Anyone should still be able to define a `Comment` (defined as a constant of `Object`) class with just `class Comment` at the top-level, even if with `REXML::Comment` + `include REXML`.

BTW, I thought `class Object::Comment < String; end` might be a workaround but it does not (as Jeremy found out as well above):
```ruby
$ ruby -v -rrexml -e 'include REXML; class Object::Comment < String; end'
ruby 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [x86_64-linux]
-e:1:in `<main>': superclass mismatch for class Comment (TypeError)
```

This is also very surprising (the intention is to define `Object::Comment` with a superclass of `Object`):
```ruby
$ ruby -v -rrexml -e 'include REXML; class Comment; end; p Comment.ancestors'
ruby 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [x86_64-linux]
[REXML::Comment, Comparable, REXML::Child, REXML::Node, Object, REXML, PP::ObjectMixin, Kernel, BasicObject]
```

----------------------------------------
Bug #18832: Suspicious superclass mismatch
https://bugs.ruby-lang.org/issues/18832#change-98086

* Author: fxn (Xavier Noria)
* Status: Open
* Priority: Normal
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
The following code:

```ruby
module M
  class C
  end
end

include M

p Object.const_defined?(:C, false)

class C < String # (1)
end
```

prints `false`, as expected, but then raises `superclass mismatch for class C (TypeError)` at (1).

I believe this is a bug, because `Object` itself does not have a `C` constant, so (1) should just work, and the superclasse of `M::C` should be irrelevant.



-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>