[ruby-core:126766] [Ruby Bug#22273] Aliasing doesn't interact well with Module#prepend

18 Sep 2026

      Issue #22273 has been updated by jeremyevans0 (Jeremy Evans).

Status changed from Closed to Open
Assignee set to jeremyevans0 (Jeremy Evans)

Reopening, since this should stay open until removal occurs.

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Bug #22273: Aliasing doesn't interact well with Module#prepend
https://bugs.ruby-lang.org/issues/22273#change-119065

* Author: luke-gru (Luke Gruber)
* Status: Open
* Assignee: jeremyevans0 (Jeremy Evans)
* Backport: 3.3: DONTNEED, 3.4: DONTNEED, 4.0: DONTNEED
----------------------------------------
Currently, aliasing doesn't interact well with `Module#prepend` in my opinion.

### Example

```ruby
module Kernel
  prepend(Module.new do
    def require(feature)
      puts "requiring feature (prepend): #{feature}"
      super
    end
  end)
end

module Kernel
  alias original_require require
  def require(feature)
    puts "requiring feature (alias): #{feature}"
    original_require(feature)
  end
end

require "set"
```

This produces this behavior:

```
requiring feature (prepend): set
requiring feature (alias): set
requiring feature (prepend): set
../ruby/test.rb:5:in 'require': super: no superclass method 'require' for main (NoMethodError)
```

I would expect this behavior:

```
requiring feature (prepend): set
requiring feature (alias): set
# Then, the original require would succeed
```

This has caused issues such as [22263](https://bugs.ruby-lang.org/issues/22263) and has [confused gem authors](https://github.com/fxn/zeitwerk/pull/203#issuecomment-1107777206). In the second link, the ignored alias was due to [this bug](https://github.com/ruby/ruby/commit/c59c4d717a2e687972341eab1574196e97d7d7be) which has recently been fixed.

### Bug?

As far as I know this is intentional behavior introduced in Ruby 2.0 [here](https://bugs.ruby-lang.org/issues/7842). There are even tests and specs that codify this behavior such as `test_prepend_super_in_alias` and `prepend_spec.rb`.

Even though it's intentional, I don't believe it's well thought out. I'm interested in hearing arguments for and against the current behavior (with code examples, preferably).

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