[ruby-core:122045] [Ruby Bug#21316] Namespaces leak with permanent names

13 May 2025

      Issue #21316 has been updated by make_now_just (Hiroya Fujinami).

I found an issue on `Marshal` and `Namespace` maybe related to this ticket.

When dumping an object defined in a namespace using Marshal, the result will vary depending on whether the namespace is held as a variable or constant, and whether `Marshal.dump` is performed inside or outside the namespace.

In other words, we have the following files:

`ns.rb`:
```ruby
class Foo
  def dump_in_ns = Marshal.dump(self)
end
```

`main.rb`:
```ruby
ns = Namespace.new
ns.require("./ns.rb")

NS = Namespace.new
NS.require("./ns.rb")

puts "var / in ns"
begin
  ns::Foo.new.dump
  p :ok
rescue => ex
  p :error
  p ex
end
puts

puts "const / in ns"
begin
  NS::Foo.new.dump
  p :ok
rescue => ex
  p :error
  p ex
end
puts

puts "var / out ns"
begin
  Marshal.dump(ns::Foo.new)
  p :ok
rescue => ex
  p :error
  p ex
end
puts

puts "const / out ns"
begin
  Marshal.dump(NS::Foo.new)
  p :ok
rescue => ex
  p :error
  p ex
end
```
Then, the result is as follows:
```console
$ RUBY_NAMESPACE=1 ruby main.rb
var / in ns
:error
#<NoMethodError: undefined method 'dump' for an instance of #<Namespace:0x000000012018ed88>::Foo>

const / in ns
:error
#<NoMethodError: undefined method 'dump' for an instance of NS::Foo>

var / out ns
:error
#<TypeError: can't dump anonymous class #<Namespace:0x000000012018ed88>::Foo>

const / out ns
:ok
```

I'm not sure this issue is completely related to this ticket,  but `Marshal.dump` should work in any case.

----------------------------------------
Bug #21316: Namespaces leak with permanent names
https://bugs.ruby-lang.org/issues/21316#change-113195

* Author: fxn (Xavier Noria)
* Status: Open
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Namespaces are not transparent for this program

```ruby
C = Class.new
C.name == 'C'
```

because under a non-main user namespace, the name of `C` has the namespace as a prefix.

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