From: "jneen (Jeanine Adkisson) via ruby-core" <ruby-core@...>
Date: 2026-02-07T06:37:06+00:00
Subject: [ruby-core:124708] [Ruby Bug#21323] irb fails to start with Namespace

Issue #21323 has been updated by jneen (Jeanine Adkisson).


In fact, I believe this is still happening somewhat with IRB:

```
$ ./bin/irb 
irb(main):001> TOPLEVEL_BINDING.eval("A = 1")
=> 1
irb(main):002> A
=> 1
irb(main):003> 

$ RUBY_BOX=1 ./bin/irb 
/private/tmp/ruby/bin/ruby: warning: Ruby::Box is experimental, and the behavior may change in the future!
See https://docs.ruby-lang.org/en/4.0/Ruby/Box.html for known issues, etc.
irb(main):001> TOPLEVEL_BINDING.eval("A = 1")
=> 1
irb(main):002> A
(irb):2:in '<main>': uninitialized constant A (NameError)
        from /private/tmp/ruby/lib/ruby/gems/4.0.0/gems/irb-1.16.0/exe/irb:9:in '<top (r
equired)>'
        from /private/tmp/ruby/lib/ruby/site_ruby/4.0.0/rubygems.rb:324:in 'Kernel.load'
        from /private/tmp/ruby/lib/ruby/site_ruby/4.0.0/rubygems.rb:324:in 'Gem.activate
_and_load_bin_path'
        from ./bin/irb:25:in '<main>'
irb(main):003> Ruby::Box.current
=> #<Ruby::Box:1,root>
```

----------------------------------------
Bug #21323: irb fails to start with Namespace
https://bugs.ruby-lang.org/issues/21323#change-116303

* Author: Eregon (Benoit Daloze)
* Status: Closed
* ruby -v: ruby 3.5.0dev (2025-05-10T07:50:29Z namespace-on-read-.. bd4f57f96b) +PRISM [x86_64-linux]
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
```
$ irb
irb(main):001> 6 * 7
=> 42

$ RUBY_NAMESPACE=1 irb
/home/eregon/prefix/ruby-master/bin/ruby: warning: Namespace is experimental, and the behavior may change in the future!
See doc/namespace.md for know issues, etc.
/home/eregon/prefix/ruby-master/lib/ruby/3.5.0+0/did_you_mean/core_ext/name_error.rb:11: warning: irb is not part of the default gems since Ruby 3.5.0. Install irb from RubyGems.
/home/eregon/prefix/ruby-master/lib/ruby/3.5.0+0/did_you_mean/core_ext/name_error.rb:11: warning: irb is not part of the default gems since Ruby 3.5.0. Install irb from RubyGems.
<internal:/home/eregon/prefix/ruby-master/lib/ruby/3.5.0+0/rubygems/core_ext/kernel_require.rb>:141:in 'Kernel#require': cannot load such file -- irb (LoadError)
Did you mean?  erb
	from <internal:/home/eregon/prefix/ruby-master/lib/ruby/3.5.0+0/rubygems/core_ext/kernel_require.rb>:141:in 'Kernel#require'
	from /home/eregon/prefix/ruby-master/lib/ruby/gems/3.5.0+0/gems/irb-1.15.2/exe/irb:7:in 'Namespace::Loader#require'
	from /home/eregon/prefix/ruby-master/lib/ruby/gems/3.5.0+0/gems/irb-1.15.2/exe/irb:7:in '<top (required)>'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in 'Kernel#load'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in 'Namespace::Loader#load'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in '<main>'
<internal:/home/eregon/prefix/ruby-master/lib/ruby/3.5.0+0/rubygems/core_ext/kernel_require.rb>:136:in 'Kernel#require': cannot load such file -- irb (LoadError)
Did you mean?  erb
	from <internal:/home/eregon/prefix/ruby-master/lib/ruby/3.5.0+0/rubygems/core_ext/kernel_require.rb>:136:in 'Kernel#require'
	from /home/eregon/prefix/ruby-master/lib/ruby/gems/3.5.0+0/gems/irb-1.15.2/exe/irb:7:in 'Namespace::Loader#require'
	from /home/eregon/prefix/ruby-master/lib/ruby/gems/3.5.0+0/gems/irb-1.15.2/exe/irb:7:in '<top (required)>'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in 'Kernel#load'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in 'Namespace::Loader#load'
	from /home/eregon/.rubies/ruby-master/bin/irb:25:in '<main>'
zsh: exit 1     RUBY_NAMESPACE=1 irb
```



-- 
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