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