Issue #21343 has been updated by byroot (Jean Boussier). Seems adjacent to https://bugs.ruby-lang.org/issues/21330. The `klass` field like the `flags` one isn't part of the `classext_t`, so it's not effectively namespaced. ---------------------------------------- Bug #21343: Namespace: singleton classes of root namespace leak between namespaces https://bugs.ruby-lang.org/issues/21343#change-113287 * Author: jhawthorn (John Hawthorn) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Ruby classes all have singleton classes, those singleton classes have singleton classes, and so on with infinite nesting. Since we don't have infinite resources, we create these lazily. Because of this, only a certain number of singleton classes exist in the root namespace. At a certain depth, mutable singleton classes end up shared between namespaces. ``` ruby File.write("/tmp/ntest.rb", <<~'RUBY') p String.singleton_class.singleton_class::Foo String.singleton_class.singleton_class::Bar = 456 RUBY String.singleton_class.singleton_class::Foo = 123 ns = Namespace.new ns.require("/tmp/ntest.rb") p String.singleton_class.singleton_class::Bar ``` ``` RUBY_NAMESPACE=1 ruby nstest2.rb ruby: warning: Namespace is experimental, and the behavior may change in the future! See doc/namespace.md for known issues, etc. 123 456 ``` -- https://bugs.ruby-lang.org/