NthPortal left a comment

`this: @nullOut` or `local: @nullOut` sets the local variable slot to`null` after loading the value on the stack.Mixin forwarders, static mixin accessors and bridges set the receiverlocal to `null` if the target method is annotated `@nullOut`, forexample.Co-authored-by: Stefan Zeiger <szeiger@novocode.com>

Needs a restarr to work!The forwarder / alias `IterableOnceOps./:` uses `@nullOut` to clearthe `this` reference before calling `foldLeft`. The annotation isalso on the method itself to ensure mixin forwarders (generated inthe subclass) and the static mixin accessor (generated in the trait)null out the receiver before invoking `/:`.After removing `LazyList.foldLeft`, it inherits the implementationfrom LinearSeqOps. That method again uses `@nullOut` twice, onceto clear `this` when it's no longer needed, and once on the methodfor the generated accessors.I think we should *not* use `@nullOut` everywhere in the standardlibrary, only on methods that cannot be overridden in LazyList, like`/:`.`@nullOut` works correctly on `mkString` too, but unfortunately the`addString` override in LazyList prevents GC of processed elementsdue to cycle detection.