Malte UblandClaude Opus 5.5 fec779abbb Use the events module and EventEmitter as untyped constructor values ...

In JavaScript, `ReleaseEmitter = EventEmitter` over `const EventEmitter =
require("events")` was refused with SC1090 ("a runtime-provided class value
as an untyped value"), and `class Channel extends require("events")` failed
on the require call as a value. Bundled npm code does both, for example a
small semaphore that aliases EventEmitter and constructs its release channel
through the alias.

- The events module binding and the EventEmitter or stream class itself
  turn untyped as the runtime's untyped constructor that constructor
  functions already use (scr_dyn_builtin_class.c). `new` through it builds
  an emitter object with Node's listener API, and `===` against the class
  compares identity.
- `x instanceof EventEmitter` on an untyped value also recognizes a boxed
  compiled emitter (an instance of a program class extending EventEmitter),
  which the prototype test alone answered false for. The same holds through
  an untyped binding narrowed to the class.
- `class X extends require("events")` extends the runtime emitter, as
  through a require binding.
- A typed array of the class built from such values (`[EventEmitter]`) is
  refused with SC1090 rather than failing its class check at run time.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-10-20 12:41:53 -07:00

..

docs

Merge main

2026-10-20 11:36:33 -05:00

limitations

Use the events module and EventEmitter as untyped constructor values

2026-10-20 12:41:53 -07:00