Violations of internal method invariants?

Tom Van Cutsem at
Thu Jul 31 08:36:31 PDT 2014

2014-07-31 15:43 GMT+02:00 Jason Orendorff <jason.orendorff at>:

> Right Thing: I think [[PreventExtensions]] on these objects should
> always return false. I think [[DefineProperty]] on these objects
> should return false if Desc.[[Configurable]] is false or if it's
> missing and would default to false. That'll cause Object.freeze(form)
> and Object.defineProperty(form, "x", {configurable: false}) to throw a
> TypeError. Seems legit.

+1. They key point is that [[DefineOwnProperty]] should not try to coerce
configurable:false to configurable:true. It should just reject such
property updates.

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