Is it spec-compliant to forbid setPrototypeOf(Object.prototype, foo)?

[T.J. Crowder]

On Thu, Feb 2, 2017 at 12:19 PM, Michał Wadas <michalwadas at gmail.com> wrote:

> Right now this code:
>
> Object.setPrototypeOf(Object.prototype, Object.create(null))
>
> throws in both Chrome and Firefox. I couldn't find any mention of special
> [[SetPrototypeOf]] of %ObjectPrototype%, did I miss something?
>
Yes. :-) You missed that `Object.prototype` is an immutable prototype
exotic object:

*
https://tc39.github.io/ecma262/#sec-properties-of-the-object-prototype-object
* https://tc39.github.io/ecma262/#sec-immutable-prototype-exotic-objects

...which does indeed have a special [[SetPrototypeOf]] which (indirectly)
returns false if you try to change the [[Prototype].
`Object.setPrototypeOf` throws when [[SetPrototypeOf]] returns false:
https://tc39.github.io/ecma262/#sec-object.setprototypeof

-- T.J.
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