Should deleting Symbol.builtin fall back to brand checks?

[ljharb]

In the same way as deleting Symbol.toStringTag falls back to brand checks, should this?

Using the example from the readme (which currently erroneously says "non-function value", but should say "non-string value"):

Uint8Array[Symbol.builtin];             // 'Uint8Array'

Builtin.typeOf(new Uint8Array(0));      // 'Uint8Array'

Uint8Array[Symbol.builtin] = undefined;

Builtin.typeOf(new Uint8Array(0));      // 'object'

delete Uint8Array[Symbol.builtin];

Builtin.typeOf(new Uint8Array(0));      // 'Uint8Array' or 'object'?

[jasnell]

I'd say it falls back to default behavior... so after the delete it would return Uint8Array

Oh... and as we discussed previously, Uint8Array[Symbol.builtin] is a function... so Uint8Array[Symbol.builtin]() returns Uint8Array.

[ljharb]

ohh right sorry, early morning review :-p some of the examples have it as a string still.

[ljharb]

That sounds great tho - the spec text for getting the builtin value for x would then roughly be:

1. Get x[Symbol.builtin]
2. if it's not undefined and isn't callable, throw
3. if callable, call it and ToString the result
4. else, call an abstract operation that does the series of brand checks that Object.prototype.toString does, but ideally with a few more of them added

?