1609434 - Support iterating during eager evaluation

Status: NEW

(DevTools :: Console, enhancement, P2)

Description

[Brian Hackett [Laid off!]]

The native functions called during iterations like "[...someSet.values()]" are not permitted by the native call filtering done during eager eager evaluations. I tried to handle these as part of bug 1607608 but not very hard, and it would be nice to follow up and allow these.

Comment 1

[Oriol Brufau [:Oriol]]

I can cover

• %ArrayIteratorPrototype%.next with new Array()[Symbol.iterator]().next
• %IteratorPrototype% [ @@iterator ] with function*(){}()[Symbol.iterator]
• %MapIteratorPrototype%.next with new Map()[Symbol.iterator]().next
• %RegExpStringIteratorPrototype%.next with new RegExp()[Symbol.matchAll]().next
• %SetIteratorPrototype%.next with new Set()[Symbol.iterator]().next
• %StringIteratorPrototype%.next with ""[Symbol.iterator]().next
• AsyncGenerator.prototype.next with async function*(){}().next
• Generator.prototype.next with function*(){}().next
• String.prototype [ @@iterator ] with ...allProperties(String.prototype)

These are already covered:

• Array.prototype [ @@iterator ] (by Array.prototype.values)
• %TypedArray% [ @@iterator ] (by Int8Array.prototype.values)
• Map.prototype [ @@iterator ] (by Map.prototype.entries)
• Set.prototype [ @@iterator ] (by Set.prototype.values)

No idea about

• %AsyncFromSyncIteratorPrototype%.next
• %ForInIteratorPrototype%.next

Comment 2

[Oriol Brufau [:Oriol]]

I realized that I can't just whitelist the next() iterator methods, because they have side-effects in general:

var it = [1,2,3].values();
it.next(); // { value: 1, done: false }
it.next(); // { value: 2, done: false }

So they should only be allowed if the iterator has been created during the eager evaluation.

This is similar to Object.assign({}, {a:1}) where Object.assign should be usually prevented but here it would be fine.

I don't know how to address this, unassigning myself.