On Sat, Oct 29, 2016 at 07:40:56PM -0400, Caitlin Potter wrote: > What do you mean by “nobody’s stuff broke”?
I mean "nobody seems to have complained yet, so there can't be that many people who rely on the specced behavior". > I would be surprised if nothing broke if v8 or JavaScriptCore or > Chakra switched to the FireFox approach (which is only broken in the > specific case where the target is a JSArray, based on what Jordan is > saying). If you can prove that nothing breaks if other browsers > implement that change Nope, I can't, and I assume that nobody was able to prove that making Object.prototype.[[Prototype]] immutable wouldn't break anything either. However, I think that it's pretty clear that, if such a change is only made for arrays inheriting from %ArrayPrototype%, someone would have to do some pretty weird stuff to actually run into this edgecase. > (and, if similar changes are implemented for pop/shift/unshift, since > IMHO those apis need to behave consistently), Yeah, I guess so. > then maybe it’s not an unreasonable change. > > > On Oct 29, 2016, at 7:07 PM, Jann Horn <[email protected]> wrote: > > > > On Sat, Oct 29, 2016 at 03:15:48PM -0700, Jordan Harband wrote: > >> That just means anyone relying on that behavior is broken in Firefox - if > >> their code would work in all of the other browsers, then it's a Firefox > >> bug, not something the spec can change. > > > > But apparently, nobody's stuff broke. > > In the Linux kernel, the approach to API changes is basically "you can > > change things as long as no existing userspace code breaks because of > > those changes", which I think is reasonable. > > And as far as I can tell, ECMAScript uses a similar approach; for > > example, AFAIK in ECMAScript 6.0, the following code would have worked, > > but ECMAScript 7.0 breaks it (by making %ObjectPrototype% an immutable > > prototype exotic object): > > > > Reflect.setPrototypeOf(Object.prototype, {__proto__:null, a:1}); > > console.log(({}).a); > > > > So clearly, reasonable breakage in new ECMAScript versions is permitted. > > _______________________________________________ > > es-discuss mailing list > > [email protected] > > https://mail.mozilla.org/listinfo/es-discuss >
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