RFC: upgrade to V8 4.2?

[bnoordhuis]

The 4.2 branch was created about a week ago. Have we decided how and when to upgrade?

The C++ API changes are minor this time. I didn't try but I wouldn't be surprised if io.js compiled with zero modifications. Updating nan is probably straightforward as well.

On the JS front we have ES6 classes and rest parameters, although the latter is still behind a flag.

/cc @iojs/tc @domenic @kkoopa

[Fishrock123]

I thought it was agreed upon "when v8 x.x ships in stable chrome"?

[cjihrig]

I think shipping v8 x.x in io.js when it ships in stable Chrome makes the most sense. There was also talk about a canary channel, but I don't think that has been nailed down yet.

[bnoordhuis]

Let me see if I have this straight: 41 goes gold in about 10 days, then six weeks later it's succeeded by 42. That means late April or early May?

[cjihrig]

I think for our stable releases (the only kind we have right now), that is reasonable since we know the v8 team can't "break the Internet" at that point. Maybe at the next TC meeting we should try to make some more progress on the canary/next/whatever topic so that we can at least test against a newer v8.

[indutny]

@bnoordhuis please no :) Let's be on the same page with stable Chrome

[kkoopa]

Don't know if NAN would require much updating for 4.2 either, it's 4.3 that can become more problematic.

[domenic]

Please also consider my comments at #952 regarding us floating a revert on top of 4.1. We should stop doing that if possible so that we truly are on the same page as stable Chrome.

[rvagg]

@domenic the problem with just jumping on board fully with V8 is that their versioning doesn't build in anything helpful other than the version of Chrome they are fixed to. We are apparently much more concerned about messaging ABI/API changes via our versioning and are therefore much more sensitive to breaking changes. If we can get the V8 team to be a bit more consistent that would help but I suspect that actually following their "stable" will help the most from now on.

[mgol]

Chrome 41 was just released.

[Fishrock123]

Looks like it shipped with v8 4.1.0.21, if I'm reading that correctly.

[rvagg]

which is what we have .. so does that mean we're _stable_ now?? 🎆 🍷 🎉

[domenic]

I'm having a hard time reading https://omahaproxy.appspot.com/ (V8 version says "none"), but maybe we can assume that the beta corresponds.

And, I'd say we can't consider ourselves stable until we un-revert, per my tedious and repetitive harping on that point here and elsewhere :)

[rvagg]

fwiw on this particular issue @domenic I'm happy with doing an "un-revert" and bumping minor as long as we sync with NAN to make it painless

[targos]

@domenic
chrome://version/ says JavaScript V8 4.1.0.21

[bnoordhuis]

Per yesterday's TC meeting, we'll stay at 4.1 for now (including the revert of an ABI change) and will upgrade to 4.2 once it goes stable.

The first release with V8 4.2 will be a flag day event: we'll have to bump NODE_MODULE_VERSION because of ABI and API changes, meaning everyone will have to recompile their add-ons.

It's probably still going to be a minor version bump for io.js because the changes so far don't look invasive enough that nan won't be able to handle it.