xcode: expect 8.3.3/recognise 9.0 on 10.13

[DomT4]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run brew tests with your changes locally?

---

Wee follow up to #2732.

[mistydemeo]

I'll take your word on the versions! Haven't gotten a VM going yet.

[MikeMcQuaid]

@mistydemeo @DomT4 FYI we need to wait on bumping the Xcode version until we've updated our CI boxes. Currently all builds there are failing as a result.

[DomT4]

@MikeMcQuaid Sorry, I meant to leave a note that someone would need to sort that side of things out.

Thanks for merging @mistydemeo ❤️. I couldn't get APFS working inside VMware (useful 30 day free trial allows me to determine how much it'd trash my own system to update, heh) but otherwise it wasn't a complete nightmare. If I upgraded from Sierra to High Sierra (which I'm still not convinced isn't a temporary "haha got ya" name) and enabled APFS it refused to boot.

[jmoody]

Is it too soon to require Xcode 9.0 for High Sierra?

For Sierra, Xcode 8.0 was the only option, but for High Sierra, Xcode 8.3.3 might be a better candidate for the minimum Xcode until 9.0 is out of beta (or the early betas at least).

I am fishing for feedback before I create an issue or pull request.

Thanks for brew - I depend on this tool. Keep up the good work.

[ilovezfs]

Is it too soon to require Xcode 9.0 for High Sierra?

No, on balance the problems are usually the reverse where we get issues filed that only occur if you're using the older Xcode.