Xcode required on macOS

[fu5ha]

Expected Behaviour

Example compiles on macOS

Example & Steps To Reproduce

1. Follow getting started guide
2. cargo run --bin example-runner
3. Build fails

System Info

• OS: macOS 10.14.6

Backtrace

Backtrace

========== VulkanSamples ==========

  VulkanSamples repo: https://github.com/LunarG/VulkanSamples.git
  VulkanSamples revision: a1fe1176690ec2574deb4dd3be6c4e62d1f5d186
  Fetching origin

  ========== Started building dependency libraries at 10:43:02 AM ==========
  Please be patient on first build
  Building external libraries for macOS

  --- stderr
  HEAD is now at 51cbda5f Merge branch 'develop' for release 1.2.2
  HEAD is now at 7f9879b Update for Vulkan-Docs 1.2.154
  HEAD is now at e6f5ce6b Merge pull request #1471 from KhronosGroup/fix-1467
  HEAD is now at bacaef32 Update spirv-tools and spirv-headers known goods (#2401)
  HEAD is now at 0a1fb588 Update CHANGES
  HEAD is now at 060627f Register the ANGLE compiler (#168)
  HEAD is now at 2bfd6a75 vulkaninfo: Add json output for portability subset
  HEAD is now at a1fe11766 Update to 1.2.154 headers
  xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
  thread 'main' panicked at 'failed to fetchDependencies', /Users/gray/.cargo/git/checkouts/ash-molten-2e22393c7b19b606/d0cb9e5/build.rs:97:9

This actually originates within ash-molten, and according to this nodejs/node-gyp#569 it can just be ignored (?). So I'll probably file an issue on that repo.

For now, this can be fixed by installing full Xcode instead of just the command line tools and then running, changing the path to Xcode.app if needed

sudo xcode-select -s /Applications/Xcode.app/Contents/Developer

[khyperia]

We should probably just add that line to the getting started guide, so I think this is a doc issue

[DJMcNab]

At the time this issue was made, I think we only had the ash example runner.

As far as I know, this issue was opened before we had the wgpu example; it's possible that this is only a problem with the ash runner - if so, documenting it in the readme of the ash example runner might make sense?

I don't have access to hardware on which I could verify this.

An alternative strategy is fixing the underlying ash-molten issue, of course.

[khyperia]

I thiiiink this was fixed by #252 - at least, when I was testing stuff in ark on mac and accidentally removed the pre-built feature, I suddenly hit this exact error message and needed to install full xcode (but didn't need xcode with pre-built)

The issue Gray reported earlier in this thread would be the one to track making non-pre-built work without full xcode.

Also yeah, this issue is about ash-molten, which isn't used anywhere in the crate graph by wgpu, so, this issue is specific to example-runner-ash.