Crash when running caps example

[pftbest]

$ cargo run --example=caps
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/examples/caps`
Vendor: "Intel"
Family: "Iris Pro Graphics"
Max threads per threadgroup: MTLSize { width: 512, height: 512, depth: 512 }
Integrated GPU: true
Headless: false
D24S8: false
2017-09-14 02:48:20.562 caps[691:20772] -[MTLIGAccelDevice argumentBuffersSupport]: unrecognized selector sent to instance 0x7fc75f006e00
Segmentation fault: 11

$ cargo run --example=caps --release
    Finished release [optimized] target(s) in 0.0 secs
     Running `target/release/examples/caps`
Vendor: "Intel"
Family: "Iris Pro Graphics"
Max threads per threadgroup: MTLSize { width: 512, height: 512, depth: 512 }
Integrated GPU: true
Headless: false
D24S8: false
2017-09-14 02:50:18.811 caps[792:23178] -[MTLIGAccelDevice argumentBuffersSupport]: unrecognized selector sent to instance 0x7ff27881e800
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:335:20
note: Run with `RUST_BACKTRACE=1` for a backtrace.
fatal runtime error: failed to initiate panic, error 5
Abort trap: 6

[kvark]

Thanks for filing the issue! Would you be interested to investigate and provide a PR? It doesn't sound too complicated, related the recent argument buffer support changes.

[pftbest]

Documentation says that this property is only supported on macOS 10.13+ but I have sierra 10.12.6 maybe that's why it crashes