Fix missing family check flag

[VladasZ]

Description
iOS 12 doesn't have supports_family method and it crashes when this method is called. There was already a check for that using family_check flag. But it was missing in one place.

Xcode crash logs:

2024-05-25 20:52:31.043060+0300 TestGame[355:12589] [DYMTLInitPlatform] platform initialization successful
2024-05-25 20:52:31.154605+0300 TestGame[355:12422] Metal GPU Frame Capture Enabled
2024-05-25 20:52:31.157163+0300 TestGame[355:12422] Metal API Validation Enabled
2024-05-25 20:52:31.194143+0300 TestGame[355:12422] -[MTLDebugDevice supportsFamily:]: unrecognized selector sent to instance 0x102209200
2024-05-25 20:52:31.201718+0300 TestGame[355:12422] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[MTLDebugDevice supportsFamily:]: unrecognized selector sent to instance 0x102209200'

Testing
I ran it on my iPhone 5s and it didn't crash.

Checklist

• Run cargo fmt.
• Run cargo clippy. If applicable, add:
  • --target wasm32-unknown-unknown
  • --target wasm32-unknown-emscripten
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.

[Wumpf]

Good catch!
Wondering though why this line here isn't an issue? https://github.com/gfx-rs/wgpu/blob/trunk/wgpu-hal/src/metal/adapter.rs#L515 It seems that in order to determine family_check we first do a family check..?

[VladasZ]

That is weird. Documentation says that iOS 13.0+ is minimal supported version:
https://developer.apple.com/documentation/metal/mtldevice/3143473-supportsfamily .
Maybe actually the method does exist but MTLGPUFamily enum ends somewhere between Apple2 and `Apple4
on iOS 12?

version.major < 8 is false so supports_family is never called in this expression.

[Friz64]

This only landed in the v0.20 branch, was this intentional?

[Wumpf]

oh shoot, I didn't pay enough attention there. Thank you so much @Friz64 for pointing this out!

@VladasZ we usually first push to trunk and then cherry-pick back for main. As is, this fix would get lost with the next major release. Can you please create a PR against trunk?

(luckily this patch would be perfectly fine for backporting, so it's alright to release it with 0.20.1)

[VladasZ]

@Wumpf sorry. Didn't know that. I tried to use trunk at first but it had some breaking changes and I didn't want to use it. So I fixed it in v0.20.
Here is the new PR: #5754