Advantage of using MoltenVK over Metal

[sotrh]

I was asked about the advantage of using features = ["vulkan"] on MacOS, and I didn't know the answer.

sotrh/learn-wgpu#62

I felt I should come here to get more details.

[kvark]

"vulkan" is not for MoltenVK specifically, it's for Vulkan Portability. For example, it can be used with gfx-portability.

Regardless of the backing, it's not intended for shipping. The main reason this is exposed is to be able to get the Vulkan validation layers output. If the developer doesn't have access to Linux or Windows machines, and for some reason wgpu-rs validation doesn't catch a problem, it's helpful to see what Vulkan validation has to say.