Cannot select MSL version with naga-cli

[pcleavelin]

Forgive me if this should be a bug report (not sure it really qualifies).

I've been working on a project that originally used wgpu but have switched codebases/languages, however I still want to use the naga compiler. Since I'm on macOS (Apple Silicon) I'm compiling WGSL shader code to MSL using naga-cli v.0.19.0. Although, when using instancing (in particular @builtin(instance_index)) running naga shader.wgsl shader.metal outputs

attribute 'instance_id' is not supported for target MSL version

This looks to be because naga-cli uses the default version (which is MSL 1.0) when compiling, but naga-cli has no way to choose which metal version to use.

I've currently been using my own fork which adds support for this here. I can submit a PR for this, but I wasn't sure if there was a reason for leaving this feature out.

Also sorry if this is a duplicate issue, it can be hard to filter out issues only pertaining to the CLI.

[cwfitzgerald]

Yes, lets have it!