Fix for incorrect GLSL validation on witeonly image uniforms

[spencerkohan]

Related to this issue: gfx-rs/wgpu#4530

I noticed the validation on layout qualifiers for writeonly image uniforms was not working according to the GLSL spec.

I saw there was already a TODO in the code, and the fix seemed straightforward so I made a PR for this.

[JCapucho]

Thanks for trying to fix the issue, but unfortunately this doesn't solve the underlying problem it just side steps the error gating it.

The problem is that naga doesn't have a way to express a storage image without a format, so we initialize it by default r8uint and expect the user to change the format.

naga/src/front/glsl/types.rs

Lines 170 to 173 in 7e3750a

	let class = ImageClass::Storage {
	format: crate::StorageFormat::R8Uint,
	access: crate::StorageAccess::all(),
	};

So your solution is just making all writeonly images without storage format default to r8uint.

Also if try this on the original issue reproduction case, it won't work, because the storage format kind and the data vector kind aren't equal.

[spencerkohan]

Ok I see the problem. Would this be somehow solvable by making format optional on ImageClass::Storage, or is there a hard requirement to have the format later on?

I am wondering how spriv-cross solves this problem.

[JCapucho]

That would be a possibility, but the real problem is figuring out how to handle it in the backends.

So I recommend you first research how this would map to the different backends and then we can discuss how this would map to the IR.

[JCapucho]

Forgot to mark it as requesting changes

[cwfitzgerald]

Hello, thank you for your PR against Naga!

As part of gfx-rs/wgpu#4231, we have moved development of Naga into the wgpu repository in the Naga subfolder. We have transferred all issues, but we are unable to automatically transfer PRs.

As such, please recreate your PR against the wgpu repository. We apologize for the inconvenience this causes, but will make contributing to both projects more streamlined going forward.

We are leaving PRs open, but once they are transferred, please close the original Naga PR.