Should error when shader has multiple group-bindings with the same values

[stefnotch]

Description

When I write a shader like

@group(0) @binding(0)
var<storage,read_write> foo: array<u32>;
        
@group(0) @binding(0)
var<storage,read_write> bar: array<u32>;

then I would expect that to result in an error. After all, the WGSL specification says

Two different resource variables in a shader must not have the same group and binding values, when considered as a pair.
https://www.w3.org/TR/WGSL/#resource-interface

Repro steps
The shader above.

Expected vs observed behavior
I expect a shader creation error. The actual behaviour is that naga happily accepts this.

Amusingly, Chrome also seems to accept it. (At least the version of Microsoft Edge that I tested does accept this.)

Platform

• Windows 11
• WGSL trunk on commit 583cc6a (one of the latest commits)

[stefnotch]

(Yes I was trying out all the forbidden edge cases while writing unit tests for my #5713 😆 )

[teoxoy]

The resource interface of a shader is the set of module-scope resource variables statically accessed by functions in the shader stage.

Could you try to add an entry-point using those 2 bindings and see if it still works?

[stefnotch]

Ah, I clearly didn't read the spec properly. Yes, it works as expected when one uses the bindings

naga/tests/wgsl_errors.rs

#[test]
fn duplicated_group_binding() {
    check_validation! {
        "@group(0) @binding(0)
        var<storage,read_write> foo: array<f32>;
                
        @group(0) @binding(0)
        var<storage,read_write> bar: array<f32>;
        
        @vertex
        fn main() -> @builtin(position) vec4<f32> {
            let a = foo[0];
            let b = bar[0];
            return vec4<f32>(a, b, 0.0, 1.0);
        }":
        Err(naga::valid::ValidationError::EntryPoint {
            stage: naga::ShaderStage::Vertex,
            source: naga::valid::EntryPointError::BindingCollision(..),
            ..
        })
    }
}

And there are also tests in the official testing suite
https://github.com/gpuweb/cts/blob/b0f5b1839f40f8f793ec2e4a6eecae41a273e0b3/src/webgpu/shader/validation/shader_io/group_and_binding.spec.ts#L135-L138

So I can safely close this.