[wgsl-in] Rejection of matrix consts

[hanawatson]

AFAIK, const matrices should be able to be initialized as normal (e.g. mat2x2<f32>(0.0, 0.0, 0.0, 0.0)) but naga seems to reject them.

WGSL example:

let const0: mat2x2<f32> = mat2x2<f32>(0.0, 0.0, 0.0, 0.0);

@stage(compute) @workgroup_size(1)
fn main() {
    var var0 = 0;
}

Error:

error: 
          ┌─ test.wgsl:1:33
          │
        1 │ let const0: mat2x2<f32> = mat2x2<f32>(0.0, 0.0, 0.0, 0.0);
          │                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ naga::Constant [2]
        
        Constant [2] 'const0' is invalid: 
                Composing expects 2 components but 4 were given

The error seems to get worse in terms of clarity if the matrix isn't directly named, i.e.:

WGSL:

let const0: array<mat2x2<f32>, 1> = array<mat2x2<f32>, 1>(mat2x2<f32>(0.0, 0.0, 0.0, 0.0));

@stage(compute) @workgroup_size(1)
fn main() {
    var var0 = 0;
}

Error:

 error: 
        
        Constant [3] '' is invalid: 
                Composing expects 2 components but 4 were given

[hanawatson]

Edit: this also seems to happen with other types

WGSL:

let const0: vec3<f32> = vec3<f32>(0.0);

@stage(compute) @workgroup_size(1)
fn main() {
    var var0 = 0;
}

Error:

   error: 
          ┌─ test.wgsl:1:29
          │
        1 │ let const0: vec3<f32> = vec3<f32>(0.0);
          │                             ^^^^^^^^^^ naga::Constant [2]
        
        Constant [2] 'const0' is invalid: 
                Composing expects 3 components but 1 were given

The above error also applies for array<f32, 3> etc. that are initialized with one parameter.

[teoxoy]

#1957 and this one have the same underlying cause; global constructors currently use a different code-path (to make sure all the expressions are const) and feature wise it's not on par with the non global constructors.

We should figure this out when we get to implement creation-time expressions.

[bzm3r]

Ran into this headfirst today 😩

[cdecompilador]

also rejects array constants