WGSL validation issue when creating mat3x3<f32> as constant

[redwarp]

I've been writing some WGSL shader that creates a mat3x3<f32> using the mat3x3(e1,...,e9): mat3x3<T>

It works well if I define my matrix inside a function:

fn rgb_to_xyz(rgb: vec4<f32>) -> vec4<f32> {
    var r = rgb.r;
    var g = rgb.g;
    var b = rgb.b;

    if (r > 0.04045) {
        r = pow(((r + 0.055) / 1.055), 2.4);
    } else {
        r =  r / 12.92;
    }
    if (g > 0.04045) {
        g = pow(((g + 0.055) / 1.055), 2.4);
    } else {
        g =  g / 12.92;
    }
    if (b > 0.04045) {
        b = pow(((b + 0.055) / 1.055), 2.4);
    } else {
        b =  b / 12.92;
    }
    r = r * 100.0;
    g = g * 100.0;
    b = b * 100.0;
        
    let m = mat3x3<f32>(
        0.4124, 0.2126, 0.0193,
        0.3576, 0.7152, 0.1192,
        0.1805, 0.0722, 0.9505
    );

    var xyz = m * vec3<f32>(r, g, b);
    return vec4<f32>(xyz, 1.0);
}

When moving m outside of the function to make it a constant, naga complains with:

error: 
  ┌─ rgb_to_lab.wgsl:4:19
  │
4 │       let m = mat3x3<f32>(
  │ ╭───────────────────^
5 │ │         0.4124, 0.2126, 0.0193,
6 │ │         0.3576, 0.7152, 0.1192,
7 │ │         0.1805, 0.0722, 0.9505
8 │ │     );
  │ ╰─────^ naga::Constant [10]

Constant [10] 'm' is invalid:
        Composing expects 3 components but 9 were given

Full shader code that is not validated by naga:

@group(0) @binding(0) var input_texture : texture_2d<f32>;
@group(0) @binding(1) var output_texture : texture_storage_2d<rgba32float, write>;

let m = mat3x3<f32>(
    0.4124, 0.2126, 0.0193,
    0.3576, 0.7152, 0.1192,
    0.1805, 0.0722, 0.9505
);

fn rgb_to_xyz(rgb: vec4<f32>) -> vec4<f32> {
    var r = rgb.r;
    var g = rgb.g;
    var b = rgb.b;

    if (r > 0.04045) {
        r = pow(((r + 0.055) / 1.055), 2.4);
    } else {
        r =  r / 12.92;
    }
    if (g > 0.04045) {
        g = pow(((g + 0.055) / 1.055), 2.4);
    } else {
        g =  g / 12.92;
    }
    if (b > 0.04045) {
        b = pow(((b + 0.055) / 1.055), 2.4);
    } else {
        b =  b / 12.92;
    }
    r = r * 100.0;
    g = g * 100.0;
    b = b * 100.0;
    
    var xyz = m * vec3<f32>(r, g, b);
    return vec4<f32>(xyz, 1.0);
}

fn xyz_to_lab(xyz: vec4<f32>) -> vec4<f32> {
    var x = xyz.x / 95.0489;
    var y = xyz.y / 100.0;
    var z = xyz.z / 108.8840;

    if (x > 0.008856) {
        x = pow(x, 1.0/3.0);
    } else {
        x = (7.787 * x) + (16.0 / 116.0);
    }
    if (y > 0.008856) {
        y = pow(y, 1.0/3.0);
    } else {
        y = (7.787 * y) + (16.0 / 116.0);
    }
    if (z > 0.008856) {
        z = pow(z, 1.0/3.0);
    } else {
        z = (7.787 * z) + (16.0 / 116.0);
    }
    let l = (116.0 * y) - 16.0;
    let a = 500.0 * (x - y);
    let b = 200.0 * (y - z);

    return vec4<f32>(l, a, b, 1.0);
}

@compute
@workgroup_size(16, 16)
fn main(
    @builtin(global_invocation_id) global_id : vec3<u32>,
) {
    let dimensions = textureDimensions(output_texture);
    let coords = vec2<i32>(global_id.xy);

    if(coords.x >= dimensions.x || coords.y >= dimensions.y) {
        return;
    }

    let lab = xyz_to_lab(rgb_to_xyz(textureLoad(input_texture, coords, 0)));
    textureStore(output_texture, coords, lab);
}

Full shader that is validated by naga, no problem:

@group(0) @binding(0) var input_texture : texture_2d<f32>;
@group(0) @binding(1) var output_texture : texture_storage_2d<rgba32float, write>;


fn rgb_to_xyz(rgb: vec4<f32>) -> vec4<f32> {
    var r = rgb.r;
    var g = rgb.g;
    var b = rgb.b;

    if (r > 0.04045) {
        r = pow(((r + 0.055) / 1.055), 2.4);
    } else {
        r =  r / 12.92;
    }
    if (g > 0.04045) {
        g = pow(((g + 0.055) / 1.055), 2.4);
    } else {
        g =  g / 12.92;
    }
    if (b > 0.04045) {
        b = pow(((b + 0.055) / 1.055), 2.4);
    } else {
        b =  b / 12.92;
    }
    r = r * 100.0;
    g = g * 100.0;
    b = b * 100.0;
    
    let m = mat3x3<f32>(
        0.4124, 0.2126, 0.0193,
        0.3576, 0.7152, 0.1192,
        0.1805, 0.0722, 0.9505
    );

    var xyz = m * vec3<f32>(r, g, b);
    return vec4<f32>(xyz, 1.0);
}

fn xyz_to_lab(xyz: vec4<f32>) -> vec4<f32> {
    var x = xyz.x / 95.0489;
    var y = xyz.y / 100.0;
    var z = xyz.z / 108.8840;

    if (x > 0.008856) {
        x = pow(x, 1.0/3.0);
    } else {
        x = (7.787 * x) + (16.0 / 116.0);
    }
    if (y > 0.008856) {
        y = pow(y, 1.0/3.0);
    } else {
        y = (7.787 * y) + (16.0 / 116.0);
    }
    if (z > 0.008856) {
        z = pow(z, 1.0/3.0);
    } else {
        z = (7.787 * z) + (16.0 / 116.0);
    }
    let l = (116.0 * y) - 16.0;
    let a = 500.0 * (x - y);
    let b = 200.0 * (y - z);

    return vec4<f32>(l, a, b, 1.0);
}

@compute
@workgroup_size(16, 16)
fn main(
    @builtin(global_invocation_id) global_id : vec3<u32>,
) {
    let dimensions = textureDimensions(output_texture);
    let coords = vec2<i32>(global_id.xy);

    if(coords.x >= dimensions.x || coords.y >= dimensions.y) {
        return;
    }

    let lab = xyz_to_lab(rgb_to_xyz(textureLoad(input_texture, coords, 0)));
    textureStore(output_texture, coords, lab);
}

[redwarp]

Note: I'm testing using the latest master, hash e7fc8e6

[teoxoy]

Thanks for the report!
This seems to be a duplicate of #1956