[glsl-in][wgsl-out] Nested loop miscompilation

[Uriopass]

The following glsl code with a simple nested loop:

main.frag

void main() {
    float total = 0.0;

    for (int y = -1 ; y <= 1 ; y++) {
        for (int x = -1; x <= 1; x++) {
            total += x + y;
        }
    }
}

when translated to wgsl gives

main.wgsl

fn main_1() {
    var total: f32 = 0.0;
    var y: i32 = -1;
    var x: i32 = -1;

    loop {
        let _e5 = y;
        if (!((_e5 <= 1))) {
            break;
        }
        {
            loop {
                let _e15 = x;
                if (!((_e15 <= 1))) {
                    break;
                }
                {
                    let _e22 = total;
                    let _e23 = x;
                    let _e24 = y;
                    total = (_e22 + f32((_e23 + _e24)));
                }
                continuing {
                    let _e19 = x;
                    x = (_e19 + 1);
                }
            }
        }
        continuing {
            let _e9 = y;
            y = (_e9 + 1);
        }
    }
    return;
}

[[stage(fragment)]]
fn main() {
    main_1();
    return;
}

Which is obviously wrong as x is not declared within the scope of the first nested loop, thus reusing it and summing total to -3 instead of 0.

I got this bug while implementing PCF, nested loops do exist in shaders! :D

Note that trying to declare the x out of the for like so doesn't work:

main.frag

void main() {
    float total = 0.0;

    for (int y = -1 ; y <= 1 ; y++) {
        int x = -1;
        for (; x <= 1; x++) {
            total += x + y;
        }
    }
}

Workaround

Declare main.frag like so:

main.frag

void main() {
    float total = 0.0;
    int x;
    for (int y = -1 ; y <= 1 ; y++) {
        x = -1;
        for (; x <= 1; x++) {
            total += x + y;
        }
    }
}

Tested with naga-cli 8.0. I've searched through naga's issue but didn't find anything like it.