uniform half4 colorGreen, colorRed;

half x = 1;
bool out_params_are_distinct_from_global(out half y) {
    y = 2;
    return x == 1 && y == 2;
}

half4 main(float2 coords) {
    return out_params_are_distinct_from_global(x) ? colorGreen : colorRed;
}