build panic: not a rvalue about slint

[ogoffart]

Thanks for the bug report.

I was able to reproduce with a minimal testcase:

export component DrawerLeft {
    private property <length> logic_width;
    rect := Rectangle {
        init => {
            logic_width = root.width;
        }
        @children
    }
}

export component A {
    hello := DrawerLeft { }
}

export component App inherits Window {
    world := A { }
}

From a first investigation, the problem is that the const_propagation::const_propagation pass introduces some Invalid expression in the init code. The init code is referencing property such as root.hello-width while at this point, it should be hello-3-width, so something went wrong in one of the compiler pass that had to move properties around.
I will have to investigate this further.