Can't set x:Bind.Converter to StaticResource in a Window

[MikeHillberg]

Describe the bug

Window doesn't have a Resources property, so you set resources typically in the root of the Window content. If you try to use that in an x:Bind Converter using a {StaticResource}, it fails in the generated x:Bind code on the SetConverterLookupRoot call with the error:

Argument 1: cannot convert from 'App5.MainWindow' to 'Microsoft.UI.Xaml.FrameworkElement'

public global::Microsoft.UI.Xaml.Markup.IComponentConnector GetBindingConnector(int connectionId, object target)
{
    global::Microsoft.UI.Xaml.Markup.IComponentConnector returnValue = null;
    switch(connectionId)
    {
    case 1: // MainWindow.xaml line 1
        {                    
            global::Microsoft.UI.Xaml.Window element1 = (global::Microsoft.UI.Xaml.Window)target;
            MainWindow_obj1_Bindings bindings = new MainWindow_obj1_Bindings();
            returnValue = bindings;
            bindings.SetDataRoot(this);
            bindings.SetConverterLookupRoot(this); // <=== Error
            this.Bindings = bindings;
            element1.Activated += bindings.Activated;
        }
        break;
    }
    return returnValue;
}

See also #3442, where were it not for this compiler error, the scenario still wouldn't work for a different issue.

Steps to reproduce the bug

<Window
    x:Class="App5.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App5">
    
    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
        <StackPanel.Resources>
            <local:MyConverter x:Key="myConverter"/>
        </StackPanel.Resources>
        
        <TextBlock Text="{x:Bind TestProp, Converter={StaticResource myConverter}}"/>
    </StackPanel>
    
</Window>

public class MyConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        return "World";
    }

    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        throw new NotImplementedException();
    }
}

Expected behavior

No response

Screenshots

No response

NuGet package version

No response

Windows app type

• UWP
• Win32

Device form factor

No response

Windows version

No response

Additional context

No response

[hawkerm]

Duplicate of #4966?

[StephenLPeters]

Looks like it to me. @RealTommyKlein if you agree can you close this.

[krschau]

Duplicate of #4966