CollectionViewHandler2 RelativeSource binding to AncestorType not working

[rysbilinski]

Description

Using RelativeSource binding AncestorType doesn't seem to work using CollectionViewHandler2

Steps to Reproduce

1. Add a collecitonview to a page, and bind a property in the itemtemplate to the PageModel using RelativeBinding source of AncestorType:

<CollectionView.ItemTemplate>
    <DataTemplate>
        <StackLayout Padding="10">
            <Label Text="{Binding .}" />
            <Button
                Command="{Binding ShowDialogCommand, Source={x:RelativeSource AncestorType={x:Type pm:RelativeSourceBindingPageModel}}}"
                CommandParameter="{Binding .}"
                Text="Show Dialog" />
        </StackLayout>
    </DataTemplate>
</CollectionView.ItemTemplate>

2. Enable CollectionViewHandler2:

#if IOS || MACCATALYST
            builder.ConfigureMauiHandlers(handlers =>
            {
                handlers.AddHandler<Microsoft.Maui.Controls.CollectionView, Microsoft.Maui.Controls.Handlers.Items2.CollectionViewHandler2>();
                handlers.AddHandler<Microsoft.Maui.Controls.CarouselView, Microsoft.Maui.Controls.Handlers.Items2.CarouselViewHandler2>();
            });
#endif

3. run the app on iOS and you will see that the binding simply doesn't work
4. disabling CollectionViewHandler2 resolves the issue

See the RelativeSourceBindingPage in the attached reproduction repository CollectionViewHandler2Bugs/Pages/RelativeSourceBindingPage.xaml

Link to public reproduction project repository

https://github.com/rysbilinski/CollectionViewHandler2Bugs

Version with bug

9.0.10 SR1

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

8.0.100 SR10

Affected platforms

iOS

Affected platform versions

No response

Did you find any workaround?

If you use the normal CollectionViewHandler then the binding works as expected

 builder
                .UseMauiApp<App>().ConfigureFonts(fonts =>
                {
                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                    fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
                })
                .UseMauiCommunityToolkit();
//#if IOS || MACCATALYST
//            builder.ConfigureMauiHandlers(handlers =>
//            {
//                handlers.AddHandler<Microsoft.Maui.Controls.CollectionView, Microsoft.Maui.Controls.Handlers.Items2.CollectionViewHandler2>();
//                handlers.AddHandler<Microsoft.Maui.Controls.CarouselView, Microsoft.Maui.Controls.Handlers.Items2.CarouselViewHandler2>();
//            });
//#endif

Relevant log output

[PureWeen]

possibly related https://github.com/dotnet/maui/issues/25195

[kevinxufei]

I can repro this issue at iOS platform on the latest 17.13.0 Preview 1.0(9.0.100 &9.0.0),but I can't verify it on .net8(8.0.100) due to error CS0234.

[rysbilinski]

I can repro this issue at iOS platform on the latest 17.13.0 Preview 1.0(9.0.100 &9.0.0),but I can't verify it on .net8(8.0.100) due to error CS0234.

won't this be because this handler was inteoduced in .NET 9.0?