Microsoft-ui-xaml: WinUI in Desktop app is silently crashed if I put Grid descendant to the Grid.Children collection

[BorzillaR]

Hello!

I created a "Blank App, Packaged (WinUI in Desktop) from VS templates.

In MainPage.xaml I set a name for the root grid.

<Grid x:Name="RootGrid"> </Grid>

Next, in MainPage.xaml.cs, I created a Grid descendant and put it to the Children collection of the RootGrid.

public sealed partial class MainWindow : Window { public MainWindow() { this.InitializeComponent(); RootGrid.Children.Add(new MyGrid() { Background = new SolidColorBrush(Colors.Red) }); } } public class MyGrid : Grid { }

The main window shows for a seconds and application exits without any errors or exceptions.

Version Info

NuGet package version: Microsoft.WinUI 3.0.0-preview2.200713.0
Windows 10 version: 1903 (OS Build 18362.1082)

[StephenLPeters]

@stevenbrix is this another cswinrt issue were we fail when deriving from a winrt type?

[BorzillaR]

Seems another case of this issue.

If I set a descendant of FrameworkElement to custom dependency property, application is crashed too.

    public class MyClass : DependencyObject {
        public FrameworkElementDescendant MyProperty {
            get { return (FrameworkElementDescendant)GetValue(MyPropertyProperty); }
            set { SetValue(MyPropertyProperty, value); }
        }

        public static readonly DependencyProperty MyPropertyProperty =
            DependencyProperty.Register("MyProperty", typeof(FrameworkElementDescendant), typeof(MyClass), new PropertyMetadata(null));

    }
    public class FrameworkElementDescendant : FrameworkElement { }

        public MainWindow() {
            this.InitializeComponent();
            MyClass c = new();
            c.MyProperty = new FrameworkElementDescendant();
        }

There is a message in output:

The thread 0x79bc has exited with code 0 (0x0).
Unhandled exception at 0x77898DF0 (ntdll.dll) in App29.exe: RangeChecks instrumentation code detected an out of range array access.
The Common Language Runtime cannot stop at this exception. Common causes include: incorrect COM interop marshalling and memory corruption. To investigate further use native-only debugging.

[gmurray81]

There a good work around for this? Exceedingly difficult to make anything interesting work when I'm constantly hitting this in different scenarios.

[PureWeen]

Here's a reproduction based on the original posters code
Issue3310.zip

[stevenbrix]

Sorry for the lack of response on this. Thank you all for the details and repro apps.

We don’t currently have a workaround, I’ll spend some time this morning validating this is fixed with preview3 and respond to this thread.

[stevenbrix]

@PureWeen and @BorzillaR, I just validated that the attached repro app no longer has an issue with preview3

[stevenbrix]

@BorzillaR - I'm closing this out now that preview3 has been released. Please respond if you are still experiencing this issue.