SwitchPresenter sample in gallery crashes under Windows App SDK

[Arlodotexe]

Describe the bug

When running the gallery with the Wasdk head on the latest main commit, the 'SwitchPresenter' sample will crash the app:

Exception message:

The text associated with this error code could not be found.

Failed to assign to property 'Microsoft.UI.Xaml.Controls.ItemsControl.ItemsSource'. [Line: 21 Position: 19]

Stack trace:

   at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|38_0(Int32 hr)
   at ABI.Microsoft.UI.Xaml.IApplicationStaticsMethods.LoadComponent(IObjectReference _obj, Object component, Uri resourceLocator, ComponentResourceLocation componentResourceLocation)
   at Microsoft.UI.Xaml.Application.LoadComponent(Object component, Uri resourceLocator, ComponentResourceLocation componentResourceLocation)
   at PrimitivesExperiment.Samples.SwitchPresenter.SwitchPresenterValueSample.InitializeComponent() in /_/components/Primitives/samples/obj/Debug/net8.0-windows10.0.22621.0/SwitchPresenter/SwitchPresenterValueSample.g.i.cs:line 39

This behavior is not present when running the gallery under UWP.

Steps to reproduce

1. Clone the repo
2. Generate the gallery solution, include the Primitives component and the wasdk multitarget/head.
3. Build and deploy the wasdk gallery 
4. Navigate to the 'SwitchPresenter' sample page and observe crash.

Expected behavior

No crash

Screenshots

No response

Code Platform

• UWP
• WinAppSDK / WinUI 3
• Web Assembly (WASM)
• Android
• iOS
• MacOS
• Linux / GTK

Windows Build Number

• Windows 10 1809 (Build 17763)
• Windows 10 1903 (Build 18362)
• Windows 10 1909 (Build 18363)
• Windows 10 2004 (Build 19041)
• Windows 10 20H2 (Build 19042)
• Windows 10 21H1 (Build 19043)
• Windows 10 21H2 (Build 19044)
• Windows 10 22H2 (Build 19045)
• Windows 11 21H2 (Build 22000)
• Other (specify)

Other Windows Build number

No response

App minimum and target SDK version

• Windows 10, version 1809 (Build 17763)
• Windows 10, version 1903 (Build 18362)
• Windows 10, version 1909 (Build 18363)
• Windows 10, version 2004 (Build 19041)
• Windows 10, version 2104 (Build 20348)
• Windows 11, version 22H2 (Build 22000)
• Other (specify)

Other SDK version

No response

Visual Studio Version

No response

Visual Studio Build Number

No response

Device form factor

No response

Additional context

No response

Help us help you

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[AndrewKeepCoding]

This seems not to be a SwitchPresenter issue. The ComboBox in the sample code is crashing the app. I'm not sure why but the crash can be avoided by not passing an Array of enum to the ComboBox.

These are not fixes:

EnumValuesExtension.cs

protected override object ProvideValue()
{
    // This crashes the app.
    // return Enum.GetValues(Type!);

    // This does not crash the app.
    return Enum.GetNames(Type!);
}

or just:

SwitchPresenterValueSample.xaml.cs

public SwitchPresenterValueSample()
{
    this.InitializeComponent();

    // This crashes the app.
    // this.AnimalPicker.ItemsSource = Enum.GetValues(typeof(Animal));

    // This does not crash the app.
    Animal[] animals = [Animal.Cat, Animal.Dog, Animal.Bunny, Animal.Llama, Animal.Parrot, Animal.Squirrel];
    this.AnimalPicker.ItemsSource = animals;
}

[Arlodotexe]

Looks like it's an issue with generated code for types passed into EnumValuesExtension.

This call to Enum.GetValues(Type) seems to be working as expected. Following the return value in the debugger, the type is passed into a generated LookupVtableEntries method in WinRT.

When it reaches the WinRT.PrimitivesExperiment_SamplesGenericHelpers.GlobalVtableLookup, it isn't finding the PrimitivesExperiment.Samples.SwitchPresenter.Animal[] because it hasn't been generated:

This might be related to this other workaround we had to do to get XamlTypeInfo to generate on .NET Native/UWP:

Though it seems like this doesn't work for NativeAot/Wasdk.

@Sergio0694 What are your thoughts?

[Sergio0694]

Interesting, this works fine in my ComputeSharp sample app (UWP, .NET 9).

It seems the CsWinRT generator is missing that Enum.GetValues call. Which I mean, makes sense, since it cannot see the Type argument being passed to it from there. I don't see how that code can work. The extension itself is also marked as not AOT-safe for pretty much the same reason. FYI @manodasanW, do you have any thoughts on this? Seems by design to me.

[michael-hawker]

For now, I'll update the sample to avoid using the Enum call. @Arlodotexe I'll close this when I open that PR for the SwitchPresenter work I'm looking at. Will use @AndrewKeepCoding's just static array approach, I think.

Mind summarizing the main issues related to the intersection of things in a new issue we can use to track elsewhere? Or should we be opening something on CsWinRT? Since we have the attribute here on the Enum call, shouldn't that get flagged somewhere? Or is that a XAML Compiler thing?

[michael-hawker]

Huh, actually with the array approach @AndrewKeepCoding shared for the sample I'm still seeing a different error "Value does not fall within the expected range" (though it works with UWP still no problem...)

>	WinRT.Runtime.dll!WinRT.ExceptionHelpers.ThrowExceptionForHR.__Throw|38_0(int hr) Line 134	C#
 	Microsoft.WinUI.dll!ABI.Microsoft.UI.Xaml.Controls.IItemsControlMethods.set_ItemsSource(WinRT.IObjectReference _obj, object value)	Unknown
 	Microsoft.WinUI.dll!Microsoft.UI.Xaml.Controls.ItemsControl.ItemsSource.set(object value)	Unknown

Maybe I won't be fixing this sample then yet... 🤔