Bug: "Specified cast is not valid" when calling OnCollectionChanged of ObservableCollection when AOT is enabled

[karmeye]

Description

InvalidCastException "Specified cast is not valid." when <PublishAot>true</PublishAot> and calling AddRange, which in turn calls

OnCollectionChanged(
   new NotifyCollectionChangedEventArgs(
        action: NotifyCollectionChangedAction.Add,
	changedItems: collection as System.Collections.IList ?? collection.ToList(),
	startingIndex: Count - count));

Stack trace (also see screenshot below)

at System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(Int32 errorCode)
at WinRT.ComWrappersSupport.CreateCCWForObjectForABI(Object obj, Guid iid)
at WinRT.ComWrappersSupport.CreateCCWForObjectForMarshaling(Object obj, Guid iid)
at WinRT.MarshalInspectable`1.CreateMarshaler2(T o, Guid iid, Boolean unwrapObject)
at WinRT.MarshalInterface`1.CreateMarshaler2(T value, Guid iid)
at ABI.Microsoft.UI.Xaml.Interop.WinRTNotifyCollectionChangedEventArgsRuntimeClassFactory.CreateInstanceWithAllParameters(NotifyCollectionChangedAction action, IList newItems, IList oldItems, Int32 newIndex, Int32 oldIndex)
at ABI.System.Collections.Specialized.NotifyCollectionChangedEventArgs.CreateMarshaler2(NotifyCollectionChangedEventArgs value)
at ABI.System.Collections.Specialized.NotifyCollectionChangedEventHandler.NativeDelegateWrapper.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
at Abc.Core.ObservableCollectionEx`1.AddRange(IEnumerable`1 collection)

When AOT is disabled there is no exception thrown (even if publishing trimmed).

Steps To Reproduce

1. Create a WinUI project
2. Add <PublishAot>true</PublishAot>
3. Add ObservableCollectionEx from here
4. Call the AddRange method

Expected Behavior

No exception thrown.

Version Info

• WindowsAppSdk 1.6.241114003
• .NET 9

Additional Context

[manodasanW]

Can you also specify what is the runtime type of the parameter being passed to AddRange?

[karmeye]

@manodasanW It is a custom class:

public class PersonItem : IEquatable<PersonItem?>
{
	public PersonItem(...)
	{
	}

	public PersonItem(...)
	{
	}

	public PersonItem(...)
	{
	}

	public PersonItem(...)
	{
        ...
	}

	#region Properties

    public string DisplayName { get; private set; }

    ...

	#endregion

	#region Overrides

	public override string ToString() => DisplayName;

	public override bool Equals(object? obj) => Equals(obj as PersonItem);

	public override int GetHashCode() => HashCode.Combine(Uuid);

	#endregion

	#region Interfaces

	#region IEquatable<T>

	public bool Equals(PersonItem? other)
	{
		return other is not null &&
			   EqualityComparer<Uuid>.Default.Equals(Uuid, other.Uuid);
	}

	#endregion

	#endregion

	#region Operators

	public static bool operator ==(PersonItem? left, PersonItem? right)
	{
		return EqualityComparer<PersonItem>.Default.Equals(left, right);
	}

	public static bool operator !=(PersonItem? left, PersonItem? right)
	{
		return !(left == right);
	}

	#endregion
}

[manodasanW]

Thanks, is it a list of that you are constructing (i.e. new List<Person>()) or an array or collection expression? It might be worth trying out the latest CsWinRT 2.2.0 release as we do have improved error messages which should say the type name when InvalidCastException happens. This release has not shipped as the default yet in the .NET SDK, so you would need to explicitly specify it to try it out.