C++/WinRT - Can't two-way bind primitive types to IInspectable

[JaiganeshKumaran]

Describe the bug

Can't two-way bind a property of a primitive type to IInspectable because the generated code uses unknown_cast, which doesn't exist, instead of unbox_value.

Steps to reproduce the bug

1. Create a property of a primitive type in a view model.
2. Two-way bind it from XAML on a property of type IInspectable (Object).
3. See error in the generated code.

Expected behavior

Generated code should correctly use unbox_value.

Screenshots

NuGet package version

WinUI 2 - Microsoft.UI.Xaml 2.8.1

Windows version

Windows 11 (21H2): Build 22000

Additional context

Workaround by defining unknown_cast in pch.h:

namespace winrt
{
    template <typename T>
    T unknown_cast(IInspectable const& value)
    {
        return unbox_value<T>(value);
    }
}

[github-actions[bot]]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[JaiganeshKumaran]

This issue needs to be fixed, as it prevents basic tasks with x:Bind in a C++/WinRT application. Please anyone.

[JaiganeshKumaran]

@bpulliam

[JaiganeshKumaran]

Also, consider allowing C++ developers to contribute to the open-source XAML compiler.

[JesseCol]

Hi, does this repro in WinAppSDK / WinUI3? Or just in WinUI2? Thanks!

[JaiganeshKumaran]

@JesseCol Yes, the generated code is still broken in WinUI 3.