[C++/WinRT] Two way binding from String to IInspectable not compiling

[JaiganeshKumaran]

Describe the bug

Binding a string two way to a control where the property is actually an IInspectable and not an hstring doesn't seem to compile.

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Define a string in IDL and implement INotifyPropertyChanged
2. Try binding it to a control's property where the type is an IInspectable and not a hstring
3. See error

Expected behavior

Two way binding for string should work

Version Info
WinUI 3 - Project Reunion 0.5: 0.5.0

Windows app type:

UWP	Win32
No	Yes

Windows 10 version	Saw the problem?
October 2020 Update (19042)	Yes

Device form factor	Saw the problem?
Desktop	Yes

Additional context

The generated code seems to call winrt::to_hstring for bind back however winrt::to_hstring doesn't take an IInspectable. It should use unbox_value to get the boxed hstring value for the object.

[StephenLPeters]

@RealTommyKlein FYI

[JaiganeshKumaran]

Can confirm that this issue also exists in WinUI 2 and Platform XAML.

[github-actions]

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.