CommunityToolkit.MVVM 8.4.1 and 8.4.2 seems to break intellisense on VS2022

[jordi-z80]

Describe the bug

when updating from CT 8.4.0 to 8.4.1 or 8.4.2, intellisense starts showing red squiggles on all the ObservableProperties.

I know this is probably not your fault, probably an Intellisense problem, feel free to close it. At least will be useful as a reference for other users.

Regression

No response

Steps to reproduce

Given the following environment (NET 9, VS2022 17.14.31 , CT.MVVM 8.4.0 )

[ObservableProperty] private string _searchText = string.Empty;
...
SearchText = "hello";

Compile, no intellisense problems.

Change CT.MVVM to 8.4.2.
Compile, intellisense shows squiggly lines.

Expected behavior

Not showing red lines.

Screenshots

No response

IDE and version

VS 2022

IDE version

17.14.31

Nuget packages

• CommunityToolkit.Common
• CommunityToolkit.Diagnostics
• CommunityToolkit.HighPerformance
• CommunityToolkit.Mvvm (aka MVVM Toolkit)

Nuget package version(s)

8.4.2

Additional context

No response

Help us help you

No, just wanted to report this

[th3oth3rjak3]

To give more context to the problem, it actually shows intellisense errors in either case. For example:

public partial class MainViewModel : ViewModelBase
{
    [ObservableProperty]
    public partial string Greeting { get; set; } = "Welcome to Avalonia!";
}

This will cause Greeting to be underlined with red squigglies, the code successfully compiles and runs, and the binding in the MainWindow.axaml shows no errors. There are two errors associated with this first condition listed below.

• CS9248: Partial property must have an implementation part.
• CS8050: Only auto-implemented properties, or properties that use the 'field' keyword, can have initializers.

However, if you use the old style syntax, it will cause there to be intellisense errors in the .axaml file because it can't resolve the property Greeting since there's only a field _greeting or greeting. The code below won't have any intellisense errors, but again, the .axaml file will. The specific error for this condition is "The property 'Greeting' does not exist on 'YourApp.ViewModels.MainViewModel'."

public partial class MainViewModel : ViewModelBase
{
    [ObservableProperty]
    private string greeting = "Welcome to Avalonia!";
}