Observable property attribute with negative enum values stops generating code #681

Describe the bug

This is a weird bug that I came across by accident.
If an observable property annotated with the ObservablePropertyAttribute has another attribute for the generated property and that attribute has an enum with a negative value, the code generation stops working. I'm assuming there might be a crash with the code generator when it encounters this case and no code is generated further.
This bug can be easily reproduced with the code below.

Regression

No response

Steps to reproduce

This bug occurred when I tested in .NET 7 in a WPF project with Visual Studio 17.5.5 and the latest CommunityToolkit.Mvvm 8.2.0. It probably would happen with other versions.
Using the following code the bug can be reproduced:

using CommunityToolkit.Mvvm.ComponentModel;
using System.ComponentModel;

namespace MvvmBug;
public partial class MainViewModel : ObservableObject
{
    [ObservableProperty]
    private bool _test1;

    [ObservableProperty]
    [property: DefaultValue(PositiveEnum.Something)]
    private PositiveEnum _test2;

    [ObservableProperty]
    [property: DefaultValue(NegativeEnum.Problem)]
    private NegativeEnum _test3;

    [ObservableProperty]
    private int _test4;

    public MainViewModel()
    {
        Test1 = true;
        Test2 = PositiveEnum.Else;
    }
}

public enum PositiveEnum
{
    Something = 0,
    Else = 1
}

public enum NegativeEnum
{
    Problem = -1,
    OK = 0
}

Changing the default value for _test3 to NegativeEnum.OK will allow the code to compile without errors, changing back to NegativeEnum.Problem and the code generator stops working.
Also note that if using the NegativeEnum.Problem, removing the 'property:' before the DefaultValueAttribute doesn't seem to have the problem. It only occurs for attributes passed to the property generated.

Expected behavior

An enum with a negative value in a property attribute shouldn't stop the code generator.

Screenshots

No response

IDE and version

VS 2022

IDE version

17.5.5

Nuget packages

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

Nuget package version(s)

8.2.0

Additional context

No response

Help us help you

No, just wanted to report this