Source generators fail on nested/generic types with Roslyn 4.0.1 #605

Describe the bug

Roslyn 4.0.1 doesn't accept special characters in filename hints, and cause generators to fail with nested/generic types.

Steps to reproduce

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

#nullable enable

namespace MyApp;

partial class Foo
{
    partial class MyViewModel<T> : ObservableObject
    {
        [ObservableProperty]
        private string? a;
    }
}

Expected behavior

Should work fine.

IDE and version

VS 2022, VS 2022 Preview

Nuget packages

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

Nuget package version(s)

8.1.0