[Bug]: `IViewForGenerator` "leaks" other attributes to generated code

[n-ski]

Describe the bug 🐞

If a class is marked with the IViewForAttribute<T>, the generator will carry over other attributes to the generated partial class. This means that such attributes as SingleInstanceViewAttribute and ViewContractAttribute cannot be used in conjunction with IViewForAttribute<T>.

Step to reproduce

1. From the CLI, run dotnet new globaljson --sdk-version 8.0.400

2. dotnet new wpf

3. dotnet add package ReactiveUI --version 20.1.63

4. dotnet add package ReactiveUI.SourceGenerators --version 2.0.9

5. Add a minimal view model class and attributes in MainWindow.xaml.cs.

   using System.Text;
   using System.Windows;
   using System.Windows.Controls;
   using System.Windows.Data;
   using System.Windows.Documents;
   using System.Windows.Input;
   using System.Windows.Media;
   using System.Windows.Media.Imaging;
   using System.Windows.Navigation;
   using System.Windows.Shapes;
   +using ReactiveUI;
   +using ReactiveUI.SourceGenerators;
   
   namespace WpfApp1;
   
   /// <summary>
   /// Interaction logic for MainWindow.xaml
   /// </summary>
   +[IViewFor<MainViewModel>]
   +[SingleInstanceView]
   public partial class MainWindow : Window
   {
       public MainWindow()
       {
           InitializeComponent();
       }
   }
   
   +public class MainViewModel : ReactiveObject;

6. Run dotnet build to compile. Observe the compilation error.

   C:\Users\anon\source\WpfApp1\obj\Debug\net8.0-windows\ReactiveUI.SourceGenerators\ReactiveUI.SourceGenerators.IViewForGenerator\MainWindow.IViewFor.g.cs(14,10): error CS0579: Duplicate 'global::ReactiveUI.SingleInstanceViewAttribute' attribute [C:\Users\anon\source\WpfApp1\WpfApp1_bnyjhzvr_wpftmp.csproj]

Reproduction repository

https://github.com/n-ski/RxUIIViewForGeneratorBugSample

Expected behavior

I should be able to use IViewForAttribute<T> with other attributes.

Screenshots 🖼️

No response

IDE

Rider Windows

Operating system

Windows

Version

21H2

Device

No response

ReactiveUI Version

20.1.63

Additional information ℹ️

No response

[ethpch]

Other attributes also need this one.

[Description("Property")]
[Reactive]
string? _myProperty;

generated

[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ReactiveGenerator", "2.0.0.0")]
/// <inheritdoc cref="_myProperty"/>
[global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
public string? MyProperty { get => _myProperty; set => this.RaiseAndSetIfChanged(ref _myProperty, value); }

Description is missing.

Tested in version 2.0.9 and 1.1.31. Neither of them can handle this.

Maybe an optional parameter is better, like [Reactive(ForwardAttributes = true)].

[github-actions[bot]]

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