C# 11.0 Generic Attributes cannot be parsed correctly

[Washi1337]

AsmResolver Version

5.0.0

.NET Version

.NET 7.0

Operating System

Linux

Describe the Bug

With the introduction of generic custom attributes in C# 11.0, the runtime has changed the implementation of custom attribute signatures slightly to support instantiated type parameters. AsmResolver currently does not support this, and crashes upon encountering such a CA signature.

How To Reproduce

Compile and run the following program:

[Metadata<int>(1337)]
[Metadata<int>(Value = 1337)]
internal class Program
{
    public static void Main(string[] args)
    {
        var module = ModuleDefinition.FromFile(typeof(Program).Assembly.Location);
        var type = module.TopLevelTypes.First(t => t.Name == nameof(Program));

        foreach (var attribute in type.CustomAttributes)
        {
            Console.WriteLine(attribute.Constructor);

            Console.WriteLine("- Fixed arguments: ");
            for (var i = 0; i < attribute.Signature.FixedArguments.Count; i++)
                Console.WriteLine($"\t- {i}: {attribute.Signature.FixedArguments[i].Element}");

            Console.WriteLine("- Named arguments: ");
            foreach (var arg in attribute.Signature.NamedArguments)
                Console.WriteLine($"\t- {arg.MemberName}: {arg.Argument.Element}");
        }
    }
}

[AttributeUsage(AttributeTargets.All, AllowMultiple = true)]
public class MetadataAttribute<T> : Attribute
{
    public MetadataAttribute()
    {
        Value = default;
    }

    public MetadataAttribute(T value)
    {
        Value = value;
    }

    public T? Value
    {
        get;
        set;
    }
}

Expected Behavior

System.Void MetadataAttribute<System.Int32>::.ctor(!0)
- Fixed arguments: 
        - 0: 1337
- Named arguments: 
System.Void MetadataAttribute<System.Int32>::.ctor()
- Fixed arguments: 
- Named arguments: 
        - Value: 1337

Actual Behavior

System.Void MetadataAttribute`1<System.Int32>::.ctor(!0)
- Fixed arguments: 
Unhandled exception. System.NotSupportedException: Unsupported element type Var in custom attribute argument.
   at AsmResolver.ThrowErrorListener.RegisterException(Exception exception)
   at AsmResolver.DotNet.Serialized.ModuleReaderContext.RegisterException(Exception exception)
   at AsmResolver.ErrorListenerExtensions.NotSupported(IErrorListener self, String message)
   at AsmResolver.DotNet.Signatures.CustomAttributeArgumentReader.ReadValue(BlobReaderContext& context, BinaryStreamReader& reader, TypeSignature valueType)
   at AsmResolver.DotNet.Signatures.CustomAttributeArgument.FromReader(BlobReaderContext& context, TypeSignature argumentType, BinaryStreamReader& reader)
   at AsmResolver.DotNet.Signatures.SerializedCustomAttributeSignature.Initialize(IList`1 fixedArguments, IList`1 namedArguments)
   at AsmResolver.DotNet.Signatures.CustomAttributeSignature.EnsureIsInitialized()
   at AsmResolver.DotNet.Signatures.CustomAttributeSignature.get_FixedArguments()
   at Program.Main(String[] args)

Additional Context

No response