Why Compiler Error CS0311?

[CodingOctocat]

public static async Task<TResponse> SendAsync<TMessage, TRequest, TResponse, TToken>(this IMessenger messenger, TMessage message, TToken token)
    where TMessage : AsyncTaskRequestMessage<TRequest, TResponse>
    where TToken : IEquatable<TToken>
{
    var response = await await messenger.Send(message, token);

    return response;
}

public class AsyncTaskRequestMessage<TRequest, TResponse> : AsyncRequestMessage<Task<TResponse>>
{
    [MaybeNull]
    public TRequest Request { get; set; }

    public AsyncTaskRequestMessage([MaybeNull] TRequest request)
    {
        Request = request;
    }
}

// CS0311, Why?
await Messenger.SendAsync(new AsyncTaskRequestMessage<string?, bool>(result.FilePath), "LoadFile");

[333fred]

Please provide the actual error message given.

[CodingOctocat]

Compiler Error CS0311

The issue may be that C# doesn't support this kind of generic type inference.

[CyrusNajmabadi]

He means: please provide a full example, such that we can see the compiler error reported in this code. You can use sharplab.io for this, and provide a link to that here. Thanks :)

[CodingOctocat]

sharplab.io/#78130

sharplab reports CS0411 instead of CS0311.

[333fred]

C# does not do inference through constraints. See dotnet/csharplang#6930.