Await inside usings.

[JohanLarsson]

using (var webClient = new WebClient())
{
    return webClient.DownloadStringTaskAsync(address);
}

We talked about this in chat, this can lead to situations where it is undefined if the IDisposable is disposed or not.

[tugberkugurlu]

This would be amazing to have but I imagine would be a bit hard to figure out.

[AArnott]

I think we could spec this as flagging when these conditions hold:

1. The method does not use the async keyword in its signature.
2. A return statement appears within a using block, with an expression that is an invocation

[JohanLarsson]

https://github.com/DotNetAnalyzers/IDisposableAnalyzers/blob/master/documentation/IDISP013.md

[JohanLarsson]

For 2 we probably want an exception for Task.FromResult()