using System;

using System.Threading;

using System.Threading.Tasks;

using System.Collections.Generic;

using System.Runtime.CompilerServices;

public class Program

{

    public static async Task Main()

    {

        using var cts = new CancellationTokenSource();

        cts.Cancel();

        Console.WriteLine("Start Main.");

        var task = EnumerateAsync(cts.Token);

        Console.WriteLine("Started task.");

        // If we supersede a fresh token with a cancelled one here, our new cancelled token wins

        // However, if we supersede a cancelled token with a fresh token, as demonstrated, the original cancelled token wins!

        // The draft specs seem no longer accurate

        // Rather, the cancellation tokens are combined

        await foreach (var _ in task.WithCancellation(default)) // Had expected delays, using a non-cancelled token that we thought would replace the original token

        {

        }

​

        Console.WriteLine("Finish Main.");

    }

    private static async IAsyncEnumerable<object> EnumerateAsync([EnumeratorCancellation] CancellationToken ct = default)

    {

        Console.WriteLine("Start EnumerateAsync.");

        await Task.Delay(1500, ct).ContinueWith(_ => {});

        Console.WriteLine("Finish EnumerateAsync.");

        yield break;

    }

}

​