warning this call is not awaited, execution of the current method continues

I'm quite late to this discussion, but there is also the option to use the #pragma pre-processor directive. I have some async code here and there that I explicitly do not want to await in some conditions, and I dislike warnings and unused variables just like the rest of you:

#pragma warning disable 4014
SomeMethodAsync();
#pragma warning restore 4014

The "4014" comes from this MSDN page: Compiler Warning (level 1) CS4014.

See also the warning/answer by @ryan-horath here https://stackoverflow.com/a/12145047/928483.

Exceptions thrown during an async call that is not awaited will be lost. To get rid of this warning, you should assign the Task return value of the async call to a variable. This ensures you have access to any exceptions thrown, which will be indicated in the return value.

Update for C# 7.0

C# 7.0 adds a new feature, discard variables: Discards - C# Guide, which can also help in this regard.

_ = SomeMethodAsync();

If you really don't need the result, you can simply change the GetNameAsync's signature to return void:

public static async void GetNameAsync()
{
    ...
}

Consider to see answer to a related question: What's the difference between returning void and returning a Task?

Update

If you need the result, you can change the GetNameAsync to return, say, Task<string>:

public static async Task<string> GetNameAsync()
{
    string firstname = await PromptForStringAsync("Enter your first name: ");
    string lastname = await PromptForStringAsync("Enter your last name: ");
    return firstname + lastname;
}

And use it as follows:

public static void DoStuff()
{
    Task<string> task = GetNameAsync();

    // Set up a continuation BEFORE MainWorkOfApplicationIDontWantBlocked
    Task anotherTask = task.ContinueWith(r => {
            Console.WriteLine(r.Result);
        });

    MainWorkOfApplicationIDontWantBlocked();

    // OR wait for the result AFTER
    string result = task.Result;
}

I'm not particularly fond of the solutions that either assign the task to an unused variable, or changing the method signature to return void. The former creates superfluous, non-intuitive code, while the latter may not be possible if you're implementing an interface or have another usage of the function where you want to use the returned Task.

My solution is to create an extension method of Task, called DoNotAwait() that does nothing. This will not only suppress all warnings, ReSharper or otherwise, but makes the code more understandable, and indicates to future maintainers of your code that you really intended for the call to not be awaited.

Extension method:

public static class TaskExtensions
{
    public static void DoNotAwait(this Task task) { }
}

Usage:

public static void DoStuff()
{
    GetNameAsync().DoNotAwait();
    MainWorkOfApplicationIDontWantBlocked();
}

Edited to add: this is similar to Jonathan Allen's solution where the extension method would start the task if not already started, but I prefer to have single-purpose functions so that the caller's intent is completely clear.

Tags:

C#

Async Await

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