How to correctly rethrow an exception of task already in faulted state?

Question

I have a synchronous method which, amongst other things, checks the status of a pending task and rethrows its exception, if any:

void Test(Task task)
{
    // ...
    if (task.IsFaulted)
        throw task.Exception;
    // ...
}

This doesn't propagate the exception stack trace information and is debugger-unfriendly.

Now, if the Test was async, it would not be as simple and natural as this:

async Task Test(Task task)
{
    // ...
    if (task.IsFaulted)
        await task; // rethrow immediately and correctly
    // ...
}

Question: how to do it right for a synchronous method? I have come up with this but I do not like it:

void Test(Task task)
{
    // ...
    if (task.IsFaulted)
        new Action(async () => await task)();
    // ...
}

Answer 1

To properly re-throw an exception, you should use ExceptionDispatchInfo:

ExceptionDispatchInfo.Capture(task.Exception.InnerException).Throw();

You can also do:

task.GetAwaiter().GetResult();

P.S. Your Action approach will not work correctly, since you're creating an async void method, and you cannot catch exceptions propagated from that method.