Prefer Func<Task> over Func<ValueTask> overload when using async lambdas

[maxkoshevoi]

I have one method with two overloads:

void Foo(Func<Task> task)
void Foo(Func<ValueTask> task)

All works well until async lambda is passed as a first argument: Foo(async () => {}). Since lambda itself doesn't have a type, compiler doesn't know what overload I'm trying to invoke and it gives the ambiguity error. I can use explicit cast to resolve it (Foo((Func<Task>)(async () => {}))), but I don't want to force users of Foo to write it every time in this situation.

Can I somehow set void Foo(Func<Task> task) as a tiebreaker? So that there is no compile errors when user writes this Foo(async () => {})

[YairHalberstadt]

I did it by using a dummy optional parameter:

https://github.com/YairHalberstadt/stronginject/blob/86f0e766bb2a2028d302f9402db166ca42cb7b84/StrongInject/ContainerExtensions.cs#L44-L56

So in your case that would be:

/// <summary>
/// A class with no possible value other than null. Used to mark an optional parameter which should never be set.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public sealed class DummyParameter
{
    private DummyParameter() { }
}
    
void Foo(Func<Task> task)
void Foo(Func<ValueTask> task, DummyParameter? _ = null)

[maxkoshevoi]

Thank you so much! That helped a lot.
I used your advice in reverse. My methods have lots of optional parameters, so I created overloads for void Foo(Func<Task> task) without them.

xamarin/XamarinCommunityToolkit@ca6b606

[huoyaoyuan]

Another idea: use different names and named argument?

void Foo(Func<Task> taskFunc);
void Foo(Func<ValueTask> valueTaskFunc);

Foo(taskFunc: () => ...)

(haven't tried it, but I think it could work)

[maxkoshevoi]

Thank you! This also will work, but I think it's a little unobvious to the user (and would require some work from them). Implemented both solutions in my code with this as a backup one.