Make Void as a valid return type

[marius02]

Right now System.Void is not a valid return type in C#.

            public async Task<Unit> Handle(Command request, CancellationToken cancellationToken)
            {
                var activity = await _context.Activities.FindAsync(request.Activity.Id);
                _mapper.Map(request.Activity, activity);

                await _context.SaveChangesAsync(cancellationToken);
                return Unit.Value;
            }

In this case Unit just simulates a void return.

Are there any restrictios, why Void cannot be a valid return type?

[HaloFour]

System.Void is not permitted to be used as a generic type argument by the runtime and by the ECMA 335 specification.

See: #1604
#696
#2767
#1279
#3288

[juwens]

I see this as a problem too.

People need to implement workarounds like this in every advanced project: https://chtenb.dev/?page=unit-cs

I guess adding a Unit type to the standard library would be nice. (like they did in F#)

[tacosontitan]

Is there a reason you can't just use Task as the return type?

public async Task Handle(Command request, CancellationToken cancellationToken)
{
    var activity = await _context.Activities.FindAsync(request.Activity.Id);
    _mapper.Map(request.Activity, activity);
    await _context.SaveChangesAsync(cancellationToken);
}

[leo-costa]

I assume because you need to create the same function for anything returning Task. You duplicate the function because you can't return void.