That sounds correct to me. A function that takes one argument is different from a function that takes zero arguments, even when that one argument is Void (the empty tuple). What diagnostic would you have preferred?

cc @rudkx

Yes this is expected behavior at this point.

I floated a pitch at one point to fix this because it makes it difficult to write generic code that composes well in some cases, but there was little to no enthusiasm for doing anything about it and I haven't had time to pursue it since.

@xedin, perhaps we could have a better diagnostic here to make it more clear what the issue is?

Yes, I think it makes sense to say that it expected on argument not got 0 or something similar...

@swift-ci create

@belkadan @rudkx @xedin

Thanks for the speedy responses guys - I realize now that the error is perfectly fine, this was just a gap in my understanding of `Void`. What I wish is that there were a way to use my `Executable<Input>` typealias to represent `()->()`. Given the fact that there is only one possible value of `Void` it does feel to me that the need for that input qualifies as boilerplate code, but I can understand that introducing the idea of treating a function type with no arguments as being equivalent to a function type with one (trivial) argument might be very unsound.