[Vala] Ref parameters to async methods

[Nor Jaidi Tuah <norjaidi tuah ubd edu bn>]

Is there any technical reason why
reference parameters are not supported for async methods?

My work around to this is simply to replace
  async void foo (ref X x)  // cannot compile

with
  async void foo (ClosureX cx)
where Closure is
  class ClosureX {
     X x;
  }

But why can't the compiler do this for us?
I must be missing something.

hand
Nor Jaidi Tuah