Function argument returning void or non-void type

Question

I am in the middle of writing some generic code for a future library. I came across the following problem inside a template function. Consider the code below:

Answer 1

if you can place the "some generic stuff" in the destructor of a bar class (inside a security try/catch block, if you're not sure that doesn't throw exceptions, as pointed by Drax), you can simply write

template 
auto foo (F &&f)
 {
   bar b;

   return std::forward(f)(/*some args*/);
 }

So the compiler compute f(/*some args*/), exec the destructor of b and return the computed value (or nothing).

Observe that return func();, where func() is a function returning void, is perfectly legal.