c++ - Construction of a void Type?

Question

I was given a piece of code that uses void() as an argument. The code doesn't compile... obviously?

Can we instantiate anything of type void? I believed the answer was no, with the exception of a void*. For example:

1. Writing the function void askVoid(void param) {} errors:

A parameter may not have void type

2. Writing the function void askNaught() {} and calling it with askNaught(void())` errors:

error C2660: takeNaught: function does not take 1 arguments

3. Writing the templatized function template <typename T> void takeGeneric(T param) {} and calling it with takeGeneric(void()) errors:

error C2893: Failed to specialize function template void takeGeneric(T)

4. Declaring void voidType errors:

Incomplete type is not allowed

5. Declaring auto autoVoid = void() errors:

Cannot deduce auto type

6. Declaring void* voidPtr works fine, but remove_pointer_t<decltype(voidPtr)> decltypeVoid errors:

error C2182: decltypeVoid: illegal use of type void

That's it, right? There is no place for void() in C++ is there? This is just bad code I've been given, right?

Answer 1

C++ (and I say C++, not C) allows (§6.6.3 comma 2) functions with void return type to return a void expression, that is:

void foo() { return void(); }

But notice it is not constructing a temporary void!