[otabdeveloper4]

Void means "it is a syntax error to construct a value of this type". This is not a type that exists in category theory or Haskell. (But similar to the "bottom" type.)

Hence, "void*" - a pointer to something, but it would be a syntax error to derefence this pointer.

[gpderetta]

In that regard void behaves like any incomplete type. In C and C++ you cannot construct objects of incomplete types nor you can assign through pointers of incomplete types. But you can construct pointers to void and other incomplete types.

Differently to other incomplete types void has some special behaviour: you can declare a function as returning void and return with no arguments is also special cased. You can also cast to void.

A void with proper unit semantics would simply be a complete type instead. The only special case would be return with no arguments implicitly returning a void instance, but that would be pure sugar.