Why can't we declare a variable of type void?

Question

I\'m looking for a formal explanation of that fact in the Standard. I\'ve found what 3.9.1/9 says and trying to give an explanation used that section.

S

Answer 1

You cannot declare a variable of type void because variables must have object type or be references, extern void f; doesn't declare a reference, and void is not an object type:

Section 3 [basic] says that

A variable is introduced by the declaration of a reference other than a non-static data member or of an object.

Section 3.9 [basic.types] says that

An object type is a (possibly cv-qualified) type that is not a function type, not a reference type, and not a void type.