Pointer Arith (Using the GNU Compiler Collection (GCC))

#### 6.13.2 Arithmetic on `void`- and Function-Pointers ¶

In GNU C, addition and subtraction operations are supported on pointers to `void` and on pointers to functions. This is done by treating the size of a `void` or of a function as 1.

A consequence of this is that `sizeof` is also allowed on `void` and on function types, and returns 1.

The option `-Wpointer-arith` requests a warning if these extensions are used.