>>417
配列じゃないオブジェクトへのポインタ演算のルールは要素数 1 の配列といっしょ。
5.7 [expr.add] p4
> For the purposes of these operators, a pointer to a nonarray object
> behaves the same as a pointer to the first element of an array of length
> one with the type of the object as its element type.