化けた。
ま、>>233が規格理解してない半可通という事が証明されてしまったわけだ。ｗ

5.2.10 p7
A pointer to an object can be explicitly converted to a pointer to an object of
different type. Except that converting an rvalue of type "pointer to T1" to the
type "pointer to T2" (where T1 and T2 are object types and where the alignment
requirements of T2 are no stricter than those of T1) and back to its original type
yields the original pointer value, the result of such a pointer conversion is
unspecified.