sizeof (*p)[1] is refused

typedef float vec4[4]; typedef vec4 mat4[4];
mat4 a; mat4 *p = &a;
printf("%d\n", (int)sizeof (*p)[1]);   /* gcc 16; pxx: error: expected ')' */

Measured 2026-09-27 on the v441 pin and after bug-c-an-array-of-pointers-to-arrays-has-no-pointee-shape-so-deref-loads-instead-of-decaying; both refuse. sizeof((*p)[1]) with outer parentheses has not been measured separately.