stdc_trailing_zeros_ull
return (stdc_trailing_zeros_ull(~ull));
return (stdc_trailing_zeros_ull(ull) + 1);
.so_ull = stdc_trailing_zeros_ull,
extern unsigned int stdc_trailing_zeros_ull(unsigned long long) _C23_UNSEQ_ATTR;
char(*)[8]: stdc_trailing_zeros_ull(val))