> On Aug 21, 2024, at 17:54, Bill Wendling <isanb...@gmail.com> wrote:
>
>> if (__builtin_get_counted_by(p->array)) {
>> size_t max_value =
>> type_max(typeof(*__builtin_get_counted_by(p->array)));
>> if (count > type_max)
>> ...fail cleanly...
>> *__builtin_get_counted_by(p->array) = count;
>> }
>>
>> I don't strictly need to READ the value (but it seems nice). Currently I can
>> already do a READ with something like this:
>>
>> size_t count = __builtin_dynamic_object_size(p->array, 1) /
>> sizeof(*p->array);
>>
>> But I don't have a way to examine the counter _type_ without
>> __builtin_get_counted_by, so I prefer it over __builtin_set_counted_by.
>>
> Another thing to point out, the documented type signature of
> __builtin_get_counted_by() is more-or-less meaningless. It should be
> adjusted during SEMA to a pointer to the count's type. It's only "void
> *" if the 'counted_by' attribute.
For GCC’s implementation, the returned type of the __builtin_get_counted_by is:
The TYPE of the returned value must be a pointer type pointing to the
corresponding type of the counted-by object or a VOID pointer type in
case of a NULL pointer being returned.
Qing
>
> -bw
