> On Jun 11, 2025, at 15:45, Joseph Myers <josmy...@redhat.com> wrote:
>
> On Wed, 11 Jun 2025, Qing Zhao wrote:
>
>> When I was adding more testing cases for the pointee type being
>> structure/union, I have a question for the following case:
>>
>> struct item5 {
>> int a;
>> float b[];
>> };
>>
>> struct pointer_array_9 {
>> ...
>> int count5;
>> struct item5 *array_5 __attribute__ ((counted_by (count5)));
>> };
>>
>> In the above, “struct item5” is a structure type with flexible array
>> member, whose size is not know during compilation time, as a result, the
>> size of the whole structure is unknown during compilation time, shall we
>> reject such cases?
>
> Since the standard doesn't allow a structure with a flexible array member
> (or a union containing such a structure, recursively) to be an element of
> an array, it seems reasonable to reject such cases as well.
Okay. I will do that.
Then how about the following case:
typedef struct item3 Item3;
struct pointer_array_9 {
int count3;
Item3 *array_3 __attribute__ ((counted_by (count3)));
}
struct item3 {
int a;
float b[];
}
In the above, the “Item3” is an incomplete type inside “struct
pointer_array_9”, whose definition is given
afterward.
Theoretically, C FE should issue error for the above counted_by attribute.
However, when and how should we
Implement this in C FE:
when we examine the counted_by attribute for “array_3” inside “struct
pointer_array_9”, there is no any information
on the TYPE of “Item3” yet, only when we see the definition of “struct item3”
afterward, we know that this structure
includes a FAM, the previous “counted_by” attribute should not be added for
“array_3”.
Is there a way to trace back to “struct pointer_array_9” when the definition of
“struct item3” is parsed?
When should we issue error for such case?
Thanks.
Qing
>
> --
> Joseph S. Myers
> josmy...@redhat.com
