On Wed, 11 Jun 2025, Qing Zhao wrote:
> 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?
In general I think we'd only expect an error if the information required
to give it is visible at the point where the counted_by attribute is used.
There might be a possibility of giving an error for this case when the
pointer gets dereferenced (and thus the counted_by information gets
implicitly used).
--
Joseph S. Myers
[email protected]
