On Wed, 10 Apr 2024, Qing Zhao wrote:

> Okay, the above is very clear, thanks a lot for the explanation.
> So, basically, for “counted-by” attribute:
> **The following is good:
> struct f { 
>   int b;
>   int c;
>   int a[]  __attribute__ ((counted_by (b))) };
> struct f {
>   int b;
>   int c;
>   int a[] __attribute__ ((counted_by (b))) };
> 
> **The following should error:
> 
> struct f { 
>   int b;
>   int c;
>   int a[]  __attribute__ ((counted_by (b))) };
> struct f {
>   int b;
>   int c;
>   int a[] __attribute__ ((counted_by (c))) };  /* error here */
> 
> For the same tag in different scopes case:
> 
> struct f { 
>   int b;
>   int c;
>   int a[]  __attribute__ ((counted_by (b))) }  y0;
> 
> void test1(void) 
> {   
> struct f {
>   int b;
>   int c;
>   int a[] __attribute__ ((counted_by (c))) } x;
> 
>   y0 = x;  /* will report incompatible type error here */
> }
> 
> Are the above complete?

Yes, that looks like what should be tested (with the addition of the case 
of same tag, different scopes, same counted_by so compatible).

-- 
Joseph S. Myers
josmyers@redhat.com