Thanks for the comments. > On Apr 10, 2024, at 13:35, Joseph Myers <josmy...@redhat.com> wrote: > > On Fri, 29 Mar 2024, Qing Zhao wrote: > >> + /* Issue error when there is a counted_by attribute with a different >> + field as the argument for the same flexible array member field. */ > > There's another case of this to consider, though I'm not sure where best > to check for it (Martin might have suggestions) - of course this case will > need testcases as well.
Looks like this additional case relates to the new C23 feature, where is the documentation on this new feature, I need to study a little bit on this, thanks. > > Suppose, as allowed in C23, a structure is defined twice in the same > scope, A stupid question first, the same scope means the same file? (Or same function) Is there a testing case for this feature in current GCC source tree I can take a look? (and Then I can use it to construct the new testing case for the counted-by attribute). > but the two definitions of the structure use inconsistent > counted_by attributes. Where in the current C FE to handle the same structure is defined twice in the same scope? Which routine In the C FE? > I'd say that, when the declarations are in the > same scope (thus required to be consistent), it should be an error for the > two definitions of what is meant to be the same structure to use > incompatible counted_by attributes (even though the member declarations > are otherwise the same). Agreed. Wil add such checking. > > In C23 structures defined with the same tag in different scopes are > compatible given requirements including compatible types for corresponding > elements. Again, which routine in the C FE handle such case? I’d like to take a look at the current Handling and how to update it for the counted-by attribute. > It would seem most appropriate to me for such structures with > incompatible counted_by attributes to be considered *not* compatible types Is there a utility routine for checking “compatible type”? > (but it would be valid to define structures with the same tag, different > scopes, and elements the same except for counted_by - just not to use them > in any way requiring them to be compatible). Updating that routine (checking compatible type) with the new “counted-by” attribute Might be enough for this purpose, I guess. > >> +The @code{counted_by} attribute may be attached to the C99 flexible array >> +member of a structure. It indicates that the number of the elements of the >> +array is given by the field "@var{count}" in the same structure as the > > As noted previously, the "" quotes should be removed there (or replaced by > ``'' quotes). Okay, will update this. thanks. Qing > > -- > Joseph S. Myers > josmy...@redhat.com >