On Wed, Jan 14, 2026 at 08:00:54PM -0800, Kees Cook wrote:
> On Wed, Jan 14, 2026 at 07:36:47PM +0000, Bill Wendling wrote:
> > Introduce __counted_by_ptr(), which works like __counted_by(), but for
> > pointer struct members.
> >
> > struct foo {
> > int a, b, c;
> > char *buffer __counted_by_ptr(bytes);
> > short nr_bars;
> > struct bar *bars __counted_by_ptr(nr_bars);
> > size_t bytes;
> > };
> >
> > Because "counted_by" can only be applied to pointer members in very
> > recent compiler versions, its application ends up needing to be distinct
> > from flexibe array "counted_by" annotations, hence a separate macro.
> >
> > Note that Clang's support for "void *" members will be in version 22.
> > So, when using Clang, you'll need to wait until its release before using
> > the feature with "void *". No such restriction applies to GCC's version
> > 16.
>
> I think to keep operational parity, we should limit counted_ptr on Clang
> to version 22 then, otherwise we'll have problems using it on void *.
Ooh, you got that fixed! Nice!
