Hi Martin, On Mon, Jan 05, 2026 at 03:42:54PM +0100, Martin Uecker wrote: > > If you make it a constraint violation, a conforming implementation > > can reject a program with unknown attributes while now it is required > > to translate it.
And remember, an implementation is also required to implement
struct [[alx::packed]] foo {
char a;
int64_t b;
char c;
int64_t d;
};
exactly as
struct foo {
char a;
int64_t b;
char c;
int64_t d;
};
(because no implementation recognizes alx:: attributes.)
If this is not an Earthly Demon, tell me what is.
> > I would also perfer if Clang and GCC would not
> > emit the warning by default, but a warning is still ok as long as the
> > program is translated.
>
> At the same time, there is nothing useful we would gain from your proposal.
As a starter, we'd reject the code shown above. That's a useful gain,
isn't it?
But okay, I give up on trying to fix non-scoped attributes.
Since Aaron complained about stdc::attr attributes because they wouldn't
be useful in C++, my third attempt at having useful attributes will be
[[::attr]]. This should be acceptable in C++, because there's no
prefix, and thus nothing that says anything about C. Does this sound
good to you?
Have a lovely night!
Alex
> If we want to introduce non-ignorable new language features, we can just
> do this using a different syntax, just like we always do. There is absolutely
> no reason to use attribute syntax for this. And if this feature is
> non-ignorable, for example a new jump statement, then as I a reviewer and
> reader of C code I also really want this to look very different from some
> "hint" such as "nodiscard". I am also sure anybody working on any kind of
> tooling that analysis C code appreciates that the tool can simply
> ignore standard attributes if it wants to and keeps forward compatible to
> any of such future hints we may want to add. You add a lot of unnecessary
> cost to a lot people of you change this because then any such attribute
> must be treated as potentially affecting semantics. So please don't.
>
> Martin
>
>
>
>
--
<https://www.alejandro-colomar.es>
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