On Thu, Jul 16, 2026 at 03:48:44PM +0200, Richard Biener wrote:
> > +/* Attribute table for the callback attribute to be used by the C
> > frontends.
> > + We don't want to expose the attribute outside of the GNU namespace, so
> > it
> > + has to be separated out. */
> > +const struct attribute_spec c_common_callback_attribute[] = {
> > + { CALLBACK_ATTR_IDENT, 1, -1, true, false, false, false,
> > + handle_callback_attribute, NULL },
> > +};
> > +
> > +const struct scoped_attribute_specs c_common_callback_attribute_table
> > + = { "gnu", { c_common_callback_attribute } };
I don't really like this.
Why can't __attribute__((callback_only (...))) be supported? I thought
the LLVM attribute is callback, not callback_only.
Furthermore, even if you want to reject __attribute__((callback_only (...)))
and only allow [[gnu::callback_only (...)]]], then having a separate
scoped_attribute_specs is not the right way to do that.
In the handler you should instead check if if (flags & ATTR_FLAG_CXX11)
(if so, it is the gnu::callback_only form, otherwise perhaps warn or
error).
Jakub
