On Tue, Nov 17, 2020 at 5:55 PM Jeff King <peff@xxxxxxxx> wrote:
> I actually wonder if it is time to drop HAVE_VARIADIC_MACROS completely.
> They are in C99, and we have been introducing many other C99-isms. It
> would be a minor cleanup to a few bits of code, which perhaps isn't
> worth the risk. But I also have a vague memory of not being able to
> implement some interfaces because we couldn't count on them.
>
> Poking around, 3689539127 (add helpers for allocating flex-array
> structs, 2016-02-22) points out one such case. I think discussion of
> BUG_ON() got blocked by that, too. Looks like we also discussed them in
> the big "C99 weather balloon" thread:
There was also an idea[1] to use variadic macros to prevent `errno`
from being clobbered in a case like this:
die_errno(_("blah %s"), foobar());
In which, if foobar() changes `errno`, then die_errno() reports the wrong value.
[1]: https://lore.kernel.org/git/CAPig+cQKMxwadf9aGyC5ESa-vxDy9PzrYo+m+JaVQ3S=12PyQQ@xxxxxxxxxxxxxx/
