On Fri, 2024-03-01 at 20:45 +0000, Jonathan Wakely via Std-Proposals
wrote:
> On Fri, 1 Mar 2024 at 15:53, Tom Honermann <tom_at_[hidden]> wrote:
> >
> > On 3/1/24 6:43 AM, Jonathan Wakely via Std-Proposals wrote:
> > > On Fri, 1 Mar 2024 at 01:53, Zhihao Yuan via Std-Proposals
> > > <std-proposals_at_[hidden]> wrote:
> > > > On Thursday, February 29th, 2024 at 10:48 AM, Tom Honermann via
> > > > Std-Proposals <std-proposals_at_[hidden]> wrote:
> > > >
> > > > See also P0281R0 (Remove comma elision in variadic function
> > > > declarations). EWG rejected the paper during the Jacksonville,
> > > > 2016 meeting. There isn't much for meeting minutes. From what I
> > > > recall, concerns were mostly about the potential to break
> > > > existing code.
> > > >
> > > > My view: ship it.
> > > >
> > > > Tom.
> > > >
> > > > My view: ship it.
> > > >
> > > > And prove my stand-up outdated: https://youtu.be/PSvJ_j4rKOE
> > > I'm glad I'm not the only one who enjoys the hexadot.
> > >
> > > https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libstdc%2B%2B-v3/include/bits/refwrap.h;h=2d4338b718fca19439223512fae2a131de0784ff;hb=HEAD#l140
> >
> > Hmm, usage in a system header. And that isn't the only use.
> >
> > https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libstdc%2B%2B-v3/libsupc%2B%2B/new;h=8b07150fb94941bd29a334cfa178c922255ea394;hb=HEAD#l206
> > https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libstdc%2B%2B-v3/include/tr1/type_traits;h=f5714b0032cc8015840a90a002911da62bc9dd27;hb=HEAD#l229
> >
> > That last one is tr1, so I'm not sure it matters much. The paper
> > should
> > probably note these uses. They probably don't affect deprecation
> > since
> > deprecation warnings are typically suppressed for uses in system
> > headers, but they could be an issue for removal. This suggests
> > getting
> > some implementation experience might be worthwhile as well (e.g.,
> > add a
> > warning to gcc, build it and libstc++, run the testsuite).
>
> Libstdc++ headers are changed in lockstep with GCC itself, so if this
> change goes ahead I'll just add the commas to libstdc++ (and weep
> quietly to mourn the loss of the hexadot).
>
> There's a minor issue for libstdc++ headers being consumed by non-GCC
> compilers, so somebody trying to use today's libstdc++ headers with a
> version of Clang that implements this proposal would be an issue.

You could commit the comma ahead of the deprecation (less cleverness ==
improvement) and backport them to clear the field.


> My
> thinking is that if you're trying to use -std=c++2c -stdlib=libstdc++
> with clang then you had better make sure you have up-to-date
> libstdc++
> headers. It's not reasonable to expect headers from 2024 to support
> -std=c++2c well.
>
> Uses in non-stdlib code are more of a concern.