[cfe-dev] The state of Concepts in Clang

[Hubert Tong via cfe-dev]

Hi Hannes,

At this time, I have been working on Concepts in Clang. I am not sure how
"people" are using concepts in GCC, but my experience on unit testing
produced a number of internal compiler errors (and I have not found the
error messages to be helpful in general). Some cases of those internal
compiler errors stem from the cases being underspecified in the TS.

I am not sure an ETA makes sense if the shape of what is going to be
delivered is changing. For example, the TS has a one-size-fits-all
normalization process which can be overly eager; part of the Clang
implementation effort would be to implement (in consultation with the
committee) the intended behaviour for each of the uses of normalization.

-- HT

On Thu, Feb 9, 2017 at 3:17 PM, Hannes Hauswedell <h2+lists2017 at fsfe.org>
wrote:

> Hi Hubert,
>
> thanks for the reply and the "warning sign". I am aware that the
> discussion on Concepts is ongoing, but there is the published ISO/IEC TS
> 19217:2015 that GCC implements and it has been rather stable from my
> knowledge.
> In any case my original question still remains: is there an ETA for
> concepts in Clang? Is there a person responsible for it right now that
> could have more details?
>
> Thanks,
> Hannes
> --
> pgp-key: https://hannes.hauswedell.net/hannes_hauswedell_public_key.asc
> fingerprint: FC35 7547 7916 DA55 DC42 27EA 1D57 8E18 A109 60BF
>
> On 05.02.2017 18:57, Hubert Tong wrote:
> > The Concepts TS implementation for Clang is occurring on trunk; so you
> are
> > looking in the right place.
> > Regardless of the implementation status in Clang, the TS remains an
> > experimental design, which may be subject to change.
> > So, I think that using relying on the Concepts TS in production carries
> > some risks: even if the support is there, it might not be the same as GCC
> > or the current version of the TS.
> >
> > -- HT
> >
> > On Sun, Feb 5, 2017 at 8:43 AM, Hannes Hauswedell via cfe-dev <
> > cfe-dev at lists.llvm.org> wrote:
> >
> >> Hi everyone,
> >>
> >> I wanted to ask what the current state of the Concepts TS is in Clang. I
> >> saw some older list threads last year, but also didn't see much in
> >> regard of commits, but maybe I am also looking in the wrong places.
> >>
> >> The status page lists it as WIP, but from my own experience I know that
> >> WIP can me anything from "we are running the last tests before release"
> >> to "I have put it on the TODO list".
> >>
> >> The background is that we are currently redesigning a large template
> >> library and would really like to make use of concepts. Working with GCC
> >> during development is not a problem, but when we start distributing
> >> first release candidates maybe a year from now, it would be important to
> >> have Clang support, too.
> >>
> >> If someone could shed light on the current status and whether there is
> >> an ETA that would help us a lot. Note that I am not implying that anyone
> >> should do anything for us, it's just important for us to know whether
> >> it's something we can likely expect for e.g. clang-6 or "definetely not
> >> in the next two years".
> >>
> >> Thank you,
> >> Hannes
> >> --
> >> pgp-key: https://hannes.hauswedell.net/hannes_hauswedell_public_key.asc
> >> fingerprint: FC35 7547 7916 DA55 DC42 27EA 1D57 8E18 A109 60BF
> >>
> >>
> >> _______________________________________________
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> >>
> >>
> >
>
>
>
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