C++ Logo

SG10

Advanced search

Subject: Re: [SG10] [isocpp-core] No __cpp_concepts in the C++20 draft
From: Barry Revzin (barry.revzin_at_[hidden])
Date: 2019-11-07 08:38:06


On Thu, Nov 7, 2019 at 2:33 PM Jason Merrill <jason_at_[hidden]> wrote:

> On Mon, Sep 16, 2019 at 5:34 PM Casey Carter via Core <
> core_at_[hidden]> wrote:
>
>> We haven't had a __cpp_concepts since the TS specified its value as
>> 201507 - which GCC defines. I've been making up values since then for
>> various compilers which cmcstl2 supports to various degrees:
>> * clang-concepts defines __cpp_concepts to 201707L - the date of the
>> Toronto merge - to indicate support for concepts as merged.
>> * MSVC uses 201811L - the date of the P1084 merge - to indicate that it
>> supports the above plus P1084's changes to return-type-requirements.
>> (Unfortunately MSVC does not yet support the changes in P1141 which were
>> merged at the same meeting.)
>>
>> I'd appreciate a bump for the changes in Cologne. P1452 seems significant
>> enough to me, but regardless it would be nice to have a way to discriminate
>> between what MSVC will support in 16.3 and C++20 concepts' final form.
>>
>
> FYI http://wiki.edg.com/pub/Wg21belfast/CoreWorkingGroup/d1902r1.html does
> not propose to bump the value beyond 201811L.
>

This is one of the papers missing from the big table, sorry about that. I
can give you a new draft to bump it to 201907L. This is an omission.

Barry



SG10 list run by sg10-owner@lists.isocpp.org