From: "Daniel Krügler" <daniel.kruegler@gmail.com>
To: Jonathan Wakely <jwakely@redhat.com>
Cc: "libstdc++" <libstdc++@gcc.gnu.org>,
gcc-patches List <gcc-patches@gcc.gnu.org>
Subject: Re: [committed] libstdc++: Allow visiting inherited variants [PR 90943]
Date: Sat, 2 Oct 2021 14:49:25 +0200 [thread overview]
Message-ID: <CAGNvRgCuPz52iQiL=__iJ1QfyXRRAH+wD42NKCcxxLrjy5xKAw@mail.gmail.com> (raw)
In-Reply-To: <YVdko00+wrQ1d3TL@redhat.com>
Am Fr., 1. Okt. 2021 um 21:57 Uhr schrieb Jonathan Wakely via
Libstdc++ <libstdc++@gcc.gnu.org>:
>
> Implement the changes from P2162R2 (as a DR for C++17).
>
> Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/90943
> * include/std/variant (__cpp_lib_variant): Update value.
> (__detail::__variant::__as): New helpers implementing the
> as-variant exposition-only function templates.
> (visit, visit<R>): Use __as to upcast the variant parameters.
> * include/std/version (__cpp_lib_variant): Update value.
> * testsuite/20_util/variant/visit_inherited.cc: New test.
>
> Tested powerpc64le-linux. Committed to trunk.
>
I'm wondering why the first __as overload is not noexcept as well (or
asking it the other way around: Why different exception-specifications
are used for the different overloads):
+ // The __as function templates implement the exposition-only "as-variant"
+
+ template<typename... _Types>
+ constexpr std::variant<_Types...>&
+ __as(std::variant<_Types...>& __v)
+ { return __v; }
- Daniel
next prev parent reply other threads:[~2021-10-02 12:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 19:42 Jonathan Wakely
2021-10-02 12:49 ` Daniel Krügler [this message]
2021-10-03 9:07 ` Jonathan Wakely
2021-10-04 14:26 ` Jonathan Wakely
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAGNvRgCuPz52iQiL=__iJ1QfyXRRAH+wD42NKCcxxLrjy5xKAw@mail.gmail.com' \
--to=daniel.kruegler@gmail.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=jwakely@redhat.com \
--cc=libstdc++@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).