From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id F359B3858C2B; Mon,  8 May 2023 21:16:47 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F359B3858C2B
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1683580608;
	bh=VhahA+jh+PsImOWJNMPnuFysiD8GJ3mRwIT4XZaVPe8=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=WkyHLfiyi4ffzx0za3dZMLaRBzM7eLcpur8ZGrzsN4WefPDEUWHaD5k+5NN2aoC9G
	 0sSkk7ioYJkAa2IjojcJ86xwSh5+Ggdioo/soIAGO42sIgztxLzdJi46v5RgbNDKoZ
	 TTf580Xgmt7+7C6qCqd+lQHdvW2lHdqHaqioobzU=
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/99277] C++2a synchronisation is inefficient in GCC 11
Date: Mon, 08 May 2023 21:16:47 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: ABI
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: FIXED
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 12.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-99277-4-RWZfLJFjTc@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-99277-4@http.gcc.gnu.org/bugzilla/>
References: <bug-99277-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99277

--- Comment #22 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Thiago Macieira from comment #19)
> (In reply to Jonathan Wakely from comment #18)
> > We have not committed to a stable ABI for C++20 yet.
>=20
> That was my argument when creating this bug report two years ago: if it's
> available in the standard headers to be used without explicit, opt-in
> actions by the users, it's committed.

N.B. explicit opt-in is required: -std=3Dc++20 or similar.

The default mode does not provide std::barrier etc.=