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 4BC263858CDA; Mon,  9 Jan 2023 16:14:57 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4BC263858CDA
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1673280897;
	bh=q1rTB8hin9RBdXf2P3po9q30AKOCjEN+euSzqjunhVo=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=eQHjA4oz6Ga/Rzwq7y2k0EIWVJKi3yxbkVaJs8RDnuKfSIdEl3nd0afDO2P5Ugn0t
	 8nrHTBqKNCncuPwho1TLpMcZ93yQiPekegIwjqP5MFgywt12Rj2byUjoWdSXSKhMHB
	 RAICnDJzFQrHzfM0CO8Xvh6Y4QjGQfzCiZzEb9nQ=
From: "ruilvo at ua dot pt" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/108342] std::complex: ignoring packed attribute
 because of unpacked non-POD field
Date: Mon, 09 Jan 2023 16:14:56 +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: 12.2.1
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ruilvo at ua dot pt
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-108342-4-tsvsLgMfVi@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-108342-4@http.gcc.gnu.org/bugzilla/>
References: <bug-108342-4@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=3D108342

--- Comment #3 from Rui Oliveira <ruilvo at ua dot pt> ---
(In reply to Andrew Pinski from comment #1)
>=20
> I know about _Atomic and std::atomic but not std::complex and _Complex.
> Because std::complex was part of C++98 which was done before C99's _Compl=
ex
> ...

[complex.numbers.general] mentions:

If z is an lvalue of type cv complex<T> then:=20
the expression reinterpret_=C2=ADcast<cv T(&)[2]>(z) is well-formed,

https://eel.is/c++draft/complex.numbers.general

Basically stating that std::complex<T> is layouted exactly the same as T[2]=
.=20

C standard says something similar iirc.=