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 96B043858D37; Thu, 20 Apr 2023 19:25:44 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 96B043858D37
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1682018744;
	bh=a8QEY5bqfTrhnj+uKBO/aPzDFDJ7XaLF/z9MnKQcLDE=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=BN/uKsVU+L1qlODV6cQm6olm2HWolrHOjZwAClPgrSSzqWylZmxr1kccjOZrrVWBv
	 +7smjpsSiMVK8nhkFX0hvcADbN4WYPkjiSp4K1bZM6Tc1aoiumK8UUcVEWYOk3HKb0
	 TZv7y04zywSauMCq91jXScs5wgeVIDyWnLbwZJPQ=
From: "panigstein at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/108993] Value initialization does not occur for derived
 class , for gcc versions > 5
Date: Thu, 20 Apr 2023 19:25:44 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.2.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: panigstein at hotmail dot com
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-108993-4-DKwN1rOJde@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-108993-4@http.gcc.gnu.org/bugzilla/>
References: <bug-108993-4@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=3D108993

--- Comment #6 from Pablo Anigstein <panigstein at hotmail dot com> ---
(In reply to Jonathan Wakely from comment #3)
> (In reply to Pablo Anigstein from comment #2)
> > (In reply to Andrew Pinski from comment #1)
> > > Hmm,
> > >  I noticed that since GCC 7 with -std=3Dc++17, the b.x is not initial=
ized at
> > > all. So the question I have is there a difference between C++ standar=
ds here?
>=20
> Derived is an aggregate in C++17, so b{} does aggregate init, not value i=
nit.
>=20
> > > Note the issue is we call Base's constructor after doing the zero
> > > initialization and the Base's constructor has a clobber in it which I=
 think
> > > is correct.
>=20
> Maybe we should only clobber in the complete object constructor _ZN4BaseC=
1Ev
> and not in _ZN4BaseC2Ev.
>=20
> > > This is all front-end generation and not exactly related to the
> > > optimizations directly.
> >=20
> > There is no difference between C++ standards in this respect.
>=20
> Before C++11 there was no zero-init at all. Since C++11 the spec keeps
> changing, but the effects of zero-init are substantially the same. But
> Derived is an aggregate since C++17.
Thank you for the correction. I still think there is non-conformance for all
standards including C++17, I will post a modified example in a comment belo=
w.

>=20
> Aside: What does the comment "not a default constructor" mean in the
> testcase?
I guess he meant "user-provided".=