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 8A5FB3858402; Thu,  9 Dec 2021 14:23:07 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8A5FB3858402
From: "mathieu.malaterre at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/103629] Possible miscompilation triggered by
 -fvisibility=hidden
Date: Thu, 09 Dec 2021 14:23:07 +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: 11.2.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: mathieu.malaterre at gmail dot com
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: INVALID
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-103629-4-vr1PNzPbPf@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-103629-4@http.gcc.gnu.org/bugzilla/>
References: <bug-103629-4@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
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Thu, 09 Dec 2021 14:23:07 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103629

--- Comment #7 from Mathieu Malaterre <mathieu.malaterre at gmail dot com> =
---
(In reply to Andrew Pinski from comment #6)
> (In reply to Mathieu Malaterre from comment #5)
> > (In reply to Andrew Pinski from comment #4)
> > > (In reply to Mathieu Malaterre from comment #3)
> > > > $ export CXXFLAGS=3D-fvisibility=3Dhidden
> > >=20
> > > Yes you can't just use -fvisibility=3Dhidden without the source being=
 ready
> > > for it.
> >=20
> > Andrew, could you please be a bit more specific. I do not see any chang=
es
> > related to duplicate `typeinfo` or `visibility=3Dhidden` in the changel=
og:
> >=20
> > * https://gcc.gnu.org/gcc-11/changes.html
>=20
> right there has been no major changes in this area as far as I Know.=20
>=20
> >=20
> > `-fvisibility=3Dhidden` was added in 2015 in the Debian/OpenVDB package=
 and
> > has worked quite well for all users so far. It would be nice if gcc/ld =
would
> > help track any `type_info` issue, in large portable c++ codebase.
>=20
> It was working by accident before. Do you know why it was added? Has the
> code upstream in OpenVDB been fixed for adding the visibility attribute
> where needed?

OpenVDB is supposed to be /portable/ c++. The dll export mechanism has been
working on windows arch since basically day-one.

The gcc implementation is at:

*
https://github.com/AcademySoftwareFoundation/openvdb/blob/master/openvdb/op=
envdb/Platform.h#L218-L219

IMHO this is following the wiki from:

* https://gcc.gnu.org/wiki/Visibility=