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 6E1BF388E802; Tue,  5 May 2020 11:47:58 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6E1BF388E802
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1588679278;
 bh=iRJDkIASWsJJ8QUApvOFL5ZdDljkKNJnUJPcpiC/IW4=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=AcSuyPRXGf8e/U/LL/oA1WRf7GxliUV/fDaw8f3mW3MDI5TscZXK4zHpTMVYqut3X
 ev9H8GoGVgx5ChFmdAAb7ew0Tc4AGwbd4GRnU1+Rr7nn6Sw0sblUevzkxuXW+NryW5
 V2PDn3c2lxZpfPQoMPQHKn+BXrQvzxvcGcNVASlQ=
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/94951] dereferencing type-punned pointer will break
 strict-aliasing rules when using super class for a template type
Date: Tue, 05 May 2020 11:47:58 +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: 9.3.0
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
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: bug_status everconfirmed keywords cf_reconfirmed_on
Message-ID: <bug-94951-4-bpaX1gADGZ@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-94951-4@http.gcc.gnu.org/bugzilla/>
References: <bug-94951-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Tue, 05 May 2020 11:47:58 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94951

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
           Keywords|                            |diagnostic
   Last reconfirmed|                            |2020-05-05

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
We're warning via

#0  warning_at (location=3D426247, opt=3D664,=20
    gmsgid=3D0x2a36f08 "dereferencing type-punned pointer will break
strict-aliasing rules") at ../../src/trunk/gcc/diagnostic.c:1442
#1  0x0000000000e324c9 in strict_aliasing_warning (loc=3D426247,=20
    type=3D<pointer_type 0x7ffff6d9fbd0>, expr=3D<addr_expr 0x7ffff6d97480>)
    at ../../src/trunk/gcc/c-family/c-warn.c:729
#2  0x0000000000d45def in cp_build_indirect_ref_1 (loc=3D426535,=20
    ptr=3D<nop_expr 0x7ffff6d974a0>, errorstring=3DRO_NULL, complain=3D3,=20
    do_fold=3Dtrue) at ../../src/trunk/gcc/cp/typeck.c:3364
#3  0x0000000000d46191 in cp_build_fold_indirect_ref (
    pointer=3D<nop_expr 0x7ffff6d974a0>) at ../../src/trunk/gcc/cp/typeck.c=
:3444
#4  0x00000000009ecb7a in build_base_path (code=3DPLUS_EXPR,=20
    expr=3D<nop_expr 0x7ffff6d974a0>, binfo=3D<tree_binfo 0x7ffff6da0060>,=
=20
    nonnull=3D1, complain=3D3) at ../../src/trunk/gcc/cp/class.c:513
#5  0x0000000000d4309f in build_class_member_access_expr (object=3D...,=20
    member=3D<field_decl 0x7ffff6d9eab0 someData>,=20
    access_path=3D<record_type 0x7ffff6d9f5e8 B>, preserve_reference=3Dfals=
e,=20
    complain=3D3) at ../../src/trunk/gcc/cp/typeck.c:2603
#6  0x0000000000d45377 in finish_class_member_access_expr (object=3D...,=20
    name=3D<identifier_node 0x7ffff6d9b980 someData>, template_p=3Dfalse,=20
    complain=3D3) at ../../src/trunk/gcc/cp/typeck.c:3209=