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 833F83870852; Tue,  2 Jun 2020 05:39:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 833F83870852
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1591076386;
 bh=bxS61d8YqA2KHznoOjliLiNASKySapuoXg8Bi8GCqxY=;
 h=From:To:Subject:Date:From;
 b=ZskDED55FqP/E89V1XmbxbgdMipVAF4WP3vfegSr6HFtkh7AdXz+nq5bQoaaeTlIM
 9Q4JBeA1h2zt0Tm2391aniGhzcYsjB1h+0fcjw9RpSsSU25Kc7SjEdHR4ak9Mzj+/f
 PTSerNoWfsdw8vOO4obH/bbXXiyBGr3W5ypKR4K4=
From: "haoxintu at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95473] New: GCC misses -Wnull-dereference warning in a
 simple code
Date: Tue, 02 Jun 2020 05:39:46 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: haoxintu at gmail 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: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-95473-4@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, 02 Jun 2020 05:39:46 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95473

            Bug ID: 95473
           Summary: GCC misses -Wnull-dereference warning in a simple code
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

$cat null_ref.cc
int main(){
    int &x1 =3D *(int *)nullptr; // null reference
    return 0;
}

GCC can not catch any warning when I use -Wnull-dereference option.=20
I also try to add -O1~Os, but GCC still produces nothing.

While in clang

$clang++-trunk -Wnull-dereference null_ref.cc=20
null_ref.cc:2:15: warning: binding dereferenced null pointer to reference h=
as
undefined behavior [-Wnull-dereference]
    int &x1 =3D *(int *)nullptr; // null reference
              ^~~~~~~~~~~~~~~
1 warning generated.

$g++ --version
g++ (GCC) 11.0.0 20200526 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.=