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 6DA8E385DC14; Fri, 15 May 2020 23:49:16 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6DA8E385DC14
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1589586556;
 bh=JRDJvTJ0r8XahsvzmWV/Xy6sH5y4m939R5Ge7cLw6ng=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=lqEcOZ2gXImL0VJDNr0iXueoQjmsiQ4ZEbRP42vI5w1w3jUTjGVt7hcipdc4hYmW+
 dIcx2YBzJiVXD9UagXVABIgsuWyt5LO6mWI1ZTXXFyrYMpEgaupz9QrpEpPNY/Rs53
 5AFsRfplTTSYi/h6Tl7+ZEHRS0/gakvJKxTvf3go=
From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95156] -Wtautological-compare warns in C but not C++
Date: Fri, 15 May 2020 23:49:16 +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: 11.0
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: msebor 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: version bug_status everconfirmed cc
 cf_known_to_fail keywords cf_reconfirmed_on
Message-ID: <bug-95156-4-rP1JtgZgJw@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-95156-4@http.gcc.gnu.org/bugzilla/>
References: <bug-95156-4@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: Fri, 15 May 2020 23:49:16 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95156

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |11.0
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
                 CC|                            |msebor at gcc dot gnu.org
      Known to fail|                            |10.1.0, 11.0, 9.2.0
           Keywords|                            |diagnostic
   Last reconfirmed|                            |2020-05-15

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
In C mode the warning function, warn_tautological_bitwise_comparison (const
op_location_t &loc, tree_code code, tree lhs, tree rhs), gets a BIT_AND_EXPR
while in C++ mode it's passed a NOP_EXPR that casts the result of the same
BIT_AND_EXPR as in C to int.  The cast seems pointless since the type of the
BIT_AND_EXPR already is int.

I couldn't find a version where G++ did issue the expected warning so it's =
not
a regression.

(As an aside, the volatile qualifier isn't necessary to reproduce the bug.)=