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 AFD98385C426; Mon, 23 Mar 2020 00:21:15 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org AFD98385C426
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1584922875;
 bh=vHQh4GEUPd6B60OfI5jPS/10Q0c1a1Y6VTtgNX5d+qA=;
 h=From:To:Subject:Date:From;
 b=m1iQWz+RIQFVXsWNhPmd3in7F5TBjpjwUep6jBCpnnkKFi18Xoeb1O8bCD5mohEyI
 cU82ublDlZigExCmZnck4ft2lLEhiZhNTQ4IOg3OARoczEbmBUpBjxxZ+f/a8Q7ve0
 3vYesc6EDp5qM6c+pGJbfEgOg4MebWjDwgWX5EmU=
From: "ndkrempel at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/94264] New: Array-to-pointer conversion not performed on
 array prvalues
Date: Mon, 23 Mar 2020 00:21:15 +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: 9.3.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ndkrempel 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-94264-4@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: <http://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: Mon, 23 Mar 2020 00:21:15 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94264

            Bug ID: 94264
           Summary: Array-to-pointer conversion not performed on array
                    prvalues
           Product: gcc
           Version: 9.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ndkrempel at gmail dot com
  Target Milestone: ---

I think the most clearcut example is:

int main() {
  using T =3D int[];
  T{1, 2} =3D=3D nullptr;
}

This compiles fine with clang, and is supported by the standard: the =3D=3D
operator explicitly performs array-to-pointer conversion
(https://eel.is/c++draft/expr#eq-1), and array-to-pointer conversion is
explicitly defined for rvalue arrays (https://eel.is/c++draft/expr#conv.arr=
ay).

Other examples (which again all compile with clang) are:

+T{1, 2};
  Here the standard wording seems to have a minor bug, as unary "+" does not
explicitly perform the array-to-pointer conversion, and the general rubric =
for
applying it (https://eel.is/c++draft/expr#basic.lval-6) only applies to
glvalues as written.

T{1, 2} + 1;
  Ditto.

*(T{1, 2} + 1);
  Interesting as T{1, 2}[1] should be equivalent to this (modulo the value
category of the result, https://eel.is/c++draft/expr#sub), yet the former is
rejected by gcc and the latter accepted.=