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 17325385828B; Mon,  6 Jun 2022 12:50:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 17325385828B
From: "ppalka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/105841] [12/13 Regression] Change in behavior of CTAD for
 alias templates
Date: Mon, 06 Jun 2022 12:50:42 +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: 12.0
X-Bugzilla-Keywords: rejects-valid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ppalka 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: 12.2
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: see_also cf_known_to_work cf_known_to_fail
 cf_reconfirmed_on cc target_milestone short_desc bug_status keywords
 everconfirmed
Message-ID: <bug-105841-4-xYoTm4uszP@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-105841-4@http.gcc.gnu.org/bugzilla/>
References: <bug-105841-4@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: Mon, 06 Jun 2022 12:50:43 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105841

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=3D103852
      Known to work|                            |11.3.0
      Known to fail|                            |12.1.0, 13.0
   Last reconfirmed|                            |2022-06-06
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |ppalka at gcc dot gnu.org
   Target Milestone|---                         |12.2
            Summary|Change in behavior of CTAD  |[12/13 Regression] Change
                   |for alias templates         |in behavior of CTAD for
                   |                            |alias templates
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |rejects-valid
     Ever confirmed|0                           |1

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
We started rejecting the testcase after r12-7984-ga11f204e5a30d1.

Reduced rejects-valid example:

template<class T, int N>
struct A { A(...); };

template<class T, class... Ts>
A(T, Ts...) -> A<T, sizeof...(Ts)>;

template<class T, int N=3D0>
using B =3D A<T, N>;

B b(0, 0);

Removing B's default template argument makes us accept again.=