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 897063858C39; Wed, 15 Sep 2021 20:29:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 897063858C39
From: "dangelog at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/102283] Inconsistent/wrong overload resolution when using
 an initializer list and a defaulted template parameter
Date: Wed, 15 Sep 2021 20:29:46 +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: 11.2.1
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: dangelog 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: 
Message-ID: <bug-102283-4-iFwAt0aXvX@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-102283-4@http.gcc.gnu.org/bugzilla/>
References: <bug-102283-4@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: Wed, 15 Sep 2021 20:29:46 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102283

--- Comment #2 from Giuseppe D'Angelo <dangelog at gmail dot com> ---
Hi,

Do you think that in my original testcase the call should be rejected as
ambiguous as well? (It seems "reasonable" to me, but maybe I'm missing some
niche detail about overload resolution when combined with template deductio=
n.)


This small variation over the testcase:


struct A { };
struct B { };

template <typename T =3D A>
void f(T &&); // #1
void f(const B&) =3D delete; // #2

int main() {
  f({});
}

This now makes GCC select #2, and fail to compile because it's deleted; Cla=
ng
and MSVC still select #1. But a further, minor change:


struct A { };
struct B { };

template <typename T =3D int> // <-- changed this
void f(T &&); // #1
void f(const B&) =3D delete; // #2

int main() {
  f({});
}

makes GCC select #1...=