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 E2DD5383D834; Mon, 21 Jun 2021 13:33:22 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E2DD5383D834
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/101137] std::conjunction result error
Date: Mon, 21 Jun 2021 13:33:22 +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: 11.1.0
X-Bugzilla-Keywords: accepts-invalid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: WAITING
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-101137-4-7VCNPHHvpz@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-101137-4@http.gcc.gnu.org/bugzilla/>
References: <bug-101137-4@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, 21 Jun 2021 13:33:23 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101137

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #3)
> template<typename T>
> concept SignedIntegralRef1
>   =3D std::is_lvalue_reference_v<T> && SignedIntegral1<T>;

Oops, that should be
std::is_lvalue_reference_v<T> && SignedIntegral1<std::remove_reference_t<T>>
(which is easy to spot when you break the wall of text into pieces).

It's irrelevant here anyway, because you can never have a type like
deque<int&>, so it would make a lot more sense for your code to have separa=
te
concepts as above, and then for the the concepts like Container you only ne=
ed
to use the SignedIntegral1 concept, because the container's value type can'=
t be
a reference.

N.B. defining traits just to use as arguments to std::conjunction just to
define concepts is ... peculiar.

Why not just define the concepts directly? It will compile much faster.

template<typename T>
concept ContainerOfSignedIntegral
  =3D Container<T> && SignedIntegral<typename T::value_type>;

template<typename T0, typename T1>
concept SignedIntegralConvertCopy1
  =3D ContainerOfSignedIntegral<T0> && !ForwardList<T0>
    && ContainerOfSignedIntegral<T1>
    && (!std::same_as<typename T1::value_type, typename T2::value_type>);

template<typename T0, typename... T1>
concept SignedIntegralConvertCopy =3D (SignedIntegralConvertCopy1<T0, T1> &&
...);=