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 83F5C3858C52; Fri,  5 May 2023 18:54:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 83F5C3858C52
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1683312883;
	bh=aFgR2dQ7cyMDebhS0TAnqEVcBYc5kQZvYlIM8UKxGHw=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=Yzg214sumXBzz6MM2uxyfv9G6pvs0X0xIp49GL4lqx15qgZZa85mGEpYh77fSoXIZ
	 o2q/HnNLWe4NCCjAqfbKbO1PNapF66fk+HmRGhOGn4it1sS7i0DMHPeQjqcAeS+4sH
	 U0Wl7NJBwYHVDb0QuJjq0BoCc050OcOsbDhPvGIo=
From: "ldalessandro at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109751] boost iterator_interface fails concept check
 starting in gcc-13
Date: Fri, 05 May 2023 18:54:43 +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: unknown
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ldalessandro 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-109751-4-fhodq3WCAc@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109751-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109751-4@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
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109751

--- Comment #8 from Luke Dalessandro <ldalessandro at gmail dot com> ---
(In reply to Andrew Pinski from comment #7)
> I think the error message is correct.
>=20
> In the original code we have:
> ```
> ...
>   template<typename _Iter>
>     concept incrementable =3D regular<_Iter> && requires(_Iter __i) { { _=
_i++
> } -> same_as<_Iter>; };
> ...
>=20
> namespace boost { namespace stl_interfaces { inline namespace v2 {
>     template<      typename D,      typename IteratorConcept,     typename
> DifferenceType>
>     struct iterator_interface
>     {
>       friend constexpr bool operator>=3D(D lhs, D rhs)
>         requires std::equality_comparable<D> {        }
>     };
> ...
>=20
> template<typename T>
> struct iterator : boost::stl_interfaces::iterator_interface<iterator<T>,
> std::forward_iterator_tag, T>
> {
>     bool operator=3D=3D(iterator) const;
> };
>=20
> ```
> iterator<T> is not complete until after the instantiation is finished but=
 we
> have a std::equality_comparable which does the confusion

Right.

I was sort of surprised that that boost code could get away with a requires=
 on
any of those CRTP functions where it uses the CRTP "D" type, but I tested
gcc-12 and all the clangs, and nvc++, and msvc 19, and gcc-13 was the only =
one
reporting problems here, so I went with consensus.=