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 BD4453835831; Sun,  9 Jan 2022 09:10:42 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org BD4453835831
From: "slyfox at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/103891] clang-13 fails to compile libstdc++'s
 std::variant<std::vector<int>>: error: attempt to use a deleted function
Date: Sun, 09 Jan 2022 09:10:42 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: slyfox at gcc dot gnu.org
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: MOVED
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-103891-4-N0T5SMthsw@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-103891-4@http.gcc.gnu.org/bugzilla/>
References: <bug-103891-4@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: Sun, 09 Jan 2022 09:10:42 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103891

--- Comment #5 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #4)
> I suppose we could just do:
>=20
> --- a/libstdc++-v3/include/std/variant
> +++ b/libstdc++-v3/include/std/variant
> @@ -54,7 +54,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
>  {
>  _GLIBCXX_BEGIN_NAMESPACE_VERSION
>=20=20
> -#if __cplusplus >=3D 202002L && __cpp_concepts
> +#if __cplusplus >=3D 202002L && __cpp_concepts && __GNUC__ >=3D 12
>  // P2231R1 constexpr needs constexpr unions and constrained destructors.
>  # define __cpp_lib_variant 202106L
>  #else
>=20
> And then improve it later if GCC updates __cpp_concepts

That almost works:

In file included from bug.cc:12:
stdc++-include/c++/12.0.0/variant:300:18: error: no template named
'__aligned_membuf' in namespace '__gnu_cxx'
      __gnu_cxx::__aligned_membuf<_Type> _M_storage;
      ~~~~~~~~~~~^

On clang it also needs `#include <ext/aligned_buffer.h>` as well.=