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 DD992386F444; Mon, 26 Oct 2020 10:03:09 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DD992386F444
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/97569] Declaring a struct in a field declaration of another
 struct. gcc and clang difference.
Date: Mon, 26 Oct 2020 10:03:09 +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: accepts-invalid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
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-97569-4-Flbf5QUc3m@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-97569-4@http.gcc.gnu.org/bugzilla/>
References: <bug-97569-4@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, 26 Oct 2020 10:03:10 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97569

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ah right, so

  int main()
  {
      struct A
      {
        struct B *b;
        struct C {} *c;
      };

      using U =3D B;
      using V =3D C;=20=20=20
  }

For the `struct C {}` case that explicitly defines (and declares) a new str=
uct
in the scope of A, i.e. A::C, and so it's definitely correct that it isn't
declared in the enclosing block scope. That case is substantially different,
and all compilers agree on that.

For `struct B *b` the standard says that implicitly declares a new type, but
not as a member of A. [basic.scope.pdecl] p7 (7.2) says that the the identi=
fier
B "is declared in the smallest namespace or block scope that contains the
declaration." And that's the block scope of main. So I think GCC is correct,
and Clang is wrong. EDG agrees with GCC FWIW.=