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 495DA3858C35; Sun,  3 Dec 2023 20:54:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 495DA3858C35
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1701636886;
	bh=AomGokalGxkI8UMGeXaJzlnRCJbr1HTTD0zqkn1M7W8=;
	h=From:To:Subject:Date:From;
	b=c5YigDdr8S7dbFUtGY6yprTCIezEenaELtLHl8JR4ldAJ5Hsa3d7RYoqoyiLC3G8+
	 mH4m6adDXF4uAQcsQXXKn2Bq+fAy2pr3ieBh1G57z+LCtLahdKLtZ41BIStwOp4qg0
	 T62zWKj40TYwB7w7ZUKmp+nAGWGgicgamIWaw0sM=
From: "luigighiron at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/112839] New: Unable to default initialize member variable
 in specific circumstances
Date: Sun, 03 Dec 2023 20:54:45 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: luigighiron 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: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-112839-4@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=3D112839

            Bug ID: 112839
           Summary: Unable to default initialize member variable in
                    specific circumstances
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: luigighiron at gmail dot com
  Target Milestone: ---

The following code is not accepted by GCC:

struct A {
    struct B {
        int C =3D 0;
    };
    A() =3D default;
    A(int) {}
    std::pair<B, B> p;
};

The error message generated indicates that it was unable to find a construc=
tor
to call in the constructor A(int).

Doing any of the following seems to remove the error:
1. Removing the constructor A()
2. Explicitly define the constructor A()
3. Defining a default constructor for B (that isn't defaulted)
4. Removing the default value from C
5. Initializing p when it is being declared, i.e. std::pair<B, B> p{};
6. Defining B outside of the class
7. Using a non-default constructor in the member initializer list

Clang, MSVC, and old versions of GCC (version 8, version 5, and version 4)
accept this code.=