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 ECBF43851C0F; Tue, 19 May 2020 23:30:41 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org ECBF43851C0F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1589931041;
 bh=Ux9/tVzjrDDEsTT5ocuPWB8cpjPIPBrnIuCdz1F9XgQ=;
 h=From:To:Subject:Date:From;
 b=lWWb2JMSUZSGU01L5rB/ogAIPLUx4hGmAUP3/m/bA8BUSIr1ALb96ZsGhd/NbCj8+
 bI0GvMCvHXOuyawZS0yYbgwdRpoozA6MeDeyFhq9ALoyhKZ3tD+WiFmo02IzkHL3Y9
 pBWRPyFRIPgw//ALwUUT8L6aw0FSF4RTZX2AGnII=
From: "fboranek at atlas dot cz" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95226] New: Faulty aggregate initialization of vector with
 struct with float
Date: Tue, 19 May 2020 23:30:41 +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: 8.3.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: fboranek at atlas dot cz
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-95226-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Tue, 19 May 2020 23:30:42 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95226

            Bug ID: 95226
           Summary: Faulty aggregate initialization of vector with struct
                    with float
           Product: gcc
           Version: 8.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fboranek at atlas dot cz
  Target Milestone: ---

# Steps to reproduce

//prog.cc

#include <vector>
#include <iostream>

struct T {
    uint32_t a;
    float b {.8};
};

int main()
{
    T t =3D {1};
    std::vector<T> tt =3D {{1}, {2}};

    std::cout << t.a << ", " << t.b << std::endl;
    std::cout << tt[0].a << ", " << tt[0].b << std::endl;
    std::cout << tt[1].a << ", " << tt[1].b << std::endl;
}

// g++ prog.cc -Wall -Wextra -std=3Dc++17

For gcc 9.3.0, 9.2.0, 9.1.0, 8.1.0 the behavior is correct and output of the
program is:

1, 0.8
1, 0.8
1, 0.8

For gcc 8.3.0, 8.2.0 the output of the program is:

1, 0.8
1, -1.58819e-23
1072273817, 2.8026e-45

The second object in the vector is wrongly initialized.

The code can be fixed by changing of initialization of float T::b to {.8f},=
 {0}
or {}. It seems that only initialization by double is affected.
I used wandbox.org to test diffrent version of gcc and prevous and newer
version are OK. It sound like regression in 8.3.0 and 8.2.0, but 8.3.0 is i=
n a
current stable Debian, which worried me.


# Used gcc from Debina Buster (current stable)
gcc (Debian 8.3.0-6) 8.3.0=