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 4E7E53858D20; Tue,  5 Mar 2024 15:11:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4E7E53858D20
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1709651506;
	bh=z87hBW9tCa/Sw9eJkRlAQb9HohOZXFSvnyFD4fGGngw=;
	h=From:To:Subject:Date:From;
	b=GqbeyfljbNeaty+NNxQ6eLk1XJ2XJSAw27+1mzk8Ee8CbMVrQvmhWu0gb9d601zBR
	 kQJIr70zVoXZkX3On4NzVl2fS72jgfWWCOTX9wOmyHjn19xfXu5IVZYKjug8FB6woq
	 qycoHRzxlqjfHwvg6zdeYvMz7mdtcdmS7d4mA9H8=
From: "howard.hinnant at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/114240] New: sys_days not being parsed with only a
 date in the stream
Date: Tue, 05 Mar 2024 15:11:45 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: howard.hinnant 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-114240-4@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=3D114240

            Bug ID: 114240
           Summary: sys_days not being parsed with only a date in the
                    stream
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: howard.hinnant at gmail dot com
  Target Milestone: ---

#include <chrono>
#include <iostream>
#include <sstream>

int main(int argc, char**argv){

    std::istringstream ssStart{"2024-01-01"};
    std::istringstream ssEnd("2024-02-01");
    ssStart.exceptions(std::ios::failbit);

    std::chrono::sys_days tStart, tEnd;
    ssStart >> std::chrono::parse("%Y-%m-%d ", tStart);
    ssEnd >> std::chrono::parse("%Y-%m-%d ", tEnd);

    auto tDays =3D tEnd-tStart;
    std::cout << ssStart.str() << "," << ssEnd.str() << "," << tDays.count(=
) <<
std::endl;
}

Expected output:

2024-01-01,2024-02-01,31

Actual output:

terminate called after throwing an instance of 'std::__ios_failure'
  what():  basic_ios::clear: iostream error

I expected this function: http://eel.is/c++draft/time.clock.system.nonmembe=
rs#6
to successfully parse the days-precision time_point because there is suffic=
ient
information in the stream to form a valid date.

Demo: https://wandbox.org/permlink/FrtMteIddnb4ogpZ=