<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Issue 2512: Y2K bites; what is an "unambiguous year identifier"?</title>
<meta property="og:title" content="Issue 2512: Y2K bites; what is an &quot;unambiguous year identifier&quot;?">
<meta property="og:description" content="C++ library issue. Status: Open">
<meta property="og:url" content="https://cplusplus.github.io/LWG/issue2512.html">
<meta property="og:type" content="website">
<meta property="og:image" content="http://cplusplus.github.io/LWG/images/cpp_logo.png">
<meta property="og:image:alt" content="C++ logo">
<style>
  p {text-align:justify}
  li {text-align:justify}
  pre code.backtick::before { content: "`" }
  pre code.backtick::after { content: "`" }
  blockquote.note
  {
    background-color:#E0E0E0;
    padding-left: 15px;
    padding-right: 15px;
    padding-top: 1px;
    padding-bottom: 1px;
  }
  ins {background-color:#A0FFA0}
  del {background-color:#FFA0A0}
  table.issues-index { border: 1px solid; border-collapse: collapse; }
  table.issues-index th { text-align: center; padding: 4px; border: 1px solid; }
  table.issues-index td { padding: 4px; border: 1px solid; }
  table.issues-index td:nth-child(1) { text-align: right; }
  table.issues-index td:nth-child(2) { text-align: left; }
  table.issues-index td:nth-child(3) { text-align: left; }
  table.issues-index td:nth-child(4) { text-align: left; }
  table.issues-index td:nth-child(5) { text-align: center; }
  table.issues-index td:nth-child(6) { text-align: center; }
  table.issues-index td:nth-child(7) { text-align: left; }
  table.issues-index td:nth-child(5) span.no-pr { color: red; }
  @media (prefers-color-scheme: dark) {
     html {
        color: #ddd;
        background-color: black;
     }
     ins {
        background-color: #225522
     }
     del {
        background-color: #662222
     }
     a {
        color: #6af
     }
     a:visited {
        color: #6af
     }
     blockquote.note
     {
        background-color: rgba(255, 255, 255, .10)
     }
  }
</style>
</head>
<body>
<hr>
<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#Open">Open</a> status.</em></p>
<h3 id="2512"><a href="lwg-active.html#2512">2512</a>. Y2K bites; what is an "unambiguous year identifier"?</h3>
<p><b>Section:</b> 28.3.4.6.2.3 <a href="https://wg21.link/locale.time.get.virtuals">[locale.time.get.virtuals]</a> <b>Status:</b> <a href="lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Hubert Tong <b>Opened:</b> 2015-06-19 <b>Last modified:</b> 2017-09-07</p>
<p><b>Priority: </b>4
</p>
<p><b>View other</b> <a href="lwg-index-open.html#locale.time.get.virtuals">active issues</a> in [locale.time.get.virtuals].</p>
<p><b>View all other</b> <a href="lwg-index.html#locale.time.get.virtuals">issues</a> in [locale.time.get.virtuals].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I recently encountered a failure related to questionable use of <code>do_get_year</code>. The platform where the code happened 
to work had an implementation which handled certain three-digit "year identifiers" as the number of years since 
1900 (<a href="http://www.drdobbs.com/cpp/remembering-y2k/228701726">this article</a> describes such an implementation).
<p/>
28.3.4.6.2.3 <a href="https://wg21.link/locale.time.get.virtuals">[locale.time.get.virtuals]</a> makes it implementation defined whether two-digit years are accepted, etc., but does not 
say anything specifically about three-digit years.
<p/>
The implementation freedom to not report errors in 28.3.4.6.2 <a href="https://wg21.link/locale.time.get">[locale.time.get]</a> paragraph 1 also seems to be too broad.
<p/>
See also the discussion following <a href="http://listarchives.isocpp.org/cgi-bin/wg21/message?wg=lib&amp;msg=38042">c++std-lib-38042</a>.
</p>

<p><i>[2016-08 Chicago]</i></p>

<p>Wed PM: This has been this way since C++98. Don't think it's a P2.</p>
<p>Change to P4, and move to Open.</p>


<p id="res-2512"><b>Proposed resolution:</b></p>





</body>
</html>
