<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Issue 3499: Timed lockable and mutex requirements are imprecise about duration and time_point</title>
<meta property="og:title" content="Issue 3499: Timed lockable and mutex requirements are imprecise about duration and time_point">
<meta property="og:description" content="C++ library issue. Status: New">
<meta property="og:url" content="https://cplusplus.github.io/LWG/issue3499.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#New">New</a> status.</em></p>
<h3 id="3499"><a href="lwg-active.html#3499">3499</a>. Timed lockable and mutex requirements are imprecise about <code>duration</code> and <code>time_point</code></h3>
<p><b>Section:</b> 32.2.5.4 <a href="https://wg21.link/thread.req.lockable.timed">[thread.req.lockable.timed]</a>, 32.6.4.3 <a href="https://wg21.link/thread.timedmutex.requirements">[thread.timedmutex.requirements]</a> <b>Status:</b> <a href="lwg-active.html#New">New</a>
 <b>Submitter:</b> Tim Song <b>Opened:</b> 2020-11-14 <b>Last modified:</b> 2020-11-21</p>
<p><b>Priority: </b>3
</p>
<p><b>View all issues with</b> <a href="lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The timed lockable and mutex requirements currently use "<code>rel_time</code> denotes an object of an 
instantiation of duration, and <code>abs_time</code> denotes an object of an instantiation of <code>time_point</code>" 
to define the variables used to specify the timed lock functions. During LWG review of 
<a href="https://wg21.link/p2160r0">P2160R0</a>, it was noted that this definition is deficient in two
aspects:
</p>
<ul>
<li><p>It doesn't allow for <i>cv</i>-qualification of <code>rel_time</code> and <code>abs_time</code></p></li>
<li><p>For <code>time_point</code>s, it should require that the clock is a real <i>Cpp17Clock</i>. We impose 
that requirement via 32.2.1 <a href="https://wg21.link/thread.req.paramname">[thread.req.paramname]</a>, but there are no template parameters named 
<code>Clock</code> here.</p></li>
</ul>

<p><i>[2020-11-21; Reflector prioritization]</i></p>

<p>
Set priority to 3 during reflector discussions.
</p>


<p id="res-3499"><b>Proposed resolution:</b></p>





</body>
</html>
