<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Issue 75: Contradiction in codecvt::length's argument types</title>
<meta property="og:title" content="Issue 75: Contradiction in codecvt::length's argument types">
<meta property="og:description" content="C++ library issue. Status: TC1">
<meta property="og:url" content="https://cplusplus.github.io/LWG/issue75.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#TC1">TC1</a> status.</em></p>
<h3 id="75"><a href="lwg-defects.html#75">75</a>. Contradiction in <code>codecvt::length</code>'s argument types</h3>
<p><b>Section:</b> 28.3.4.2.5 <a href="https://wg21.link/locale.codecvt">[locale.codecvt]</a> <b>Status:</b> <a href="lwg-active.html#TC1">TC1</a>
 <b>Submitter:</b>  Matt Austern <b>Opened:</b> 1998-09-18 <b>Last modified:</b> 2023-03-29</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#locale.codecvt">issues</a> in [locale.codecvt].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#TC1">TC1</a> status.</p>
<p><b>Discussion:</b></p>
<p>The class synopses for classes <code>codecvt&lt;&gt;</code> (22.2.1.5)
and <code>codecvt_byname&lt;&gt;</code> (22.2.1.6) say that the first
parameter of the member functions <code>length</code> and
<code>do_length</code> is of type <code>const stateT&amp;</code>. The member
function descriptions, however (22.2.1.5.1, paragraph 6; 22.2.1.5.2,
paragraph 9) say that the type is <code>stateT&amp;</code>.  Either the
synopsis or the summary must be changed. </p>

<p>If (as I believe) the member function descriptions are correct,
then we must also add text saying how <code>do_length</code> changes its
<code>stateT</code> argument. </p>


<p id="res-75"><b>Proposed resolution:</b></p>
<p>In 28.3.4.2.5 <a href="https://wg21.link/locale.codecvt">[locale.codecvt]</a>, and also in 28.3.4.2.6 <a href="https://wg21.link/locale.codecvt.byname">[locale.codecvt.byname]</a>,
change the <code>stateT</code> argument type on both member
<code>length()</code> and member <code>do_length()</code> from </p>

<blockquote>
  <p><code>const stateT&amp;</code></p>
</blockquote>

<p>to</p>

<blockquote>
  <p><code>stateT&amp;</code></p>
</blockquote>

<p>In 28.3.4.2.5.3 <a href="https://wg21.link/locale.codecvt.virtuals">[locale.codecvt.virtuals]</a>, add to the definition for member
<code>do_length</code> a paragraph:</p>

<blockquote>
  <p>Effects: The effect on the <code>state</code> argument is ``as if''
  it called <code>do_in(state, from, from_end, from, to, to+max,
  to)</code> for <code>to</code> pointing to a buffer of at least
  <code>max</code> elements.</p>
</blockquote>




</body>
</html>
