<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Issue 592: Incorrect treatment of rdbuf()->close() return type</title>
<meta property="og:title" content="Issue 592: Incorrect treatment of rdbuf()->close() return type">
<meta property="og:description" content="C++ library issue. Status: NAD Editorial">
<meta property="og:url" content="https://cplusplus.github.io/LWG/issue592.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#NAD_Editorial">NAD Editorial</a> status.</em></p>
<h3 id="592"><a href="lwg-closed.html#592">592</a>. Incorrect treatment of rdbuf()->close() return type</h3>
<p><b>Section:</b> 31.10.4.4 <a href="https://wg21.link/ifstream.members">[ifstream.members]</a> <b>Status:</b> <a href="lwg-active.html#NAD_Editorial">NAD Editorial</a>
 <b>Submitter:</b> Christopher Kohlhoff <b>Opened:</b> 2006-08-17 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#ifstream.members">issues</a> in [ifstream.members].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD Editorial">NAD Editorial</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I just spotted a minor problem in 27.8.1.7
[lib.ifstream.members] para 4 and also 27.8.1.13
[lib.fstream.members] para 4. In both places it says:
</p>
<blockquote>
<pre>
void close();
</pre>
<p>
Effects: Calls rdbuf()-&gt;close() and, if that function returns false, ...
</p>
</blockquote>
<p>
However, basic_filebuf::close() (27.8.1.2) returns a pointer to the
filebuf on success, null on failure, so I think it is meant to
say "if that function returns a null pointer". Oddly, it is
correct for basic_ofstream.
</p>


<p id="res-592"><b>Proposed resolution:</b></p>
<p>
Change 31.10.4.4 <a href="https://wg21.link/ifstream.members">[ifstream.members]</a>, p5:
</p>

<blockquote><p>
<i>Effects:</i> Calls <code>rdbuf()-&gt;close()</code> and, if that function
<ins>fails (</ins>returns <del><code>false</code></del> <ins>a null pointer)</ins>,
calls <code>setstate(failbit)</code> (which may throw <code>ios_base::failure</code>
(27.4.4.3)).
</p></blockquote>

<p>
Change 31.10.6.4 <a href="https://wg21.link/fstream.members">[fstream.members]</a>, p5:
</p>

<blockquote><p>
<i>Effects:</i> Calls <code>rdbuf()-&gt;close()</code> and, if that function
<ins>fails (</ins>returns <del><code>false</code></del> <ins>a null pointer)</ins>,
calls <code>setstate(failbit)</code> (which may throw <code>ios_base::failure</code>
(27.4.4.3)).
</p></blockquote>



<p><i>[
Kona (2007): Proposed Disposition: NAD, Editorial
]</i></p>





</body>
</html>
