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<title>Issue 2755: &sect;[string.view.io] uses non-existent basic_string_view::to_string function</title>
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<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#C++17">C++17</a> status.</em></p>
<h3 id="2755"><a href="lwg-defects.html#2755">2755</a>. &sect;[string.view.io] uses non-existent <code>basic_string_view::to_string</code> function</h3>
<p><b>Section:</b> 27.3.5 <a href="https://wg21.link/string.view.io">[string.view.io]</a>, 27.4.4.4 <a href="https://wg21.link/string.io">[string.io]</a> <b>Status:</b> <a href="lwg-active.html#C++17">C++17</a>
 <b>Submitter:</b> Billy Baker <b>Opened:</b> 2016-07-26 <b>Last modified:</b> 2020-09-06</p>
<p><b>Priority: </b>0
</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++17">C++17</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In looking at N4606, [string.view.io] has an <i>Effects</i> clause that references <code>basic_string_view::to_string</code> 
which no longer exists after the application of <a href="https://wg21.link/p0254r2">P0254R2</a>.
</p>

<p><i>[2016-07-26, Marshall suggests concrete wording]</i></p>

<p><i>[2016-07 Chicago LWG]</i></p>

<p>Monday: P0 - tentatively ready</p>


<p id="res-2755"><b>Proposed resolution:</b></p>
<p>This wording is relative to N4606.</p>

<ol>
<li><p>Modify 27.4.4.4 <a href="https://wg21.link/string.io">[string.io]</a> as indicated:</p>

<blockquote>
<pre>
template&lt;class charT, class traits, class Allocator&gt;
  basic_ostream&lt;charT, traits&gt;&amp;
    operator&lt;&lt;(basic_ostream&lt;charT, traits&gt;&amp; os,
               const basic_string&lt;charT, traits, Allocator&gt;&amp; str);
</pre>
<blockquote>
<p>
-5- <i>Effects:</i> <ins>Equivalent to: <code>return os &lt;&lt; basic_string_view&lt;charT, 
traits&gt;(str);</code></ins><del>Behaves as a formatted output function (31.7.6.3.1 <a href="https://wg21.link/ostream.formatted.reqmts">[ostream.formatted.reqmts]</a>) 
of <code>os</code>. Forms a character sequence <code>seq</code>, initially consisting of the elements defined by the 
range <code>[str.begin(), str.end())</code>. Determines padding for <code>seq</code> as described in 
31.7.6.3.1 <a href="https://wg21.link/ostream.formatted.reqmts">[ostream.formatted.reqmts]</a>. Then inserts <code>seq</code> as if by calling <code>os.rdbuf()-&gt;sputn(seq, n)</code>, 
where <code>n</code> is the larger of <code>os.width()</code> and <code>str.size()</code>; then calls <code>os.width(0)</code>.</del>
<p/>
<del>-6- <i>Returns:</i> <code>os</code></del>
</p>
</blockquote>
</blockquote>
</li>

<li><p>Modify 27.3.5 <a href="https://wg21.link/string.view.io">[string.view.io]</a> as indicated:</p>

<blockquote>
<pre>
template&lt;class charT, class traits&gt;
  basic_ostream&lt;charT, traits&gt;&amp;
    operator&lt;&lt;(basic_ostream&lt;charT, traits&gt;&amp; os,
               basic_string_view&lt;charT, traits&gt; str);
</pre>
<blockquote>
<p>
-1- <i>Effects:</i> <del>Equivalent to: <code>return os &lt;&lt; str.to_string();</code></del><ins>Behaves 
as a formatted output function (31.7.6.3.1 <a href="https://wg21.link/ostream.formatted.reqmts">[ostream.formatted.reqmts]</a>) of <code>os</code>. Forms a character 
sequence <code>seq</code>, initially consisting of the elements defined by the range <code>[str.begin(), 
str.end())</code>. Determines padding for <code>seq</code> as described in 31.7.6.3.1 <a href="https://wg21.link/ostream.formatted.reqmts">[ostream.formatted.reqmts]</a>. Then 
inserts <code>seq</code> as if by calling <code>os.rdbuf()-&gt;sputn(seq, n)</code>, where <code>n</code> is the larger of 
<code>os.width()</code> and <code>str.size()</code>; then calls <code>os.width(0)</code>.</ins>
<p/>
<ins>-?- <i>Returns:</i> <code>os</code></ins>
</p>
</blockquote>
</blockquote>
</li>
</ol>





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