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<title>Issue 2322: Associative(initializer_list, stuff) constructors are underspecified</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++14">C++14</a> status.</em></p>
<h3 id="2322"><a href="lwg-defects.html#2322">2322</a>. Associative(<code>initializer_list</code>, stuff) constructors are underspecified</h3>
<p><b>Section:</b> 23.2.7 <a href="https://wg21.link/associative.reqmts">[associative.reqmts]</a>, 23.2.8 <a href="https://wg21.link/unord.req">[unord.req]</a> <b>Status:</b> <a href="lwg-active.html#C++14">C++14</a>
 <b>Submitter:</b> Stephan T. Lavavej <b>Opened:</b> 2013-09-21 <b>Last modified:</b> 2017-07-05</p>
<p><b>Priority: </b>0
</p>
<p><b>View other</b> <a href="lwg-index-open.html#associative.reqmts">active issues</a> in [associative.reqmts].</p>
<p><b>View all other</b> <a href="lwg-index.html#associative.reqmts">issues</a> in [associative.reqmts].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++14">C++14</a> status.</p>
<p><b>Discussion:</b></p>
<p>
23.2.7 <a href="https://wg21.link/associative.reqmts">[associative.reqmts]</a> specifies both <code>X(i,j)</code> and <code>X(i,j,c)</code>, but only <code>X(il)</code>.  
23.4.3.1 <a href="https://wg21.link/map.overview">[map.overview]</a> declares "<code>map(initializer_list&lt;value_type&gt;, const Compare&amp; = Compare(), 
const Allocator&amp; = Allocator());</code>" but 23.4.3.2 <a href="https://wg21.link/map.cons">[map.cons]</a> intentionally doesn't explain it, relying 
on the big table's requirements. As a result, <code>map(il, c)</code>'s behavior is not actually specified by the Standard.  
(All of the other ordered associative containers also provide such constructors.)
<p/>
The unordered associative containers are similarly affected, although they have more arguments. (Again, the actual 
containers are correctly depicted with the desired constructors, their behavior just isn't specified.)
</p>

<p><i>[Issaquah 2014-02-11: Move to Immediate]</i></p>




<p id="res-2322"><b>Proposed resolution:</b></p>
<p>This wording is relative to N3691.</p>

<ol>
<li><p>Edit 23.2.7 <a href="https://wg21.link/associative.reqmts">[associative.reqmts]</a>, Table 102 &mdash; "Associative container requirements", as indicated:</p>

<blockquote>
<table border="1">
<caption>Table 102 &mdash; Associative container requirements (in addition to container) (continued)</caption>
<tr>
<th>Expression</th>
<th>Return type</th>
<th>Assertion&#47;note pre-&#47;post-condition</th>
<th>Complexity</th>
</tr>

<tr>
<td colspan="4" align="center">
<code>&hellip;</code>
</td>
</tr>

<tr>
<td>
<code>X(il);</code>
</td>
<td>
<code></code>
</td>
<td>
Same as <code>X(il.begin(), il.end())</code>.
</td>
<td>
<del>s</del><ins>S</ins>ame as <code>X(il.begin(), il.end())</code>.
</td>
</tr>

<tr>
<td>
<ins><code>X(il, c);</code></ins>
</td>
<td>
<code>&nbsp;</code>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), c)</code>.</ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), c)</code>.</ins>
</td>
</tr>

<tr>
<td colspan="4" align="center">
<code>&hellip;</code>
</td>
</tr>

</table>
</blockquote>
</li>

<li><p>Edit 23.2.8 <a href="https://wg21.link/unord.req">[unord.req]</a>, Table 103 "Unordered associative container requirements", as indicated:</p>

<blockquote>
<table border="1">
<caption>Table 103 &mdash; Unordered associative container requirements (in addition to container)</caption>
<tr>
<th>Expression</th>
<th>Return type</th>
<th>Assertion&#47;note pre-&#47;post-condition</th>
<th>Complexity</th>
</tr>

<tr>
<td colspan="4" align="center">
<code>&hellip;</code>
</td>
</tr>

<tr>
<td>
<code>X(il)</code>
</td>
<td>
<code>X</code>
</td>
<td>
Same as <code>X(il.begin(), il.end())</code>.
</td>
<td>
Same as <code>X(il.begin(), il.end())</code>.
</td>
</tr>

<tr>
<td>
<ins><code>X(il, n)</code></ins>
</td>
<td>
<ins><code>X</code></ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), n)</code>.</ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), n)</code>.</ins>
</td>
</tr>

<tr>
<td>
<ins><code>X(il, n, hf)</code></ins>
</td>
<td>
<ins><code>X</code></ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), n, hf)</code>.</ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), n, hf)</code>.</ins>
</td>
</tr>

<tr>
<td>
<ins><code>X(il, n, hf, eq)</code></ins>
</td>
<td>
<ins><code>X</code></ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), n, hf, eq)</code>.</ins>
</td>
<td>
<ins>Same as <code>X(il.begin(), il.end(), n, hf, eq)</code>.</ins>
</td>
</tr>

<tr>
<td colspan="4" align="center">
<code>&hellip;</code>
</td>
</tr>

</table>
</blockquote>

</li>

</ol>






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