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<title>Issue 2373: Make new entities and names in namespace std conforming extensions</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#NAD">NAD</a> status.</em></p>
<h3 id="2373"><a href="lwg-closed.html#2373">2373</a>. Make new entities and names in namespace <code>std</code> conforming extensions</h3>
<p><b>Section:</b> 16.4.6 <a href="https://wg21.link/conforming">[conforming]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Chandler Carruth <b>Opened:</b> 2014-03-22 <b>Last modified:</b> 2015-05-22</p>
<p><b>Priority: </b>3
</p>
<p><b>View all other</b> <a href="lwg-index.html#conforming">issues</a> in [conforming].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Technically, right now, it is not a conforming extension to add a new function to namespace <code>std</code>. Doing so could cause 
unqualified lookup on the name of that function in the presence of a using directive to find a different function. This seems 
an unreasonable restriction on library vendors providing conforming extensions, as such a using directive seems inherently risky 
in unqualified name lookup.
</p>
<p>
16.4.6.5 <a href="https://wg21.link/member.functions">[member.functions]</a> implies that adding overloads to a method <em>is</em> a conforming extension, and within some 
limits the same is true for global functions due to 16.4.6.4 <a href="https://wg21.link/global.functions">[global.functions]</a>.
<p/>
It would likely be useful to specify that other new entities are valid conforming extensions, or preclude them where they pose 
serious compatibility problems.
</p>

<p><i>[Lenexa 2015-05-06: Move to NAD]</i></p>

<p>JY: It's a design question, move to LEWG?</p>
<p>AM: NAD: extensions led to us being unable to use the names hash_map, leading to unordered_map etc. Will result in collisions between members.</p>
<p>MC: Agrees, implementations that extend std:: must use __ugly_names for this reason.</p>
<p>JY: I would not oppose NAD.</p>
<p>Move to NAD, consensus.</p>



<p id="res-2373"><b>Proposed resolution:</b></p>





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