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<title>Issue 1316: scoped_allocator_adaptor operator== has no definition</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++11">C++11</a> status.</em></p>
<h3 id="1316"><a href="lwg-defects.html#1316">1316</a>. <code>scoped_allocator_adaptor operator==</code> has no definition</h3>
<p><b>Section:</b> 20.6 <a href="https://wg21.link/allocator.adaptor">[allocator.adaptor]</a> <b>Status:</b> <a href="lwg-active.html#C++11">C++11</a>
 <b>Submitter:</b> Pablo Halpern <b>Opened:</b> 2009-02-11 <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#allocator.adaptor">issues</a> in [allocator.adaptor].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++11">C++11</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The WP 
(<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n3000.pdf">N3000</a>)
contains these declarations:
</p>

<blockquote>
<pre>template &lt;class OuterA1, class OuterA2, class... InnerAllocs&gt;
  bool operator==(const scoped_allocator_adaptor&lt;OuterA1, InnerAllocs...&gt;&amp; a,
                  const scoped_allocator_adaptor&lt;OuterA2, InnerAllocs...&gt;&amp; b);
template &lt;class OuterA1, class OuterA2, class... InnerAllocs&gt;
  bool operator!=(const scoped_allocator_adaptor&lt;OuterA1, InnerAllocs...&gt;&amp; a,
                  const scoped_allocator_adaptor&lt;OuterA2, InnerAllocs...&gt;&amp; b);</pre>
</blockquote>

<p>
But does not define what the behavior of these operators are.
</p>

<p><i>[
Post-Rapperswil:
]</i></p>


<blockquote><p>
Moved to Tentatively Ready after 5 positive votes on c++std-lib.
</p></blockquote>

<p><i>[
Adopted at 2010-11 Batavia
]</i></p>




<p id="res-1316"><b>Proposed resolution:</b></p>
<p>
Add a new section after 20.6.4 <a href="https://wg21.link/allocator.adaptor.members">[allocator.adaptor.members]</a>:
</p>

<blockquote>
<p><b>Scoped allocator operators  [scoped.adaptor.operators]</b></p>

<pre>template &lt;class OuterA1, class OuterA2, class... InnerAllocs&gt;
  bool operator==(const scoped_allocator_adaptor&lt;OuterA1, InnerAllocs...&gt;&amp; a,
                  const scoped_allocator_adaptor&lt;OuterA2, InnerAllocs...&gt;&amp; b);</pre>

<blockquote><p>
<i>Returns:</i> <code>a.outer_allocator() == b.outer_allocator()</code>
if <code>sizeof...(InnerAllocs)</code> is zero; otherwise,
<code>a.outer_allocator() == b.outer_allocator() &amp;&amp;
a.inner_allocator() == b.inner_allocator()</code>.
</p></blockquote>

<pre>template &lt;class OuterA1, class OuterA2, class... InnerAllocs&gt;
  bool operator!=(const scoped_allocator_adaptor&lt;OuterA1, InnerAllocs...&gt;&amp; a,
                  const scoped_allocator_adaptor&lt;OuterA2, InnerAllocs...&gt;&amp; b);</pre>

<blockquote><p>
<i>Returns:</i> <code>!(a == b)</code>.
</p></blockquote>

</blockquote>






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