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<title>Issue 1005: numeric_limits partial specializations not concept enabled</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_Concepts">NAD Concepts</a> status.</em></p>
<h3 id="1005"><a href="lwg-closed.html#1005">1005</a>. <code>numeric_limits</code> partial specializations not concept enabled</h3>
<p><b>Section:</b> 17.3.5 <a href="https://wg21.link/numeric.limits">[numeric.limits]</a> <b>Status:</b> <a href="lwg-active.html#NAD_Concepts">NAD Concepts</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2009-03-11 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#numeric.limits">active issues</a> in [numeric.limits].</p>
<p><b>View all other</b> <a href="lwg-index.html#numeric.limits">issues</a> in [numeric.limits].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD Concepts">NAD Concepts</a> status.</p>
<p><b>Discussion:</b></p>

<p><b>Addresses JP 26</b></p>

<p>
<code>numeric_limits</code> [partial specializations] does not use concept.
</p>

<p><i>[
Summit:
]</i></p>


<blockquote><p>
Alisdair will provide a solution as part of treatment of axioms and LWG <a href="lwg-closed.html#902" title="Regular is the wrong concept to constrain numeric_limits (Status: NAD Concepts)">902</a><sup><a href="https://cplusplus.github.io/LWG/issue902" title="Latest snapshot">(i)</a></sup>.
</p></blockquote>

<p><i>[
Post Summit:
]</i></p>


<blockquote><p>
Alisdair recommends NAD as the partial specializations are already
constrained by requirements on the primary template.
</p></blockquote>

<p><i>[
Batavia (2009-05):
]</i></p>

<blockquote><p>
The Working Draft does not in general repeat a primary template's constraints
in any specializations.
Move to NAD.
</p></blockquote>

<p><i>[
2009-05-25 Howard adds:
]</i></p>


<blockquote><p>
A c++std-lib thread starting at c++std-lib-23880 has cast doubt that NAD is the
correct resolution of this issue.  Indeed the discussion also casts doubt that
the current proposed wording is the correct resolution as well.  Personally I'm
inclined to reset the status to Open.  However I'm reverting the status to 
that which it had prior to the Batavia recommendation.  I'm setting back to Review.
</p></blockquote>


<p id="res-1005"><b>Proposed resolution:</b></p>
<p>
Change 17.3.5 <a href="https://wg21.link/numeric.limits">[numeric.limits]</a>:
</p>

<blockquote><pre>
template&lt;<del>class</del> <ins>Regular</ins> T&gt; class numeric_limits&lt;const T&gt;;
template&lt;<del>class</del> <ins>Regular</ins> T&gt; class numeric_limits&lt;volatile T&gt;;
template&lt;<del>class</del> <ins>Regular</ins> T&gt; class numeric_limits&lt;const volatile T&gt;;
</pre></blockquote>






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