<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/136800>136800</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc++] Should we backport `hash<nullptr_t>` and conditionally enabled `hash` from P0513R0?
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            question,
            libc++,
            lwg-issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          frederick-vs-ja
      </td>
    </tr>
</table>

<pre>
    [P0513R0](https://wg21.link/p0513r0) resolved [LWG2543](https://cplusplus.github.io/LWG/issue2543), [LWG2791](https://cplusplus.github.io/LWG/issue2791), [LWG2809](https://cplusplus.github.io/LWG/issue2809), and [LWG2817](https://cplusplus.github.io/LWG/issue2817). Among these LWG issues, LWG2543 (`hash<nullptr_t>`) and LWG2817 (conditionally enabled `hash`, affecting `hash<unique_ptr>`) affects pre-C++17 utilities.

Currently there's implementation divergence:
- libc++ doesn't backport LWG2543 or LWG2817.
- libstdc++ backports LWG2817 but not LWG2543.
- MSVC STL backports both LWG2543 or LWG2817.

Should we backport LWG2543 and/or LWG2817?
</pre>
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