<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/70198>70198</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Backport 66f4a1399d7de3d38312a5b251d4f8acd75237ca to 17.x
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          AaronBallman
      </td>
    </tr>
</table>

<pre>
    This is a pretty serious issue with `thread_local` in C23 mode where it gets the C++ semantics rather than C's `_Thread_local` semantics.
</pre>
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