<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/143454>143454</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc][errno] Deprecate `LIBC_ERRNO_MODE_SYSTEM` in favor of `LIBC_ERRNO_MODE_SYSTEM_INLINE`.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc
      </td>
    </tr>

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

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

<pre>
    In `LIBC_ERRNO_MODE_SYSTEM`, we still create a temporary global object `libc_errno` and then point it to the system libc `errno`.  To use system libc `errno`, it would be more efficient to make `libc_errno` a macro defined as `errno`, just as `LIBC_ERRNO_MODE_SYSTEM_INLINE`.  It also allow us to skip linking against `libc.src.errno.errno` target.
</pre>
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