<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/83080>83080</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libunwind] Wrong default for LIBUNWIND_ENABLE_FRAME_APIS?
        </td>
    </tr>

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

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

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

<pre>
    In short - I recently hit the following issue with >=libunwind-18.1.0_rc1 on Gentoo:
_Anything_ using libunwind started failing with `/usr/lib64/libc++abi.so.1: undefined symbol: __deregister_frame_info`.
For more info the downstream bugreport is [here](https://bugs.gentoo.org/925024).

Eventually I tracked it down to the newly introduced `LIBUNWIND_ENABLE_FRAME_APIS` defaulting to `OFF` (https://github.com/llvm/llvm-project/commit/5eb44df1b64dbd1a86b099128092a7fd2001c0ba).

What confuses me is that the commit message clearly says:
> Default this to on, so as not to remove the apis from
> environments that already have them.

but the actual option defaults to `OFF`.

(Downstream said to CC author @Sterling-Augustine and reviewer @MaskRay)
</pre>
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