<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/58655>58655</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-format] Add an option to ignore unknown format options.
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          H-G-Hristov
      </td>
    </tr>
</table>

<pre>
    When using a newer `clang-format` format options in a `.clang-format` configuration with an older `clang-format` an error will be reported which in my case breaks my build system.
I can use the CLI option `--Wno-error=unknown` to turn the error to warnings but I need to also add code to ignore them: 

>  --Wno-error=<value>            - If set don't error out on the specified warning type.
    =unknown                     -   If set, unknown format options are only warned about.

I propose a CLI option to completely ignore any unknown format options something like `--Wno-error=ignore-unknown`.
</pre>
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