<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/96824>96824</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang-tidy header filters should allow for case insensitive comparisons
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang-tidy
      </td>
    </tr>

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

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

<pre>
    clang-tidy header filters should allow for case insensitive comparisons. This is specially important on large Windows projects where the OS is case insensitive and there is a lot of legacy mixing casing.
More specifically I am referring to `--exclude-header-filter`, `--header-filter`, `ExcludeHeaderFilterRegex`, `HeaderFilterRegex`.

The docs say [`By default, the POSIX extended regular expression (ERE) syntax is assumed.`](https://llvm.org/doxygen/classllvm_1_1Regex.html#a79ae71c4eeaf1d835aa4106155fa2aaeae62480697e924b5793194a07ac798df4:~:text=by%20default%2C%20the%20posix%20extended%20regular%20expression%20(ere)%20syntax%20is%20assumed.). AFAICT ERE does not support modifiers on the regex itself ie `(?i)`.
</pre>
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