<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/59741>59741</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-tidy] Support multiple casing options for readability-identifier-naming
        </td>
    </tr>

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

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

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

<pre>
    Currently, for readablity-identifier-naming, I can make one of these choices:

* require `lower_case`
* require `CamelCase`
* don't enforce any casing at all

But what I really want is _either_ `lower_case` _or_ `CamelCase`. Some names simply have to be `lower_case` due to interaction with other libraries (for instance, iterators need to have `value_type`, not `ValueType`, and metafunctions really need to have `type` not `Type`). But other than those, we'd prefer to use `CamelCase` for other types. 

Choosing to enforce one or other style leads to lots of `NOLINT` annotations. But choosing to enforce no style opens the door to names we definitely do not want to allow. Would it be possible to add support for `x|y` in addition to just either `x` or `y`?
</pre>
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