<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJzNVE2PmzAQ_TXmMgpyzFdy4JCE7aWHHpp7ZJsBvDEY2SYr-utryG4_pGxVqaq00gAevTcz78nGwtRzGUvNh3bjVT2T5EBoReiB5PQ11vTUobx-Gb0yg_vBAdjAFZcaALDIay6UVn7eqBoHrxqFdjPwXg1tfNLcuRN3-FYJcON6wqWWsEKbF7QXueCseCjg_j5iYyy-J9JjP2ruA36Syzw4z4SdQBijgSQVfD1XoNwFh6m_3AIpwMnTEmu183aSHu6wN5eQB-VAiuPrsKIiyfH9SX_ucx8X1DRcB5fJ0-PGD10fGo_2v5r-eJ7PHYKbexFcKAe9cm4VltNLeEAN0CjrPLgRpeJafVvGLbYnv_BHiy4cwYXnUJqh_o0YR3WZ1PtkzyM--c7Y0nUWr9uUsmiyuuy8H9dTzj6FaJXvJhFL04dE69vbZzNa84zShzSom9CFRZZk2zTqyl0h0jxnWZ0JRnm930m-T4pU0K1ocsZlpLlA7UqSHQljA77A2iKsSVZF_65AlYyyEHRLU5qnLJa7DBOec1HkexSCkZRiz5WOlz6xsW1ky7WlmFoXQK2cdz_BsN2qHRBXwUGhV16vyS83R1bBZ5zD38z-9ipgDETgXh34sNvS1BitPsrVxHdx5Gd0>53514</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-tidy] Key "readability-identifier-naming.ClassCase" breaks the code
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          shrek1402
      </td>
    </tr>
</table>

<pre>
    .clang-tidy:
```
CheckOptions:
  - key:   readability-identifier-naming.ClassCase
    value: 'lower_case'
```

Before:
```
template<class Ty, bool = STD is_enum_v<Ty>>
struct _enum_to_string {
};
template<class Ty>
struct _enum_to_string<Ty, false> {
};
```

After:
```
template<class Ty, bool = STD is_enum_v<Ty>>
struct enum_to_string {
};
template<class Ty>
struct _enum_to_string<Ty, false> {
};
```

The symbol is missing `_` in first specializing, but is present in second specializing.
</pre>
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