<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/74214>74214</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc++][test] User-defined `std::ctype<Char>` specialization lacks `tolower()`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++
      </td>
    </tr>

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

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

<pre>
    Found while running libc++'s test suite with MSVC's STL.

The following code is non-conforming:

https://github.com/llvm/llvm-project/blob/7ec4f6094e54911794c142b5d88496a220d807d6/libcxx/test/std/localization/locale.categories/category.numeric/locale.num.get/user_defined_char_type.pass.cpp#L76-L86

This specialization doesn't meet all of the Standard's requirements for `std::ctype` because it's missing a bunch of stuff. In particular, it's missing a `tolower()` member function, which is what MSVC's STL wants.
</pre>
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