<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/121334>121334</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang allows for multiple declarations introduced by `using enum`
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Rush10233
      </td>
    </tr>
</table>

<pre>
    The following code is accepted by clang under `-std=c++20`:

```c++
struct S2 {
  enum B {
    A
  };
  using enum B ;
};
```

MSVC and GCC choose to reject it as there would be a name conflict:

```c++
<source>:5:16: error: 'using S2::B::A' conflicts with a previous declaration
    5 | using enum B ;
      |                ^
<source>:3:5: note: previous declaration 'S2::B S2::A'
    3 |     A
      |     ^
```

While the `using enum B` statement here actually seems to be meaningless, I'm not quite sure whether this should be rejected or not.

https://godbolt.org/z/3e3aGxnWW
</pre>
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