<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/121429>121429</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang accepts invalid `static_cast` from derived type to private base type in case of rvalue reference
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          wangbo15
      </td>
    </tr>
</table>

<pre>
    Clang does not report any error for the following code:

```c++
struct A { int a;};
struct X : private A{};

int main() {
    X x;
    int a=static_cast<A&&>(x).a;
}
```

Please note that this can be correctly rejected if the target type is not a rvalue reference.

GCC, EDG, and MSVC reject it:

```c++
<source>: In function 'int main()':
<source>:6:29: error: 'A' is an inaccessible base of 'X'
    6 |     int a=static_cast<A&&>(x).a;
      |  
```

Please see https://godbolt.org/z/aW1s6a7ec
</pre>
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