<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64530>64530</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Explicitly default special member functions with qualifiers not always rejected
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            c++20,
            clang:frontend,
            quality-of-implementation,
            accepts-invalid
      </td>
    </tr>

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

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

<pre>
    https://github.com/llvm/llvm-project/blob/247cc265e74e25164ee7ce85e6c9c53b3d177740/clang/lib/Sema/SemaDeclCXX.cpp#L7720 is looking for `const` and `volatile` qualifiers explicitly when it really should be looking for any qualifiers on the method. For example:
```
struct R {
  R& operator=(const R&) volatile = default; // Correctly diagnosed
};

struct S {
  S& operator=(const S&) const = default;  // Correctly diagnosed
};

struct T {
  T& operator=(const T&) __restrict = default; // Silently accepted
};

struct U {
  U& operator=(const U&) _Nonnull = default; // Silently accepted
};
```
https://godbolt.org/z/7qaj77qPo
</pre>
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