<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/54623>54623</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            _Atomic structure assignment in C++ mode is broken
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            c++,
            rejects-valid,
            clang:diagnostics
      </td>
    </tr>

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

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

<pre>
    The following code should compile in C++ mode same as it compiles in C mode:
```
_Atomic struct x { int x; } x1;

int main() {
  _Atomic struct x y1 = x1; // error: cannot initialize a variable of type '_Atomic(struct x)' with an lvalue of type '_Atomic(struct x)'
  struct x y2 = x1; // error: no viable conversion from '_Atomic(struct x)' to 'struct x'
}
```
We give two different errors in C++ mode for this code but it is valid C code.

While working on this, we should also consider what the direct list initialization behavior should be:
```
_Atomic struct x { int x; } x1;

int main() {
  _Atomic struct x y3{x1}; // error: illegal initializer type '_Atomic(struct x)'
  struct x y4{x1}; // error: cannot initialize a member subobject of type 'int' with an lvalue of type '_Atomic(struct x)'
}
```
At the very least, the diagnostics for this case should be improved, but I am not certain why we would reject this code.
</pre>
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