<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/154096>154096</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            struct A { int a; }; struct A { int a; }; is rejected by clang -std=c23
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          pascal-cuoq
      </td>
    </tr>
</table>

<pre>
    I have read https://github.com/llvm/llvm-project/issues/149965 but this seems like a different issue.

I understand that the program `struct A { int a; }; struct A { int a; };` is valid C23. GCC 15.2 accepts it with `-std=c23` and rejects it with `-std=c17`. It is rejected by Clang 20.1.0 with `-std=c23`:

```
<source>:5:8: error: redefinition of 'A'
    5 | struct A { int a; };
      |        ^
<source>:3:8: note: previous definition is here
    3 | struct A { int a; };
      |        ^
1 error generated.
Compiler returned: 1
```

CE link: https://gcc.godbolt.org/z/Ej7vzY4z5
</pre>
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