<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64357>64357</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang 16 -> 17 migration path for -pedantic -Wno-gnu-empty-initializer
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    We have a user building with `-pedantic` who has `-Wno-gnu-empty-initializer` set on their codebase.
Preflighting Clang 17 adoption, their code is failing because `-Wno-gnu-empty-initializer` no longer exists.
That's now covered under `-Wno-c2x-extensions` but this doesn't suppress that warning on Clang 16.
You can't use both flags, because `-Wno-gnu-empty-intializer` is no longer a flag in Clang 17, which means there is no combination of flags that lets you suppress this warning across adjacent clang versions.
Can we re-add this warning flag to leave a migration path that lets them continue to build with two adjacent clang versions?

Reproducer to check against:
```c
struct Example {
 int x;
};

int main(void) {
    struct Example example = {};
}
```

- Clang 16: `-Werror -pedantic -Wno-gnu-empty-intializer` - OK
- Clang 17: `-Werror -pedantic -Wno-c2x-extensions` - OK
- Clang 16: `-Werror -pedantic -Wno-c2x-extensions` - does not suppress the diagnostic, fails with `-Wgnu-empty-intializer`.
- Clang 17: `-Werror -pedantic -Wno-gnu-empty-intializer` - fails with `-Wunknown-warning-option`
</pre>
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