<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/58406>58406</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            no warning for unused std::error_code
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Trass3r
      </td>
    </tr>
</table>

<pre>
    ```cpp
#include <system_error>
void foo()
{
    std::error_code ec;
}
```
The code does get optimized away as system_category() is [[gnu::const]] but there is no -Wunused warning.

https://godbolt.org/z/M68ToY78b
</pre>
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