<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/54338>54338</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Invalid macro identifiers cause weird diagnostic output
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          cor3ntin
      </td>
    </tr>
</table>

<pre>
    ```cpp
#define 🦄 &
int 🦄;```

Produces

```cpp
<source>:2:5: error: unexpected character <U+1F984>
int Unknown code<U+1F984>;
    ^~~~~~~~~
```

The **Unknowm code** in the diagnostic here is is unexpected an confusing, we'd expect the source line to be reproduced accurately
</pre>
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