<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/56159>56159</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            -Wreserved-macro-identifier does not catch command line macros
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            good first issue,
            clang:frontend,
            clang:diagnostics
      </td>
    </tr>

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

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

<pre>
    If you define or undefine a reserved macro name within the TU, we properly diagnose it. But if you define or undefine a macro using the command line, we do not issue any diagnostics. I think the command line should be treated the same as within a TU.

Live example: https://godbolt.org/z/3edqooWr9
</pre>
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