<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/156694>156694</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [CI] PR Authors have no idea their PR is tested by rebasing onto main
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            infrastructure
      </td>
    </tr>

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

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

<pre>
    In https://github.com/llvm/llvm-project/pull/154814, the author got a test failure from CI that only reproduced when they rebased their changes onto the `main` of the current time. I see the reason to do it this way, it will catch surprise failures exactly like the one in this case.

Except, I might spend a few hours trying to compare more obvious things like host OS, cmake configurations, etc. before attempting to rebase. Especially as we advise against rebasing during review and who knows what changes I'd end up bringing in.

Can we leave clues somewhere in the build or testing reports to make authors aware of the situation?

Perhaps we could end the log with `Building PR #whatever when rebased onto main (at <hash>) failed.")` ? Then it will be the first thing the author sees after clicking the results link from GitHub.

@boomanaiden154 What do you think?
</pre>
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