<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/119223>119223</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Class template constraint failure not explained if encountered through deduction guide
        </td>
    </tr>

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

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

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

<pre>
    If a class template instantiation fails due to constraint satisfaction, clang normally prints a note saying what constraint(s) were unsatisfied.

However, if the instantiation occurs as part of attempting to match a deduction guide, this note is omitted, making it hard to tell what failed.

Sample case: https://godbolt.org/z/75dM3PEoK
</pre>
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