<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/84492>84492</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            CTAD for alias templates: implement the "is_deducible" constrain
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            c++20,
            clang:frontend
      </td>
    </tr>

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

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

<pre>
    We have an initial support at #77890 now.

However, the feature is not fully implemented yet, the `is_deducible` constrain is missing, see the FIXME at https://github.com/llvm/llvm-project/blob/main/clang/lib/Sema/SemaTemplate.cpp#L2909-L2914, and related testcase at https://github.com/llvm/llvm-project/blob/main/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp#L188-L200


</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJyskkFvnDAQhX-NuVggM4YABw6bTVErpadGam6VgWFxa2xkD0n231dmd7XtsVIvWJoZnt6b-VQI-mQRW1Y-MoDZ_UJtGQArnxK10ex8e6klvRvP7Xfks3pDrizXVpNWhodtXZ0nrogzkFVVN4Jb954x8cTE4fL97N7xDT2DI6cZ-YSKNo9cB24d8Wkz5sz1shpc0BKO_Ix0m2UPQocfI47boHuD7EHwwdlAXmkbBRYdgranOB4Q91-6L69fP0U_M9EamDww6Bh0J03z1meDWxh0xrzdnnT17icOxKDrjesZdIuKO-gGo6JwZ3QsfsNFXZ8XXFajCLNhXRnIZ2hEkz5DkxfRhrIj9xj7IycMNKiA_9FNlLz6OL6-xsbHB4h0IDWmdF4xVUarcLOW13X6DEL8eY1kbOXYyEYl2OaVaBpRFxKSuS2rqpGlLGUNU95jPVYyrytZQYXFJPsi0S0IKIQUdV5IWdQZCCGqhxInmdeN7HNWCFyUNlmMkjl_SnQIG7Z1UTSQGNWjCVfUBgaPDB5BRNrgGCt7QnmYvLOEdrxi6Nt9L_12CqwQRgcKd3nSZLA9vhye-OQ837Nzut4nbvvO1QUngL9wArjjlGzetP98pT1gYNDtGX8HAAD__y2vDXo">