<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/143788>143788</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Possibly wrong reachability analysis with global module fragments in module partitions
        </td>
    </tr>

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

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

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

<pre>
    The following C++23 code is rejected by clang version 20.1.6, saying that the declaration of `S` is unreachable in `I.cpp`.
```
// H.hpp
struct S{};

// M.cppm
export module M;

// P.cppm
module;
#include "H.hpp"
module M:P;

using T = S;

// I.cpp
module M;
import :P;

T f() { return {}; }
```

A variation involving no module partitions is accepted, and I do not find a reason for the rejection in the standard.  My reading of 10.4 and 10.7 is that the definition is reachable, with emphasis on 10.4.3.1 and 10.7.3.2.
</pre>
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