<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/160218>160218</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Header-unit using declaration not visible.
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          HassanSajjad-302
      </td>
    </tr>
</table>

<pre>
    Minimal Reproducer

A.hpp

```
using INT = int;
```


file.cpp

```
template<typename T>
class Cat {};

Cat<INT> a; 
```

```clang.exe -std=c++2b -fmodule-header=user -xc++-header A.hpp -o A.pcm```

```clang.exe -std=c++2b -fmodule-file="A.pcm" file.cpp```

Output:

```
file.cpp:4:5: error: declaration of 'INT' must be imported from module '.\A.hpp' before it is required
    4 | Cat<INT> a;
      |     ^
A.hpp:1:7: note: declaration here is not visible
    1 | using INT = int;
      |       ^
1 error generated.
```
</pre>
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