<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/58532>58532</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Using legacy header with clang in windows11
        </td>
    </tr>

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

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

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

<pre>
    I am trying to write some codes in c++20 standard. I write some simple code in c++ module way. And I write '#include <iostream>' because 'import <iostream>' can not be compiled in clang-15.0.2 compiler. Then I meet compile error.

The code is:
```c++
// md.ixx
module;
#include <iostream>
export module md;

export int func() {
    return 114514;
}
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJx1UcuO4yAQ_Bp8aY0F-BUfOMwkM9q5734ANh2bEYYI8Cb5-yW2M4lWu6iFoauK7mp3Tl3FJ8gJor9qO0B0cPY6IgQ3IfROYQBtoSf8LQWnEKK0SnqVw-czM-jpZFbBEx8mp-aUPstrDq9WfWsIbwgvtO3NnASk2GsXokc5keI9YdBhL-ew8NLDzsd_cHppwbqYuKnsdNIG1VLaSDu8sCqnOb8DPoefI9pUfkKM9yyg987nhB4IfV33xNo8BFJsOVLTNTZTW5Z_pIBJ5fpyWVOrWVJ8M_5ncIHxsvjaJjSph-4Z1jbCcbap9I7wFkizkSAtj3H2FhgrK1Y-5M3hr74zFKyu66JhDW8zJQrVFq3Moo4Gxa9w--0GB9lfYUSp0MNZx3Gd422gZ22VOwfGstkbMcZ4Wmaz-B8Sc-7yNNB0Meb3_fNy8u4L-5iuOoQZQzpUu6rg2SgklkzVjO2Oaa9lrXi9q4-0b3ZdS9u6yIzs0ARBqjdSHTItOOWcUc5YQzltc6xoWXRl2fG-OTZVTUqKk9QmvxXOnR8yL5YeunkICTQ6xPAAZQh6sIj39-UcR-fFfr8_xR_Z0q1YWv0D4o3zIg">