<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/56012>56012</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Modules] Can't compile importable C++ library headers
        </td>
    </tr>

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

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

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

<pre>
    After upgrading `20cf77f77..1ad01f4f7`, I get
```
[ 50%] Building CXX object CMakeFiles/waarudo.details.std.dir/waarudo.details.std.cpp.o
/home/johel/root/clang/bin/clang++   -stdlib=libc++ -pedantic -Wall -Wextra -Wconversion -Werror=missing-field-initializers -O3 -DNDEBUG -fmodules -fbuiltin-module-map -std=c++2b -MD -MT CMakeFiles/waarudo.details.std.dir/waarudo.details.std.cpp.o -MF CMakeFiles/waarudo.details.std.dir/waarudo.details.std.cpp.o.d -o CMakeFiles/waarudo.details.std.dir/waarudo.details.std.cpp.o -c /home/johel/Documents/C++/Repos/Waarudo/sources/details/std/waarudo.details.std.cpp
/home/johel/Documents/C++/Repos/Waarudo/sources/details/std/waarudo.details.std.cpp:4:15: error: header file <algorithm> (aka '/home/johel/root/clang/bin/../include/c++/v1/algorithm') cannot be imported because it is not known to be a header unit
export import <algorithm>;
              ^
```

It's as if the "Clang builtins module map file" didn't exist. https://github.com/llvm/llvm-project/blob/main/clang/docs/Modules.rst last changed 7 months ago, so I'm not sure what's going on.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy1VNtunDAQ_Rp4GYG4LGH3gYe9RqmUtqpaJa_GNuDE2Mg22bRf3zGQprdIrdIi4zFjc3zmeDy1Zp-rbeO4gXFoDWFCtRBcJFlCm7LEFscpYUnarJoS3UG2hytouQuSQ5BsvWdu82exgwLXFEFxgN0o5IS2v70FXd9x6mB_Te75SUhug-x0JsSMTMeMOyKkja1jMRPmhRk6DLFetslOne45mjvdcYnWaO3QUElUi7YW6vlrhw0AIgSRog7yA_Z0cUcDZ0Q5QSG6IVJizx-dIWipVg_cWKGVdxqjDf7ZC2sxoqgRXLJIKOEEkeILroPoXQ7R4e3huPt0CVHTazZilDiqUQYnVDR7op4MExVEW0hkNUTXB3w_vloeBDm9GiRmEOl_QIXCr-d00HTsuXIedD-Hj6MPfNDeczOD4cjq0dBp6wXY-1C0Fzd8KTH-34b5doVvWmAHS35soeOE4U1qUDcI8j2RrTbCdX2QH1GNNbknaMo_zN84xk4oKkfm19Jv9B9S7J6xPeAGKFFKO6g5iH7QxnGGY0pGiw4HwoKfvVf6rMBpv4w8sR0xj2f9-KP_cwH4OYAg382r4IcnKI6_rwVTf4VhlRaIBdGA61CVLNv7KGG5FxbmiwH-YnjdcAEwwVCA0gF_FNbF0Dk3WNQXw8bWIqGxjqnG0E9SPjyZaDDaVxkvoNQ1mp58XwhOTFN_rtfz3YyNdSAJdrTDedSrRC7KdUi31b7QWQ1XSKOfpLOj4XDuyBxQq31l0yoOWZWzTb4hoRNO8gpL4ILva-CezHEg18HnxKwsqXG4ZCNgNTLEfF4Ow4ajkdVfx4t1aZyyt7hI0izsqtWK102WN2m2XmMpz5q6WNO8WCV1STJeNKEkNZfW00XBFT_DBIFjpB2KKkuyLLlI8zTP10UZZ5tVWZZ8s_ZfRVkGq4SjuDL2PGJt2tBUE6V6bC1OSjw2-zxJsGy2ik_qeHwyuk6b6o3P_uPl-3Dau5q4fwWo7hzs">