<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/57136>57136</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang-cl does not recognize /external:W
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          CAD97
      </td>
    </tr>
</table>

<pre>
    I tried building my Visual Studio project using:

```
msbuild /p:ClToolExe=clang-cl.exe /p:ClToolPath=$((gcm clang-cl).Path | Split-Path -Parent)
```

The build failed with clang-cl mistaking the `/external` flag as a filename:

```
clang-cl : error : no such file or directory: '/external:W3' [D:\git\cad97\kdlxx\examples\mini.vcxproj]
```

Per [the docs](https://clang.llvm.org/docs/UsersManual.html#id10), I'm filing an issue for the valid cl.exe flag that clang-cl does not understand.

```
> cl /? | Select-String "/external"

/external:I <path>      - location of external headers
/external:env:<var>     - environment variable with locations of external headers
/external:anglebrackets - treat all headers included via <> as external
/external:W<n>          - warning level for external headers
/external:templates[-]  - evaluate warning level across template instantiation chain
```
</pre>
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