<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/147131>147131</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc++] Calling `std::filesystem::canonical` on ramdisks throws an exception on Windows
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          wepavos293
      </td>
    </tr>
</table>

<pre>
    Calling `std::filesystem::canonical` on paths located on ramdisk throws `std::__1::__fs::filesystem::filesystem_error`. It's caused by internal call to `GetFinalPathNameByHandleW`.

The problematic call:
[posix_compat.h#L344](https://github.com/llvm/llvm-project/blob/main/libcxx/src/filesystem/posix_compat.h#L344)

A similar issue was resolved in the past by adding special handling for these cases:
[Path.inc#L384](https://github.com/llvm/llvm-project/blob/main/llvm/lib/Support/Windows/Path.inc#L384)

**Reproduction Steps:**

1. Create a ramdisk using software like ImDisk.
2. Compile and run the following code on the ramdisk:
```
#include <filesystem>
#include <iostream>

int main(){
        std::cout << std::filesystem::canonical(std::filesystem::current_path()) << std::endl; 
        return 0;
}
```

Sorry for posting from a burner account, GitHub now enforces 2FA for accounts interacting with high-impact projects.
</pre>
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