Function makeDirW [src]
Creates a single directory with a relative or absolute null-terminated WTF-16 LE-encoded path.
To create multiple directories to make an entire path, see makePath.
To operate on only absolute paths, see makeDirAbsoluteW.
  Prototype
 pub fn makeDirW(self: Dir, sub_path: [*:0]const u16) MakeError!void  Parameters
self: Dirsub_path: [*:0]const u16 Possible Errors
In WASI, this error may occur when the file descriptor does not hold the required rights to create a new directory relative to it.
WASI-only; file paths must be valid UTF-8.
Windows-only; file paths provided by the user must be valid WTF-8. https://simonsapin.github.io/wtf-8/
On Windows, \\server or \\server\share was not found.
The Operating System returned an undocumented error code.
This error is in theory not possible, but it would be better to handle this error than to invoke undefined behavior.
When this error code is observed, it usually means the Zig Standard Library needs a small patch to add the error code to the error set for the respective function.
Source
 pub fn makeDirW(self: Dir, sub_path: [*:0]const u16) MakeError!void {
    try posix.mkdiratW(self.fd, mem.span(sub_path), default_mode);
}