scolapasta-path incorrectly mutates verbatim paths on Windows

[lopopolo]

artichoke/scolapasta-path/src/paths/windows.rs

Lines 48 to 56 in 53b84b7

	pub fn normalize_slashes(path: PathBuf) -> Result<Vec<u8>, PathBuf> {
	let mut buf = OsString::from(path).into_string()?.into_bytes();
	for byte in &mut buf {
	if *byte == b'\\' {
	*byte = b'/';
	}
	}
	Ok(buf)
	}

This routine should check to see if the path is a "verbatim path" (also knowns as a Windows extended-length path), which means it has a prefix of \\?\. These paths should not be modified. The Ruby engine should treat them as opaque.

See: https://users.rust-lang.org/t/understanding-windows-paths/58583.

This can be checked by using the Path::components iterator and checking whether the first element yielded by this iterator is Component::Prefix where the inner prefix_component.kind().is_verbatim() gives true.

The Prefix docs give these examples for the various types of paths, which we should add tests for:

assert_eq!(Verbatim(OsStr::new("pictures")),
           get_path_prefix(r"\\?\pictures\kittens"));
assert_eq!(VerbatimUNC(OsStr::new("server"), OsStr::new("share")),
           get_path_prefix(r"\\?\UNC\server\share"));
assert_eq!(VerbatimDisk(b'C'), get_path_prefix(r"\\?\c:\"));
assert_eq!(DeviceNS(OsStr::new("BrainInterface")),
           get_path_prefix(r"\\.\BrainInterface"));
assert_eq!(UNC(OsStr::new("server"), OsStr::new("share")),
           get_path_prefix(r"\\server\share"));
assert_eq!(Disk(b'C'), get_path_prefix(r"C:\Users\Rust\Pictures\Ferris"));

The linked discourse thread also includes these examples:

\\?\UNC\server\share\folder\file.txt
\\?\C:\foo