> For the very simple case of "I want a command-line option which specifies a path as an OsString", Rust’s way of doing things makes things hard. By comparison, in C++, I am used to dealing with paths as std::string on Unix and std::wstring or std::u16string on Windows, and this C++ approach is a lot easier.

FYI, you can convert an `OsStr` (or `OsString`) into a [`Path`](https://doc.rust-lang.org/std/path/struct.Path.html) with zero overhead and get all the useful things you want to do with paths: https://play.rust-lang.org/?version=stable&mode=debug&editio...

> Rust’s OsString design is too smart by half, and if I use env::args_os(), I can’t easily do simple tasks like "test if this string starts with '-'" or "split this string by the first '=', if it exists". As far as I can tell, the way to go is to convert OsString to Vec<u8>, do your processing there, and then convert back

For commandline arguments that you actually need to parse there's nothing wrong with asserting that you only accept valid Unicode, and then you can just use `to_str()`: https://doc.rust-lang.org/std/ffi/struct.OsStr.html#method.t...

If you have a `Vec<u8>` or `String` or whatever you can just treat it as an `OsStr` (with no overhead) because both of those (and a bunch of other things) implement `AsRef<OsStr>`: https://doc.rust-lang.org/std/path/struct.Path.html#method.n...