[adastra22]

OsStr/OsString is what you would use in those circumstances. Path/PathBuf specifically for filenames or paths, which I think uses OsStr/OsString internally. I've never looked at OsStr's internals but I wouldn't be surprised if it is a wrapper around &[u8].

Note that &[u8] would allow things like null bytes, and maybe other edge cases.

[kragen]

You can't get null bytes from a command-line argument. And going by https://news.ycombinator.com/item?id=44991638 it's common to not use OsString when accepting command-line arguments, because std::env::args yields Strings, which means that probably most Rust programs that accept filenames on the command line have this bug.

[adastra22]

Rust String can contain null bytes! Rust uses explicit string lengths. Agree though that most OS wouldn't be able to pass null bytes in arguments though.

[kragen]

Right, but it can't contain invalid UTF-8, which is valid in both command-line parameters and in filenames on Linux, FreeBSD, and other normal Unixes. See my link above for a demonstration of how this causes bugs in Rust programs.