Why does bin_name() return str rather than OsString?

[Minoru]

lexopt tries not to convert strings unless absolutely necessary, but bin_name() deviates from that. The source code doesn't explain why. If bin_name() returned OsString, that'd be more consistent with other methods.

[blyxxyz]

I wrote up some considerations here but they fell through the gaps the first time I scrapped the method.

The main use case I envisioned for it was to show in help messages and error messages. Try running /bin/cat --help and /bin/cat doesnotexist: if you have GNU cat then you'll see

Usage: /bin/cat [OPTION]... [FILE]...

/bin/cat: doesnotexist: No such file or directory

It does this based on argv[0].

It's easy to format a &str but hard to format an &OsStr. With the current API you can do println!("Usage: {} blabla", parser.bin_name().unwrap_or("myprog"));, but if it returned an &OsStr you'd have to do more work.

Unlike a normal argument, which might be an actual file you have to open, I don't think there are any common cases where you'd absolutely have to process your own command name even if it's invalid unicode. (It's not even a good way of finding the actual executable.) But then a lossy decode might make more sense than ignoring it.

(I want to remove/overhaul the whole method, as discussed in #5 (comment))

[Minoru]

Thanks! This answers my question completely, so I'll close the issue.