fix: seq panic on no arguments #4749

[NikolaiSch]

This is in reference to issue #4749, where just running seq ends up panicking. I have added a new NoArguments error, and refactored the display formatting, in order to match GNU messages.

[sylvestre]

please fix the clippy warning and add a test to make sure we don't regress
thanks

[NikolaiSch]

affirmative. on it asap, expect it within 24 hours!

[NikolaiSch]

please fix the clippy warning and add a test to make sure we don't regress

thanks

however i have a question, that made clippy fail for me, selinux was not imported correctly for me, but i didn't change any of that code, so what should my next approach be?

[tertsdiepraam]

I don't understand. Following the clippy lint made clippy fail because of selinux? Or selinux is making clippy fail in general? In the latter case, turning off the feat_selinux feature should help.

[cakebaker]

@NikolaiSch ping?

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail-2/inotify-dir-recreate

[sylvestre]

I fixed the clippy warnings

[cakebaker]

Argh, somehow I made a mess, just wanted to add a test... I added a test to get this PR merged finally.

[tertsdiepraam]

I think we can merge this, but in my opinion, the Display impl is a bit overengineered. It could just be this:

impl Display for SeqError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::ParseError(s, e) => {
                let error_type = match e {
                    ParseNumberError::Float => "floating point",
                    ParseNumberError::Nan => "'not-a-number'",
                    ParseNumberError::Hex => "hexadecimal",
                };
                write!(f, "invalid {} argument: {}", error_type, s.quote())
            }
            Self::ZeroIncrement(s) => write!(f, "invalid Zero increment value: {}", s.quote()),
            Self::NoArguments => write!(f, "missing operand"),
        }
    }
}

and then the argtype and arg methods could be removed.

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail-2/inotify-dir-recreate

[cakebaker]

Thanks :)