Fix wrapping bugs

[mgeisler]

I've been working towards integrating my textwrap crate and along the way, I found some small problems in the existing wrap_help function in clap. I basically added new code that calls both textwrap::fill and wrap_help and panicked on any difference:

fn wrap_help(help: &mut String, longest_w: usize, avail_chars: usize) {
    let input = help.clone();
    let mut old = help.clone();
    old_wrap_help(&mut old, longest_w, avail_chars);

    let mut wrapped = String::with_capacity(help.len());
    for (i, line) in help.lines().enumerate() {
        if i > 0 {
            wrapped.push('\n');
        }
        wrapped.push_str(&textwrap::fill(line, avail_chars));
    }

    // TODO: move up, This keeps old behavior of not wrapping at all
    // if one of the words would overflow the line
    if longest_w < avail_chars {
        *help = wrapped;
    }

    if *old != *help {
        println!("********************************");
        println!("longest_w: {}, avail_chars: {}", longest_w, avail_chars);
        println!("help: {:3} bytes: {:?}", input.len(), input);
        println!("old:  {:3} bytes: {:?}", old.len(), old);
        println!("new:  {:3} bytes: {:?}", help.len(), help);
        println!("********************************");
        panic!("bad wrap");
    }
}

fn old_wrap_help(help: &mut String, longest_w: usize, avail_chars: usize) {
    // ... as before

This PR fixes two small problems discovered this way, one of which became #828.

[coveralls]

Coverage increased (+0.006%) to 89.088% when pulling 08be630 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[kbknapp]

Thanks for tackling this! I'm fine with the coveralls failing, so don't worry about that. But I need the Travis checks to pass, and it looks like it's failing on stable and 1.11.0 (minimum supported version of Rust).

[mgeisler]

Yeah, I'll look into the build failures later -- hopefully tonight!

[coveralls]

Coverage decreased (-0.008%) to 89.074% when pulling 564c5f0 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[coveralls]

Coverage decreased (-0.008%) to 89.074% when pulling 564c5f0 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[coveralls]

Coverage decreased (-0.008%) to 89.074% when pulling 564c5f0 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[coveralls]

Coverage decreased (-0.008%) to 89.074% when pulling 564c5f0 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[coveralls]

Coverage decreased (-0.008%) to 89.074% when pulling 564c5f0 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[mgeisler]

The build failures have been fixed.

[coveralls]

Coverage decreased (-0.008%) to 89.074% when pulling 564c5f0 on mgeisler:fix-wrapping-bugs into 72d7bf3 on kbknapp:master.

[kbknapp]

Excellent, thanks!

@homu r+

[homu]

📌 Commit 564c5f0 has been approved by kbknapp

[homu]

⌛ Testing commit 564c5f0 with merge e9e01e1...

[homu]

☀️ Test successful - status