getopts should use grapheme clusters for text alignment

[Kimundi]

It should at minimum align to number of codepoints (characters), (and now that PR #8710 has landed, it should be doing that minimum), but the only correct thing would be to align to grapheme clusters.

test case

extern mod extra;
use extra::getopts::groups;

fn main() {
    let optgroups = ~[
        groups::optflag("a", "apple",        "apple description"),
        groups::optflag("b", "banana\u00AB", "banana description"),
        groups::optflag("c", "br\xfbl\xe9e", "br\xfbl\xe9e quite long description"),
        groups::optflag("k", "kiwi\u20AC",   "kiwi description"),
        groups::optflag("o", "orange\u2039", "orange description"),
        groups::optflag("r",
                        "raspberry-but-making-this-option-way-too-long",
                        "raspberry description is also quite long indeed longer than every other piece of text we might encounter here and thus will be automatically broken up"),
    ];
    println(usage("Usage: fruits", optgroups));
}

current output:

% rustc /tmp/issue5516.rs && /tmp/issue5516 --help
warning: no debug symbols in executable (-arch x86_64)
Usage: fruits

Options:
    -a --apple          apple description
    -b --banana«        banana description
    -c --brûlée         brûlée quite long descripti
    -k --kiwi€          kiwi description
    -o --orange‹        orange description
    -r --raspberry-but-making-this-option-way-too-long 
                        raspberry description is also quite long indeed longer
                        than every other piece of text we might encounter here
                        and thus will be automatically broken up

Note that in addition to things failing to line up, it is also cutting off the end of the text for the brûlée case. That issue should also be fixed.

[catamorphism]

Nominating for milestone 5, production-ready

[graydon]

just a bug, removing milestone/nomination.

[pnkfelix]

Visiting for triage, email from 2013-08-19

The grapheme-oriented solution is blocked on #7043.

But we can at least put in the codepoint-oriented solution for the time being.

[pnkfelix]

(updating description to reflect PR #8710.)

[emberian]

With the advent of libunicode this would presumably be a lot easier!

[emberian]

It's also possible that we want to get rid of getops and replace it with docopt.

[bluss]

Note that graphemes don't tell you the display width of text. There is a rudimentary codepoint-oriented width function in libunicode though.

[steveklabnik]

This issue has been moved to the getopts repo: rust-lang/getopts#7