Use stack's dynamic completions

[chrismwendt]

Stack has support for on-the-fly completions, so let's use them.

[faho]

What does the output look like? Is it actually any good?

Also note that this is reachable with a function called stack, so passing the path is awkward because there might not be a command. Why is that needed anyway?

[chrismwendt]

This is the output:

 function _stack
    set -l cl (commandline --tokenize --current-process)
    # Hack around fish issue #3934
    set -l cn (commandline --tokenize --cut-at-cursor --current-process)
    set -l cn (count $cn)
    set -l tmpline --bash-completion-enriched --bash-completion-index $cn
    for arg in $cl
      set tmpline $tmpline --bash-completion-word $arg
    end
    for opt in (/Users/chrismwendt/.local/bin/stack $tmpline)
      if test -d $opt
        echo -E "$opt/"
      else
        echo -E "$opt"
      end
    end
end

complete --no-files --command stack --arguments '(_stack)'

Seems to work better than the static file (notice how it completes options, too, not just commands):

stack --fish-completion-script stack | source works just as well, committed in 0ff59a7.

[faho]

Merged, thanks!