Don't split passthrough options on whitespace

[bb010g]

Otherwise, stg email send -G '--subject=Latest patch' translates to git send-mail '--subject=Latest' 'patch', and the command errors with

error: `git send-email`: fatal: ambiguous argument 'patch': unknown revision or path not in the working tree.

Also, Zsh completion reuses the current git completion, whatever it is. Ideally, stg -C foo diff -D --bar -D --baz= would complete the same as git -C foo diff --bar --baz=, but it's currently limited to completing the same as git -C foo diff --baz=, so multi-word options won't complete properly (not that they would before). If Zsh provided a companion associative array to opt_args that contained indices for each value represented in opt_args, we could filter to the current word and provide virtually perfect completion, but this will involve submitting a patch to Zsh to enhance both comparguments and _arguments.

[jpgrayson]

Thank you for this PR, @bb010g.

I am in agreement that for the --git-opts options to stg email send and stg email format it will be better to support a single git option per StGit --git-opts occurrence. This is a good use case to accommodate correctly.

For diff options, the Python implementation allows multiple space-separated options as the value to --diff-opts as well as allowing multiple occurrences of --diff-opts, which is why this was implemented the way it was. This relates to #187.

By only allowing a single git diff option per --diff-opts, there is a compatibility break with StGit 1.x. I am not sure how attached anyone might be to being able to specify multiple space-separated options, which has made me hesitant to make this change. That said, I agree that a 1:1 mapping between a --diff-opts occurrence and a git diff option is conceptually cleaner and solves the problem of supporting values with spaces.

A question I had was whether git diff options were exposed to the same problem you identified with git email send -G '--subject=Latest patch'? I.e. are there any git diff-tree options that may need space-separated values? Here is what I'm seeing:

• --anchored=<text>
• --word-diff-regex=<regex>
• --color-words[=<regex>]
• -S<string>
• -G<regex>
• --relative[=<path>]
• -I<regex>, --ignore-matching-lines=<regex>
• --line-prefix=<prefix>
• --pretty[=<format>]

So yes, a lot of options that where a user may want a space separated value. I'm in agreement that git diff options should also support values with spaces in them. The most straightforward way of doing this is the change you've made to have the 1:1 mapping between StGit -O/--diff-opts occurrences and git diff options. I can imagine other, less straightforward approaches that involve StGit having its own shell-like quoting rules, but I think that path, in addition to being much more complicated to implement, will be worse for users than this small compatibility break with StGit 1.x.

So I am inclined to merge this change.

However, I am also going to do some follow-on changes:

• Rename --diff-opts to --diff-opt. I will retain --diff-opts as a hidden alias.
• Rename --git-opts to --git-opt. No alias for this one since it is new to StGit 2.0.
• Repair the now broken tests.
• Add tests for --diff-opt options with value containing spaces. E.g. --diff-opt=--line-prefix="x x x ".
• Repair code formatting.
• Improve the zsh completions to:
  • Comprehend already-specified --diff-opt and --git-opt values. I.e. so that already used options are excluded from the completions.
  • Only offer completions for git options and not arguments to git diff-tree/git send-email/git format-patch.

[bb010g]

Thank you!

If you're looking at making those sorts of changes, renaming --diff-opt to --diff-tree-opt for clarity might be a good idea, or at least referring to it in documentation as <diff-tree-opt>.

Improve the zsh completions to:

• Comprehend already-specified --diff-opt and --git-opt values. I.e. so that already used options are excluded from the completions.

• Only offer completions for git options and not arguments to git diff-tree/git send-email/git format-patch.

From what I discovered while writing this patch, I expect both of those to be rather challenging. For the former, you want to accumulate --diff-opt values up to that point using the same parsing strategy as _arguments, but without actually using _arguments (which is hard! _arguments parses via comparguments, which is a C-coded Zsh builtin), and for the latter, you want to somehow inform the behavior of a completion function that you have no knowledge of. These are both points that, to my knowledge, Zsh itself needs improvements on. All that said, best of luck solving these problems.