Re: [PATCH v3 03/15] merge-tree: add option parsing and initial shell for real merge function

> > ...also, even if we did require the `--write-tree` flag, we'd still
> > have to look at argc.  Since the option parsing handles both modes,
> > someone could leave off --write-tree, but include a bunch of other
> > options that only make sense with --write-tree.  Individually checking
> > the setting of every extra flag along with write_tree is a royal pain
> > and I don't want to repeat that for each new option added.  Simply
> > checking argc allows you to provide an error message if the user does
> > that.
> >
> > (And I think it's sad that in Git we often forgot to warn and notify
> > users of options that are only functional with certain other
> > arguments; it makes it harder for users to figure out, and has in the
> > past even made it harder for other developers to figure out what was
> > meant and how things are to be used.  I think I've seen multiple Git
> > devs be confused over ls-files --directory and --no-empty-directory
> > options, assuming they'd do something sensible for tracked files, when
> > in fact those arguments are simply ignored because they are only
> > modifiers for how untracked files are treated.)
>
> There's a much simpler way to do what you're trying to do here which is
> to only parse --write-tree, and as soon as you have that pass off two
> one function or the other, and have those functions call
> parse_options().