Re: [PATCH v2 11/14] bisect: move even the option parsing to `bisect--helper`

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi Ævar,

On Wed, 23 Feb 2022, Ævar Arnfjörð Bjarmason wrote:

> On Tue, Feb 22 2022, Johannes Schindelin via GitGitGadget wrote:
>
> > From: Johannes Schindelin <johannes.schindelin@gmx.de>
> >
> > On our journey to a fully built-in `git bisect`, this is the
> > second-to-last step.
> >
> > Side note: The `if (!strcmp(...)) ... else if (!strcmp(...)) ... else if
> > (!strcmp(...)) ...` chain seen in this patch was not actually the first
> > idea how to convert the command modes to sub-commands. Since the
> > `bisect--helper` command already used the `parse-opions` API with neatly
> > set-up command modes, naturally the idea was to use `PARSE_OPT_NODASH`
> > to support proper sub-commands instead. However, the `parse-options` API
> > is not set up for that, and even after making that option work with long
> > options, it turned out that `STOP_AT_NON_OPTION` and `KEEP_UNKNOWN`
> > would have to be used but these options were not designed to work
> > together. So it would appear as if a lot of work would have to be done
> > just to be able to use `parse_options()` just to parse the sub-command,
> > instead of a simple `if...else if` chain, the latter being a
> > dramatically simpler implementation.
>
> As I noted in
> https://lore.kernel.org/git/220129.86pmobauyt.gmgdl@evledraar.gmail.com/:
>
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> >  builtin/bisect--helper.c | 133 ++++++++++++++++-----------------------
> >  git-bisect.sh            |  49 +--------------
> >  2 files changed, 56 insertions(+), 126 deletions(-)
> >
> > diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> > index 5228964937d..ef0b06d594b 100644
> > --- a/builtin/bisect--helper.c
> > +++ b/builtin/bisect--helper.c
> > @@ -20,18 +20,34 @@ static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
> >  static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
> >  static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
> >
> > -static const char * const git_bisect_helper_usage[] = {
> > -	N_("git bisect--helper --bisect-reset [<commit>]"),
> > -	N_("git bisect--helper --bisect-terms [--term-good | --term-old | --term-bad | --term-new]"),
> > -	N_("git bisect--helper --bisect-start [--term-{new,bad}=<term> --term-{old,good}=<term>]"
> > -					    " [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<paths>...]"),
> > -	N_("git bisect--helper --bisect-next"),
> > -	N_("git bisect--helper [--bisect-state] (bad|new) [<rev>]"),
> > -	N_("git bisect--helper [--bisect-state] (good|old) [<rev>...]"),
> > -	N_("git bisect--helper --bisect-replay <filename>"),
> > -	N_("git bisect--helper --bisect-skip [(<rev>|<range>)...]"),
> > -	N_("git bisect--helper --bisect-visualize"),
> > -	N_("git bisect--helper --bisect-run <cmd>..."),
> > +static const char * const git_bisect_usage[] = {
> > +	N_("git bisect help\n"
> > +	   "\tprint this long help message."),
> > +	N_("git bisect start [--term-{new,bad}=<term> --term-{old,good}=<term>]\n"
> > +	   "\t\t [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<pathspec>...]\n"
> > +	   "\treset bisect state and start bisection."),
> > +	N_("git bisect (bad|new) [<rev>]\n"
> > +	   "\tmark <rev> a known-bad revision/\n"
> > +	   "\t\ta revision after change in a given property."),
> > +	N_("git bisect (good|old) [<rev>...]\n"
> > +	   "\tmark <rev>... known-good revisions/\n"
> > +	   "\t\trevisions before change in a given property."),
> > +	N_("git bisect terms [--term-good | --term-bad]\n"
> > +	   "\tshow the terms used for old and new commits (default: bad, good)"),
> > +	N_("git bisect skip [(<rev>|<range>)...]\n"
> > +	   "\tmark <rev>... untestable revisions."),
> > +	N_("git bisect next\n"
> > +	   "\tfind next bisection to test and check it out."),
> > +	N_("git bisect reset [<commit>]\n"
> > +	   "\tfinish bisection search and go back to commit."),
> > +	N_("git bisect (visualize|view)\n"
> > +	   "\tshow bisect status in gitk."),
> > +	N_("git bisect replay <logfile>\n"
> > +	   "\treplay bisection log."),
> > +	N_("git bisect log\n"
> > +	   "\tshow bisect log."),
> > +	N_("git bisect run <cmd>...\n"
> > +	   "\tuse <cmd>... to automatically bisect."),
> >  	NULL
> >  };
>
> Even that doesn't explain why this needs to be changed as
> well.

True. The explanation is easy: I am not in the business of changing the
usage shown by `git bisect -h`.

> we no longer understand "git bisect <subcommand> -h", but did before
> etc.

... for some definition of "understand" ;-) See for yourself:

	$ git bisect visualize -h
	usage: git bisect--helper --bisect-reset [<commit>]
	   or: git bisect--helper --bisect-terms [--term-good | --term-old | --term-bad | --term-new]
	   or: git bisect--helper --bisect-start [--term-{new,bad}=<term> --term-{old,good}=<term>] [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<paths>...]
	   or: git bisect--helper --bisect-next
	   or: git bisect--helper --bisect-state (bad|new) [<rev>]
	   or: git bisect--helper --bisect-state (good|old) [<rev>...]
	   or: git bisect--helper --bisect-replay <filename>
	   or: git bisect--helper --bisect-skip [(<rev>|<range>)...]
	   or: git bisect--helper --bisect-visualize
	   or: git bisect--helper --bisect-run <cmd>...

	    --bisect-reset        reset the bisection state
	    --bisect-next-check   check whether bad or good terms exist
	    --bisect-terms        print out the bisect terms
	    --bisect-start        start the bisect session
	    --bisect-next         find the next bisection commit
	    --bisect-state        mark the state of ref (or refs)
	    --bisect-log          list the bisection steps so far
	    --bisect-replay       replay the bisection process from the given file
	    --bisect-skip         skip some commits for checkout
	    --bisect-visualize    visualize the bisection
	    --bisect-run          use <cmd>... to automatically bisect.
	    --no-log              no log for BISECT_WRITE

That's not a helpful usage for `git bisect visualize`. It's better to
leave it to a future patch for `bisect_visualize()` to handle `-h`.

In other words, what you point out as a bug is actually fixing one.

I find the other comments on not using the `parse_options()` machinery
similar, and your feedback seems to flatly dismiss the side note in the
commit message as irrelevant.

To be clear: I spent a substantial amount of time trying to extend the
`parse_options()` machinery to support dash-less subcommands. The end
result was neither elegant nor particularly useful.

So, with all due respect, I disagree with your disagreeing.

Ciao,
Johannes