Re: [PATCH v3 0/4] Introduce --first-parent flag for git bisect

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 1, 2020, 19:06 UTC
Message-ID: <xmqq36562nki.fsf@gitster.c.googlers.com>
In-Reply-To: <20200801175840.1877-1-alipman88@gmail.com>

Aaron Lipman <alipman88@gmail.com> writes:

Show 9 quoted lines

>> I suspect that you would ask the same question to whoever added
>> no_checkout to this thing, and I wouldn't be surprised if we end up
>> removing both of these parameters (and parsing of the options inside
>> cmd_bisect__helper()) after thinking about them, but anyway, let's
>> read on.
>
> Hmm. Is there a preferred way to to add a --first-parent line to the
> output of "git bisect start --help" via the parse-options API without
> removing the --first-parent option from argv in the process?

I'd rather not to see the code made ugly if the only reason why you have duplicated command line parsing is to support "git bisect start -h" while cmd_bisect__helper() still exists.

That function is supposed to be a thin shim layer whose only reason of its existence is to serve as an interface with the scripted version of "git bisect". When everything is migrated from the shell script, cmd_bisect__helper() should disappear.

In its place, cmd_bisect() written in C would become a dispatcher that only looks at the first token on the command line that comes after ["git", "bisect"] and calls "bisect_start()", "bisect_next()", etc. with the remainder of the command line with options such as "--first-parent" and "--no-checkout", which will be parsed by bisect_start() etc. parsing its argc/argv[] passed by cmd_bisect(). It is likely that cmd_bisect() would not have any call to parse_options(); instead cmd_start() etc. would call parse_options() with their own option[] table.

So I am not sure if the change between v2 and v3 is going in the right direction.

> As long as we're capturing the --first-parent option in
> cmd_bisect__helper(), checking argv for a --first-parent flag in
> bisect_start() is pointless.

This is going backwards, as far as I can tell. If anything, I'd rather see cmd_bisect__helper() get fixed so that it does not parse "--first-parent" (and similarly, "--no-checkout" that you imitated) into first_parent_only (and no_checkout) variables and passed as parameters to bisect_start(). cmd_bisect__helper() should instead just let these flags (and there may be others) sit in argc/argv[] and have bisect_start() parse them, together with all other options bisect_start() already has its parser for.

Thanks.