Re: [PATCH 05/13] bisect run: keep some of the post-v2.30.0 output

From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: "Đoàn Trần Công Danh" <congdanhqx@gmail.com>
Cc: git@vger.kernel.org, Taylor Blau <me@ttaylorr.com>,
	Jeff King <peff@peff.net>,
	Christian Couder <chriscool@tuxfamily.org>
Subject: Re: [PATCH 05/13] bisect run: keep some of the post-v2.30.0 output
Date: Tue, 08 Nov 2022 04:11:27 +0100	[thread overview]
Message-ID: <221108.86y1smrube.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <Y2mwN3bpaiN/7vJh@danh.dev>

On Tue, Nov 08 2022, Đoàn Trần Công Danh wrote:

> On 2022-11-07 22:40:33+0100, Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>> 
>> On Sun, Nov 06 2022, Đoàn Trần Công Danh wrote:
>> 
>> > From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
>> >
>> > Preceding commits fixed output and behavior regressions in
>> > d1bbbe45df8 (bisect--helper: reimplement `bisect_run` shell function
>> > in C, 2021-09-13), which did not claim to be changing the output of
>> > "git bisect run".
>> >
>> > But some of the output it emitted was subjectively better, so once
>> > we've asserted that we're back on v2.29.0 behavior, let's change some
>> > of it back:
>> >
>> > - We now quote the arguments again, but omit the first " " when
>> >   printing the "running" line.
>> > - Ditto for other cases where we emitted the argument
>> > - We say "found first bad commit" again, not just "run success"
>> 
>> So, something you refactored here was that there's now a
>> do_bisect_run(), and:
>> 
>> > -static int do_bisect_run(const char *command, int argc, const char **argv)
>> > +static int do_bisect_run(const char *command, int argc UNUSED, const char **argv UNUSED)
>> >  {
>> >  	struct child_process cmd = CHILD_PROCESS_INIT;
>> > -	struct strbuf buf = STRBUF_INIT;
>> > +	const char *trimed = command;
>> >  
>> > -	strbuf_join_argv(&buf, argc, argv, ' ');
>> > -	printf(_("running %s\n"), buf.buf);
>> > -	strbuf_release(&buf);
>> > +	while (*trimed && isspace(*trimed))
>> > +		trimed++;
>> > +	printf(_("running %s\n"), trimed);
>> >  	cmd.use_shell = 1;
>> >  	strvec_push(&cmd.args, command);
>> >  	return run_command(&cmd);
>> 
>> Instead of trimming with strbuf_ltrim() we're now using this loop, but
>> in any case, this has had the effect that you're only fixing one of many
>> of the output changes. We're still adding this leading whitespace to the
>> other messages we emit.
>
> Sorry, I can't follow, we're fixing in do_bisect_run, which meant we
> fixed all of the output changes for leading whitespace, no?
>
> 'do_bisect_run' will be called from normal 'git bisect run' iteration
> and also after receiving code 126/127 for the very first run.
>
> Which is the other cases you're talking about?

The other uses of command.buf in my initial version, i.e. I did:

	-       strbuf_reset(&command);
	-       strbuf_join_argv(&command, argc, argv, ' ');
	+       /* Quoted, but skip initial " " */
	+       strbuf_ltrim(&command);

And the command.buf is then used by:

	printf(_("running %s\n"), command.buf);
	res = run_command_v_opt(run_args.v, RUN_USING_SHELL);

Which your version covers, but also this, in bisect_run() just a few
lines later:

	error(_("unable to verify '%s' on good"
	      " revision"), command.buf);

And, for:

	error(_("bisect run failed: exit code %d from"
	      " '%s' is < 0 or >= 128"), res, command.buf);

In the original *.sh version of this it used the same variable.

But yours deals with the refactored do_bisect_run() from René's
e8de018438e (bisect--helper: factor out do_bisect_run(), 2022-10-27).

So that first "running" takes place in its ownown do_bisect_run()
function, and you only skip past the whitespace in the "const char
*command" local to that function.

Thus you're only trimming the whitespace for 1/3 cases, the 2/3 being
noted in the 04/13 as the ones I didn't write a test for.

I think this squashed in should be functionally equivalent:

	diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
	index f16b9df8fd6..493e062e76d 100644
	--- a/builtin/bisect--helper.c
	+++ b/builtin/bisect--helper.c
	@@ -1141,20 +1141,17 @@ static int get_first_good(const char *refname UNUSED,
	 	return 1;
	 }

	-static int do_bisect_run(const char *command, int argc UNUSED, const char **argv UNUSED)
	+static int do_bisect_run(const char *command, const char *trimmed)
	 {
	 	struct child_process cmd = CHILD_PROCESS_INIT;
	-	const char *trimed = command;

	-	while (*trimed && isspace(*trimed))
	-		trimed++;
	-	printf(_("running %s\n"), trimed);
	+	printf(_("running %s\n"), trimmed);
	 	cmd.use_shell = 1;
	 	strvec_push(&cmd.args, command);
	 	return run_command(&cmd);
	 }

	-static int verify_good(const struct bisect_terms *terms, const char *command, int argc, const char **argv)
	+static int verify_good(const struct bisect_terms *terms, const char *command, const char *trimmed)
	 {
	 	int rc;
	 	enum bisect_error res;
	@@ -1174,7 +1171,7 @@ static int verify_good(const struct bisect_terms *terms, const char *command, in
	 	if (res != BISECT_OK)
	 		return -1;

	-	rc = do_bisect_run(command, argc, argv);
	+	rc = do_bisect_run(command, trimmed);

	 	res = bisect_checkout(&current_rev, no_checkout);
	 	if (res != BISECT_OK)
	@@ -1187,6 +1184,7 @@ static int bisect_run(struct bisect_terms *terms, const char **argv, int argc)
	 {
	 	int res = BISECT_OK;
	 	struct strbuf command = STRBUF_INIT;
	+	struct strbuf trimmed = STRBUF_INIT;
	 	const char *new_state;
	 	int temporary_stdout_fd, saved_stdout;
	 	int is_first_run = 1;
	@@ -1200,8 +1198,10 @@ static int bisect_run(struct bisect_terms *terms, const char **argv, int argc)
	 	}

	 	sq_quote_argv(&command, argv);
	+	strbuf_addbuf(&trimmed, &command);
	+	strbuf_ltrim(&trimmed);
	 	while (1) {
	-		res = do_bisect_run(command.buf, argc, argv);
	+		res = do_bisect_run(command.buf, trimmed.buf);

	 		/*
	 		 * Exit code 126 and 127 can either come from the shell
	@@ -1211,7 +1211,7 @@ static int bisect_run(struct bisect_terms *terms, const char **argv, int argc)
	 		 * missing or non-executable script.
	 		 */
	 		if (is_first_run && (res == 126 || res == 127)) {
	-			int rc = verify_good(terms, command.buf, argc, argv);
	+			int rc = verify_good(terms, command.buf, trimmed.buf);
	 			is_first_run = 0;
	 			if (rc < 0) {
	 				error(_("unable to verify '%s' on good"

Some of that's a bit of a hassle with e8de018438e, but this way we use
the whitespace-prefixed for run_command(), but not for the output. Maybe
we can just always use the trimmed version, I didn't check.

This approach would also mean that you can drop your 03/13 and 06/13
surrounding this commit, in 03/13 you added that argv/argc because:

	[...]	
	In a later change, we would like to restore the old behaviours,
	which would need information regarding argc and argv.

That "later change" is your 04/13, then in 05/13 you're back to them
being UNUSED, before 06/13 finally drops them.

But if we just pass both trimmed & non-trimmed into do_bisect_run() to
begin with we don't need to go through all of that...