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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Derrick Stolee <derrickstolee@github.com>,
	Elijah Newren <newren@gmail.com>,
	Eric Sunshine <sunshine@sunshineco.com>
Subject: Re: [PATCH v4 0/6] add and apply a rule to find "unused" init+free
Date: Mon, 11 Jul 2022 12:54:03 +0200	[thread overview]
Message-ID: <220711.86wncj7w8p.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <YsvwLIfjZffUWOP/@coredump.intra.peff.net>


On Mon, Jul 11 2022, Jeff King wrote:

> On Tue, Jul 05, 2022 at 03:46:54PM +0200, Ævar Arnfjörð Bjarmason wrote:
>
>> This series adds a coccinelle rule to find and remove code where the
>> only reference to a variable in a given function is to malloc() &
>> free() it, where "malloc" and "free" also match
>> "strbuf_init/strbuf_release", and then later in the series anything
>> that looks like a init/free pattern.
>
> As before, I'm perfectly happy with the actual transformations here.

Thanks!

>> Changes since v3[1]
>> 
>>  * Add a "coccicheck-test" target in an early and new patch, the
>>    structure mirrors that of coccinelle.git's own tests. As the
>>    diffstat shows we have a *.c and *.res file which is C code
>>    before/after a *.cocci rule is applied.
>
> I have mixed feelings on this. I'm not opposed per se, and I even like
> the fact that it provides examples of what we expect a rule to do. But I
> worry about a world where the cost of using coccinelle goes up because
> now transformations need to have tests along with them. The idea of
> cocci is to make your life a little simpler and more efficient when
> fixing up the code base (as opposed to perl, etc).

That's fair, and I suppose we could add some really complex tests that
e.g. include the original headers.

But right now these just work on stand-alone *.c files with no includes,
and the runtime is thus trivial. So I thought it was OK to run it along
with the main job.

> But if it comes with a bunch of boilerplate tasks, that might no
> longer be the case. I'm already often on the fence about using cocci
> just because of the hours I've sunk into debugging and puzzling things
> out.
>
> I dunno. Maybe the bar is higher for stuff like this that we expect to
> continue to find problems as time goes on (because it is not "here is a
> transition", but "this is a common and easy mistake to make").
>
> So again, I'm not really opposed to this patch in particular, but I want
> to express caution at the direction we might be going, and at applying
> new rules over-zealously.

Yeah, we definitely need to be more careful with "ongoing" rules like
these, but hopefully between the tests & lack of false positives this
one looks sane...

>>  * We now catch init/reset patterns as well as init/release fully
>>    (i.e. for the "struct strbuf" early on)
>
> Yeah, that makes sense.
>
> -Peff


      reply	other threads:[~2022-07-11 11:25 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20 11:57 [PATCH] cocci: add and apply a rule to find "unused" variables Ævar Arnfjörð Bjarmason
2022-06-21 22:44 ` [PATCH v2 0/2] add and apply a rule to find "unused" init+free Ævar Arnfjörð Bjarmason
2022-06-21 22:44   ` [PATCH v2 1/2] cocci: add and apply a rule to find "unused" variables Ævar Arnfjörð Bjarmason
2022-06-22 16:02     ` Junio C Hamano
2022-06-21 22:44   ` [PATCH v2 2/2] cocci: remove "when strict" from unused.cocci Ævar Arnfjörð Bjarmason
2022-07-01 10:30   ` [PATCH v3 0/4] add and apply a rule to find "unused" init+free Ævar Arnfjörð Bjarmason
2022-07-01 10:30     ` [PATCH v3 1/4] cocci: add and apply a rule to find "unused" strbufs Ævar Arnfjörð Bjarmason
2022-07-01 18:04       ` Jeff King
2022-07-01 19:55       ` Eric Sunshine
2022-07-01 10:30     ` [PATCH v3 2/4] cocci: catch unused "strbuf" using an xmalloc() pattern Ævar Arnfjörð Bjarmason
2022-07-01 10:30     ` [PATCH v3 3/4] cocci: remove "when strict" from unused.cocci Ævar Arnfjörð Bjarmason
2022-07-01 21:33       ` Eric Sunshine
2022-07-01 10:30     ` [PATCH v3 4/4] cocci: generalize "unused" rule to cover more than "strbuf" Ævar Arnfjörð Bjarmason
2022-07-01 18:09     ` [PATCH v3 0/4] add and apply a rule to find "unused" init+free Jeff King
2022-07-05 13:46     ` [PATCH v4 0/6] " Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 1/6] Makefile: remove mandatory "spatch" arguments from SPATCH_FLAGS Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 2/6] Makefile & .gitignore: ignore & clean "git.res", not "*.res" Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 3/6] cocci: add a "coccicheck-test" target and test *.cocci rules Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 4/6] cocci: have "coccicheck{,-pending}" depend on "coccicheck-test" Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 5/6] cocci: add and apply a rule to find "unused" strbufs Ævar Arnfjörð Bjarmason
2022-07-05 13:47       ` [PATCH v4 6/6] cocci: generalize "unused" rule to cover more than "strbuf" Ævar Arnfjörð Bjarmason
2022-07-06 19:30       ` [PATCH v4 0/6] add and apply a rule to find "unused" init+free Junio C Hamano
2022-07-11  9:41       ` Jeff King
2022-07-11 10:54         ` Ævar Arnfjörð Bjarmason [this message]

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