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From: Junio C Hamano <gitster@pobox.com>
To: Stefan Beller <sbeller@google.com>
Cc: SZEDER Gábor <szeder.dev@gmail.com>, Jeff King <peff@peff.net>,
	git <git@vger.kernel.org>,
	Jonathan Tan <jonathantanmy@google.com>
Subject: Re: New semantic patches vs. in-flight topics [was: Re: [PATCH 00/19] Bring more repository handles into our code base]
Date: Wed, 24 Oct 2018 10:22:16 +0900
Message-ID: <xmqq5zxsrvef.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <CAGZ79kZO6tAUOjO4YCostLmogGSwMmxGHj7g1kM1fNJWqJoFUA@mail.gmail.com> (Stefan Beller's message of "Tue, 23 Oct 2018 10:30:40 -0700")

Stefan Beller <sbeller@google.com> writes:

>> Anyway, even though "make coccicheck" does not run in subsecond,
>> I've updated my machinery to rebuild the integration branches so
>> that I can optionally queue generated coccicheck patches, and what I
>> pushed out tonight has one at the tip of 'pu' and also another at
>> the tip of 'next'.  The latter seems to be passing all archs and
>> executing Windows run.
>
> That is pretty exciting!
>
> Looking at the commit in next, you also included the suggestion
> from [1] to use a postincrement instead of a preincrement and I got
> excited to see how we express such a thing in coccinelle,
> but it turns out that it slipped in unrelated to the coccinelle patches.

See below, which was sitting in my working tree.

> How would we go from here?
> It is not obvious to me how such changes would be integrated,
> as regenerating them on top of pu will not help getting these changes
> merged down, and applying the semantic patch on next (once
> sb/more-repo-in-api lands in next) would created the merge conflicts for
> all topics that are merged to next after that series.

Conflicts with later topics is indeed worrysome.  That is why I did
it as an experiment.  If it becomes too painful, I'd probably stop
doing it while merging to anything other than 'pu', and then we can
follow the more distributed approach along the lines of what Szeder
suggested, to see how smoothly it goes.

-- >8 --
Subject: [PATCH] cocci: simplify "if (++u > 1)" to "if (u++)"

It is more common to use post-increment than pre-increment when the
side effect is the primary thing we want in our code and in C in
general (unlike C++).

Initializing a variable to 0, incrementing it every time we do
something, and checking if we have already done that thing to guard
the code to do that thing, is easier to understand when written

	if (u++)
		; /* we've done that! */
	else
		do_it(); /* just once. */

but if you try to use pre-increment, you end up with a less natural
looking

	if (++u > 1)

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 contrib/coccinelle/preincr.cocci | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 contrib/coccinelle/preincr.cocci

diff --git a/contrib/coccinelle/preincr.cocci b/contrib/coccinelle/preincr.cocci
new file mode 100644
index 0000000000..7fe1e8d2d9
--- /dev/null
+++ b/contrib/coccinelle/preincr.cocci
@@ -0,0 +1,5 @@
+@ preincrement @
+identifier i;
+@@
+- ++i > 1
++ i++
-- 
2.19.1-542-gc4df23f792


  reply index

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-16 23:35 [PATCH 00/19] Bring more repository handles into our code base Stefan Beller
2018-10-16 23:35 ` [PATCH 01/19] sha1_file: allow read_object to read objects in arbitrary repositories Stefan Beller
2018-10-16 23:35 ` [PATCH 02/19] packfile: allow has_packed_and_bad to handle " Stefan Beller
2018-10-16 23:35 ` [PATCH 03/19] object-store: allow read_object_file_extended to read from " Stefan Beller
2018-10-16 23:35 ` [PATCH 04/19] object-store: prepare read_object_file to deal with " Stefan Beller
2018-10-16 23:35 ` [PATCH 05/19] object-store: prepare has_{sha1, object}_file[_with_flags] to handle " Stefan Beller
2018-10-16 23:35 ` [PATCH 06/19] object: parse_object to honor its repository argument Stefan Beller
2018-10-16 23:35 ` [PATCH 07/19] commit: allow parse_commit* to handle arbitrary repositories Stefan Beller
2018-10-16 23:35 ` [PATCH 08/19] commit-reach.c: allow paint_down_to_common " Stefan Beller
2018-10-16 23:35 ` [PATCH 09/19] commit-reach.c: allow merge_bases_many " Stefan Beller
2018-10-16 23:35 ` [PATCH 10/19] commit-reach.c: allow remove_redundant " Stefan Beller
2018-10-16 23:35 ` [PATCH 11/19] commit-reach.c: allow get_merge_bases_many_0 " Stefan Beller
2018-10-16 23:35 ` [PATCH 12/19] commit-reach: prepare get_merge_bases " Stefan Beller
2018-10-16 23:35 ` [PATCH 13/19] commit-reach: prepare in_merge_bases[_many] " Stefan Beller
2018-10-16 23:35 ` [PATCH 14/19] commit: prepare get_commit_buffer " Stefan Beller
2018-10-16 23:35 ` [PATCH 15/19] commit: prepare repo_unuse_commit_buffer " Stefan Beller
2018-10-16 23:35 ` [PATCH 16/19] commit: prepare logmsg_reencode " Stefan Beller
2018-10-16 23:35 ` [PATCH 17/19] pretty: prepare format_commit_message " Stefan Beller
2018-10-16 23:35 ` [PATCH 18/19] submodule: use submodule repos for object lookup Stefan Beller
2018-10-19 20:37   ` Jonathan Tan
2018-10-25  9:14   ` SZEDER Gábor
2018-10-31 13:38   ` Derrick Stolee
2018-11-01 19:13     ` Stefan Beller
2018-10-16 23:35 ` [PATCH 19/19] submodule: don't add submodule as odb for push Stefan Beller
2018-10-19 20:39   ` Jonathan Tan
2018-10-17 12:41 ` [PATCH 00/19] Bring more repository handles into our code base Derrick Stolee
2018-10-17 17:53   ` Stefan Beller
2018-10-18 18:37     ` [RFC PATCH 0/2] Bring the_repository into cmd_foo Stefan Beller
2018-10-18 18:37       ` [RFC PATCH 1/2] repository: have get_the_repository() to remove the_repository dependency Stefan Beller
2018-10-18 18:37       ` [RFC PATCH 2/2 (BREAKS BUILD)] builtin/merge-base.c: do not rely on the_repository any more Stefan Beller
2018-10-18 21:01       ` [RFC PATCH 0/2] Bring the_repository into cmd_foo Jonathan Tan
2018-10-18 23:23         ` Stefan Beller
2018-10-19  7:23 ` [PATCH 00/19] Bring more repository handles into our code base Junio C Hamano
2018-10-22 17:39 ` New semantic patches vs. in-flight topics [was: Re: [PATCH 00/19] Bring more repository handles into our code base] SZEDER Gábor
2018-10-22 18:54   ` Stefan Beller
2018-10-25  1:59     ` SZEDER Gábor
2018-10-25 19:25       ` Stefan Beller
2018-10-22 22:49   ` Junio C Hamano
2018-10-23  0:26     ` Stefan Beller
2018-10-23  4:24       ` Junio C Hamano
2018-10-23  9:38     ` Junio C Hamano
2018-10-23 10:15       ` Carlo Arenas
2018-10-23 10:21         ` Junio C Hamano
2018-10-23 17:30       ` Stefan Beller
2018-10-24  1:22         ` Junio C Hamano [this message]
2018-10-25  5:39   ` Jeff King

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