Re: New semantic patches vs. in-flight topics [was: Re: [PATCH 00/19] Bring more repository handles into our code base]

Stefan Beller [off-list ref] writes:

quoted

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 <redacted>
---
 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