linux-kernel - Re: [PATCH RFC] checkpatch: flag split arithmetic operations with CHECK

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Date:	Tue, 5 May 2015 16:08:57 +0200
From:	Nicholas Mc Guire <der.herr@...r.at>
To:	Andy Whitcroft <apw@...onical.com>
Cc:	Nicholas Mc Guire <hofrat@...dl.org>,
	Joe Perches <joe@...ches.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] checkpatch: flag split arithmetic operations with
	CHECK

On Tue, 05 May 2015, Andy Whitcroft wrote:

> On Tue, May 05, 2015 at 10:53:36AM +0200, Nicholas Mc Guire wrote:
> > Simple arithmetic operations should be on one line, if they can be fit,
> > rather than splitting at the operator. As this is not in the CodingStyle it 
> > is limited to --strict use of checkpatch.pl and emits a CHECK only.
> > 
> > Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> > ---
> > 
> > Patches by people like me splitting arithmetic operations, e.g.:
> >                        hdw->encoder_run_timer.expires = jiffies +
> >                                 msecs_to_jiffies(TIME_MSEC_ENCODER_OK);
> > were flagged by Joe Perches but checkpatch.pl was not fussing, not even
> > with --strict. This extension should flag such lines as CHECK only, as 
> > this is not mandated by the CodingStyle and in some cases they are 
> > justified (e.g. kernel/sched/fair.c:760 and a few other examples in that
> > file)
> > 
> > Limitation: this is for + and - only still have to figure out some false
> >             positives for the * and /, % ($Arithmetic) case.
> 
> I assume that these relate to being able to confirm the variant of the
> operator, unary/binary etc.  If you look for "annotate_values", after
> that is run there is additional information for each character of the
> current line, tracking the type of the operator.  This is used when
> determining spacing for + etc later as unary ones are typically tight
> bound and binary ones spaced out.  You might find that useful, if that
> is your issue.  And indeed you might find it useful for determining if
> the +/- you find at line end is indeed unary.  Running with --debug
> values=1 should dump out the variants information for those.
>
thanks - looks like a useful (somewhat cryptic) starting point

15 > .  x = y - x
15 > EEEVVNNVVNNTTT
15 >  ________B____

will give it a try to generalize it for all basic binary operators.

thx!
hofrat 
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