Re: [Cocci] coccinelle: Convert comma to semicolons (was Re: [PATCH] checkpatch: Add test for comma use that should be semicolon)

From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: Joe Perches <joe@perches.com>
Cc: Julia Lawall <julia.lawall@inria.fr>,
	kernel-janitors <kernel-janitors@vger.kernel.org>,
	kernelnewbies <kernelnewbies@kernelnewbies.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Andrew Morton <akpm@linux-foundation.org>,
	cocci <cocci@systeme.lip6.fr>,
	Giuseppe Scrivano <gscrivan@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andy Whitcroft <apw@shadowen.org>
Subject: Re: [Cocci] coccinelle: Convert comma to semicolons (was Re: [PATCH] checkpatch: Add test for comma use that should be semicolon)
Date: Fri, 21 Aug 2020 23:35:38 -0400	[thread overview]
Message-ID: <162653.1598067338@turing-police> (raw)
In-Reply-To: <744af177c09f8ce22c99d6e1df458bced558518b.camel@perches.com>

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On Fri, 21 Aug 2020 18:08:08 -0700, Joe Perches said:
> (forwarding on to kernel-janitors/mentees and kernelnewbies)
>
> Just fyi for anyone that cares:
>
> A janitorial task for someone might be to use Julia's coccinelle
> script below to convert the existing instances of commas that
> separate statements into semicolons.

Note that you need to *really* check for possible changes in semantics.
It's *usually* OK to do that, but sometimes it's not...

for (i=0; i++, last++; !last) {

changing that comma to a ; will break the compile.  In other cases, it can
introduce subtle bugs.

> > I do appreciate that coccinelle adds braces for multiple
> > expression comma use after an if.
> >
> > i.e.:
> > 	if (foo)
> > 		a = 1, b = 2;
> > becomes
> > 	if (foo) {
> > 		a = 1; b = 2;
> > 	}

Yeah.  Like there, if you forget to add the {}.

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