linux-kernel - Re: [PATCH] checkpatch: prefer = {} initializations to = {0}

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Message-ID: <83ffab14de1c2af00d38d532ffecdda1f9e936ab.camel@perches.com>
Date:   Thu, 05 Aug 2021 11:28:14 -0700
From:   Joe Perches <joe@...ches.com>
To:     Julia Lawall <julia.lawall@...ia.fr>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Andy Whitcroft <apw@...onical.com>,
        cocci <cocci@...teme.lip6.fr>,
        Dwaipayan Ray <dwaipayanray1@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] checkpatch: prefer = {} initializations to = {0}

On Thu, 2021-08-05 at 20:17 +0200, Julia Lawall wrote:
> On Thu, 5 Aug 2021, Joe Perches wrote:
> > On Thu, 2021-08-05 at 05:27 -0700, Joe Perches wrote:
> > > On Thu, 2021-08-05 at 13:43 +0300, Dan Carpenter wrote:
> > > > The "= {};" style empty struct initializer is preferred over = {0}.
> > > > It avoids the situation where the first struct member is a pointer and
> > > > that generates a Sparse warning about assigning using zero instead of
> > > > NULL.  Also it's just nicer to look at.
> > 
> > Perhaps a cocci script like the below could help too:
> > 
> > $ cat zero_init_struct.cocci
> > @@
> > identifier name;
> > identifier t;
> > @@
> > 
> > 	struct name t = {
> > -	       0
> > 	};
> > 
> > @@
> > identifier name;
> > identifier t;
> > identifier member;
> > @@
> > 
> > 	struct name t = {
> > 	       ...,
> > 		.member = {
> > -		0
> > 		},
> > 		...,
> > 	};
> 
> My test turns up over 1900 occurrences.  There is the question of whether
> {} or { } is preferred.  The above semantic patch replaces {0} by {} and
> ( 0 } by { }.

I saw that and I don't recall how to force one style or another
to be output.