On Fri, Dec 07, 2018 at 09:31:06AM -0200, Mauro Carvalho Chehab wrote:
> Em Fri, 7 Dec 2018 12:14:50 +0100
> Hans Verkuil <hverkuil@xxxxxxxxx> escreveu:
>
> > On 12/07/2018 11:56 AM, Mauro Carvalho Chehab wrote:
> > > A common mistake is to assume that initializing a var with:
> > > struct foo f = { 0 };
> > >
> > > Would initialize a zeroed struct. Actually, what this does is
> > > to initialize the first element of the struct to zero.
> > >
> > > According to C99 Standard 6.7.8.21:
> > >
> > > "If there are fewer initializers in a brace-enclosed
> > > list than there are elements or members of an aggregate,
> > > or fewer characters in a string literal used to initialize
> > > an array of known size than there are elements in the array,
> > > the remainder of the aggregate shall be initialized implicitly
> > > the same as objects that have static storage duration."
> > >
> > > So, in practice, it could zero the entire struct, but, if the
> > > first element is not an integer, it will produce warnings:
> > >
> > > drivers/staging/media/sunxi/cedrus/cedrus.c:drivers/staging/media/sunxi/cedrus/cedrus.c:78:49: warning: Using plain integer as NULL pointer
> > > drivers/staging/media/sunxi/cedrus/cedrus_dec.c:drivers/staging/media/sunxi/cedrus/cedrus_dec.c:29:35: warning: Using plain integer as NULL pointer
> > >
> > > A proper way to initialize it with gcc is to use:
> > >
> > > struct foo f = { };
> > >
> > > But that seems to be a gcc extension. So, I decided to check upstream
> >
> > No, this is not a gcc extension. It's part of the latest C standard.
>
> Sure? Where the C standard spec states that? I've been seeking for
> such info for a while, as '= {}' is also my personal preference.
>
> I tried to build the Kernel with clang, just to be sure that this
> won't cause issues with the clang support
My test says that clang works with {}.
I support this in Smatch as well.
regards,
dan carpenter
