[PATCH] Fix for bug 11684

[Ralph Boehme]

On Thu, Jan 21, 2016 at 01:06:37PM -0800, Jeremy Allison wrote:
> On Thu, Jan 21, 2016 at 09:25:53PM +0100, Michael Adam wrote:
> > On 2016-01-21 at 20:50 +0100, Volker Lendecke wrote:
> > > On Thu, Jan 21, 2016 at 08:45:42PM +0100, Ralph Boehme wrote:
> > > > > {} is non-standard, other compilers will not accept this.
> > > > 
> > > > We use it all over the place.
> > > 
> > > Ok, sorry for the noise. We should go through and convert
> > > all the {0} that we already have to {}. We should at least
> > > be consistent.
> > 
> > From a quick git grep, we seem to use
> > 
> > - { 0 }  in 91 places
> > - { 0, } in 72 places
> > - { }    in 7 places
> > 
> > So yes, we should systematize, but probably not to {} ... :-)
> 
> As I recall, the (broken) gcc version we have wants a sub-{}
> for every internal struct inside the struct we're initializing.
> That correct ?

Not quite. It wants a sub {} when the first member is of complex type.

The gcc version doesn't suffer from this anymore so I didn't spot the
issue.

$ cat ~/files/test.c
struct foo {
        char c[2];
        int i;
};

struct bar {
        int i;
        char c[2];
};

struct struct1 {
        struct foo foo;
        int i;
};

struct struct2 {
        int i;
        struct foo foo;
};

int main(int argc, char **rgv)
{
        struct foo foo = { 0 };
        struct bar bar = { 0 };
        struct struct1 struct1 = { 0 };
        struct struct2 struct2 = { 0 };

        return 0;
}

$ gcc --version
gcc (GCC) 5.3.1 20151207 (Red Hat 5.3.1-2)
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc -Wmissing-braces /home/ralph/files/test.c -o test
$

On sn-devel144:

$ gcc --version
gcc-4.8.real (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc -Wmissing-braces -o test test.c
test.c: In function ‘main’:
test.c:23:10: warning: missing braces around initializer [-Wmissing-braces]
   struct foo foo = { 0 };
          ^
test.c:23:10: warning: (near initialization for ‘foo.c’) [-Wmissing-braces]
test.c:25:10: warning: missing braces around initializer [-Wmissing-braces]
   struct struct1 struct1 = { 0 };
          ^
test.c:25:10: warning: (near initialization for ‘struct1.foo’) [-Wmissing-braces]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119

Backports of the fix are available but apparently not included in the
Ubuntu version.

Imho we should for now just use {}, it seems all relevent compiler
support this non-standard form.

-Ralph

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de,mailto:kontakt@sernet.de