[Spice-devel] [PATCH x11spice] Fix compliation on gcc 4.X.

[Uri Lublin]

On 3/11/20 9:10 PM, Jeremy White wrote:
> Hi,
> 
> I'm afraid that does not help on the gcc 4.8.5 on RHEL 7.X, particularly 
> with structures that contain other structures.
> 
> gcc -Wall -DTHREE -o /dev/null -c test.c
> test.c: In function ‘handle_sigterm’:
> test.c:12:12: warning: missing braces around initializer [-Wmissing-braces]
>       struct sigaction act = { 0 };

missing-braces --> it works with { {0} };

I guess when using a RHEL-7 gcc (version 4.x) there is a difference
between struct and union (or other non-simple structures).

With my test program there is no problem with RHEL-7 gcc with either {0} 
and {0,}

I see there already exists { } initialization for a struct sigaction in 
the code.

Also the code in src.c below fails to compile for me with missing-braces 
too (which may solved by {{0}}).

To summarize, I'm OK with this patch.

Uri.

>              ^
> test.c:12:12: warning: (near initialization for 
> ‘act.__sigaction_handler’) [-Wmissing-braces]
> 
> Attached is the test program.
> 
> Cheers,
> 
> Jeremy
> 
> On 3/11/20 1:27 PM, Uri Lublin wrote:
>> Hi,
>>
>> Thanks for the ping on IRC.
>>
>> On 9/17/19 7:23 PM, Jeremy White wrote:
>>> gcc 4.x warns if you use a { 0 } initialization construct
>>> for a structure with an initial member that is also a struct.
>>>
>>> The { } construct is simpler and appears to work on a wider
>>> range of gcc versions.
>>
>> On my Fedora 31, gcc (version 9.2.1) does complain about {} but not 
>> about {0}
>> when built with -Wpedantic (see simple program below).
>>
>>
>> Does {0, } works better for you ?
>>
>>
>> ================
>>
>> #include <stdio.h>
>>
>> struct S {int a, b; };
>>
>> void print_s(struct S* ps)
>> {
>>      if (!ps) { printf("null\n"); return; }
>>      printf("(%d, %d)\n", ps->a, ps->b);
>> }
>>
>> int main ()
>> {
>>          struct S s = { };
>>
>>          print_s(&s);
>>      return 0;
>> }
>>
>>
>> ================
>>
>> Uri.
>>
>>>
>>> This is a correction to fdfdf1107be100b983de1bff4beee8e6360f670b
>>>
>>> Signed-off-by: Jeremy White <jwhite at codeweavers.com>
>>> ---
>>>   src/gui.c    | 2 +-
>>>   src/listen.c | 2 +-
>>>   src/main.c   | 2 +-
>>>   src/spice.c  | 2 +-
>>>   4 files changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/src/gui.c b/src/gui.c
>>> index 88acf5c9..3c26b864 100644
>>> --- a/src/gui.c
>>> +++ b/src/gui.c
>>> @@ -147,7 +147,7 @@ void session_disconnect_client(session_t *session)
>>>   int main(int argc, char *argv[])
>>>   {
>>>       gui_t gui;
>>> -    session_t session = { 0 };
>>> +    session_t session = { };
>>>       setlocale(LC_ALL, "");
>>>       gui_create(&gui, &session, argc, argv);
>>> diff --git a/src/listen.c b/src/listen.c
>>> index 452fd81f..76c0798a 100644
>>> --- a/src/listen.c
>>> +++ b/src/listen.c
>>> @@ -117,7 +117,7 @@ int listen_parse(const char *listen_spec, char 
>>> **addr, int *port_start, int *por
>>>   static int try_port(const char *addr, int port)
>>>   {
>>>       static const int on = 1, off = 0;
>>> -    struct addrinfo ai = { 0 }, *res, *e;
>>> +    struct addrinfo ai = { }, *res, *e;
>>>       char portbuf[33];
>>>       int sock, rc;
>>> diff --git a/src/main.c b/src/main.c
>>> index 71cbb465..890ff133 100644
>>> --- a/src/main.c
>>> +++ b/src/main.c
>>> @@ -55,7 +55,7 @@ int main(int argc, char *argv[])
>>>   {
>>>       int rc;
>>> -    session_t session = { 0 };
>>> +    session_t session = { };
>>>       int display_opened = 0;
>>>       int spice_started = 0;
>>> diff --git a/src/spice.c b/src/spice.c
>>> index 08a5d09a..561c85ff 100644
>>> --- a/src/spice.c
>>> +++ b/src/spice.c
>>> @@ -474,7 +474,7 @@ static int send_monitors_config(spice_t *s, int 
>>> w, int h)
>>>   int spice_create_primary(spice_t *s, int w, int h, int 
>>> bytes_per_line, void *shmaddr)
>>>   {
>>> -    QXLDevSurfaceCreate surface = { 0 };
>>> +    QXLDevSurfaceCreate surface = { };
>>>       surface.height = h;
>>>       surface.width = w;
>>>
>>
>