On 03/15/2014 11:26 AM, Hans Verkuil wrote:
> Hi!
>
> I'm trying to cut down the list of sparse warnings and errors I get when
> compiling drivers/media. Most of them are obviously our problem, but there
> is one that seems to be a sparse bug:
>
> drivers/media/v4l2-core/v4l2-dv-timings.c:30:9: error: unknown field name in initializer
>
> This uses the v4l2_dv_timings type which is defined here:
>
> include/uapi/linux/videodev2.h
>
> and which has an anonymous union:
>
> struct v4l2_dv_timings {
> __u32 type;
> union {
> struct v4l2_bt_timings bt;
> __u32 reserved[32];
> };
> } __attribute__ ((packed));
>
> The macro used in the source above comes from this header:
>
> include/uapi/linux/v4l2-dv-timings.h
>
> and is defined as follows:
>
> #if __GNUC__ < 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ < 6))
> /* Sadly gcc versions older than 4.6 have a bug in how they initialize
> anonymous unions where they require additional curly brackets.
> This violates the C1x standard. This workaround adds the curly brackets
> if needed. */
> #define V4L2_INIT_BT_TIMINGS(_width, args...) \
> { .bt = { _width , ## args } }
> #else
> #define V4L2_INIT_BT_TIMINGS(_width, args...) \
> .bt = { _width , ## args }
> #endif
>
> /* CEA-861-E timings (i.e. standard HDTV timings) */
>
> #define V4L2_DV_BT_CEA_640X480P59_94 { \
> .type = V4L2_DV_BT_656_1120, \
> V4L2_INIT_BT_TIMINGS(640, 480, 0, 0, \
> 25175000, 16, 96, 48, 10, 2, 33, 0, 0, 0, \
> V4L2_DV_BT_STD_DMT | V4L2_DV_BT_STD_CEA861, 0) \
> }
>
> The problem is that it seems that sparse follows the old pre-4.6 rules for
> initializing anonymous unions instead of what is actually in the C standard.
>
> If I add ' || defined(__CHECKER__)' to the #if above it will pass without
> generating sparse errors.
>
> Is this something that can be fixed in sparse, or am I forced to add the
> 'defined(__CHECKER__)' to the #if condition?
Here is a simple test case for this problem:
====== anon-union.c ======
struct s {
union {
int val;
};
};
static struct s foo = { .val = 5, };
/*
* check-name: duplicate extern array
*
* check-error-start
* check-error-end
*/
====== anon-union.c ======
Running sparse gives:
anon-union.c:7:26: error: unknown field name in initializer
Regards,
Hans
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