On 05/10/2011 07:45 AM, Victor wrote:
> I want to build the linux kernel at O0 optimize level. The first problem
> that I face was something about constant.
> I have study it for a day time, but it haven't sovled.
> There is the problem.
>
> #include <stdio.h>
>
> int main()
> {
> int *map;
> const size_t size = 128 * sizeof(map[0]);
>
> ((void)(sizeof(struct { int:-!!(size > ((1UL) << 12)); })));
> }
>
> When I compile this program use gcc test.c, it fail with
> test.c: In function âmainâ:
> test.c:8:24: error: bit-field â<anonymous>â width not an integer
> constant
>
> When I compile this program use gcc test.c -O, it success.
>
> Because I want to debug the linux kernel, how can compile the test
> program above don't use O1 O2 O3.
I can't think of any way of doing this. The field width expression
isn't an integer constant expression, as required by the standard.
It should be
#include <stdio.h>
int main()
{
int *map;
#define size (128 * sizeof(map[0]))
((void)(sizeof(struct { int:-!!(size > ((1UL) << 12)); })));
}
Andrew.
