https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65033
--- Comment #9 from Bin Fan <bin.x.fan at oracle dot com> ---
I verified this bug is fixed in 5.1.0. However, it is only fixed in g++, so now
in 5.1.0, gcc and g++ reports different result:
-bash-4.1$ cat is_lock_free.c
#include <stdatomic.h>
#include <stdio.h>
#define N 10
typedef struct {
char a[3];
} s3_t;
_Atomic s3_t array[N];
s3_t obj;
int main()
{
int i;
for (i=0;i<N;i++) {
printf ("%x\t", &array[i]);
printf("%d\n", atomic_is_lock_free (&array[i]));
}
for (i=0;i<N;i++) {
atomic_store (&array[i], obj);
}
return 0;
}
gcc -latomic is_lock_free.c
./a.out
20ff7 0
20ffa 1
20ffd 1
21000 1
21003 1
21006 0
21009 1
2100c 1
2100f 0
21012 1
-bash-4.1$ cat is_lock_free.cc
#include <atomic>
#include <stdio.h>
using namespace std;
#define N 10
struct s3_t {
char a[3];
};
atomic<s3_t> array[N];
s3_t obj;
int main()
{
int i;
for (i=0;i<N;i++) {
printf ("%x\t", &array[i]);
printf("%d\n", atomic_is_lock_free (&array[i]));
}
for (i=0;i<N;i++) {
atomic_store (&array[i], obj);
}
return 0;
}
g++ -std=c++11 -latomic is_lock_free.cc
./a.out
21524 0
21527 0
2152a 0
2152d 0
21530 0
21533 0
21536 0
21539 0
2153c 0
2153f 0
Isn't the difference between C and C++ still a problem?
