From Timon Gehr:
```
#include <stdio.h>
struct __attribute__((packed)) S{
     long long x:8;
};
int main(){
     printf("%ld\n",sizeof(long long)); // 8
     printf("%ld\n",sizeof(struct S)); // 1
}
```
gcc gives 8 and 1, dmd gives 8 and 8.