gcc/testsuite/gcc.dg/bf-ms-layout-3.c

/* Test for MS bitfield layout */
/* { dg-do run { target *-*-mingw* *-*-cygwin* i?86-*-* x86_64-*-* } } */

extern void abort();

struct s1_t {
    char a;
    char b __attribute__ ((aligned (16)));
} __attribute__ ((ms_struct));
struct s1_t s1;

struct s2_t {
  char a;
  char b;
} __attribute__ ((ms_struct));
struct s2_t s2;

struct s3_t {
  __extension__ char a : 6;
  char b __attribute__ ((aligned (16)));
} __attribute__ ((ms_struct));
struct s3_t s3;

struct s4_t {
  __extension__ char a : 6;
  char b __attribute__ ((aligned (2)));
} __attribute__ ((ms_struct));
struct s4_t s4;

struct s5_t {
  __extension__ char a : 6;
  char b __attribute__ ((aligned (1)));
} __attribute__ ((ms_struct));
struct s5_t s5;

__extension__
static __PTRDIFF_TYPE__ offs (const void *a, const void *b)
{
  return (__PTRDIFF_TYPE__) ((const char*)a  - (const char*)b);
}

int main()
{
  if (offs (&s1.b, &s1) != 16
      || offs (&s2.b, &s2) != 1
      || offs (&s3.b, &s3) != 16
      || offs (&s4.b, &s4) != 2
      || offs (&s5.b, &s5) != 1)
    abort ();
  return 0;
}