typedef struct
{
  int bla_u32;
  short bla_u16;
  char bla_u8;

  /* <-- this gap will be filled in the unpacked version */
}  uneven;

#define StaticAssert(cond, msg) switch(0){case 0:case cond:;}

void checkSizes()
{
  uneven unpacked;
#pragma pack(push, 1)
typedef struct
{
  int bla_u32;
  short bla_u16;
  char bla_u8;

  /* <-- this gap will be filled in the unpacked version */
}  uneven;
#pragma pack(pop)
  uneven packed;
  StaticAssert(sizeof(unpacked) == sizeof(packed), "uneven contains gaps");
}