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#define CONCAT(a, b) a##b
#define CONCAT2(a, b) CONCAT(a, b)
#define STATIC_ASSERT(condition) \
int CONCAT2(some_array, __LINE__)[(condition) ? 1 : -1]
#ifdef _MSC_VER
// Visual Studio
__declspec(align(8)) union some_union1
{
char some;
};
#else
// GCC
union some_union1
{
char some;
} __attribute__((__aligned__(8)));
#endif
// in either case, the union gets bigger!
STATIC_ASSERT(sizeof(union some_union1)==8);
// bit-fields are evil
union some_union2
{
char ch:3;
};
STATIC_ASSERT(sizeof(union some_union2)==sizeof(char));
// bit-fields are evil
union some_union3
{
int i:3;
};
STATIC_ASSERT(sizeof(union some_union3)==sizeof(int));
#ifdef _MSC_VER
// bit-fields are evil
#pragma pack(push, 1)
union some_union4
{
int i:23;
};
#pragma pack(pop)
// Visual Studio ignores the 'packed'
STATIC_ASSERT(sizeof(union some_union4)==sizeof(int));
STATIC_ASSERT(__alignof(union some_union4) == 1);
#else
// bit-fields are evil
union some_union4
{
int i:23;
} __attribute__((__packed__));
STATIC_ASSERT(sizeof(union some_union4)==3);
STATIC_ASSERT(_Alignof(union some_union4) == 1);
#endif
union some_union5
{
int i;
};
#ifdef _MSC_VER
STATIC_ASSERT(__alignof(union some_union5) == 4);
#else
STATIC_ASSERT(_Alignof(union some_union5) == 4);
#endif
#ifdef _MSC_VER
#pragma pack(push, 1)
union some_union6 {
int i;
};
#pragma pack(pop)
// Packing may affect alignment
STATIC_ASSERT(__alignof(union some_union6) == 1);
#else
union some_union6
{
int i;
} __attribute__((__packed__));
// Packing may affect alignment
STATIC_ASSERT(_Alignof(union some_union6)==1);
#endif
int main()
{
}
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