One other version of the same problem: array members do not obey the alignment on Windows:

#include

using namespace std;

class __declspec(align(16,0)) Vector
{
public:
float f[3];
};

int main()
{
cout << sizeof(Vector) << endl;

Vector v;
cout << &v << endl;

Vector vv[2];
cout << sizeof(vv) << endl;
cout << &vv[0] << endl;
cout << &vv[1] << endl;

return 0;
}

On linux, you get:
annwn:~> icc -o b b.cc; b
16
bffff670
32
bffff680
bffff690

So sizeof(Vector) is 16, and array members stay aligned.
On Windows, you get 12 for sizeof(Vector), and array members are not aligned.

???

TIA

(Note: I will post one other problem related to this...)

After adding enough headers to compile, my Intel 7.0 Windows and linux compilers give sizeof's 32 and 48, and all pointers 16-byte aligned. Likewise, g++ on linux, with the declspec()'s removed to permit compilation, does the same, as do both Intel compilers.

g++ complains the headers required by the Intel compilers aren't standard compliant, but it accepts them on linux. On Windows, my g++ rejects any close variant of your code.

I've seen cases where Intel compilers don't align properly without use of declspec(), but this is not among them. I don't know how the extreme confusion caused by declspec() is to be resolved, but I would avoid it where it's unnecessary.

Now, on Windows:
icl 7.0 result:
16
32
0x0012FF40
0x0012FF50
0x0012FF60
0x0012FF70

gcc-3.2 result:
11: warning: 'align' attribute directive ignored

16
24
0x22feb8
0x22fec0
0x22fed0
0x22fed8