Bug in bitfield handling?

[<Paul_Koning at Dell dot com>]

This seems to be a bug:

struct bug
{
    int f1:1;
    unsigned long long f2:31;
};

struct bug test = { 1, 0x8000ULL };

int main (int c, char **v)
{
    unsigned long long tf2;
    
    tf2 = test.f2 << 16;
    if (tf2 == 0x80000000ULL)
        return 0;
    return 1;
}

Since the underlying type of field f2 is unsigned long long, I would not expect the expression "test.f2 << 16" to do sign extending of a 32 bit intermediate result.  But that is in fact what GCC produces, for x86_64-linux (gcc 4.7.0).

If I explicitly cast test.f2 to unsigned long long before the shift, the expected result appears.  But I shouldn't have to do that cast, given that the type of f2 is already unsigned long long, correct?

	paul