core.atomic bug? windows 2008r2 dmd 2.69.2 x64

[sdv via Digitalmars-d]

struct sts
{
        size_t a1;
        struct m1{
                size_t a9;
                size_t a10;
        }
        shared m1       t1;
}

int main(string[] argv)
{

        auto y1 = new sts();
        cas(&y1.t1,y1.t1,y1.t1);

    return 0;
}