bt

static void test(T)()
{
    const mn = T.min, mx = T.max;
    enum nBits = 8*T.sizeof;
    foreach (const ix; 0 .. nBits-1)
    {
        assert(!mn.bt(ix));
    }
    assert(mn.bt(nBits - 1));
    foreach (const ix; 0 .. T.sizeof)
    {
        assert(mx.bt(ix));
    }
}
test!byte;
test!short;
test!int;
test!long;