Is this a bug in bitwise arithmetic?

default
{
    state_entry()
    {
        integer test = 2147483647;
        llOwnerSay("Starting with " + (string)test);
        test = test << 1;
        llOwnerSay("After shift left, " + (string)test);
        test = test >> 1;
        llOwnerSay("After shift right, " + (string)test);
    }
}

The output is:

Starting with 2147483647. After shift left, -2. After shift right, -1.

Now, I can understand why shifting left would give -2 - the leftmost binary 1 is shifted into the sign bit. But surely in that case, shifting right again should shift that 1 back out of the sign bit and restore 2147483647 back? Is this a new bug?

Weird but right - it's treating it as -2 divided by 2 and extending the sign bit.

http://en.wikipedia.org/wiki/Arithmetic_shift

After shift left, that's correct because 0xfffffffe is the two's complement representation for -2. Integers in LSL are signed. I don't believe there's any support for 32-bit unsigned numbers.

And after shift right, yes it's also correct assuming the right shift is a numeric shift, not a logical one -- due to sign bit propagation.

The results are what I'd expect; except that a shift right could be either signed or logical. IIRC, in C/C++, shifts on signed integers are arithmetic and do sign propagation; on unsigned integers it's logical (because there is no sign bit).