How to implement opCmp?

[Patrick Schluter via Digitalmars-d-learn]

On Tuesday, 13 June 2017 at 16:49:14 UTC, H. S. Teoh wrote:
> On Tue, Jun 13, 2017 at 10:51:40AM -0400, Steven Schveighoffer 
> via Digitalmars-d-learn wrote: [...]
>> I think Andrei has a nice way to do opCmp for integers that's 
>> a simple subtraction and negation or something like that.
> [...]
>
> In theory, cmp(int x, int y) can be implemented simply as (x - 
> y).
> However, this fails when integer overflow occurs.  Does Andrei 
> have a
> nice way of doing this that isn't vulnerable to integer 
> overflow?
>

return (x > y) - (x < y);

According to this stackoverflow question it looks like a good 
candidate
https://stackoverflow.com/questions/10996418/efficient-integer-compare-function