alt Hacker Newssigned overflow (or underflow) is frequently undefined behavior. (often because it's undefined in C)
unsigned is frequently defined. (often because it's defined in C)
tough choice.
(honestly I just lean towards "over/underflow should raise unless explicitly allowed", the ratio of unintended to intended-and-fully-checked overflow behavior is almost certainly FAR beyond 100:1)
Of course unsigned is defined. That's besides the point. The point is: how often in your code, do you expect 1 minus 2 to equal a very large number, vs. the number -1.