gcc optimization? bug? and its practial implication to project

Question

My questions are divided into three parts

Question 1
Consider the below code,

#include 
using namespace std;

i         


        

Answer 1

It's a known problem, and I don't think it's considered a bug in the compiler. When I compile with gcc 4.5 with -Wall -O2 it warns

warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false

Although your code does overflow.

You can pass the -fno-strict-overflow flag to turn that particular optimization off.