No useful and reliable way to detect integer overflow in C/C++?

Question

No, this is not a duplicate of How to detect integer overflow?. The issue is the same but the question is different.

---

The gcc compiler can optimize away an

Answer 1

Just use the correct type for b:

int a;
unsigned b = a;
if (b == (unsigned)INT_MIN) printf("overflow");  // never optimized away
else b = abs(a);

Edit: Test for overflow in C can be safely done with the unsigned type. Unsigned types just wrap around on arithmetic and signed types are safely converted to them. So you can do any test on them that you like. On modern processors this conversion is usually just a reinterpretation of a register or so, so it comes for no runtime cost.