Earlier quoted context omitted.
What’s a workaday hacker and what’s UB?
UB = undefined behaviour. You can write code that is valid as in "can be compiled" but outside of C++ standard. It is duty of programmer to not have those, as compiler usually assumes that there's no UB in your code and can do unintuitive things with optimizations. e.g int foo(int8_t x) { x += 120 return x; } int bar(int8_t y) { int z = foo(y); if (y > 8) { do_important_thing(z); } } `do_important_thing` may be optim…
To be pedantic, C has no 8- or 16-bit addition operators, since everything sub-int is scaled up to int to do arithmetic. Therefore, the `x += 120;` line never overflows, since it is actually `x = (int8_t)((int)x + 120);`, and the possible range of `(int)x + 120` is comfortably within the range of expressible ints, while the conversion to int8_t is defined to wrap around when oversized. So there compiler can't optimize out do_important_thing in your example.