> Undefined behavior allows the compiler to handle those cases as errors (e.g. print stack trace and crash). Or to perform static analysis. Or, to do something

> Undefined behavior allows the compiler to handle those cases as errors (e.g. print stack trace and crash). Or to perform static analysis. Or, to do something predictable. In practice, no existing compiler that I'm aware of issues a stack trace on undefined behavior at runtime. Instead, the compiler reasons from the perspective that if a section of code would have undefined behaviour under some set of circumstances, it will assume that those circumstances will never occur, and optimize accordingly (with sometimes surprising results).