From the link I posted, from cpp reference, which gives a definition for what constitutes undefined behavior:
>> ill-formed, no diagnostic required - the program has semantic errors which may not be diagnosable in general case… The behavior is undefined if such program is executed
And as for the rest of your argument, you still haven’t answered the one question that matters. Is an executable file with machine code well-defined? If it is, then once you compile a C++ program, the generated binary is well-defined. And once again, all the superfluous arguments about what could happen are irrelevant when there’s no context provided. There’s lots of different types of undefined behavior. An integer overflow by itself does not make your program susceptible to remote code execution. It’s the fact that the integer overflow gets stored in a register that later gets used to write to invalid memory, and then that invalid memory has harmful code injected into it that gets executed.
We should strive to engineer correct software. I agree. It’s all this hand waving about how all undefined behavior is equal that irks me. Because it’s not true, as evidenced by the example listed above about the program that’s “technically” ill-formed C++, but in practice compiles to a harmless program. Engineering requires an understanding of what could go wrong and why. Blindly fretting about all undefined behavior is useless and doesn’t lead to any sort of productive debates.
Engineering is all about understanding tradeoffs. Which is one of the reasons the C++ spec does not define everything in the first place. The fact that in 2023 people don’t understand that all decisions in software come with a tradeoff is lunacy. And once again, I agree that undefined behavior is bad, but to pretend that the existence of IFNDR means the whole language is unusable is silly. People use C++ everyday, and have been for almost 40 years. I’d like more productive conversations on how rust protects the user from the undefined behavior that makes an impact, not about how it doesn’t have IFNDR because that’s irrelevant to the conversation entirely.