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I am aware but without a spec we don’t know which is which. You can’t say it has no undefined behavior because what happens is you try to specify it and find ga
by monkeyelite 1y ago
I am aware but without a spec we don’t know which is which. You can’t say it has no undefined behavior because what happens is you try to specify it and find gaps or challenges.
In C undefined is used primarily when there is not a reliable and efficient mechanism for detecting a problem is happening. For example a C implementation may check every single invalid pointer deref, but more realistically it only detects only extreme out of range. So it’s undefined what happens.
- Yoric 1y agoGood point. That being said, at least in C++, undefined has been used largely as a joker for compiler optimizations. In Rust, if my memory serves, having the same code produce different results depending on the optimization level would be considered a pretty serious bug. In C++, it's par for the course.
- aw1621107 1y ago> I am aware but without a spec we don’t know which is which. I don't think I fully agree with this. A more accurate statement might be that "without a spec we don't always know which is which". You obviously don't need a spec to pin down at least some of a language's behavior, and even then the presence of a spec doesn't necessarily mean that you can answer arbitrary questions about what behavior is intended (c.f., various defect reports in the C/C++ spec asking clarifying questions, pointing out holes/deficiencies, or even admitting that certain behavior is not intended but being unsure about how to forbid it)