> Modern C# has next to no undefined behavior, you can disregard the managed features and write low level code with it, and it JIT-compiles nearly as efficientl

> Modern C# has next to no undefined behavior, you can disregard the managed features and write low level code with it, and it JIT-compiles nearly as efficiently as C. The calculus for memory-safe languages is completely different. They are not allowed to perform arbitrary, unchecked, out-of-bounds writes, so optimizations assuming those writes don't exist are sound without UB. If you mix them with an unsafe language or component that can use raw pointers, that part of the language has a lot of the same UB that C does, or else it would invalidate optimizations in the managed part of the language. If you've ever seen C++ code that needs to interact with a managed runtime, you're well aware of how careful the unmanaged part has to be to avoid treading on runtime invariants. Anyway I'm not defending C here. I'm defending UB. It exists in the language for a reason, which is that it's not meaningfully possible to optimize programs without it. If people don't want to deal with it, they should use another language that isn't C. That doesn't mean that the amount of UB in C couldn't be greatly reduced, but the article is responding to people who claim that a modern optimizing C compiler could reasonably avoid non-"platform specific" UB altogether.