[tardedmeme]

Every implementation so far has predictable behavior in all cases. Sometimes the rules for predicting it are very obscure. But it's all fully defined within the compiler's binary code. And none of them link to nasal portals.

[AlotOfReading]

How do you propose to predict the behavior of a true race condition with only the binary, faithfully translated by the compiler?

Moreover, this is at best an incredibly pedantic point, not something that changes how programmers need to approach UB. You can't review the source code of a compiler that hasn't been written yet.

[munch117]

I didn't suggest that implementations should entirely eliminate every form of UB. There is plenty of middle ground. For example, you could easily limit the consequences of integer overflow by specifying or partially specifying overflow behaviour, with very little runtime cost.

I'm not suggesting you change how you write code, but with a better implementation the code that you do write - that lives in the real world where mistakes are made - might work better. How is that being pedantic?

An interesting case where compiler writers did something like that is casting via union members, but I'm running out of time, so we can talk about that another day.

[tardedmeme]

It's fully defined by your CPU's silicon masks and your compiler's binary code that one of several things will happen.

[tsukikage]

Turns out that when you're implementing network applications, the set of things that could happen also depends on what the script kiddie on the other side of the globe feels like this morning.

Some would prefer less excitement than this.

C code should be more predictable and easier to reason about than using a macro assembler. To the extent it is not, the language has failed.

[PaulRobinson]

Given that it sits at the heart of the network stack, kernel and device drivers for every major operating system, is in many, many embedded devices in the World around us, and is responsible for making decent chunk of the global economy keep moving, that’s quite a failure case.

Perhaps some professional programmers know how to write secure software in a language with undefined behaviour. Maybe we should think about that more rather than just writing off an obviously huge success as a failure?