If it's undefined behavior according to the standard then it's following the standard. You know of course there is a trade-off between the possibility of optim

If it's undefined behavior according to the standard then it's following the standard. You know of course there is a trade-off between the possibility of optimization and strict compliance to a standard with zero or very little undefined behavior. It's wrong to say C is "lost" because of these characteristics. It might not be a good fit for what you want to do, then use whatever you think is best. Just as Rust might be better than C for some cases, the reverse is true for others.