> In Rust all of those features are delineated by unsafe.
They're also delineated in Zig, just not with a single keyword. Extern unions, unknown-length arrays, and sentinel-terminated arrays are features, with clear syntax, used for C interop only.
> It's obvious that full spatial memory safety just isn't a design goal of Zig.
It's as much of a goal in Zig as it is in Rust; both allow circumventing it with clearly marked unsafe features.
> Which is the same goal that, for example, the C++ STL has. It's a great goal, but it shouldn't be confused with Rust's goal.
You're confusing means and end. No one's ultimate goal is having this feature or another. Both Zig and Rust have, as one primary goal, helping write correct software. They just try to achieve it in different ways. Why is that good? Because we have no idea what is the most effective way of achieving that goal, so we try different approaches.
> It's my opinion in the same sense that it's my opinion that wearing seatbelts results in fewer deaths on the road.
I don't think so, because seatbelts have few accident-related downsides, while a complex language has many.
> Anyone arguing otherwise has a massive burden of proof.
I'm not arguing against seatbelts. Anyone who claims that X leads to more correct programs than Y -- not by looking at this or that property, but as a whole -- has a massive burden of proof. I am not claiming Zig is more effective at writing correct programs than Rust. After years exploring issues in software correctness -- including with different formal methods -- my claim, which is closer to consensus than controversy, is that we simply don't know. We don't know which of Zig's or Rust's approaches leads to more software, and therefore we cannot say which of those approaches is preferable, even if correctness is the main thing we care about.
> And the arguments I've seen by people arguing that you don't need temporal memory safety are weak. The idea that a simple language that doesn't have ironclad safety guarantees reduces errors over a more complex language with those guarantees sounds nice in theory, but it hasn't actually turned out that way in practice.
We simply don't know either way. We might know that a language with ironclad guarantees leads to more correct software than C, but given that Zig is as different from C as Rust is -- and as different as they are to each other -- there's nothing that allows us to extrapolate.
Your argument amounts to, "my way is the best way", and your evidence is irrelevant extrapolations. One could then ask, if Rust's design is so great, how come, at its not-so-young age -- which is quickly nearing the age at which all languages (with the possible exception of Python) have reached or approached their all-time peak popularity -- so few people use it? Could it be that there's no "room" for it? (I'm not saying that's the case at all -- I think Rust, like Zig, is a very interesting language.) Its low popularity certainly makes claims along the lines of, "the design of this language is obviously the only design for which there's room in 2022," ring quite hollow. There's no room for anything other than an approach whose success is so uncertain? Really? Given that Rust has proven quite the opposite of an overnight success, I think some humility about its design choices is appropriate.