I don’t think you are clarifying them so much as misreading them.

I'm confused by the second paragraph of your response. My point was that the lack of an explicit 'unsafe' block in Go isn’t that much of an issue, as pretty much everyone knows that Go does not make any memory safety guarantee when accessing shared state from different Goroutines. Anyone who doesn’t know this isn’t ready to get their head around writing multithreaded code in Rust. Rust’s features for doing this are cool, but they require a pretty good understanding of Rust’s complex type and lifetime system.

What a strange argument. "Pretty much everyone knows" that C/C++ aren't memory safe even for sequential code, and that it's incredibly easy to trigger thread-safety bugs in C/C++. But since "pretty much everyone knows", I suppose that makes it OK?

> Anyone who doesn’t know this isn’t ready to get their head around writing multithreaded code in Rust.

Well, if they aren't using `unsafe` in the process (or, to be fair, relying on buggy library code that uses `unsafe` inappropriately), they're not going to introduce memory unsafety via data races - no matter how "ready" they are. You just can't say the same about C/C++. Or even Go.

I don’t recommend that people use Go to write complex multithreaded code that accesses shared state. My point is that I doubt many people are doing this while erroneously thinking that their code is guaranteed to be memory safe. In other words, whatever the problems with Go may be in this regard, it’s not primarily the absence of an ‘unsafe’ keyword that’s the issue.

> I don’t recommend that people use Go to write complex multithreaded code that accesses shared state. My point is that I doubt many people are doing this while erroneously thinking that their code is guaranteed to be memory safe. In other words, whatever the problems with Go may be in this regard, it’s not primarily the absence of an ‘unsafe’ keyword that’s the issue.

I think the point here is that if the word "unsafe" exists as a language construct, someone is not wrong in assuming anything without that mark is safe. Otherwise, why isn't there a "safe" language construct?

That’s true to an extent, but it’s important to bear in mind that you can’t lexically scope memory unsafety. Rust code that doesn’t contain an 'unsafe' block should be safe assuming that all of the libraries it’s built on are safe. But those libraries may well contain 'unsafe' blocks that are (one hopes) carefully written to be memory safe.