It will force your code to be memory safe, but it can't enforce that you have the correct semantics.

https://doc.rust-lang.org/std/sync/atomic/fn.fence.html exists, but Rust can't force you to say, use the correct ordering.

Right, so no different than C in this regard.

Really, you should rarely be using raw memory barriers even in C, IMO. The C11/C++11 atomics model (which Rust also uses) is substantially nicer. Though, unfortunately, still extremely tricky to get right.

The only time that I ever had to worry about that was when writing drivers for the Linux kernel.