> Concurrency is not special here
I beg to differ. Concurrency comes with its own bag of hazards, as I mentioned in my reply to burntsushi. Comparing its invariants with Vec's length invariant/HashMap's RH invariant, and any other single threaded/internal invariants misses the point.
Unsafe discussions that I've seen rarely talk about fences - they tend to focus on raw pointer ops, ffi, transmutes, unbound lifetimes, and in general, are single thread focused.
Unsafe discussions that I've seen rarely talk about fences - they tend to focus on raw pointer ops, ffi, transmutes, unbound lifetimes, and in general, are single thread focused.