[reitzensteinm]

Could you macroexpand your claims a little here?

"An example of the unaddressed complexity: use of acquire-release semantics for head_ and tail_ atomics imposes no ordering whatsoever between observations of head_ and tail_."

The Acquire / Release in version 4 looks right to me, but I'd like to know if I'm missing something.

Also, while your linked paper is good background for what the C++11 memory model is intended to abstract over, it's almost entirely its own thing with a mountain of complexity.

Somebody else in this comment section brought atomics knowledge to an Acquire/Release fight and it didn't go well.

As a starting introduction I'd probably recommend this:

https://www.amazon.com.au/C-Concurrency-Action-Practical-Mul...

[loeg]

I think he's complaining that because the head_ and tail_ loads in push/pop are relaxed, rather than also being acquire, they can be reordered relative to the acquire tail_ and head_ loads respectively. I don't believe this impacts the correctness of the logic, but I could be missing something.