[libcxx-commits] [libcxx] [libcxx] Implementation of P1831R1 (PR #101439)

[Hristo Hristov via libcxx-commits]

Zingam wrote:

> [P1831R1](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1831r1.html) introduces 2 key sets of changes:
> 
> 1. Remove volatile variants of `tuple_size`, `tuple_element`, `variant_size`, and `variant_alternative`.
> 2. Require that the volatile overload of many methods of `atomic<T>` require that `atomic<T>::is_always_lock_free` is true.
> 
> In the case of (2) I am wondering if this should be feature gated? Currently it will add the restriction regardless of `_LIBCPP_STD_VER` - should I gate this to versions >= 20?
> 
> I'm also unsure if I'm supposed to update the status page myself, and I also wonder if I am meant to update the synopses for the modified modules?

Yes + tests?

https://github.com/llvm/llvm-project/pull/101439