Python cryptography, Rust, and Gentoo

I don't know how well the various C++ implementations are keeping up with C++20 (at least). Specifically with Concepts, Coroutines, and Modules implementation progress.

> Also, especially C/C++ are evolving at a much slower pace than Rust where almost every new upstream release contains new language features.

I think they have a longer release cadence, but the difference between Rust c. 2017 and Rust c. 2020 is, IMO, *far* smaller than the difference between C++17 and C++20 (IMO). Rust added async syntax and language features, tweaked the module import spelling (in a backwards compatible way via the editions mechanism), added const compile-time evaluation support, and other things. On the other hand, C++ got consteval, a completely new module system (that needs build systems to chase actual use of it in practice), concepts, coroutines, and many many more things.

> Sure, but the problem is that this hasn't happened yet and one of the main reasons is the fact that the language is moving so fast that alternative implementations have trouble keeping up.

I think the main thing is that Rust is a hard language to implement. mrustc skips lifetime checking, but handles the rest of the language (as of 1.29 or so). The main developer of it went onto other tasks (IIRC, academic pursuits). A community could certainly get behind it to push it further.

I don't know that it's so much "have trouble keeping up" as getting over the initial hurdle to getting a lifetime-tracking system that is independently implemented. Once that happens, I don't think much in the language would be *too* difficult to keep up with (most of the changes I'm seeing in release notes are stdlib, perf changes, or incremental language changes that are likely way easier than C++ incremental updates (as long as we're comparing)).