I feel like the standards are starting to get ahead of implementation. It's almost 2023 and C++20 still doesn't have even full support in any of the main compilers.
VC++ is mostly crossing the finish line already.
GCC is getting there thanks Red-Hat support.
Clang well, apparently all those compiler vendors that profit from it, see only a value in LLVM itself, after Apple and Google switched focus to their own languages.
- The important but half-baked features of C++20 that has never really been polished enough for actual production usage (modules, coroutines)
- Unnecessary "hyper-modern" C++ features which are dead on arrival (ranges)
- The dramatic increase in build times due to the STL library (which are accelerated by those hyper-modern C++ features) [2]
- The fleeing of LLVM/Clang engineers to other projects (as you've said, Apple engineers shifting work to Swift, and Google abandoning Clang and moving to Carbon).
- Implosions in the ISO committee (notably the controversy surrounding the rape convict)
It's really not looking good, but there aren't that much alternatives so I think people will just stick to C++17 for the moment. Listing the worthwhile competitors:
- Rust is a bit too awkward to use in many cases where C++ is used (particularly with unsafe Rust), and inherits some of the hyper-modern complexities/insanities of C++.
- Zig is still too unstable, they just finished reworking the compiler
- Jai is not even released to the public
- D might be a candidate but IMO they should really commit 100% fully for GC-less betterC mode...
- Nim still has many warts and unbaked features, and also there was a split in the compiler team [3]
[0] https://www.aristeia.com/TalkNotes/C++vstheVasa2-ups.pdf
[1] https://www.stroustrup.com/P0977-remember-the-vasa.pdf
[2] https://old.reddit.com/r/cpp/comments/o94gvz/what_happened_w...