Comment by fl0ki

It's even worse than that, because even if a new proposal had no concerns from a language & library point of view, it can still be crippled by vendor concerns because of short-sighted, entirely unforced errors the vendors made, often decades prior.

It's part of why I don't believe the C++-compatible C++-successor languages will deliver on their promises nearly as well as they think. They only solve half of the problem, which is that their translation units don't have to accommodate legacy C++ syntax.

They still have to reproduce existing C++ semantics and ABIs, their types still have to satisfy C++ SFINAE and Concepts, etc. so they're bringing all of the semantic baggage no matter what new syntax they dress it in.

And anywhere they end up introducing new abstractions to try to enforce safety, those will be incompatible with C++ enough to require hand-crafted wrappers, just like we already do with Rust, only Rust is much further along its own maturity and adoption curve than those languages are.