[casept]

IMO fixing the unsafety is impossible, because doing so would mean re-evaluating the very core idea of C++ that C is a suitable substrate for building a safe, expressive language on. We know from years of experience that C has plenty of footguns of it's own, and fixing them is not possible without a fundamental redesign of the language. Therefore, the foundation of C++ is already rotten.

If that foundation were to be redesigned one'd have to get rid of the current near-100% compatibility with C, making the interop no longer an argument for using C++. Add the fact that most real-world C++ code will also be incompatible, and the strongest argument for using C++ is gone (namely, the impressive ecosystem size and maturity).

At that point there'd be no more justification for the existence of C++ over Rust (or another language that takes Rust's good ideas and supersedes it).

[wffurr]

The raison d'être of a safer C++ would be to enable staged, tool-assisted migration for the many hundreds of millions (billions?) of lines of C++ code in the world.

I think that's plenty of reason all by itself.