Right. And of course there are still less-performance-sensitive C/C++ applications (curl, postfix, git, etc.) that could have memory-safe release versions.

But the point is also to dispel the conventional wisdom that C/C++ is necessarily intrinsically unsafe. It's a tradeoff between safety, performance and flexibility/compatibility. And you don't necessarily need to jump to a completely different language to get a different tradeoff.

Fil-C sacrifices some performance for safety and compatibility. The traditional compilers sacrifice some safety for performance and flexibility/compatibility. And scpptool aims to provide the option of sacrificing some flexibility for safety and performance. (Along with the other two tradeoffs available in the same program). The claim is that C++ turns out to be expressive enough to accommodate the various tradeoffs. (Though I'm not saying it's always gonna be pretty :)

Even with UB holes plugged, C (and C++) are still unsafe, because there are many assumptions you might want to make that you can not encode in the language.

To get an example that's easy to understand: before the introduction of the 'const' keyword, you just couldn't express that some variable should never be changed. And no amount of UB sanitisers would have fixed this for you: you just couldn't express the concept. There's lots of other areas of these languages that are still in a similar state.

Eg there's no way to express that a function should be pure, ie not have side effects (but is allowed to use mutation internally).