Rust still allows people to do (basically) whatever they want via unsafe blocks.
Yeah but I have written a lot of Rust and I have yet to use a single unsafe block.
Saying “but… unsafe!” is like saying Python isn’t memory safe because it has ctypes, or Go isn’t memory safe because of its unsafe package.
Sure, but you have to explicitly enable this feature. In c++ you can use the oldest shit from twenty years ago and your compiler happily does its job. All my c++ books are full of “you shouldn’t use xy as it is deemed unsafe now, but of course you still can”.
If a “safe C++” proposal truly proposes a safe subset, then yes your C++ code would have to opt-in to doing unsafe things. For the purposes of this discussion of a safe subset … the point is moot.
It’s not moot. The Safe C++ is opt-in to safety. It has to be because otherwise it wouldn’t be compatible with existing C++.