> Nothing at all. But sharing objects between threads is unsafe. If sharing stuff between threads in Rust is unsafe, then that is a bug which you should report

> Nothing at all. But sharing objects between threads is unsafe. If sharing stuff between threads in Rust is unsafe, then that is a bug which you should report. > You can prove that VM code is memory safe? Good for you. Uh, that's my point... VM implementations are usually not proved to be safe, any more than unsafe code in Rust is proved to be safe. > And in C++ we have value and move semantics. Which aren't bulletproof - if you're not careful, they can be used in an unsafe way. Well, this is second-hand information, so take that for what you will. You could ask pcwalton about it if you want a truly informed opinion. > So being careful in C++ is easy today, can I say that C++ is safe? :) Sure you can. You can say, "My code is safe, because I only use feature X, Y, Z / because I avoid this and that...". While someone using Rust should be able to say "My library is safe, since I make no use of unsafe blocks".