In C/C++ the default behavior, always, is very dangerous UB. Some compilers offer an option for guaranteed wrap-around, and some compilers offer an option for controlled crash. None of them is standardized or the default.
In Rust the standard mandates a guaranteed wrap-around or a controlled crash. The default behavior is crashing in debug mode and wrapping-around in release mode, but you can control that with a compiler flag.
No matter how you look at it, the Rust behavior is safer. The default behavior? Way better in Rust than in C++. Want a guaranteed wrap-around? In Rust, check. In C++, depending on the compiler. Want a guaranteed crash? In Rust, check. In C++, depending on the compiler.
Also worth noting that overflowing has much more severe consequences in C++ than in Rust, due to bounds checks.
> I don't know if Rust will ever attempt to fix this mistake
It was discussed many times, and the conclusion is: it is too expensive, and the default will only change if that will change (due to better optimizations and/or better hardware). It is not a mistake, but a conscious decision.
