4 ms·

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 c

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.

Groxx 4mo ago
> > 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. There's also wrapping_add / saturating_add for anyone concerned about this. Ya want a specific behavior? Just tell the compiler! You can also use the type wrappers so it happens implicitly! https://doc.rust-lang.org/std/num/struct.Saturating.html https://doc.rust-lang.org/std/num/struct.Saturating.html (presumably this is optimizable on hardware that has operators for this, but idk if that happens yet)
- kllrnohj 4mo ago
  > There's also wrapping_add / saturating_add for anyone concerned about this. Ya want a specific behavior? Just tell the compiler! That is exactly why Rust's behavior for +/- operators is a mistake and wrong. It should always panic and anyone that wants something different can specify that in code, where it's clear and explicit.

Groxx 4mo ago

> > 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. There's also wrapping_add / saturating_add for anyone concerned about this. Ya want a specific behavior? Just tell the compiler! You can also use the type wrappers so it happens implicitly! https://doc.rust-lang.org/std/num/struct.Saturating.html https://doc.rust-lang.org/std/num/struct.Saturating.html (presumably this is optimizable on hardware that has operators for this, but idk if that happens yet)

kllrnohj 4mo ago
> There's also wrapping_add / saturating_add for anyone concerned about this. Ya want a specific behavior? Just tell the compiler! That is exactly why Rust's behavior for +/- operators is a mistake and wrong. It should always panic and anyone that wants something different can specify that in code, where it's clear and explicit.