[phendrenad2]

It depends on what level of security you need. If you're writing a 3D game engine, a minor memory leak probably isn't worth the extra time required to write it in Rust. Even if you're writing a kernel, fuzzing and formal verification can get you 99.999 of the way to the guarantees of Rust.

[Thiez]

I feel like writing Rust is a whole lot faster and less error-prone than writing something in C. But even assuming that it's slower, it's definitely much faster than writing C and doing formal verification. Naturally formal verification can help with other properties besides memory safety, and as far as I am aware Rust is still lacking a formal semantics so when you go all-in on formal methods C can reach a provable level of quality that Rust currently cannot. But very few people develop software that way.