This is the sort of absolutism that is so pointless.
At the same time, what's equally frustrating to me is defense without a threat model. "We'll randomize this value so it's harder to guess" without asking who's guessing, how often they can guess, how you'll randomize it, how you'll keep it a secret, etc. "Defense in depth" has become a nonsense term.
The use of memory unsafe languages for parsing untrusted input is just wild. I'm glad that I'm working in a time where I can build all of my parsers and attack surface in Rust and just think way, way less about this.
I'll also link this talk[1], for the millionth time. It's Rob Joyce, chief of the NSA's TAO, talking about how to make NSA's TAO's job harder.
[0] https://arstechnica.com/information-technology/2021/01/hacke...
I'm beginning to worry that every time Rust is mentioned as a solution for every memory-unsafe operation we're moving towards an irrational exuberance about how much value that safety really has over time. Maybe let's not jump too enthusiastically onto that bandwagon.
There are likely many other examples of, say, Java not having memory safety issues. Java makes very similar guarantees to Rust, so we can extrapolate, using common sense, that the findings roughly translate.
Common sense is a really powerful tool for these sorts of conversations. "Proof" and "evidence" are complex things, and yet the world goes on with assumptions that turn out to hold quite well.
The Mozilla case study is not a real world study. It simply looks at the types of bugs that existed and says "I promise these wouldn't have existed if we had used Rust". Would Rust have introduced new bugs? Would there be an additional cost to using Rust? We don't know and probably never will. What we care about is preventing real world damage. Does Rust prevent real world damage? We have no idea.
What I'm saying is that truth is a matter of debate. We believe lots of things based on evidence much less rigorous than a formal proof in many cases - like most modern legal systems, which rely on various types of evidence, and then a jury that must form a consensus.
So saying "there is no evidence" is sort of missing the point. Safe Rust does not have memory safety issues, barring compiler bugs, therefor common sense as well as experience with other languages (Java, C#, etc), would show that that memory safety issues are likely to be far less common. Maybe that isn't the evidence that you're after, but I find that compelling.
To me, the question of "does rust improve upon memory safety relative to C/C++" is obvious to the point that it really doesn't require justification, but that's just me.
I could try to find more evidence, but I'm not sure what would convince you. There's people fuzzing rust code and finding far fewer relevant vulns - but you could find that that's not compelling, or whatever.