A "trade" implies care which isn't actually taken. What WG21 does is they assume that safety costs performance and so they throw away the safety hoping that this means they get performance. They don't measure, which is why you get to see first Herb Sutter explaining that C++ doesn't do bounds checks because they're unaffordable (notice he presents no data) and then a few years later Herb Sutter explaining that the latest C++ will offer bounds checks because they're actually affordable after all (now Google has collected the data)

In most cases it's much worse than the bounds checks, which actually did have a small cost, it's often net negative to throw away safety, C++ chose the less safe and slower option, assuming that this "trade" exists when it doesn't and if they'd measured they'd have seen the news before making the decision.

The borrow checker runs at compile-time, not run-time. Safety doesn't slow down your code except in a few small, specific ways like array bounds checks and UTF8 validity checking - but these checks also happen in unsafe rust too. The overhead is also mitigated by some of rust's other choices increasing performance. (For example, rust uses noalias everywhere, has larger codegen units by default and a better, faster standard library).

There was a really great analysis a few months ago looking at the performance impact of rust, C++ and hardened C++. They patched the compiler to see what happened when all runtime safety aspects were removed - and the result was about a 2-3% improvement. Measurable for sure, but nothing to write home about.

https://github.com/yugr/rust-slides/blob/ae3f5cc12d49e61f8f6...

> Secondly, Android C++ code is not particularly high quality, [..] Thirdly, it has a massive target on its back and is under attack by pretty much everyone.

Most code isn't particularly high quality. But I suspect google has better resources and processes than most C++ dev teams. As for security - just about all code is a target now that LLMs can find vulnerabilities so easily. I want all the software on my computer to be hardened against attacks that can be found and exploited in under $5 of compute.

> [Rust is] also quite ugly, people complain about its complexity and is unfortunately suffering from dependency explosion. I hope it’s a stepping stone to something better.

As Stroustrup once said, "There are only two kinds of languages: the ones people complain about and the ones nobody uses." It's a good sign that people are complaining about it. But otherwise I agree - I look forward to seeing how rust's borrow checker inspires new languages going forward. There's a lot more good ideas in the programming language space that we haven't scratched.