[adwn]

> In C++ you (usually) do this with `const`, which is fairly low friction, very statically analyzable, and I'm a little unclear what bug hardcore borrow-checker static stops me or my colleagues from making that `const` can't catch?

Rust catches the bug where you forget to use `const`, because the C++ compiler doesn't force you to use it. Your argument boils down to "I don't need Rust's borrow checker, I just have to remember to use a dozen tricks, follow various patterns and guidelines, run several static analyzers and runtime checks, and I'm almost there".

This is not meant as an attack against you. I used to program in C++, and I'm mostly using Rust now. The borrow checker frees up those brain resources which had to keep all those tricks, patterns, and guidelines in mind.