Memory safety catches buffer overflows. CI catches logic bugs. Neither catches the Unix API gotchas nobody documented.
And writing comprehensive tests for this behaviour is very difficult regardless of which language you are using.
I am all for rust rewrites of things. But in this case, these are mistakes which were encouraged by the lazy design of `std::fs` and the developers' lack of relevant experience.
And to clarify, I don't blame the developers for lacking the relevant experience. Working on such a project is precisely the right place to learn stuff like this.
I think it's an absurdly dumb move by Canonical to take this project and beta-test it on normal users' machines though…
You can also run some static analysis that is too long to run locally every time, but once in a while it will point out "this code pattern is legal buy is almost always a bug"
It is also possible to do some formal analysis of code on CI that you wouldn't always run locally - I'm not an expert on these.