Stop making me memorize the borrow checker

I have memorised the UB rules for C. Or rather, more accurately, I have memorised the subset of UB rules I need to memorise to be productive in the language and am very strict in sticking to only writing code which I know is well defined (and know my way around the C standard at a level where any obscure code I sometimes need to write can be verified to be well defined without too much hassle). I think Rust may be difficult But, if I forget something, or make a mistake, I'm screwed. Yes there's ubsan, there's tests, but ubsan and tests aren't guaranteed to work when ub is involved.

This is why I call C a minefield.

On that note, C++ has such an explosion of UB that I don't generally believe anyone who claims to know C++ because it seems to me to be almost infeasible to both learn all the rules, or at least the subset required to be productive, and then to write/modify code without getting lost.

With rust, the amount of rules I need to learn to understand rust's borrow checker is about the same or even less. And if I forget the rules, the borrow checker is there to back me up.

I still think that unless you need the performance, you should use a higher level language which hides this from you. It's genuinely easier to think about.

That being said, writing correct rust which is going to a: work as I intended and b: not have UB is much less mentally taxing, even when I have to reach for unsafe.

If you find it more taxing than writing C or C++ it's probably either because you haven't internalised the rules of the borrow checker, or because your C or C++ are riddled with various kinds of serious issues.

The ISO document for C has an appendix which lists all the known categories of Undefined Behaviour. It's not exactly a small list, but it's something you could memorize if you wanted to, like the list of all US interstates, where they start and where they end.

There has been a proposal to attempt this for C++ but IMO the progress on making such an appendix is slower than the rate of the change for the language, making it a never ending task. It was also expanded by the fact that on top of Undefined Behaviour C++ also explicitly has IFNDR, programs which it declares to be Ill-formed (ie they are not C++) but No Diagnostic is required (ie your compiler doesn't know that it's not C++). This is much worse than UB.