negative. For example bounds checking is turned on by default in Zig, which prevents classes of overflow safety errors.

I don't think you've necessarily understood the scope and impact of the borrow checker. Bounds checking is just a sane default (hygiene), not a game changer.

I mean, I'm the author of this?

https://github.com/ityonemo/clr

so yes, I understand that it's important. It doesn't need to be in the compiler though? I think it's likely the case that you also don't need to have annotations littering the language.

I wish you good luck! Successive attempts to achieve similar levels of analysis without annotations have failed in the C++ space, but I look forward to reading your results.

yeah afaik you cant easily intercept c++ at a meaningful IR in the same way as you can zig. Zig's AIR is almost perfect for this kind of thing.