If your C/C++ is sane, then your code was already written with lifetimes in mind and enforcing them is not a big deal. There will be places, no doubt, that you

If your C/C++ is sane, then your code was already written with lifetimes in mind and enforcing them is not a big deal. There will be places, no doubt, that you cannot do it, but if you can easily cover 80% of the code, that is way better than nothing and then you can work on redesigning the 20% (perhaps even rewriting it in another language since it has to be changed, for instance to Rust). Same argument as Rust uses for unsafe blocks. There have been specialized annotations for things like mutexes for a while in several projects which help static analyzers prove things too, so it is not new.