> If you panic in the middle, the money is lost.
Wouldn't a relational database help deal with this?
> Without noexcept, it's hard to reason about which calls can panic and which can't, so it's hard to make bulletproof cleanup paths.
Unsafe blocks usually contain very low level code, so you can understand what your code does very accurately. If the unsafe code calls a dependency which calls 150 other dependencies transitively, yeah, that's going to be pretty bad.
> Wouldn't a relational database help deal with this?
Sure. It's just a toy example. There are lots of real programs in which you temporarily violate invariants in the course of performing some task, then restore them after. Another example that comes to mind is search tree rotations.
> Unsafe blocks usually contain very low level code, so you can understand what your code does very accurately.
Perhaps at first, but code evolves.