> Panics are recoverable: initially at task boundaries, and these days at catch points. They are literally exceptions and unwind the same way. No. They provide

> Panics are recoverable: initially at task boundaries, and these days at catch points. They are literally exceptions and unwind the same way. No. They provide roughly the same functionality as exceptions and are implemented the same way. Here's the thing; exceptions implies using unwind recovery for error handling. This is not the case in Rust. The panic recovery API isn't designed to be used like this. No API relies on panics being recoverable. Panic recovery is supposed to be used for two very specific use cases: - Stopping an application/service from crashing at a higher level (eg at an event loop boundary) - Preventing unwinds from crossing into FFI. Now, you could use Rust panics to build an exception system. It wouldn't be great, but you could. Sure. But a lot of the tradeoffs of a feature need to be considered in the context of how it's going to be used. Nobody's going to implement a (serious) exception library using Rust panics. Even if they did, it wouldn't work well with the rest of the ecosystem. Panics are _not_ a "full exception mechanism". The tradeoffs are not the same as that of C++ exceptions (which are pervasively used). There are tradeoffs, mind you, but different ones. > Code running in such a context needs to avoid leaking and corrupting resources on unwind --- i.e., be exception safe. On the rust development list, people call this property literally "exception safety". Exception safety is a common issue between Rust and C++ but you rarely have to think about it in Rust (because all libraries are written assuming that panics may or may not abort, and very few applications catch panics and have to think about it for a very small area near the boundary), whereas it's more common in C++. Nobody writes libraries trying to avoid leaks on panics because catching panics is rare (and leaks are considered safe in Rust, though it usually requires contrived code to cause a leak in Rust). Overall, it is not a problem. It's something you need to think of in extremely niche cases. Equating C++ exceptions and Rust panics is oversimplifying things.