Hacker News Reader

Does Rust have something like a deep-codemodding macro that could be used to un-panic-fy an entire function etc. automatically?

Something like: Given a function, rewrite its signature to return a Result if it doesn't already, rewrite each non-Resulty return site to a Some(), add a ? to every function call, then recurse into each called function and do the same.

View on HN

It has `catch_unwind` [1], but that still retains the panicking runtime, so not sufficient in the context of the post.

[1] https://doc.rust-lang.org/std/panic/fn.catch_unwind.html

It's also not guaranteed to catch every panic - sometimes (notably if a destructor panics during unwinding) a panic can turn into a process-abort.

To add to that, Rust code is generally not written to be 'exception-safe' when panics occur: if a third-party function causes a panic, or if your own code panics from within a callback, then memory may be leaked, and objects in use may end up in an incorrect or unusable state.

You really want to avoid sharing mutable objects across a catch_unwind() boundary, and also avoid using it on a regular basis. Aside from memory leaks, panicking runs the thread's panic hook, which by default prints a stacktrace. You can override the panic hook to be a no-op, but then you won't see anything for actual panics.

Reply on news.ycombinator.com