Panics have to be catchable because it's undefined behavior for Rust to unwind through C code, so a Rust library that exposes a C API has to stop panics at the

Panics have to be catchable because it's undefined behavior for Rust to unwind through C code, so a Rust library that exposes a C API has to stop panics at the FFI boundary and propagate errors in a C-compatible way. It's not "catching" in the Java sense; nobody is using catch_panic to implement resumable error-handling.