1. ADTs with exhaustive pattern matching
2. No exceptions
3. Zero cost generics
4. Traits
5. No nulls
6. No inheritance
As a rule of thumb, languages that loudly claim not to have exceptions actually use them in some way (see POSIX C, Perl, Go).
In idiomatically written Rust you will never obtain an exception/panic (unless there is a bug), and exceptions are not used for control flow. This is not the case in Java or C++ or many other languages.
/// The compiler currently unwinds with a special sentinel value to abort
/// compilation on fatal errors. This function catches that sentinel and turns
/// the panic into a `Result` instead.
There's another example in src/tools/rustfmt/src/lib.rs, in format_snippet, where panics apparently are just suppressed.
I expect application servers for Rust to handle panics in a similar way: abort a specific request, but not terminate the whole process.