> what besides the obvious requires mangling?

Rust's symbol mangling allows multiple versions of the same library to be installed on the same system and peacefully coexist. A single Rust program can even link against two different versions of the same library (which comes in handy when two of your dependencies rely on the same library, but are updated at different rates).

You can explicitly disable mangling via an attribute:

  #[no_mangle]
  fn this_symbol_wont_be_mangled() { ... }

  > What took place of split stacks?

https://mail.mozilla.org/pipermail/rust-dev/2013-November/00...

"Instead of segmented stacks we're going to rely on the OS and MMU to help us map pages lazily."