Uninitialized automatic variables. E.g. (in C/C++):

int get_time() {
  int time;
  syscall(/* something that fails */, &time);
  return time;
}

Rust seems to think panicking is better: https://github.com/rust-lang/rust/issues/115482

probably the worst option for a library

Even worse than returning garbage? :)

Interestingly, Rust is what brought me to this rabbit hole. It does indeed panic in now()[1], but the devs seem to be reluctant to provide the try_now() variant[2].

[1] https://doc.rust-lang.org/nightly/src/std/sys/pal/unix/time.rs.html#124 [2] https://github.com/rust-lang/rust/issues/115482