backtrace.txt

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:335:20
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::_print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: std::panicking::rust_panic_with_hook
   5: std::panicking::begin_panic
   6: std::panicking::begin_panic_fmt
   7: rust_begin_unwind
   8: core::panicking::panic_fmt
   9: core::panicking::panic
  10: <core::option::Option<T>>::unwrap    <-- nothing about "bar"
  11: foo::main
  12: __rust_maybe_catch_panic
  13: std::rt::lang_start
  14: main

backtrace2.txt

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:335:20
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:69
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:58
             at src/libstd/panicking.rs:381
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:397
   4: std::panicking::begin_panic
             at src/libstd/panicking.rs:577
   5: std::panicking::begin_panic
             at src/libstd/panicking.rs:538
   6: std::panicking::try::do_call
             at src/libstd/panicking.rs:522
   7: std::panicking::try::do_call
             at src/libstd/panicking.rs:498
   8: <core::ops::range::Range<Idx> as core::fmt::Debug>::fmt
             at src/libcore/panicking.rs:71
   9: <core::ops::range::Range<Idx> as core::fmt::Debug>::fmt
             at src/libcore/panicking.rs:51
  10: <core::option::Option<T>>::unwrap
             at /Users/travis/build/rust-lang/rust/src/libcore/macros.rs:20
  11: foo::main
             at ./foo.rs:2
  12: panic_unwind::dwarf::eh::read_encoded_pointer
             at src/libpanic_unwind/lib.rs:99
  13: rust_panic
             at src/libstd/panicking.rs:459
             at src/libstd/panic.rs:361
             at src/libstd/rt.rs:59
  14: foo::bar

foo.rs

fn main() {
    bar().unwrap();
}

fn bar() -> Option<String> {
    None
}