ICE due to dereferencing core::result::Result

[gal-leib]

Code Example

this was taken from the intro doc, a few days ago. Notice that in the latest nightly you need to add a call to unwrap() after lock().

use std::thread::Thread;
use std::sync::{Arc,Mutex};

fn main() {
    let numbers = Arc::new(Mutex::new(vec![1i, 2i, 3i]));

    for i in range(0u, 3u) {
        let number = numbers.clone();
        Thread::spawn(move || {
            let mut array = number.lock();

            (*array)[i] += 1;

            println!("numbers[{}] is {}", i, (*array)[i]);
        }).detach();
    }
}

Output

fff.rs:12:14: 12:20 error: type `core::result::Result<std::sync::mutex::MutexGuard<'_, collections::vec::Vec<int>>, std::sync::poison::PoisonError<std::sync::mutex::MutexGuard<'_, collections::vec::Vec<int>>>>` cannot be dereferenced
fff.rs:12             (*array)[i] += 1;
                       ^~~~~~
fff.rs:14:47: 14:53 error: type `core::result::Result<std::sync::mutex::MutexGuard<'_, collections::vec::Vec<int>>, std::sync::poison::PoisonError<std::sync::mutex::MutexGuard<'_, collections::vec::Vec<int>>>>` cannot be dereferenced
fff.rs:14             println!("numbers[{}] is {}", i, (*array)[i]);
                                                        ^~~~~~
note: in expansion of format_args!
<std macros>:2:54: 2:77 note: expansion site
<std macros>:1:1: 3:2 note: in expansion of println!
fff.rs:14:13: 14:59 note: expansion site
error: internal compiler error: no type for node 71: expr i (id=71) in fcx 0x7fb3b9feca18
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/diagnostic.rs:182

stack backtrace:
   1:     0x7fb3c194f950 - sys::backtrace::write::h895a7595e35ffe42gnt
   2:     0x7fb3c1974660 - failure::on_fail::hb3298435971cff34kEz
   3:     0x7fb3c18db940 - rt::unwind::begin_unwind_inner::h6dee24d5dc335a63oiz
   4:     0x7fb3bcaadcc0 - rt::unwind::begin_unwind::h12623432956124006653
   5:     0x7fb3bcaae570 - diagnostic::Handler::bug::ha9b616024b46f3aebVF
   6:     0x7fb3bfb4b770 - session::Session::bug::h12be686e19b5b0bazyp
   7:     0x7fb3c0f11390 - check::FnCtxt<'a, 'tcx>::node_ty::h9b8a67e28e41ba8bSGl
   8:     0x7fb3c0f24e50 - check::writeback::WritebackCx<'cx, 'tcx>::visit_node_id::h2c4dc3387755279ctHb
   9:     0x7fb3c0f210e0 - check::writeback::WritebackCx<'cx, 'tcx>.Visitor<'v>::visit_expr::h2f0f77b56a4c1394exb
  10:     0x7fb3c0f24d50 - check::writeback::WritebackCx<'cx, 'tcx>.Visitor<'v>::visit_block::h91bc12c657353988uyb
  11:     0x7fb3c0f2c970 - visit::walk_fn::h10733558075477871190
  12:     0x7fb3c0f210e0 - check::writeback::WritebackCx<'cx, 'tcx>.Visitor<'v>::visit_expr::h2f0f77b56a4c1394exb
  13:     0x7fb3c0f210e0 - check::writeback::WritebackCx<'cx, 'tcx>.Visitor<'v>::visit_expr::h2f0f77b56a4c1394exb
  14:     0x7fb3c0f210e0 - check::writeback::WritebackCx<'cx, 'tcx>.Visitor<'v>::visit_expr::h2f0f77b56a4c1394exb
  15:     0x7fb3c0f24d50 - check::writeback::WritebackCx<'cx, 'tcx>.Visitor<'v>::visit_block::h91bc12c657353988uyb
  16:     0x7fb3c0fe32c0 - check::check_bare_fn::h24d3cb693ab9ca75Qzj
  17:     0x7fb3c0fda950 - check::check_item::hb991f99d47aa82ceSSj
  18:     0x7fb3c117b030 - check_crate::unboxed_closure.39833
  19:     0x7fb3c1175dd0 - check_crate::hb802e7bb2dee1cd6NLx
  20:     0x7fb3c1e98860 - driver::phase_3_run_analysis_passes::h83e2236a47a83223qva
  21:     0x7fb3c1e870a0 - driver::compile_input::h2bdea93b5d9f3dbfwba
  22:     0x7fb3c1fd2970 - thunk::F.Invoke<A, R>::invoke::h11261394929911795771
  23:     0x7fb3c1fd1720 - rt::unwind::try::try_fn::h18390836921836612068
  24:     0x7fb3c19da2d0 - rust_try_inner
  25:     0x7fb3c19da2c0 - rust_try
  26:     0x7fb3c1fd1a70 - thunk::F.Invoke<A, R>::invoke::h16439250889300796363
  27:     0x7fb3c1961300 - sys::thread::thread_start::haeaaf0233fbdd5c3bgw
  28:     0x7fb3bc2cf460 - start_thread
  29:     0x7fb3c1590749 - clone
  30:                0x0 - <unknown>

Version

rustc 0.13.0-nightly (7608dba 2014-12-31 10:06:21 -0800)
binary: rustc
commit-hash: 7608dba
commit-date: 2014-12-31 10:06:21 -0800
host: x86_64-unknown-linux-gnu
release: 0.13.0-nightly