auto merge of #9742 : alexcrichton/rust/issue-9739, r=brson

This changes an `assert_once_ever!` assertion to just a plain old assertion
around an atomic boolean to ensure that one particular runtime doesn't attempt
to exit twice.

Closes #9739

1 files changed, 8 insertions, 2 deletions

diff --git a/src/libstd/rt/mod.rs b/src/libstd/rt/mod.rs
index c7c4d3fc4f6..2db973b602e 100644
--- a/src/libstd/rt/mod.rs
+++ b/src/libstd/rt/mod.rs
@@ -68,7 +68,7 @@ use rt::sched::{Scheduler, Shutdown};
 use rt::sleeper_list::SleeperList;
 use rt::task::{Task, SchedTask, GreenTask, Sched};
 use rt::uv::uvio::UvEventLoop;
-use unstable::atomics::{AtomicInt, SeqCst};
+use unstable::atomics::{AtomicInt, AtomicBool, SeqCst};
 use unstable::sync::UnsafeArc;
 use vec;
 use vec::{OwnedVector, MutableVector, ImmutableVector};
@@ -311,11 +311,17 @@ fn run_(main: ~fn(), use_main_sched: bool) -> int {
     let exit_code = UnsafeArc::new(AtomicInt::new(0));
     let exit_code_clone = exit_code.clone();
 
+    // Used to sanity check that the runtime only exits once
+    let exited_already = UnsafeArc::new(AtomicBool::new(false));
+
     // When the main task exits, after all the tasks in the main
     // task tree, shut down the schedulers and set the exit code.
     let handles = Cell::new(handles);
     let on_exit: ~fn(bool) = |exit_success| {
-        assert_once_ever!("last task exiting");
+        unsafe {
+            assert!(!(*exited_already.get()).swap(true, SeqCst),
+                    "the runtime already exited");
+        }
 
         let mut handles = handles.take();
         for handle in handles.mut_iter() {