auto merge of #11283 : brson/rust/doublefailure, r=alexcrichton

Previously this was an `rtabort!`, indicating a runtime bug. Promote
this to a more intentional abort and print a (slightly) more
informative error message.

Can't test this sense our test suite can't handle an abort exit.

I consider this to close #910, and that we should open another issue about implementing less conservative semantics here.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/libstd/rt/unwind.rs b/src/libstd/rt/unwind.rs
index 358df7260f4..6be4ab97ee3 100644
--- a/src/libstd/rt/unwind.rs
+++ b/src/libstd/rt/unwind.rs
@@ -354,7 +354,13 @@ pub fn begin_unwind<M: Any + Send>(msg: M, file: &'static str, line: uint) -> !
             }
 
             if (*task).unwinder.unwinding {
-                rtabort!("unwinding again");
+                // If a task fails while it's already unwinding then we
+                // have limited options. Currently our preference is to
+                // just abort. In the future we may consider resuming
+                // unwinding or otherwise exiting the task cleanly.
+                rterrln!("task failed during unwinding (double-failure - total drag!)")
+                rterrln!("rust must abort now. so sorry.");
+                intrinsics::abort();
             }
         }