---

yaml
---
r: 236329
b: refs/heads/master
c: 54c0231
h: refs/heads/master
i:
  236327: 43bd5e6
v: v3

Author: ranma42

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: c7b84909b00dcf5f762778b4aa9783770c69416d
+refs/heads/master: 54c0231b14a71a46e6607255d509457e0df0b8be
 refs/heads/snap-stage3: 1af31d4974e33027a68126fa5a5a3c2c6491824f
 refs/heads/try: ea3892f76a2180dd4ce724f1dafd9186959702d9
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105

trunk/src/libstd/panicking.rs

@@ -52,7 +52,6 @@ fn log_panic(obj: &(Any+Send), file: &'static str, line: u32,
     let prev = LOCAL_STDERR.with(|s| s.borrow_mut().take());
     match (prev, err.as_mut()) {
         (Some(mut stderr), _) => {
-            // FIXME: what to do when the thread printing panics?
             write(&mut *stderr);
             let mut s = Some(stderr);
             LOCAL_STDERR.with(|slot| {
@@ -71,6 +70,17 @@ pub fn on_panic(obj: &(Any+Send), file: &'static str, line: u32) {
         count
     });
 
+    // If this is the third nested call, on_panic triggered the last panic,
+    // otherwise the double-panic check would have aborted the process.
+    // Even if it is likely that on_panic was unable to log the backtrace,
+    // abort immediately to avoid infinite recursion, so that attaching a
+    // debugger provides a useable stacktrace.
+    if panics >= 3 {
+        util::dumb_print(format_args!("thread panicked while processing \
+                                       panic. aborting."));
+        unsafe { intrinsics::abort() }
+    }
+
     // If this is a double panic, make sure that we print a backtrace
     // for this panic. Otherwise only print it if logging is enabled.
     let log_backtrace = panics >= 2 || backtrace::log_enabled();