auto merge of #15944 : alexcrichton/rust/task-dont-die, r=brson

Previously both spawning mechanisms were not resilient to task failures which were initiated from the task spawning infrastructure.

Closes #15895

src/test/run-pass/spawn-stack-too-big.rs

@@ -0,0 +1,47 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-macos apparently gargantuan mmap requests are ok?
+
+#![feature(phase)]
+
+#[phase(plugin)]
+extern crate green;
+extern crate native;
+
+use std::task::TaskBuilder;
+use native::NativeTaskBuilder;
+
+green_start!(main)
+
+fn main() {
+    test();
+
+    let (tx, rx) = channel();
+    TaskBuilder::new().native().spawn(proc() {
+        tx.send(test());
+    });
+    rx.recv();
+}
+
+#[cfg(not(target_word_size = "64"))]
+fn test() {}
+
+#[cfg(target_word_size = "64")]
+fn test() {
+    let (tx, rx) = channel();
+    spawn(proc() {
+        TaskBuilder::new().stack_size(1024 * 1024 * 1024 * 64).spawn(proc() {
+        });
+        tx.send(());
+    });
+
+    assert!(rx.recv_opt().is_err());
+}