From 76d468ae261bc45582588b972d6098c0edb0d698 Mon Sep 17 00:00:00 2001
From: Aaron Turon <aturon@mozilla.com>
Date: Thu, 9 Apr 2015 17:23:49 -0700
Subject: [PATCH] Ensure that .join().unwrap() works

Makes `Any + Send` implement `Debug`.

Fixes #21291
---
 src/libcore/any.rs               | 10 ++++++++++
 src/test/run-pass/issue-21291.rs | 17 +++++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 src/test/run-pass/issue-21291.rs

diff --git a/src/libcore/any.rs b/src/libcore/any.rs
index 687675f12ef..7025c76d92c 100644
--- a/src/libcore/any.rs
+++ b/src/libcore/any.rs
@@ -114,6 +114,16 @@ impl fmt::Debug for Any {
     }
 }
 
+// Ensure that the result of e.g. joining a thread can be printed and
+// hence used with `unwrap`. May eventually no longer be needed if
+// dispatch works with upcasting.
+#[stable(feature = "rust1", since = "1.0.0")]
+impl fmt::Debug for Any + Send {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.pad("Any")
+    }
+}
+
 impl Any {
     /// Returns true if the boxed type is the same as `T`
     #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/src/test/run-pass/issue-21291.rs b/src/test/run-pass/issue-21291.rs
new file mode 100644
index 00000000000..ec095d4895f
--- /dev/null
+++ b/src/test/run-pass/issue-21291.rs
@@ -0,0 +1,17 @@
+// Copyright 2015 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.
+
+// Regression test for unwrapping the result of `join`, issue #21291
+
+use std::thread;
+
+fn main() {
+    thread::spawn(|| {}).join().unwrap()
+}