Merge remote-tracking branch 'rust-lang/master' into hermit

2 files changed, 14 insertions, 2 deletions

diff --git a/src/libstd/thread/local.rs b/src/libstd/thread/local.rs
index cfaab4e22e9..46453b47fca 100644
--- a/src/libstd/thread/local.rs
+++ b/src/libstd/thread/local.rs
@@ -149,7 +149,7 @@ macro_rules! thread_local {
 #[allow_internal_unstable(thread_local_internals, cfg_target_thread_local, thread_local)]
 #[allow_internal_unsafe]
 macro_rules! __thread_local_inner {
-    (@key $(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $init:expr) => {
+    (@key $t:ty, $init:expr) => {
         {
             #[inline]
             fn __init() -> $t { $init }
@@ -184,7 +184,7 @@ macro_rules! __thread_local_inner {
     };
     ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $init:expr) => {
         $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::__thread_local_inner!(@key $(#[$attr])* $vis $name, $t, $init);
+            $crate::__thread_local_inner!(@key $t, $init);
     }
 }
 
diff --git a/src/libstd/thread/mod.rs b/src/libstd/thread/mod.rs
index 0ffa6ace2e4..0c632d2afbd 100644
--- a/src/libstd/thread/mod.rs
+++ b/src/libstd/thread/mod.rs
@@ -1271,6 +1271,18 @@ impl fmt::Debug for Thread {
 ///
 /// Indicates the manner in which a thread exited.
 ///
+/// The value contained in the `Result::Err` variant
+/// is the value the thread panicked with;
+/// that is, the argument the `panic!` macro was called with.
+/// Unlike with normal errors, this value doesn't implement
+/// the [`Error`](crate::error::Error) trait.
+///
+/// Thus, a sensible way to handle a thread panic is to either:
+/// 1. `unwrap` the `Result<T>`, propagating the panic
+/// 2. or in case the thread is intended to be a subsystem boundary
+/// that is supposed to isolate system-level failures,
+/// match on the `Err` variant and handle the panic in an appropriate way.
+///
 /// A thread that completes without panicking is considered to exit successfully.
 ///
 /// # Examples