Merge branch 'master' into update-rls-data-for-save-analysis

2 files changed, 11 insertions, 6 deletions

diff --git a/src/libstd/thread/local.rs b/src/libstd/thread/local.rs
index a53c76a333a..cb18eed8ee5 100644
--- a/src/libstd/thread/local.rs
+++ b/src/libstd/thread/local.rs
@@ -325,7 +325,10 @@ impl<T: 'static> LocalKey<T> {
     ///
     /// Once the initialization expression succeeds, the key transitions to the
     /// `Valid` state which will guarantee that future calls to [`with`] will
-    /// succeed within the thread.
+    /// succeed within the thread. Some keys might skip the `Uninitialized`
+    /// state altogether and start in the `Valid` state as an optimization
+    /// (e.g. keys initialized with a constant expression), but no guarantees
+    /// are made.
     ///
     /// When a thread exits, each key will be destroyed in turn, and as keys are
     /// destroyed they will enter the `Destroyed` state just before the
diff --git a/src/libstd/thread/mod.rs b/src/libstd/thread/mod.rs
index 30887b16c60..07bbddc62b9 100644
--- a/src/libstd/thread/mod.rs
+++ b/src/libstd/thread/mod.rs
@@ -485,15 +485,17 @@ impl Builder {
 /// let (tx, rx) = channel();
 ///
 /// let sender = thread::spawn(move || {
-///     let _ = tx.send("Hello, thread".to_owned());
+///     tx.send("Hello, thread".to_owned())
+///         .expect("Unable to send on channel");
 /// });
 ///
 /// let receiver = thread::spawn(move || {
-///     println!("{}", rx.recv().unwrap());
+///     let value = rx.recv().expect("Unable to receive from channel");
+///     println!("{}", value);
 /// });
 ///
-/// let _ = sender.join();
-/// let _ = receiver.join();
+/// sender.join().expect("The sender thread has panicked");
+/// receiver.join().expect("The receiver thread has panicked");
 /// ```
 ///
 /// A thread can also return a value through its [`JoinHandle`], you can use
@@ -1192,7 +1194,7 @@ impl<T> JoinInner<T> {
 ///     });
 /// });
 ///
-/// let _ = original_thread.join();
+/// original_thread.join().expect("The thread being joined has panicked");
 /// println!("Original thread is joined.");
 ///
 /// // We make sure that the new thread has time to run, before the main