Mark JoinHandle with #[must_use]

src/liballoc/arc.rs

@@ -164,7 +164,7 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize;
 /// for _ in 0..10 {
 ///     let five = Arc::clone(&five);
 ///
-///     thread::spawn(move || {
+///     let _t = thread::spawn(move || {
 ///         println!("{:?}", five);
 ///     });
 /// }
@@ -184,7 +184,7 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize;
 /// for _ in 0..10 {
 ///     let val = Arc::clone(&val);
 ///
-///     thread::spawn(move || {
+///     let _t = thread::spawn(move || {
 ///         let v = val.fetch_add(1, Ordering::SeqCst);
 ///         println!("{:?}", v);
 ///     });

src/librustc_driver/profile/mod.rs

@@ -22,7 +22,7 @@ pub fn begin() {
     use std::sync::mpsc::{channel};
     let (tx, rx) = channel();
     if profq_set_chan(tx) {
-        thread::spawn(move||profile_queries_thread(rx));
+        let _handle = thread::spawn(move || profile_queries_thread(rx));
     }
 }
 

src/librustc_trans/back/write.rs

@@ -1875,7 +1875,7 @@ const LLVM_WORK_PACKAGE_KIND: time_graph::WorkPackageKind =
 fn spawn_work(cgcx: CodegenContext, work: WorkItem) {
     let depth = time_depth();
 
-    thread::spawn(move || {
+    let _handle = thread::spawn(move || {
         set_time_depth(depth);
 
         // Set up a destructor which will fire off a message that we're done as

src/libstd/macros.rs

@@ -234,8 +234,8 @@ macro_rules! eprintln {
 /// let (tx1, rx1) = mpsc::channel();
 /// let (tx2, rx2) = mpsc::channel();
 ///
-/// thread::spawn(move|| { long_running_thread(); tx1.send(()).unwrap(); });
-/// thread::spawn(move|| { tx2.send(calculate_the_answer()).unwrap(); });
+/// let _t = thread::spawn(move || { long_running_thread(); tx1.send(()).unwrap(); });
+/// let _t = thread::spawn(move || { tx2.send(calculate_the_answer()).unwrap(); });
 ///
 /// select! {
 ///     _ = rx1.recv() => println!("the long running thread finished first"),

src/libstd/sync/barrier.rs

@@ -206,7 +206,7 @@ mod tests {
         for _ in 0..N - 1 {
             let c = barrier.clone();
             let tx = tx.clone();
-            thread::spawn(move|| {
+            let _t = thread::spawn(move|| {
                 tx.send(c.wait().is_leader()).unwrap();
             });
         }

src/libstd/sync/condvar.rs

@@ -45,7 +45,7 @@ impl WaitTimeoutResult {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///
     ///     // Let's wait 20 milliseconds before notifying the condvar.
@@ -103,7 +103,7 @@ impl WaitTimeoutResult {
 /// let pair2 = pair.clone();
 ///
 /// // Inside of our lock, spawn a new thread, and then wait for it to start.
-/// thread::spawn(move|| {
+/// let _t = thread::spawn(move|| {
 ///     let &(ref lock, ref cvar) = &*pair2;
 ///     let mut started = lock.lock().unwrap();
 ///     *started = true;
@@ -189,7 +189,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -254,7 +254,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -310,7 +310,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -383,7 +383,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -458,7 +458,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -517,7 +517,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -557,7 +557,7 @@ impl Condvar {
     /// let pair = Arc::new((Mutex::new(false), Condvar::new()));
     /// let pair2 = pair.clone();
     ///
-    /// thread::spawn(move|| {
+    /// let _t = thread::spawn(move|| {
     ///     let &(ref lock, ref cvar) = &*pair2;
     ///     let mut started = lock.lock().unwrap();
     ///     *started = true;
@@ -663,7 +663,7 @@ mod tests {
         for _ in 0..N {
             let data = data.clone();
             let tx = tx.clone();
-            thread::spawn(move|| {
+            let _t = thread::spawn(move|| {
                 let &(ref lock, ref cond) = &*data;
                 let mut cnt = lock.lock().unwrap();
                 *cnt += 1;
@@ -697,7 +697,7 @@ mod tests {
         let pair2 = pair.clone();
 
         // Inside of our lock, spawn a new thread, and then wait for it to start.
-        thread::spawn(move|| {
+        let _t = thread::spawn(move|| {
             let &(ref lock, ref cvar) = &*pair2;
             let mut started = lock.lock().unwrap();
             *started = true;