Change:
Yes, another incarnation of . and also have this issue. Note that is an error and has a test for it. cc
Does this also date back to 1.0, like did?
Yes. The fix would be technically a breaking change.

Discussion:
use sys_common::condvar as sys; use sys_common::mutex as sys_mutex; use sys_common::poison::{self, LockResult}; <del> use time::Duration; </del> <ins> use time::{Duration, Instant}; </ins> /// A type indicating whether a timed wait on a condition variable returned /// due to a time out or not.

} } <ins> /// Blocks the current thread until this condition variable receives a /// notification and the required condition is met. Spurious wakeups are /// ignored and this function will only return once the condition has been /// met. /// /// This function will atomically unlock the mutex specified (represented by /// `guard`) and block the current thread. This means that any calls /// to [`notify_one`] or [`notify_all`] which happen logically after the /// mutex is unlocked are candidates to wake this thread up. When this /// function call returns, the lock specified will have been re-acquired. /// /// # Errors /// /// This function will return an error if the mutex being waited on is /// poisoned when this thread re-acquires the lock. For more information, /// see information about [poisoning] on the [`Mutex`] type. /// /// [`notify_one`]: #method.notify_one /// [`notify_all`]: #method.notify_all /// [poisoning]: ../sync/struct.Mutex.html#poisoning /// [`Mutex`]: ../sync/struct.Mutex.html /// /// # Examples /// /// ``` /// use std::sync::{Arc, Mutex, Condvar}; /// use std::thread; /// /// let pair = Arc::new((Mutex::new(false), Condvar::new())); /// let pair2 = pair.clone(); /// /// thread::spawn(move|| { ///     let &(ref lock, ref cvar) = &*pair2; ///     let mut started = lock.lock().unwrap(); ///     *started = true; ///     // We notify the condvar that the value has changed. ///     cvar.notify_one(); /// }); /// /// // Wait for the thread to start up. /// let &(ref lock, ref cvar) = &*pair; /// // As long as the value inside the `Mutex` is false, we wait. /// cvar.wait_until(lock.lock().unwrap(), |started| { started }); /// ``` #[unstable(feature = "wait_until", issue = "47960")] pub fn wait_until<'a, T, F>(&self, mut guard: MutexGuard<'a, T>, mut condition: F) -> LockResult<MutexGuard<'a, T>> where F: FnMut(&mut T) -> bool { while !condition(&mut *guard) { guard = self.wait(guard)?; } Ok(guard) } </ins> /// Waits on this condition variable for a notification, timing out after a /// specified duration. ///

/// /// Note that the best effort is made to ensure that the time waited is /// measured with a monotonic clock, and not affected by the changes made to <del> /// the system time. </del> <ins> /// the system time.  This function is susceptible to spurious wakeups. /// Condition variables normally have a boolean predicate associated with /// them, and the predicate must always be checked each time this function /// returns to protect against spurious wakeups.  Additionally, it is /// typically desirable for the time-out to not exceed some duration in /// spite of spurious wakes, thus the sleep-duration is decremented by the /// amount slept.  Alternatively, use the `wait_timeout_until` method /// to wait until a condition is met with a total time-out regardless /// of spurious wakes. </ins> /// /// The returned [`WaitTimeoutResult`] value indicates if the timeout is /// known to have elapsed.

/// returns, regardless of whether the timeout elapsed or not. /// /// [`wait`]: #method.wait <ins> /// [`wait_timeout_until`]: #method.wait_timeout_until </ins> /// [`WaitTimeoutResult`]: struct.WaitTimeoutResult.html /// /// # Examples

} } <ins> /// Waits on this condition variable for a notification, timing out after a /// specified duration.  Spurious wakes will not cause this function to /// return. /// /// The semantics of this function are equivalent to [`wait_until`] except /// that the thread will be blocked for roughly no longer than `dur`. This /// method should not be used for precise timing due to anomalies such as /// preemption or platform differences that may not cause the maximum /// amount of time waited to be precisely `dur`. /// /// Note that the best effort is made to ensure that the time waited is /// measured with a monotonic clock, and not affected by the changes made to /// the system time. /// /// The returned [`WaitTimeoutResult`] value indicates if the timeout is /// known to have elapsed without the condition being met. /// /// Like [`wait_until`], the lock specified will be re-acquired when this /// function returns, regardless of whether the timeout elapsed or not. /// /// [`wait_until`]: #method.wait_until /// [`wait_timeout`]: #method.wait_timeout /// [`WaitTimeoutResult`]: struct.WaitTimeoutResult.html /// /// # Examples /// /// ``` /// use std::sync::{Arc, Mutex, Condvar}; /// use std::thread; /// use std::time::Duration; /// /// let pair = Arc::new((Mutex::new(false), Condvar::new())); /// let pair2 = pair.clone(); /// /// thread::spawn(move|| { ///     let &(ref lock, ref cvar) = &*pair2; ///     let mut started = lock.lock().unwrap(); ///     *started = true; ///     // We notify the condvar that the value has changed. ///     cvar.notify_one(); /// }); /// /// // wait for the thread to start up /// let &(ref lock, ref cvar) = &*pair; /// let result = cvar.wait_timeout_until(lock, Duration::from_millis(100), |started| { ///     started /// }).unwrap(); /// if result.1.timed_out() { ///     // timed-out without the condition ever evaluating to true. /// } /// // access the locked mutex via result.0 /// ``` #[unstable(feature = "wait_timeout_until", issue = "47960")] pub fn wait_timeout_until<'a, T, F>(&self, mut guard: MutexGuard<'a, T>, dur: Duration, mut condition: F) -> LockResult<(MutexGuard<'a, T>, WaitTimeoutResult)> where F: FnMut(&mut T) -> bool { let start = Instant::now(); loop { if condition(&mut *guard) { return Ok((guard, WaitTimeoutResult(false))); } let timeout = match dur.checked_sub(start.elapsed()) { Some(timeout) => timeout, None => return Ok((guard, WaitTimeoutResult(true))), }; guard = self.wait_timeout(guard, timeout)?.0; } } </ins> /// Wakes up one blocked thread on this condvar. /// /// If there is a blocked thread on this condition variable, then it will

#[test] #[cfg_attr(target_os = "emscripten", ignore)] <ins> fn wait_until() { let pair = Arc::new((Mutex::new(false), Condvar::new())); let pair2 = pair.clone(); // Inside of our lock, spawn a new thread, and then wait for it to start. thread::spawn(move|| { let &(ref lock, ref cvar) = &*pair2; let mut started = lock.lock().unwrap(); *started = true; // We notify the condvar that the value has changed. cvar.notify_one(); }); // Wait for the thread to start up. let &(ref lock, ref cvar) = &*pair; let guard = cvar.wait_until(lock.lock().unwrap(), |started| { started }); assert!(*guard); } #[test] #[cfg_attr(target_os = "emscripten", ignore)] </ins> fn wait_timeout_wait() { let m = Arc::new(Mutex::new(())); let c = Arc::new(Condvar::new());

#[test] #[cfg_attr(target_os = "emscripten", ignore)] <ins> fn wait_timeout_until_wait() { let m = Arc::new(Mutex::new(())); let c = Arc::new(Condvar::new()); let g = m.lock().unwrap(); let (_g, wait) = c.wait_timeout_until(g, Duration::from_millis(1), || { false }).unwrap(); // no spurious wakeups. ensure it timed-out assert!(wait.timed_out()); } #[test] #[cfg_attr(target_os = "emscripten", ignore)] fn wait_timeout_until_instant_satisfy() { let m = Arc::new(Mutex::new(())); let c = Arc::new(Condvar::new()); let g = m.lock().unwrap(); let (_g, wait) = c.wait_timeout_until(g, Duration::from_millis(0), || { true }).unwrap(); // ensure it didn't time-out even if we were not given any time. assert!(!wait.timed_out()); } #[test] #[cfg_attr(target_os = "emscripten", ignore)] fn wait_timeout_until_wake() { let pair = Arc::new((Mutex::new(false), Condvar::new())); let pair_copy = pair.clone(); let g = m.lock().unwrap(); let t = thread::spawn(move || { let &(ref lock, ref cvar) = &*pair2; let mut started = lock.lock().unwrap(); thread::sleep(Duration::from_millis(1)); started = true; cvar.notify_one(); }); let (g2, wait) = c.wait_timeout_until(g, Duration::from_millis(u64::MAX), |&notified| { notified }).unwrap(); // ensure it didn't time-out even if we were not given any time. assert!(!wait.timed_out()); assert!(*g2); } #[test] #[cfg_attr(target_os = "emscripten", ignore)] </ins> fn wait_timeout_wake() { let m = Arc::new(Mutex::new(())); let c = Arc::new(Condvar::new());