Merge pull request #62 from FenrirWolf/update-1.24

Pull in upstream changes for rust 1.24.0

8 files changed, 74 insertions, 628 deletions

diff --git a/ctr-std/src/collections/hash/map.rs b/ctr-std/src/collections/hash/map.rs
index b01420f..a82ff91 100644
--- a/ctr-std/src/collections/hash/map.rs
+++ b/ctr-std/src/collections/hash/map.rs
@@ -398,8 +398,9 @@ pub struct HashMap<K, V, S = RandomState> {
 }
 
 /// Search for a pre-hashed key.
+/// If you don't already know the hash, use search or search_mut instead
 #[inline]
-fn search_hashed<K, V, M, F>(table: M, hash: SafeHash, mut is_match: F) -> InternalEntry<K, V, M>
+fn search_hashed<K, V, M, F>(table: M, hash: SafeHash, is_match: F) -> InternalEntry<K, V, M>
     where M: Deref<Target = RawTable<K, V>>,
           F: FnMut(&K) -> bool
 {
@@ -410,6 +411,18 @@ fn search_hashed<K, V, M, F>(table: M, hash: SafeHash, mut is_match: F) -> Inter
         return InternalEntry::TableIsEmpty;
     }
 
+    search_hashed_nonempty(table, hash, is_match)
+}
+
+/// Search for a pre-hashed key when the hash map is known to be non-empty.
+#[inline]
+fn search_hashed_nonempty<K, V, M, F>(table: M, hash: SafeHash, mut is_match: F)
+    -> InternalEntry<K, V, M>
+    where M: Deref<Target = RawTable<K, V>>,
+          F: FnMut(&K) -> bool
+{
+    // Do not check the capacity as an extra branch could slow the lookup.
+
     let size = table.size();
     let mut probe = Bucket::new(table, hash);
     let mut displacement = 0;
@@ -543,24 +556,36 @@ impl<K, V, S> HashMap<K, V, S>
     }
 
     /// Search for a key, yielding the index if it's found in the hashtable.
-    /// If you already have the hash for the key lying around, use
-    /// search_hashed.
+    /// If you already have the hash for the key lying around, or if you need an
+    /// InternalEntry, use search_hashed or search_hashed_nonempty.
     #[inline]
-    fn search<'a, Q: ?Sized>(&'a self, q: &Q) -> InternalEntry<K, V, &'a RawTable<K, V>>
+    fn search<'a, Q: ?Sized>(&'a self, q: &Q)
+        -> Option<FullBucket<K, V, &'a RawTable<K, V>>>
         where K: Borrow<Q>,
               Q: Eq + Hash
     {
+        if self.is_empty() {
+            return None;
+        }
+
         let hash = self.make_hash(q);
-        search_hashed(&self.table, hash, |k| q.eq(k.borrow()))
+        search_hashed_nonempty(&self.table, hash, |k| q.eq(k.borrow()))
+            .into_occupied_bucket()
     }
 
     #[inline]
-    fn search_mut<'a, Q: ?Sized>(&'a mut self, q: &Q) -> InternalEntry<K, V, &'a mut RawTable<K, V>>
+    fn search_mut<'a, Q: ?Sized>(&'a mut self, q: &Q)
+        -> Option<FullBucket<K, V, &'a mut RawTable<K, V>>>
         where K: Borrow<Q>,
               Q: Eq + Hash
     {
+        if self.is_empty() {
+            return None;
+        }
+
         let hash = self.make_hash(q);
-        search_hashed(&mut self.table, hash, |k| q.eq(k.borrow()))
+        search_hashed_nonempty(&mut self.table, hash, |k| q.eq(k.borrow()))
+            .into_occupied_bucket()
     }
 
     // The caller should ensure that invariants by Robin Hood Hashing hold
@@ -1118,7 +1143,7 @@ impl<K, V, S> HashMap<K, V, S>
         where K: Borrow<Q>,
               Q: Hash + Eq
     {
-        self.search(k).into_occupied_bucket().map(|bucket| bucket.into_refs().1)
+        self.search(k).map(|bucket| bucket.into_refs().1)
     }
 
     /// Returns true if the map contains a value for the specified key.
@@ -1145,7 +1170,7 @@ impl<K, V, S> HashMap<K, V, S>
         where K: Borrow<Q>,
               Q: Hash + Eq
     {
-        self.search(k).into_occupied_bucket().is_some()
+        self.search(k).is_some()
     }
 
     /// Returns a mutable reference to the value corresponding to the key.
@@ -1174,7 +1199,7 @@ impl<K, V, S> HashMap<K, V, S>
         where K: Borrow<Q>,
               Q: Hash + Eq
     {
-        self.search_mut(k).into_occupied_bucket().map(|bucket| bucket.into_mut_refs().1)
+        self.search_mut(k).map(|bucket| bucket.into_mut_refs().1)
     }
 
     /// Inserts a key-value pair into the map.
@@ -1234,11 +1259,7 @@ impl<K, V, S> HashMap<K, V, S>
         where K: Borrow<Q>,
               Q: Hash + Eq
     {
-        if self.table.size() == 0 {
-            return None;
-        }
-
-        self.search_mut(k).into_occupied_bucket().map(|bucket| pop_internal(bucket).1)
+        self.search_mut(k).map(|bucket| pop_internal(bucket).1)
     }
 
     /// Removes a key from the map, returning the stored key and value if the
@@ -1269,12 +1290,7 @@ impl<K, V, S> HashMap<K, V, S>
         where K: Borrow<Q>,
               Q: Hash + Eq
     {
-        if self.table.size() == 0 {
-            return None;
-        }
-
         self.search_mut(k)
-            .into_occupied_bucket()
             .map(|bucket| {
                 let (k, v, _) = pop_internal(bucket);
                 (k, v)
@@ -1384,9 +1400,14 @@ impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S>
 {
     type Output = V;
 
+    /// Returns a reference to the value corresponding to the supplied key.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key is not present in the `HashMap`.
     #[inline]
-    fn index(&self, index: &Q) -> &V {
-        self.get(index).expect("no entry found for key")
+    fn index(&self, key: &Q) -> &V {
+        self.get(key).expect("no entry found for key")
     }
 }
 
@@ -2627,15 +2648,11 @@ impl<K, S, Q: ?Sized> super::Recover<Q> for HashMap<K, (), S>
 
     #[inline]
     fn get(&self, key: &Q) -> Option<&K> {
-        self.search(key).into_occupied_bucket().map(|bucket| bucket.into_refs().0)
+        self.search(key).map(|bucket| bucket.into_refs().0)
     }
 
     fn take(&mut self, key: &Q) -> Option<K> {
-        if self.table.size() == 0 {
-            return None;
-        }
-
-        self.search_mut(key).into_occupied_bucket().map(|bucket| pop_internal(bucket).0)
+        self.search_mut(key).map(|bucket| pop_internal(bucket).0)
     }
 
     #[inline]
diff --git a/ctr-std/src/env.rs b/ctr-std/src/env.rs
index 27bf326..c4946b6 100644
--- a/ctr-std/src/env.rs
+++ b/ctr-std/src/env.rs
@@ -723,6 +723,12 @@ pub fn args_os() -> ArgsOs {
     ArgsOs { inner: sys::args::args() }
 }
 
+#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+impl !Send for Args {}
+
+#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+impl !Sync for Args {}
+
 #[stable(feature = "env", since = "1.0.0")]
 impl Iterator for Args {
     type Item = String;
@@ -754,6 +760,12 @@ impl fmt::Debug for Args {
     }
 }
 
+#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+impl !Send for ArgsOs {}
+
+#[stable(feature = "env_unimpl_send_sync", since = "1.25.0")]
+impl !Sync for ArgsOs {}
+
 #[stable(feature = "env", since = "1.0.0")]
 impl Iterator for ArgsOs {
     type Item = OsString;
diff --git a/ctr-std/src/f32.rs b/ctr-std/src/f32.rs
index 5e5695f..a760922 100644
--- a/ctr-std/src/f32.rs
+++ b/ctr-std/src/f32.rs
@@ -1015,7 +1015,7 @@ impl f32 {
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
     #[inline]
     pub fn to_bits(self) -> u32 {
-        unsafe { ::mem::transmute(self) }
+        num::Float::to_bits(self)
     }
 
     /// Raw transmutation from `u32`.
@@ -1023,7 +1023,7 @@ impl f32 {
     /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
     /// It turns out this is incredibly portable, for two reasons:
     ///
-    /// * Floats and Ints have the same endianess on all supported platforms.
+    /// * Floats and Ints have the same endianness on all supported platforms.
     /// * IEEE-754 very precisely specifies the bit layout of floats.
     ///
     /// However there is one caveat: prior to the 2008 version of IEEE-754, how
@@ -1059,8 +1059,7 @@ impl f32 {
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
     #[inline]
     pub fn from_bits(v: u32) -> Self {
-        // It turns out the safety issues with sNaN were overblown! Hooray!
-        unsafe { ::mem::transmute(v) }
+        num::Float::from_bits(v)
     }
 }
 
@@ -1532,6 +1531,7 @@ mod tests {
         assert!(nan.to_degrees().is_nan());
         assert_eq!(inf.to_degrees(), inf);
         assert_eq!(neg_inf.to_degrees(), neg_inf);
+        assert_eq!(1_f32.to_degrees(), 57.2957795130823208767981548141051703);
     }
 
     #[test]
diff --git a/ctr-std/src/f64.rs b/ctr-std/src/f64.rs
index e4eea74..6f34f17 100644
--- a/ctr-std/src/f64.rs
+++ b/ctr-std/src/f64.rs
@@ -970,7 +970,7 @@ impl f64 {
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
     #[inline]
     pub fn to_bits(self) -> u64 {
-        unsafe { ::mem::transmute(self) }
+        num::Float::to_bits(self)
     }
 
     /// Raw transmutation from `u64`.
@@ -978,7 +978,7 @@ impl f64 {
     /// This is currently identical to `transmute::<u64, f64>(v)` on all platforms.
     /// It turns out this is incredibly portable, for two reasons:
     ///
-    /// * Floats and Ints have the same endianess on all supported platforms.
+    /// * Floats and Ints have the same endianness on all supported platforms.
     /// * IEEE-754 very precisely specifies the bit layout of floats.
     ///
     /// However there is one caveat: prior to the 2008 version of IEEE-754, how
@@ -1014,8 +1014,7 @@ impl f64 {
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
     #[inline]
     pub fn from_bits(v: u64) -> Self {
-        // It turns out the safety issues with sNaN were overblown! Hooray!
-        unsafe { ::mem::transmute(v) }
+        num::Float::from_bits(v)
     }
 }
 
diff --git a/ctr-std/src/io/cursor.rs b/ctr-std/src/io/cursor.rs
index c844770..76bcb5f 100644
--- a/ctr-std/src/io/cursor.rs
+++ b/ctr-std/src/io/cursor.rs
@@ -296,7 +296,7 @@ impl<'a> Write for Cursor<&'a mut [u8]> {
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }
 
-#[unstable(feature = "cursor_mut_vec", issue = "30132")]
+#[stable(feature = "cursor_mut_vec", since = "1.25.0")]
 impl<'a> Write for Cursor<&'a mut Vec<u8>> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         vec_write(&mut self.pos, self.inner, buf)
diff --git a/ctr-std/src/path.rs b/ctr-std/src/path.rs
index 7631a9a..e03a182 100644
--- a/ctr-std/src/path.rs
+++ b/ctr-std/src/path.rs
@@ -576,7 +576,7 @@ impl<'a> AsRef<OsStr> for Component<'a> {
     }
 }
 
-#[stable(feature = "path_component_asref", since = "1.24.0")]
+#[stable(feature = "path_component_asref", since = "1.25.0")]
 impl<'a> AsRef<Path> for Component<'a> {
     fn as_ref(&self) -> &Path {
         self.as_os_str().as_ref()
@@ -1869,7 +1869,11 @@ impl Path {
     ///
     /// let path = Path::new("/test/haha/foo.txt");
     ///
+    /// assert_eq!(path.strip_prefix("/"), Ok(Path::new("test/haha/foo.txt")));
     /// assert_eq!(path.strip_prefix("/test"), Ok(Path::new("haha/foo.txt")));
+    /// assert_eq!(path.strip_prefix("/test/"), Ok(Path::new("haha/foo.txt")));
+    /// assert_eq!(path.strip_prefix("/test/haha/foo.txt"), Ok(Path::new("")));
+    /// assert_eq!(path.strip_prefix("/test/haha/foo.txt/"), Ok(Path::new("")));
     /// assert_eq!(path.strip_prefix("test").is_ok(), false);
     /// assert_eq!(path.strip_prefix("/haha").is_ok(), false);
     /// ```
@@ -1900,6 +1904,9 @@ impl Path {
     /// let path = Path::new("/etc/passwd");
     ///
     /// assert!(path.starts_with("/etc"));
+    /// assert!(path.starts_with("/etc/"));
+    /// assert!(path.starts_with("/etc/passwd"));
+    /// assert!(path.starts_with("/etc/passwd/"));
     ///
     /// assert!(!path.starts_with("/e"));
     /// ```
diff --git a/ctr-std/src/time/mod.rs b/ctr-std/src/time.rs
index 6ce3b3e..12f2a9b 100644
--- a/ctr-std/src/time/mod.rs
+++ b/ctr-std/src/time.rs
@@ -29,9 +29,7 @@ use sys::time;
 use sys_common::FromInner;
 
 #[stable(feature = "time", since = "1.3.0")]
-pub use self::duration::Duration;
-
-mod duration;
+pub use core::time::Duration;
 
 /// A measurement of a monotonically nondecreasing clock.
 /// Opaque and useful only with `Duration`.
diff --git a/ctr-std/src/time/duration.rs b/ctr-std/src/time/duration.rs
deleted file mode 100644
index cb5bfb9..0000000
--- a/ctr-std/src/time/duration.rs
+++ /dev/null
@@ -1,587 +0,0 @@
-// Copyright 2012-2017 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.
-
-use iter::Sum;
-use ops::{Add, Sub, Mul, Div, AddAssign, SubAssign, MulAssign, DivAssign};
-
-const NANOS_PER_SEC: u32 = 1_000_000_000;
-const NANOS_PER_MILLI: u32 = 1_000_000;
-const NANOS_PER_MICRO: u32 = 1_000;
-const MILLIS_PER_SEC: u64 = 1_000;
-const MICROS_PER_SEC: u64 = 1_000_000;
-
-/// A `Duration` type to represent a span of time, typically used for system
-/// timeouts.
-///
-/// Each `Duration` is composed of a whole number of seconds and a fractional part
-/// represented in nanoseconds.  If the underlying system does not support
-/// nanosecond-level precision, APIs binding a system timeout will typically round up
-/// the number of nanoseconds.
-///
-/// `Duration`s implement many common traits, including [`Add`], [`Sub`], and other
-/// [`ops`] traits.
-///
-/// [`Add`]: ../../std/ops/trait.Add.html
-/// [`Sub`]: ../../std/ops/trait.Sub.html
-/// [`ops`]: ../../std/ops/index.html
-///
-/// # Examples
-///
-/// ```
-/// use std::time::Duration;
-///
-/// let five_seconds = Duration::new(5, 0);
-/// let five_seconds_and_five_nanos = five_seconds + Duration::new(0, 5);
-///
-/// assert_eq!(five_seconds_and_five_nanos.as_secs(), 5);
-/// assert_eq!(five_seconds_and_five_nanos.subsec_nanos(), 5);
-///
-/// let ten_millis = Duration::from_millis(10);
-/// ```
-#[stable(feature = "duration", since = "1.3.0")]
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash, Default)]
-pub struct Duration {
-    secs: u64,
-    nanos: u32, // Always 0 <= nanos < NANOS_PER_SEC
-}
-
-impl Duration {
-    /// Creates a new `Duration` from the specified number of whole seconds and
-    /// additional nanoseconds.
-    ///
-    /// If the number of nanoseconds is greater than 1 billion (the number of
-    /// nanoseconds in a second), then it will carry over into the seconds provided.
-    ///
-    /// # Panics
-    ///
-    /// This constructor will panic if the carry from the nanoseconds overflows
-    /// the seconds counter.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let five_seconds = Duration::new(5, 0);
-    /// ```
-    #[stable(feature = "duration", since = "1.3.0")]
-    #[inline]
-    pub fn new(secs: u64, nanos: u32) -> Duration {
-        let secs = secs.checked_add((nanos / NANOS_PER_SEC) as u64)
-            .expect("overflow in Duration::new");
-        let nanos = nanos % NANOS_PER_SEC;
-        Duration { secs: secs, nanos: nanos }
-    }
-
-    /// Creates a new `Duration` from the specified number of whole seconds.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_secs(5);
-    ///
-    /// assert_eq!(5, duration.as_secs());
-    /// assert_eq!(0, duration.subsec_nanos());
-    /// ```
-    #[stable(feature = "duration", since = "1.3.0")]
-    #[inline]
-    pub fn from_secs(secs: u64) -> Duration {
-        Duration { secs: secs, nanos: 0 }
-    }
-
-    /// Creates a new `Duration` from the specified number of milliseconds.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_millis(2569);
-    ///
-    /// assert_eq!(2, duration.as_secs());
-    /// assert_eq!(569_000_000, duration.subsec_nanos());
-    /// ```
-    #[stable(feature = "duration", since = "1.3.0")]
-    #[inline]
-    pub fn from_millis(millis: u64) -> Duration {
-        let secs = millis / MILLIS_PER_SEC;
-        let nanos = ((millis % MILLIS_PER_SEC) as u32) * NANOS_PER_MILLI;
-        Duration { secs: secs, nanos: nanos }
-    }
-
-    /// Creates a new `Duration` from the specified number of microseconds.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(duration_from_micros)]
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_micros(1_000_002);
-    ///
-    /// assert_eq!(1, duration.as_secs());
-    /// assert_eq!(2000, duration.subsec_nanos());
-    /// ```
-    #[unstable(feature = "duration_from_micros", issue = "44400")]
-    #[inline]
-    pub fn from_micros(micros: u64) -> Duration {
-        let secs = micros / MICROS_PER_SEC;
-        let nanos = ((micros % MICROS_PER_SEC) as u32) * NANOS_PER_MICRO;
-        Duration { secs: secs, nanos: nanos }
-    }
-
-    /// Creates a new `Duration` from the specified number of nanoseconds.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(duration_extras)]
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_nanos(1_000_000_123);
-    ///
-    /// assert_eq!(1, duration.as_secs());
-    /// assert_eq!(123, duration.subsec_nanos());
-    /// ```
-    #[unstable(feature = "duration_extras", issue = "46507")]
-    #[inline]
-    pub fn from_nanos(nanos: u64) -> Duration {
-        let secs = nanos / (NANOS_PER_SEC as u64);
-        let nanos = (nanos % (NANOS_PER_SEC as u64)) as u32;
-        Duration { secs: secs, nanos: nanos }
-    }
-
-    /// Returns the number of _whole_ seconds contained by this `Duration`.
-    ///
-    /// The returned value does not include the fractional (nanosecond) part of the
-    /// duration, which can be obtained using [`subsec_nanos`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::new(5, 730023852);
-    /// assert_eq!(duration.as_secs(), 5);
-    /// ```
-    ///
-    /// To determine the total number of seconds represented by the `Duration`,
-    /// use `as_secs` in combination with [`subsec_nanos`]:
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::new(5, 730023852);
-    ///
-    /// assert_eq!(5.730023852,
-    ///            duration.as_secs() as f64
-    ///            + duration.subsec_nanos() as f64 * 1e-9);
-    /// ```
-    ///
-    /// [`subsec_nanos`]: #method.subsec_nanos
-    #[stable(feature = "duration", since = "1.3.0")]
-    #[inline]
-    pub fn as_secs(&self) -> u64 { self.secs }
-
-    /// Returns the fractional part of this `Duration`, in milliseconds.
-    ///
-    /// This method does **not** return the length of the duration when
-    /// represented by milliseconds. The returned number always represents a
-    /// fractional portion of a second (i.e. it is less than one thousand).
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(duration_extras)]
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_millis(5432);
-    /// assert_eq!(duration.as_secs(), 5);
-    /// assert_eq!(duration.subsec_millis(), 432);
-    /// ```
-    #[unstable(feature = "duration_extras", issue = "46507")]
-    #[inline]
-    pub fn subsec_millis(&self) -> u32 { self.nanos / NANOS_PER_MILLI }
-
-    /// Returns the fractional part of this `Duration`, in microseconds.
-    ///
-    /// This method does **not** return the length of the duration when
-    /// represented by microseconds. The returned number always represents a
-    /// fractional portion of a second (i.e. it is less than one million).
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(duration_extras, duration_from_micros)]
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_micros(1_234_567);
-    /// assert_eq!(duration.as_secs(), 1);
-    /// assert_eq!(duration.subsec_micros(), 234_567);
-    /// ```
-    #[unstable(feature = "duration_extras", issue = "46507")]
-    #[inline]
-    pub fn subsec_micros(&self) -> u32 { self.nanos / NANOS_PER_MICRO }
-
-    /// Returns the fractional part of this `Duration`, in nanoseconds.
-    ///
-    /// This method does **not** return the length of the duration when
-    /// represented by nanoseconds. The returned number always represents a
-    /// fractional portion of a second (i.e. it is less than one billion).
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::from_millis(5010);
-    /// assert_eq!(duration.as_secs(), 5);
-    /// assert_eq!(duration.subsec_nanos(), 10_000_000);
-    /// ```
-    #[stable(feature = "duration", since = "1.3.0")]
-    #[inline]
-    pub fn subsec_nanos(&self) -> u32 { self.nanos }
-
-    /// Checked `Duration` addition. Computes `self + other`, returning [`None`]
-    /// if overflow occurred.
-    ///
-    /// [`None`]: ../../std/option/enum.Option.html#variant.None
-    ///
-    /// # Examples
-    ///
-    /// Basic usage:
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// assert_eq!(Duration::new(0, 0).checked_add(Duration::new(0, 1)), Some(Duration::new(0, 1)));
-    /// assert_eq!(Duration::new(1, 0).checked_add(Duration::new(std::u64::MAX, 0)), None);
-    /// ```
-    #[stable(feature = "duration_checked_ops", since = "1.16.0")]
-    #[inline]
-    pub fn checked_add(self, rhs: Duration) -> Option<Duration> {
-        if let Some(mut secs) = self.secs.checked_add(rhs.secs) {
-            let mut nanos = self.nanos + rhs.nanos;
-            if nanos >= NANOS_PER_SEC {
-                nanos -= NANOS_PER_SEC;
-                if let Some(new_secs) = secs.checked_add(1) {
-                    secs = new_secs;
-                } else {
-                    return None;
-                }
-            }
-            debug_assert!(nanos < NANOS_PER_SEC);
-            Some(Duration {
-                secs,
-                nanos,
-            })
-        } else {
-            None
-        }
-    }
-
-    /// Checked `Duration` subtraction. Computes `self - other`, returning [`None`]
-    /// if the result would be negative or if overflow occurred.
-    ///
-    /// [`None`]: ../../std/option/enum.Option.html#variant.None
-    ///
-    /// # Examples
-    ///
-    /// Basic usage:
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// assert_eq!(Duration::new(0, 1).checked_sub(Duration::new(0, 0)), Some(Duration::new(0, 1)));
-    /// assert_eq!(Duration::new(0, 0).checked_sub(Duration::new(0, 1)), None);
-    /// ```
-    #[stable(feature = "duration_checked_ops", since = "1.16.0")]
-    #[inline]
-    pub fn checked_sub(self, rhs: Duration) -> Option<Duration> {
-        if let Some(mut secs) = self.secs.checked_sub(rhs.secs) {
-            let nanos = if self.nanos >= rhs.nanos {
-                self.nanos - rhs.nanos
-            } else {
-                if let Some(sub_secs) = secs.checked_sub(1) {
-                    secs = sub_secs;
-                    self.nanos + NANOS_PER_SEC - rhs.nanos
-                } else {
-                    return None;
-                }
-            };
-            debug_assert!(nanos < NANOS_PER_SEC);
-            Some(Duration { secs: secs, nanos: nanos })
-        } else {
-            None
-        }
-    }
-
-    /// Checked `Duration` multiplication. Computes `self * other`, returning
-    /// [`None`] if overflow occurred.
-    ///
-    /// [`None`]: ../../std/option/enum.Option.html#variant.None
-    ///
-    /// # Examples
-    ///
-    /// Basic usage:
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// assert_eq!(Duration::new(0, 500_000_001).checked_mul(2), Some(Duration::new(1, 2)));
-    /// assert_eq!(Duration::new(std::u64::MAX - 1, 0).checked_mul(2), None);
-    /// ```
-    #[stable(feature = "duration_checked_ops", since = "1.16.0")]
-    #[inline]
-    pub fn checked_mul(self, rhs: u32) -> Option<Duration> {
-        // Multiply nanoseconds as u64, because it cannot overflow that way.
-        let total_nanos = self.nanos as u64 * rhs as u64;
-        let extra_secs = total_nanos / (NANOS_PER_SEC as u64);
-        let nanos = (total_nanos % (NANOS_PER_SEC as u64)) as u32;
-        if let Some(secs) = self.secs
-            .checked_mul(rhs as u64)
-            .and_then(|s| s.checked_add(extra_secs)) {
-            debug_assert!(nanos < NANOS_PER_SEC);
-            Some(Duration {
-                secs,
-                nanos,
-            })
-        } else {
-            None
-        }
-    }
-
-    /// Checked `Duration` division. Computes `self / other`, returning [`None`]
-    /// if `other == 0`.
-    ///
-    /// [`None`]: ../../std/option/enum.Option.html#variant.None
-    ///
-    /// # Examples
-    ///
-    /// Basic usage:
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// assert_eq!(Duration::new(2, 0).checked_div(2), Some(Duration::new(1, 0)));
-    /// assert_eq!(Duration::new(1, 0).checked_div(2), Some(Duration::new(0, 500_000_000)));
-    /// assert_eq!(Duration::new(2, 0).checked_div(0), None);
-    /// ```
-    #[stable(feature = "duration_checked_ops", since = "1.16.0")]
-    #[inline]
-    pub fn checked_div(self, rhs: u32) -> Option<Duration> {
-        if rhs != 0 {
-            let secs = self.secs / (rhs as u64);
-            let carry = self.secs - secs * (rhs as u64);
-            let extra_nanos = carry * (NANOS_PER_SEC as u64) / (rhs as u64);
-            let nanos = self.nanos / rhs + (extra_nanos as u32);
-            debug_assert!(nanos < NANOS_PER_SEC);
-            Some(Duration { secs: secs, nanos: nanos })
-        } else {
-            None
-        }
-    }
-}
-
-#[stable(feature = "duration", since = "1.3.0")]
-impl Add for Duration {
-    type Output = Duration;
-
-    fn add(self, rhs: Duration) -> Duration {
-        self.checked_add(rhs).expect("overflow when adding durations")
-    }
-}
-
-#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
-impl AddAssign for Duration {
-    fn add_assign(&mut self, rhs: Duration) {
-        *self = *self + rhs;
-    }
-}
-
-#[stable(feature = "duration", since = "1.3.0")]
-impl Sub for Duration {
-    type Output = Duration;
-
-    fn sub(self, rhs: Duration) -> Duration {
-        self.checked_sub(rhs).expect("overflow when subtracting durations")
-    }
-}
-
-#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
-impl SubAssign for Duration {
-    fn sub_assign(&mut self, rhs: Duration) {
-        *self = *self - rhs;
-    }
-}
-
-#[stable(feature = "duration", since = "1.3.0")]
-impl Mul<u32> for Duration {
-    type Output = Duration;
-
-    fn mul(self, rhs: u32) -> Duration {
-        self.checked_mul(rhs).expect("overflow when multiplying duration by scalar")
-    }
-}
-
-#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
-impl MulAssign<u32> for Duration {
-    fn mul_assign(&mut self, rhs: u32) {
-        *self = *self * rhs;
-    }
-}
-
-#[stable(feature = "duration", since = "1.3.0")]
-impl Div<u32> for Duration {
-    type Output = Duration;
-
-    fn div(self, rhs: u32) -> Duration {
-        self.checked_div(rhs).expect("divide by zero error when dividing duration by scalar")
-    }
-}
-
-#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
-impl DivAssign<u32> for Duration {
-    fn div_assign(&mut self, rhs: u32) {
-        *self = *self / rhs;
-    }
-}
-
-#[stable(feature = "duration_sum", since = "1.16.0")]
-impl Sum for Duration {
-    fn sum<I: Iterator<Item=Duration>>(iter: I) -> Duration {
-        iter.fold(Duration::new(0, 0), |a, b| a + b)
-    }
-}
-
-#[stable(feature = "duration_sum", since = "1.16.0")]
-impl<'a> Sum<&'a Duration> for Duration {
-    fn sum<I: Iterator<Item=&'a Duration>>(iter: I) -> Duration {
-        iter.fold(Duration::new(0, 0), |a, b| a + *b)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::Duration;
-
-    #[test]
-    fn creation() {
-        assert!(Duration::from_secs(1) != Duration::from_secs(0));
-        assert_eq!(Duration::from_secs(1) + Duration::from_secs(2),
-                   Duration::from_secs(3));
-        assert_eq!(Duration::from_millis(10) + Duration::from_secs(4),
-                   Duration::new(4, 10 * 1_000_000));
-        assert_eq!(Duration::from_millis(4000), Duration::new(4, 0));
-    }
-
-    #[test]
-    fn secs() {
-        assert_eq!(Duration::new(0, 0).as_secs(), 0);
-        assert_eq!(Duration::from_secs(1).as_secs(), 1);
-        assert_eq!(Duration::from_millis(999).as_secs(), 0);
-        assert_eq!(Duration::from_millis(1001).as_secs(), 1);
-    }
-
-    #[test]
-    fn nanos() {
-        assert_eq!(Duration::new(0, 0).subsec_nanos(), 0);
-        assert_eq!(Duration::new(0, 5).subsec_nanos(), 5);
-        assert_eq!(Duration::new(0, 1_000_000_001).subsec_nanos(), 1);
-        assert_eq!(Duration::from_secs(1).subsec_nanos(), 0);
-        assert_eq!(Duration::from_millis(999).subsec_nanos(), 999 * 1_000_000);
-        assert_eq!(Duration::from_millis(1001).subsec_nanos(), 1 * 1_000_000);
-    }
-
-    #[test]
-    fn add() {
-        assert_eq!(Duration::new(0, 0) + Duration::new(0, 1),
-                   Duration::new(0, 1));
-        assert_eq!(Duration::new(0, 500_000_000) + Duration::new(0, 500_000_001),
-                   Duration::new(1, 1));
-    }
-
-    #[test]
-    fn checked_add() {
-        assert_eq!(Duration::new(0, 0).checked_add(Duration::new(0, 1)),
-                   Some(Duration::new(0, 1)));
-        assert_eq!(Duration::new(0, 500_000_000).checked_add(Duration::new(0, 500_000_001)),
-                   Some(Duration::new(1, 1)));
-        assert_eq!(Duration::new(1, 0).checked_add(Duration::new(::u64::MAX, 0)), None);
-    }
-
-    #[test]
-    fn sub() {
-        assert_eq!(Duration::new(0, 1) - Duration::new(0, 0),
-                   Duration::new(0, 1));
-        assert_eq!(Duration::new(0, 500_000_001) - Duration::new(0, 500_000_000),
-                   Duration::new(0, 1));
-        assert_eq!(Duration::new(1, 0) - Duration::new(0, 1),
-                   Duration::new(0, 999_999_999));
-    }
-
-    #[test]
-    fn checked_sub() {
-        let zero = Duration::new(0, 0);
-        let one_nano = Duration::new(0, 1);
-        let one_sec = Duration::new(1, 0);
-        assert_eq!(one_nano.checked_sub(zero), Some(Duration::new(0, 1)));
-        assert_eq!(one_sec.checked_sub(one_nano),
-                   Some(Duration::new(0, 999_999_999)));
-        assert_eq!(zero.checked_sub(one_nano), None);
-        assert_eq!(zero.checked_sub(one_sec), None);
-    }
-
-    #[test] #[should_panic]
-    fn sub_bad1() {
-        Duration::new(0, 0) - Duration::new(0, 1);
-    }
-
-    #[test] #[should_panic]
-    fn sub_bad2() {
-        Duration::new(0, 0) - Duration::new(1, 0);
-    }
-
-    #[test]
-    fn mul() {
-        assert_eq!(Duration::new(0, 1) * 2, Duration::new(0, 2));
-        assert_eq!(Duration::new(1, 1) * 3, Duration::new(3, 3));
-        assert_eq!(Duration::new(0, 500_000_001) * 4, Duration::new(2, 4));
-        assert_eq!(Duration::new(0, 500_000_001) * 4000,
-                   Duration::new(2000, 4000));
-    }
-
-    #[test]
-    fn checked_mul() {
-        assert_eq!(Duration::new(0, 1).checked_mul(2), Some(Duration::new(0, 2)));
-        assert_eq!(Duration::new(1, 1).checked_mul(3), Some(Duration::new(3, 3)));
-        assert_eq!(Duration::new(0, 500_000_001).checked_mul(4), Some(Duration::new(2, 4)));
-        assert_eq!(Duration::new(0, 500_000_001).checked_mul(4000),
-                   Some(Duration::new(2000, 4000)));
-        assert_eq!(Duration::new(::u64::MAX - 1, 0).checked_mul(2), None);
-    }
-
-    #[test]
-    fn div() {
-        assert_eq!(Duration::new(0, 1) / 2, Duration::new(0, 0));
-        assert_eq!(Duration::new(1, 1) / 3, Duration::new(0, 333_333_333));
-        assert_eq!(Duration::new(99, 999_999_000) / 100,
-                   Duration::new(0, 999_999_990));
-    }
-
-    #[test]
-    fn checked_div() {
-        assert_eq!(Duration::new(2, 0).checked_div(2), Some(Duration::new(1, 0)));
-        assert_eq!(Duration::new(1, 0).checked_div(2), Some(Duration::new(0, 500_000_000)));
-        assert_eq!(Duration::new(2, 0).checked_div(0), None);
-    }
-}