Auto merge of #58578 - kennytm:rollup, r=kennytm

Rollup of 24 pull requests

Successful merges:

 - #56470 (Modify doctest's auto-`fn main()` to allow `Result`s)
 - #58044 (Make overflowing and wrapping negation const)
 - #58303 (Improve stability tags display)
 - #58336 (Fix search results interactions)
 - #58384 (Fix tables display)
 - #58392 (Use less explicit shifting in std::net::ip)
 - #58409 (rustdoc: respect alternate flag when formatting impl trait)
 - #58456 (Remove no longer accurate diagnostic code about NLL)
 - #58528 (Don't use an allocation for ItemId in StmtKind)
 - #58530 (Monomorphize less code in fs::{read|write})
 - #58534 (Mention capping forbid lints)
 - #58536 (Remove UB in pointer tests)
 - #58538 (Add missing fmt structs examples)
 - #58539 (Add alias methods to PathBuf for underlying OsString (#58234))
 - #58544 (Fix doc for rustc "-g" flag)
 - #58545 (Add regression test for a specialization-related ICE (#39448))
 - #58546 (librustc_codegen_llvm => 2018)
 - #58551 (Explain a panic in test case net::tcp::tests::double_bind)
 - #58553 (Use more impl header lifetime elision)
 - #58562 (Fix style nits)
 - #58565 (Fix typo in std::future::Future docs)
 - #58568 (Fix a transposition in driver.rs.)
 - #58569 (Reduce Some Code Repetitions like `(n << amt) >> amt`)
 - #58576 (Stabilize iter::successors and iter::from_fn)

src/doc/rustc/src/command-line-arguments.md

@@ -42,11 +42,11 @@ This flag prints out various information about the compiler.
 
 ## `-g`: include debug information
 
-A synonym for `-C debug-level=2`.
+A synonym for `-C debuginfo=2`, for more see [here](codegen-options/index.html#debuginfo).
 
 ## `-O`: optimize your code
 
-A synonym for `-C opt-level=2`.
+A synonym for `-C opt-level=2`, for more see [here](codegen-options/index.html#opt-level).
 
 ## `-o`: filename of the output
 

src/doc/rustc/src/lints/levels.md

@@ -90,7 +90,9 @@ This lint level gives you that.
 'forbid' is a special lint level that's stronger than 'deny'. It's the same
 as 'deny' in that a lint at this level will produce an error, but unlike the
 'deny' level, the 'forbid' level can not be overridden to be anything lower
-than an error.
+than an error.  However, lint levels may still be capped with `--cap-lints`
+(see below) so `rustc --cap-lints warn` will make lints set to 'forbid' just
+warn.
 
 ## Configuring warning levels
 

src/doc/rustdoc/src/documentation-tests.md

@@ -236,6 +236,23 @@ appears to the reader as the initial idea but works with doc tests:
 /// ```
 ```
 
+As of version 1.34.0, one can also omit the `fn main()`, but you will have to
+disambiguate the error type:
+
+```ignore
+/// ```
+/// use std::io;
+/// let mut input = String::new();
+/// io::stdin().read_line(&mut input)?;
+/// # Ok::<(), io:Error>(())
+/// ```
+```
+
+This is an unfortunate consequence of the `?` operator adding an implicit
+conversion, so type inference fails because the type is not unique. Please note
+that you must write the `(())` in one sequence without intermediate whitespace
+so that rustdoc understands you want an implicit `Result`-returning function.
+
 ## Documenting macros
 
 Here’s an example of documenting a macro:

src/liballoc/borrow.rs

@@ -182,8 +182,8 @@ pub enum Cow<'a, B: ?Sized + 'a>
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, B: ?Sized + ToOwned> Clone for Cow<'a, B> {
+impl<B: ?Sized + ToOwned> Clone for Cow<'_, B> {
-    fn clone(&self) -> Cow<'a, B> {
+    fn clone(&self) -> Self {
         match *self {
             Borrowed(b) => Borrowed(b),
             Owned(ref o) => {
@@ -193,7 +193,7 @@ impl<'a, B: ?Sized + ToOwned> Clone for Cow<'a, B> {
         }
     }
 
-    fn clone_from(&mut self, source: &Cow<'a, B>) {
+    fn clone_from(&mut self, source: &Self) {
         if let Owned(ref mut dest) = *self {
             if let Owned(ref o) = *source {
                 o.borrow().clone_into(dest);
@@ -296,11 +296,11 @@ impl<B: ?Sized + ToOwned> Deref for Cow<'_, B> {
 impl<B: ?Sized> Eq for Cow<'_, B> where B: Eq + ToOwned {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, B: ?Sized> Ord for Cow<'a, B>
+impl<B: ?Sized> Ord for Cow<'_, B>
     where B: Ord + ToOwned
 {
     #[inline]
-    fn cmp(&self, other: &Cow<'a, B>) -> Ordering {
+    fn cmp(&self, other: &Self) -> Ordering {
         Ord::cmp(&**self, &**other)
     }
 }
@@ -353,18 +353,18 @@ impl<B: ?Sized> fmt::Display for Cow<'_, B>
 }
 
 #[stable(feature = "default", since = "1.11.0")]
-impl<'a, B: ?Sized> Default for Cow<'a, B>
+impl<B: ?Sized> Default for Cow<'_, B>
     where B: ToOwned,
           <B as ToOwned>::Owned: Default
 {
     /// Creates an owned Cow<'a, B> with the default value for the contained owned value.
-    fn default() -> Cow<'a, B> {
+    fn default() -> Self {
         Owned(<B as ToOwned>::Owned::default())
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, B: ?Sized> Hash for Cow<'a, B>
+impl<B: ?Sized> Hash for Cow<'_, B>
     where B: Hash + ToOwned
 {
     #[inline]

src/liballoc/collections/binary_heap.rs

@@ -947,8 +947,8 @@ impl<T: fmt::Debug> fmt::Debug for Iter<'_, T> {
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for Iter<'a, T> {
+impl<T> Clone for Iter<'_, T> {
-    fn clone(&self) -> Iter<'a, T> {
+    fn clone(&self) -> Self {
         Iter { iter: self.iter.clone() }
     }
 }

src/liballoc/collections/btree/map.rs

@@ -1218,8 +1218,8 @@ impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> Clone for Iter<'a, K, V> {
+impl<K, V> Clone for Iter<'_, K, V> {
-    fn clone(&self) -> Iter<'a, K, V> {
+    fn clone(&self) -> Self {
         Iter {
             range: self.range.clone(),
             length: self.length,
@@ -1441,8 +1441,8 @@ impl<K, V> ExactSizeIterator for Keys<'_, K, V> {
 impl<K, V> FusedIterator for Keys<'_, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> Clone for Keys<'a, K, V> {
+impl<K, V> Clone for Keys<'_, K, V> {
-    fn clone(&self) -> Keys<'a, K, V> {
+    fn clone(&self) -> Self {
         Keys { inner: self.inner.clone() }
     }
 }
@@ -1478,8 +1478,8 @@ impl<K, V> ExactSizeIterator for Values<'_, K, V> {
 impl<K, V> FusedIterator for Values<'_, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> Clone for Values<'a, K, V> {
+impl<K, V> Clone for Values<'_, K, V> {
-    fn clone(&self) -> Values<'a, K, V> {
+    fn clone(&self) -> Self {
         Values { inner: self.inner.clone() }
     }
 }
@@ -1606,8 +1606,8 @@ impl<'a, K, V> Range<'a, K, V> {
 impl<K, V> FusedIterator for Range<'_, K, V> {}
 
 #[stable(feature = "btree_range", since = "1.17.0")]
-impl<'a, K, V> Clone for Range<'a, K, V> {
+impl<K, V> Clone for Range<'_, K, V> {
-    fn clone(&self) -> Range<'a, K, V> {
+    fn clone(&self) -> Self {
         Range {
             front: self.front,
             back: self.back,

src/liballoc/collections/btree/set.rs

@@ -907,8 +907,8 @@ impl<T: Debug> Debug for BTreeSet<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for Iter<'a, T> {
+impl<T> Clone for Iter<'_, T> {
-    fn clone(&self) -> Iter<'a, T> {
+    fn clone(&self) -> Self {
         Iter { iter: self.iter.clone() }
     }
 }
@@ -963,8 +963,8 @@ impl<T> ExactSizeIterator for IntoIter<T> {
 impl<T> FusedIterator for IntoIter<T> {}
 
 #[stable(feature = "btree_range", since = "1.17.0")]
-impl<'a, T> Clone for Range<'a, T> {
+impl<T> Clone for Range<'_, T> {
-    fn clone(&self) -> Range<'a, T> {
+    fn clone(&self) -> Self {
         Range { iter: self.iter.clone() }
     }
 }
@@ -998,8 +998,8 @@ fn cmp_opt<T: Ord>(x: Option<&T>, y: Option<&T>, short: Ordering, long: Ordering
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for Difference<'a, T> {
+impl<T> Clone for Difference<'_, T> {
-    fn clone(&self) -> Difference<'a, T> {
+    fn clone(&self) -> Self {
         Difference {
             a: self.a.clone(),
             b: self.b.clone(),
@@ -1036,8 +1036,8 @@ impl<'a, T: Ord> Iterator for Difference<'a, T> {
 impl<T: Ord> FusedIterator for Difference<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for SymmetricDifference<'a, T> {
+impl<T> Clone for SymmetricDifference<'_, T> {
-    fn clone(&self) -> SymmetricDifference<'a, T> {
+    fn clone(&self) -> Self {
         SymmetricDifference {
             a: self.a.clone(),
             b: self.b.clone(),
@@ -1070,8 +1070,8 @@ impl<'a, T: Ord> Iterator for SymmetricDifference<'a, T> {
 impl<T: Ord> FusedIterator for SymmetricDifference<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for Intersection<'a, T> {
+impl<T> Clone for Intersection<'_, T> {
-    fn clone(&self) -> Intersection<'a, T> {
+    fn clone(&self) -> Self {
         Intersection {
             a: self.a.clone(),
             b: self.b.clone(),
@@ -1108,8 +1108,8 @@ impl<'a, T: Ord> Iterator for Intersection<'a, T> {
 impl<T: Ord> FusedIterator for Intersection<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for Union<'a, T> {
+impl<T> Clone for Union<'_, T> {
-    fn clone(&self) -> Union<'a, T> {
+    fn clone(&self) -> Self {
         Union {
             a: self.a.clone(),
             b: self.b.clone(),

src/liballoc/collections/linked_list.rs

@@ -1200,16 +1200,16 @@ unsafe impl<T: Send> Send for LinkedList<T> {}
 unsafe impl<T: Sync> Sync for LinkedList<T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
+unsafe impl<T: Sync> Send for Iter<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
+unsafe impl<T: Sync> Sync for Iter<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
+unsafe impl<T: Send> Send for IterMut<'_, T> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
+unsafe impl<T: Sync> Sync for IterMut<'_, T> {}
 
 #[cfg(test)]
 mod tests {

src/liballoc/collections/vec_deque.rs

@@ -2132,8 +2132,8 @@ impl<T: fmt::Debug> fmt::Debug for Iter<'_, T> {
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Clone for Iter<'a, T> {
+impl<T> Clone for Iter<'_, T> {
-    fn clone(&self) -> Iter<'a, T> {
+    fn clone(&self) -> Self {
         Iter {
             ring: self.ring,
             tail: self.tail,
@@ -2225,7 +2225,7 @@ pub struct IterMut<'a, T: 'a> {
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]
-impl<'a, T: fmt::Debug> fmt::Debug for IterMut<'_, T> {
+impl<T: fmt::Debug> fmt::Debug for IterMut<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let (front, back) = RingSlices::ring_slices(&*self.ring, self.head, self.tail);
         f.debug_tuple("IterMut")

src/liballoc/vec.rs

@@ -2455,7 +2455,7 @@ pub struct Drain<'a, T: 'a> {
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]
-impl<'a, T: 'a + fmt::Debug> fmt::Debug for Drain<'a, T> {
+impl<T: fmt::Debug> fmt::Debug for Drain<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_tuple("Drain")
          .field(&self.iter.as_slice())

src/libcore/fmt/builders.rs

@@ -71,8 +71,10 @@ impl fmt::Write for PadAdapter<'_> {
 ///     }
 /// }
 ///
-/// // prints "Foo { bar: 10, baz: "Hello World" }"
+/// assert_eq!(
-/// println!("{:?}", Foo { bar: 10, baz: "Hello World".to_string() });
+///     format!("{:?}", Foo { bar: 10, baz: "Hello World".to_string() }),
+///     "Foo { bar: 10, baz: \"Hello World\" }",
+/// );
 /// ```
 #[must_use = "must eventually call `finish()` on Debug builders"]
 #[allow(missing_debug_implementations)]
@@ -96,6 +98,33 @@ pub fn debug_struct_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>,
 
 impl<'a, 'b: 'a> DebugStruct<'a, 'b> {
     /// Adds a new field to the generated struct output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Bar {
+    ///     bar: i32,
+    ///     another: String,
+    /// }
+    ///
+    /// impl fmt::Debug for Bar {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_struct("Bar")
+    ///            .field("bar", &self.bar) // We add `bar` field.
+    ///            .field("another", &self.another) // We add `another` field.
+    ///            // We even add a field which doesn't exist (because why not?).
+    ///            .field("not_existing_field", &1)
+    ///            .finish() // We're good to go!
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Bar { bar: 10, another: "Hello World".to_string() }),
+    ///     "Bar { bar: 10, another: \"Hello World\", not_existing_field: 1 }",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn field(&mut self, name: &str, value: &dyn fmt::Debug) -> &mut DebugStruct<'a, 'b> {
         self.result = self.result.and_then(|_| {
@@ -124,6 +153,32 @@ impl<'a, 'b: 'a> DebugStruct<'a, 'b> {
     }
 
     /// Finishes output and returns any error encountered.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Bar {
+    ///     bar: i32,
+    ///     baz: String,
+    /// }
+    ///
+    /// impl fmt::Debug for Bar {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_struct("Bar")
+    ///            .field("bar", &self.bar)
+    ///            .field("baz", &self.baz)
+    ///            .finish() // You need to call it to "finish" the
+    ///                      // struct formatting.
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Bar { bar: 10, baz: "Hello World".to_string() }),
+    ///     "Bar { bar: 10, baz: \"Hello World\" }",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn finish(&mut self) -> fmt::Result {
         if self.has_fields {
@@ -168,8 +223,10 @@ impl<'a, 'b: 'a> DebugStruct<'a, 'b> {
 ///     }
 /// }
 ///
-/// // prints "Foo(10, "Hello World")"
+/// assert_eq!(
-/// println!("{:?}", Foo(10, "Hello World".to_string()));
+///     format!("{:?}", Foo(10, "Hello World".to_string())),
+///     "Foo(10, \"Hello World\")",
+/// );
 /// ```
 #[must_use = "must eventually call `finish()` on Debug builders"]
 #[allow(missing_debug_implementations)]
@@ -193,6 +250,28 @@ pub fn debug_tuple_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>, name: &str) -> D
 
 impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     /// Adds a new field to the generated tuple struct output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(i32, String);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_tuple("Foo")
+    ///            .field(&self.0) // We add the first field.
+    ///            .field(&self.1) // We add the second field.
+    ///            .finish() // We're good to go!
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(10, "Hello World".to_string())),
+    ///     "Foo(10, \"Hello World\")",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn field(&mut self, value: &dyn fmt::Debug) -> &mut DebugTuple<'a, 'b> {
         self.result = self.result.and_then(|_| {
@@ -220,6 +299,29 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     }
 
     /// Finishes output and returns any error encountered.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(i32, String);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_tuple("Foo")
+    ///            .field(&self.0)
+    ///            .field(&self.1)
+    ///            .finish() // You need to call it to "finish" the
+    ///                      // tuple formatting.
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(10, "Hello World".to_string())),
+    ///     "Foo(10, \"Hello World\")",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn finish(&mut self) -> fmt::Result {
         if self.fields > 0 {
@@ -306,8 +408,10 @@ impl<'a, 'b: 'a> DebugInner<'a, 'b> {
 ///     }
 /// }
 ///
-/// // prints "{10, 11}"
+/// assert_eq!(
-/// println!("{:?}", Foo(vec![10, 11]));
+///     format!("{:?}", Foo(vec![10, 11])),
+///     "{10, 11}",
+/// );
 /// ```
 #[must_use = "must eventually call `finish()` on Debug builders"]
 #[allow(missing_debug_implementations)]
@@ -329,6 +433,28 @@ pub fn debug_set_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>) -> DebugSet<'a, 'b
 
 impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     /// Adds a new entry to the set output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<i32>, Vec<u32>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_set()
+    ///            .entry(&self.0) // Adds the first "entry".
+    ///            .entry(&self.1) // Adds the second "entry".
+    ///            .finish()
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![10, 11], vec![12, 13])),
+    ///     "{[10, 11], [12, 13]}",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn entry(&mut self, entry: &dyn fmt::Debug) -> &mut DebugSet<'a, 'b> {
         self.inner.entry(entry);
@@ -336,6 +462,28 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     }
 
     /// Adds the contents of an iterator of entries to the set output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<i32>, Vec<u32>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_set()
+    ///            .entries(self.0.iter()) // Adds the first "entry".
+    ///            .entries(self.1.iter()) // Adds the second "entry".
+    ///            .finish()
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![10, 11], vec![12, 13])),
+    ///     "{10, 11, 12, 13}",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn entries<D, I>(&mut self, entries: I) -> &mut DebugSet<'a, 'b>
         where D: fmt::Debug,
@@ -348,6 +496,27 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     }
 
     /// Finishes output and returns any error encountered.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<i32>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_set()
+    ///            .entries(self.0.iter())
+    ///            .finish() // Ends the struct formatting.
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![10, 11])),
+    ///     "{10, 11}",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn finish(&mut self) -> fmt::Result {
         self.inner.finish();
@@ -377,8 +546,10 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
 ///     }
 /// }
 ///
-/// // prints "[10, 11]"
+/// assert_eq!(
-/// println!("{:?}", Foo(vec![10, 11]));
+///     format!("{:?}", Foo(vec![10, 11])),
+///     "[10, 11]",
+/// );
 /// ```
 #[must_use = "must eventually call `finish()` on Debug builders"]
 #[allow(missing_debug_implementations)]
@@ -400,6 +571,28 @@ pub fn debug_list_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>) -> DebugList<'a,
 
 impl<'a, 'b: 'a> DebugList<'a, 'b> {
     /// Adds a new entry to the list output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<i32>, Vec<u32>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_list()
+    ///            .entry(&self.0) // We add the first "entry".
+    ///            .entry(&self.1) // We add the second "entry".
+    ///            .finish()
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![10, 11], vec![12, 13])),
+    ///     "[[10, 11], [12, 13]]",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn entry(&mut self, entry: &dyn fmt::Debug) -> &mut DebugList<'a, 'b> {
         self.inner.entry(entry);
@@ -407,6 +600,28 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
     }
 
     /// Adds the contents of an iterator of entries to the list output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<i32>, Vec<u32>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_list()
+    ///            .entries(self.0.iter())
+    ///            .entries(self.1.iter())
+    ///            .finish()
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![10, 11], vec![12, 13])),
+    ///     "[10, 11, 12, 13]",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn entries<D, I>(&mut self, entries: I) -> &mut DebugList<'a, 'b>
         where D: fmt::Debug,
@@ -419,6 +634,27 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
     }
 
     /// Finishes output and returns any error encountered.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<i32>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_list()
+    ///            .entries(self.0.iter())
+    ///            .finish() // Ends the struct formatting.
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![10, 11])),
+    ///     "[10, 11]",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn finish(&mut self) -> fmt::Result {
         self.inner.finish();
@@ -448,8 +684,10 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
 ///     }
 /// }
 ///
-/// // prints "{"A": 10, "B": 11}"
+/// assert_eq!(
-/// println!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)]));
+///     format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
+///     "{\"A\": 10, \"B\": 11}",
+/// );
 /// ```
 #[must_use = "must eventually call `finish()` on Debug builders"]
 #[allow(missing_debug_implementations)]
@@ -471,6 +709,27 @@ pub fn debug_map_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>) -> DebugMap<'a, 'b
 
 impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     /// Adds a new entry to the map output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<(String, i32)>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_map()
+    ///            .entry(&"whole", &self.0) // We add the "whole" entry.
+    ///            .finish()
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
+    ///     "{\"whole\": [(\"A\", 10), (\"B\", 11)]}",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn entry(&mut self, key: &dyn fmt::Debug, value: &dyn fmt::Debug) -> &mut DebugMap<'a, 'b> {
         self.result = self.result.and_then(|_| {
@@ -500,6 +759,29 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     }
 
     /// Adds the contents of an iterator of entries to the map output.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<(String, i32)>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_map()
+    ///            // We map our vec so each entries' first field will become
+    ///            // the "key".
+    ///            .entries(self.0.iter().map(|&(ref k, ref v)| (k, v)))
+    ///            .finish()
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
+    ///     "{\"A\": 10, \"B\": 11}",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn entries<K, V, I>(&mut self, entries: I) -> &mut DebugMap<'a, 'b>
         where K: fmt::Debug,
@@ -513,6 +795,27 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     }
 
     /// Finishes output and returns any error encountered.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt;
+    ///
+    /// struct Foo(Vec<(String, i32)>);
+    ///
+    /// impl fmt::Debug for Foo {
+    ///     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         fmt.debug_map()
+    ///            .entries(self.0.iter().map(|&(ref k, ref v)| (k, v)))
+    ///            .finish() // Ends the struct formatting.
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(
+    ///     format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
+    ///     "{\"A\": 10, \"B\": 11}",
+    /// );
+    /// ```
     #[stable(feature = "debug_builders", since = "1.2.0")]
     pub fn finish(&mut self) -> fmt::Result {
         let prefix = if self.is_pretty() && self.has_fields {

src/libcore/future/future.rs

@@ -81,7 +81,7 @@ pub trait Future {
     ///
     /// Once a future has completed (returned `Ready` from `poll`),
     /// then any future calls to `poll` may panic, block forever, or otherwise
-    /// cause any kind of bad behavior expect causing memory unsafety.
+    /// cause any kind of bad behavior except causing memory unsafety.
     /// The `Future` trait itself provides no guarantees about the behavior
     /// of `poll` after a future has completed.
     ///
@@ -92,7 +92,7 @@ pub trait Future {
     fn poll(self: Pin<&mut Self>, waker: &Waker) -> Poll<Self::Output>;
 }
 
-impl<'a, F: ?Sized + Future + Unpin> Future for &'a mut F {
+impl<F: ?Sized + Future + Unpin> Future for &mut F {
     type Output = F::Output;
 
     fn poll(mut self: Pin<&mut Self>, waker: &Waker) -> Poll<Self::Output> {

src/libcore/internal_macros.rs

@@ -7,7 +7,7 @@ macro_rules! forward_ref_unop {
     };
     (impl $imp:ident, $method:ident for $t:ty, #[$attr:meta]) => {
         #[$attr]
-        impl<'a> $imp for &'a $t {
+        impl $imp for &$t {
             type Output = <$t as $imp>::Output;
 
             #[inline]

src/libcore/iter/mod.rs

@@ -326,8 +326,10 @@ pub use self::sources::{Empty, empty};
 pub use self::sources::{Once, once};
 #[unstable(feature = "iter_once_with", issue = "57581")]
 pub use self::sources::{OnceWith, once_with};
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
-pub use self::sources::{FromFn, from_fn, Successors, successors};
+pub use self::sources::{FromFn, from_fn};
+#[stable(feature = "iter_successors", since = "1.34.0")]
+pub use self::sources::{Successors, successors};
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::traits::{FromIterator, IntoIterator, DoubleEndedIterator, Extend};

src/libcore/iter/sources.rs

@@ -514,7 +514,6 @@ pub fn once_with<A, F: FnOnce() -> A>(gen: F) -> OnceWith<F> {
 /// [module-level documentation]: index.html
 ///
 /// ```
-/// #![feature(iter_unfold)]
 /// let mut count = 0;
 /// let counter = std::iter::from_fn(move || {
 ///     // Increment our count. This is why we started at zero.
@@ -530,7 +529,7 @@ pub fn once_with<A, F: FnOnce() -> A>(gen: F) -> OnceWith<F> {
 /// assert_eq!(counter.collect::<Vec<_>>(), &[1, 2, 3, 4, 5]);
 /// ```
 #[inline]
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 pub fn from_fn<T, F>(f: F) -> FromFn<F>
     where F: FnMut() -> Option<T>
 {
@@ -544,10 +543,10 @@ pub fn from_fn<T, F>(f: F) -> FromFn<F>
 ///
 /// [`iter::from_fn`]: fn.from_fn.html
 #[derive(Clone)]
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 pub struct FromFn<F>(F);
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 impl<T, F> Iterator for FromFn<F>
     where F: FnMut() -> Option<T>
 {
@@ -559,7 +558,7 @@ impl<T, F> Iterator for FromFn<F>
     }
 }
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_from_fn", since = "1.34.0")]
 impl<F> fmt::Debug for FromFn<F> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("FromFn").finish()
@@ -572,13 +571,12 @@ impl<F> fmt::Debug for FromFn<F> {
 /// and calls the given `FnMut(&T) -> Option<T>` closure to compute each item’s successor.
 ///
 /// ```
-/// #![feature(iter_unfold)]
 /// use std::iter::successors;
 ///
 /// let powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10));
 /// assert_eq!(powers_of_10.collect::<Vec<_>>(), &[1, 10, 100, 1_000, 10_000]);
 /// ```
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 pub fn successors<T, F>(first: Option<T>, succ: F) -> Successors<T, F>
     where F: FnMut(&T) -> Option<T>
 {
@@ -598,13 +596,13 @@ pub fn successors<T, F>(first: Option<T>, succ: F) -> Successors<T, F>
 ///
 /// [`successors`]: fn.successors.html
 #[derive(Clone)]
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 pub struct Successors<T, F> {
     next: Option<T>,
     succ: F,
 }
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 impl<T, F> Iterator for Successors<T, F>
     where F: FnMut(&T) -> Option<T>
 {
@@ -628,12 +626,12 @@ impl<T, F> Iterator for Successors<T, F>
     }
 }
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 impl<T, F> FusedIterator for Successors<T, F>
     where F: FnMut(&T) -> Option<T>
 {}
 
-#[unstable(feature = "iter_unfold", issue = "55977")]
+#[stable(feature = "iter_successors", since = "1.34.0")]
 impl<T: fmt::Debug, F> fmt::Debug for Successors<T, F> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("Successors")

src/libcore/num/mod.rs

@@ -1215,7 +1215,7 @@ $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
             #[inline]
-            pub fn wrapping_neg(self) -> Self {
+            pub const fn wrapping_neg(self) -> Self {
                 self.overflowing_neg().0
             }
         }
@@ -1569,12 +1569,8 @@ assert_eq!(", stringify!($SelfT), "::MIN.overflowing_neg(), (", stringify!($Self
 ```"),
             #[inline]
             #[stable(feature = "wrapping", since = "1.7.0")]
-            pub fn overflowing_neg(self) -> (Self, bool) {
+            pub const fn overflowing_neg(self) -> (Self, bool) {
-                if self == Self::min_value() {
+                ((!self).wrapping_add(1), self == Self::min_value())
-                    (Self::min_value(), true)
-                } else {
-                    (-self, false)
-                }
             }
         }
 
@@ -3092,7 +3088,7 @@ assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);
         /// ```
         #[stable(feature = "num_wrapping", since = "1.2.0")]
         #[inline]
-        pub fn wrapping_neg(self) -> Self {
+        pub const fn wrapping_neg(self) -> Self {
             self.overflowing_neg().0
         }
 
@@ -3397,7 +3393,7 @@ assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!(
 ```"),
             #[inline]
             #[stable(feature = "wrapping", since = "1.7.0")]
-            pub fn overflowing_neg(self) -> (Self, bool) {
+            pub const fn overflowing_neg(self) -> (Self, bool) {
                 ((!self).wrapping_add(1), self != 0)
             }
         }

src/libcore/option.rs

@@ -874,7 +874,7 @@ impl<T> Option<T> {
     }
 }
 
-impl<'a, T: Copy> Option<&'a T> {
+impl<T: Copy> Option<&T> {
     /// Maps an `Option<&T>` to an `Option<T>` by copying the contents of the
     /// option.
     ///
@@ -895,7 +895,7 @@ impl<'a, T: Copy> Option<&'a T> {
     }
 }
 
-impl<'a, T: Copy> Option<&'a mut T> {
+impl<T: Copy> Option<&mut T> {
     /// Maps an `Option<&mut T>` to an `Option<T>` by copying the contents of the
     /// option.
     ///
@@ -916,7 +916,7 @@ impl<'a, T: Copy> Option<&'a mut T> {
     }
 }
 
-impl<'a, T: Clone> Option<&'a T> {
+impl<T: Clone> Option<&T> {
     /// Maps an `Option<&T>` to an `Option<T>` by cloning the contents of the
     /// option.
     ///
@@ -935,7 +935,7 @@ impl<'a, T: Clone> Option<&'a T> {
     }
 }
 
-impl<'a, T: Clone> Option<&'a mut T> {
+impl<T: Clone> Option<&mut T> {
     /// Maps an `Option<&mut T>` to an `Option<T>` by cloning the contents of the
     /// option.
     ///

src/libcore/slice/mod.rs

@@ -2903,7 +2903,7 @@ macro_rules! iterator {
         }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl<'a, T> ExactSizeIterator for $name<'a, T> {
+        impl<T> ExactSizeIterator for $name<'_, T> {
             #[inline(always)]
             fn len(&self) -> usize {
                 len!(self)
@@ -3098,10 +3098,10 @@ macro_rules! iterator {
         }
 
         #[stable(feature = "fused", since = "1.26.0")]
-        impl<'a, T> FusedIterator for $name<'a, T> {}
+        impl<T> FusedIterator for $name<'_, T> {}
 
         #[unstable(feature = "trusted_len", issue = "37572")]
-        unsafe impl<'a, T> TrustedLen for $name<'a, T> {}
+        unsafe impl<T> TrustedLen for $name<'_, T> {}
     }
 }
 
@@ -4365,8 +4365,8 @@ pub struct RChunks<'a, T:'a> {
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> Clone for RChunks<'a, T> {
+impl<T> Clone for RChunks<'_, T> {
-    fn clone(&self) -> RChunks<'a, T> {
+    fn clone(&self) -> Self {
         RChunks {
             v: self.v,
             chunk_size: self.chunk_size,
@@ -4455,13 +4455,13 @@ impl<'a, T> DoubleEndedIterator for RChunks<'a, T> {
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> ExactSizeIterator for RChunks<'a, T> {}
+impl<T> ExactSizeIterator for RChunks<'_, T> {}
 
 #[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<'a, T> TrustedLen for RChunks<'a, T> {}
+unsafe impl<T> TrustedLen for RChunks<'_, T> {}
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> FusedIterator for RChunks<'a, T> {}
+impl<T> FusedIterator for RChunks<'_, T> {}
 
 #[doc(hidden)]
 #[stable(feature = "rchunks", since = "1.31.0")]
@@ -4580,13 +4580,13 @@ impl<'a, T> DoubleEndedIterator for RChunksMut<'a, T> {
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> ExactSizeIterator for RChunksMut<'a, T> {}
+impl<T> ExactSizeIterator for RChunksMut<'_, T> {}
 
 #[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<'a, T> TrustedLen for RChunksMut<'a, T> {}
+unsafe impl<T> TrustedLen for RChunksMut<'_, T> {}
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> FusedIterator for RChunksMut<'a, T> {}
+impl<T> FusedIterator for RChunksMut<'_, T> {}
 
 #[doc(hidden)]
 #[stable(feature = "rchunks", since = "1.31.0")]
@@ -4711,10 +4711,10 @@ impl<'a, T> ExactSizeIterator for RChunksExact<'a, T> {
 }
 
 #[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<'a, T> TrustedLen for RChunksExact<'a, T> {}
+unsafe impl<T> TrustedLen for RChunksExact<'_, T> {}
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> FusedIterator for RChunksExact<'a, T> {}
+impl<T> FusedIterator for RChunksExact<'_, T> {}
 
 #[doc(hidden)]
 #[stable(feature = "rchunks", since = "1.31.0")]
@@ -4822,17 +4822,17 @@ impl<'a, T> DoubleEndedIterator for RChunksExactMut<'a, T> {
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> ExactSizeIterator for RChunksExactMut<'a, T> {
+impl<T> ExactSizeIterator for RChunksExactMut<'_, T> {
     fn is_empty(&self) -> bool {
         self.v.is_empty()
     }
 }
 
 #[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<'a, T> TrustedLen for RChunksExactMut<'a, T> {}
+unsafe impl<T> TrustedLen for RChunksExactMut<'_, T> {}
 
 #[stable(feature = "rchunks", since = "1.31.0")]
-impl<'a, T> FusedIterator for RChunksExactMut<'a, T> {}
+impl<T> FusedIterator for RChunksExactMut<'_, T> {}
 
 #[doc(hidden)]
 #[stable(feature = "rchunks", since = "1.31.0")]

src/libcore/str/mod.rs

@@ -823,7 +823,7 @@ impl FusedIterator for Bytes<'_> {}
 unsafe impl TrustedLen for Bytes<'_> {}
 
 #[doc(hidden)]
-unsafe impl<'a> TrustedRandomAccess for Bytes<'a> {
+unsafe impl TrustedRandomAccess for Bytes<'_> {
     unsafe fn get_unchecked(&mut self, i: usize) -> u8 {
         self.0.get_unchecked(i)
     }

src/libcore/tests/lib.rs

@@ -14,7 +14,6 @@
 #![feature(iter_copied)]
 #![feature(iter_nth_back)]
 #![feature(iter_once_with)]
-#![feature(iter_unfold)]
 #![feature(pattern)]
 #![feature(range_is_empty)]
 #![feature(raw)]

src/libcore/tests/ptr.rs

@@ -40,18 +40,17 @@ fn test() {
 }
 
 #[test]
-#[cfg(not(miri))] // This test performs invalid OOB pointer arithmetic
 fn test_is_null() {
     let p: *const isize = null();
     assert!(p.is_null());
 
-    let q = unsafe { p.offset(1) };
+    let q = p.wrapping_offset(1);
     assert!(!q.is_null());
 
     let mp: *mut isize = null_mut();
     assert!(mp.is_null());
 
-    let mq = unsafe { mp.offset(1) };
+    let mq = mp.wrapping_offset(1);
     assert!(!mq.is_null());
 
     // Pointers to unsized types -- slices
@@ -208,7 +207,6 @@ fn test_ptr_addition() {
 }
 
 #[test]
-#[cfg(not(miri))] // This test performs invalid OOB pointer arithmetic
 fn test_ptr_subtraction() {
     unsafe {
         let xs = vec![0,1,2,3,4,5,6,7,8,9];
@@ -224,8 +222,11 @@ fn test_ptr_subtraction() {
         let m_start = xs_mut.as_mut_ptr();
         let mut m_ptr = m_start.offset(9);
 
-        while m_ptr >= m_start {
+        loop {
             *m_ptr += *m_ptr;
+            if m_ptr == m_start {
+                break;
+            }
             m_ptr = m_ptr.offset(-1);
         }
 

src/librustc/cfg/construct.rs

@@ -150,9 +150,11 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
         }
     }
 
-    fn pats_all<'b, I: Iterator<Item=&'b P<hir::Pat>>>(&mut self,
+    fn pats_all<'b, I: Iterator<Item=&'b P<hir::Pat>>>(
-                                          pats: I,
+        &mut self,
-                                          pred: CFGIndex) -> CFGIndex {
+        pats: I,
+        pred: CFGIndex
+    ) -> CFGIndex {
         //! Handles case where all of the patterns must match.
         pats.fold(pred, |pred, pat| self.pat(&pat, pred))
     }

src/librustc/diagnostics.rs

@@ -408,11 +408,7 @@ fn bar(x: &str, y: &str) -> &str { }
 fn baz<'a>(x: &'a str, y: &str) -> &str { }
 ```
 
-Lifetime elision in implementation headers was part of the lifetime elision
-RFC. It is, however, [currently unimplemented][iss15872].
-
 [book-le]: https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html#lifetime-elision
-[iss15872]: https://github.com/rust-lang/rust/issues/15872
 "##,
 
 E0119: r##"

src/librustc/hir/intravisit.rs

@@ -953,7 +953,7 @@ pub fn walk_stmt<'v, V: Visitor<'v>>(visitor: &mut V, statement: &'v Stmt) {
     visitor.visit_id(statement.id);
     match statement.node {
         StmtKind::Local(ref local) => visitor.visit_local(local),
-        StmtKind::Item(ref item) => visitor.visit_nested_item(**item),
+        StmtKind::Item(item) => visitor.visit_nested_item(item),
         StmtKind::Expr(ref expression) |
         StmtKind::Semi(ref expression) => {
             visitor.visit_expr(expression)

src/librustc/hir/lowering.rs

@@ -4656,7 +4656,7 @@ impl<'a> LoweringContext<'a> {
                         hir::Stmt {
                             id: node_id,
                             hir_id,
-                            node: hir::StmtKind::Item(P(item_id)),
+                            node: hir::StmtKind::Item(item_id),
                             span: s.span,
                         }
                     })
@@ -4686,7 +4686,7 @@ impl<'a> LoweringContext<'a> {
                         hir::Stmt {
                             id: node_id,
                             hir_id,
-                            node: hir::StmtKind::Item(P(item_id)),
+                            node: hir::StmtKind::Item(item_id),
                             span: s.span,
                         }
                     })

src/librustc/hir/mod.rs

@@ -964,14 +964,19 @@ pub enum PatKind {
     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
     /// `0 <= position <= subpats.len()`
     Tuple(HirVec<P<Pat>>, Option<usize>),
+
     /// A `box` pattern.
     Box(P<Pat>),
+
     /// A reference pattern (e.g., `&mut (a, b)`).
     Ref(P<Pat>, Mutability),
+
     /// A literal.
     Lit(P<Expr>),
+
     /// A range pattern (e.g., `1...2` or `1..2`).
     Range(P<Expr>, P<Expr>, RangeEnd),
+
     /// `[a, b, ..i, y, z]` is represented as:
     ///     `PatKind::Slice(box [a, b], Some(i), box [y, z])`.
     Slice(HirVec<P<Pat>>, Option<P<Pat>>, HirVec<P<Pat>>),
@@ -1175,8 +1180,9 @@ impl fmt::Debug for Stmt {
 pub enum StmtKind {
     /// A local (`let`) binding.
     Local(P<Local>),
+
     /// An item binding.
-    Item(P<ItemId>),
+    Item(ItemId),
 
     /// An expression without a trailing semi-colon (must have unit type).
     Expr(P<Expr>),

src/librustc/hir/print.rs

@@ -1007,8 +1007,8 @@ impl<'a> State<'a> {
                 }
                 self.end()?
             }
-            hir::StmtKind::Item(ref item) => {
+            hir::StmtKind::Item(item) => {
-                self.ann.nested(self, Nested::Item(**item))?
+                self.ann.nested(self, Nested::Item(item))?
             }
             hir::StmtKind::Expr(ref expr) => {
                 self.space_if_not_bol()?;

src/librustc/middle/mem_categorization.rs

@@ -1311,12 +1311,12 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                     Def::Err => {
                         debug!("access to unresolvable pattern {:?}", pat);
                         return Err(())
-                    },
+                    }
                     Def::Variant(variant_did) |
                     Def::VariantCtor(variant_did, ..) => {
                         self.cat_downcast_if_needed(pat, cmt, variant_did)
-                    },
+                    }
-                    _ => cmt
+                    _ => cmt,
                 };
 
                 for fp in field_pats {
@@ -1347,7 +1347,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                 }
             }
 
-                PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
+            PatKind::Box(ref subpat) | PatKind::Ref(ref subpat, _) => {
                 // box p1, &p1, &mut p1.  we can ignore the mutability of
                 // PatKind::Ref since that information is already contained
                 // in the type.

src/librustc/ty/sty.rs

@@ -1167,13 +1167,13 @@ pub type Region<'tcx> = &'tcx RegionKind;
 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
 pub enum RegionKind {
-    // Region bound in a type or fn declaration which will be
+    /// Region bound in a type or fn declaration which will be
-    // substituted 'early' -- that is, at the same time when type
+    /// substituted 'early' -- that is, at the same time when type
-    // parameters are substituted.
+    /// parameters are substituted.
     ReEarlyBound(EarlyBoundRegion),
 
-    // Region bound in a function scope, which will be substituted when the
+    /// Region bound in a function scope, which will be substituted when the
-    // function is called.
+    /// function is called.
     ReLateBound(DebruijnIndex, BoundRegion),
 
     /// When checking a function body, the types of all arguments and so forth

src/librustc_codegen_llvm/Cargo.toml

@@ -2,6 +2,7 @@
 authors = ["The Rust Project Developers"]
 name = "rustc_codegen_llvm"
 version = "0.0.0"
+edition = "2018"
 
 [lib]
 name = "rustc_codegen_llvm"
@@ -10,7 +11,7 @@ crate-type = ["dylib"]
 test = false
 
 [dependencies]
-cc = "1.0.1"
+cc = "1.0.1" # Used to locate MSVC
 num_cpus = "1.0"
 rustc-demangle = "0.1.4"
 rustc_llvm = { path = "../librustc_llvm" }

src/librustc_codegen_llvm/abi.rs

@@ -1,12 +1,12 @@
-use llvm::{self, AttributePlace};
+use crate::llvm::{self, AttributePlace};
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+use crate::type_::Type;
+use crate::type_of::{LayoutLlvmExt, PointerKind};
+use crate::value::Value;
 use rustc_codegen_ssa::MemFlags;
-use builder::Builder;
-use context::CodegenCx;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::mir::operand::OperandValue;
-use type_::Type;
-use type_of::{LayoutLlvmExt, PointerKind};
-use value::Value;
 use rustc_target::abi::call::ArgType;
 
 use rustc_codegen_ssa::traits::*;

src/librustc_codegen_llvm/allocator.rs

@@ -1,13 +1,13 @@
 use std::ffi::CString;
 
-use attributes;
+use crate::attributes;
 use libc::c_uint;
 use rustc::middle::allocator::AllocatorKind;
 use rustc::ty::TyCtxt;
 use rustc_allocator::{ALLOCATOR_METHODS, AllocatorTy};
 
-use ModuleLlvm;
+use crate::ModuleLlvm;
-use llvm::{self, False, True};
+use crate::llvm::{self, False, True};
 
 pub(crate) unsafe fn codegen(tcx: TyCtxt, mods: &ModuleLlvm, kind: AllocatorKind) {
     let llcx = &*mods.llcx;

src/librustc_codegen_llvm/asm.rs

@@ -1,8 +1,8 @@
-use llvm;
+use crate::llvm;
-use context::CodegenCx;
+use crate::context::CodegenCx;
-use type_of::LayoutLlvmExt;
+use crate::type_of::LayoutLlvmExt;
-use builder::Builder;
+use crate::builder::Builder;
-use value::Value;
+use crate::value::Value;
 
 use rustc::hir;
 use rustc_codegen_ssa::traits::*;

src/librustc_codegen_llvm/attributes.rs

@@ -15,15 +15,15 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_target::spec::PanicStrategy;
 use rustc_codegen_ssa::traits::*;
 
-use abi::Abi;
+use crate::abi::Abi;
-use attributes;
+use crate::attributes;
-use llvm::{self, Attribute};
+use crate::llvm::{self, Attribute};
-use llvm::AttributePlace::Function;
+use crate::llvm::AttributePlace::Function;
-use llvm_util;
+use crate::llvm_util;
 pub use syntax::attr::{self, InlineAttr, OptimizeAttr};
 
-use context::CodegenCx;
+use crate::context::CodegenCx;
-use value::Value;
+use crate::value::Value;
 
 /// Mark LLVM function to use provided inline heuristic.
 #[inline]

src/librustc_codegen_llvm/back/archive.rs

@@ -7,12 +7,11 @@ use std::path::{Path, PathBuf};
 use std::ptr;
 use std::str;
 
-use back::bytecode::RLIB_BYTECODE_EXTENSION;
+use crate::back::bytecode::RLIB_BYTECODE_EXTENSION;
+use crate::llvm::archive_ro::{ArchiveRO, Child};
+use crate::llvm::{self, ArchiveKind};
+use crate::metadata::METADATA_FILENAME;
 use rustc_codegen_ssa::back::archive::find_library;
-use libc;
-use llvm::archive_ro::{ArchiveRO, Child};
-use llvm::{self, ArchiveKind};
-use metadata::METADATA_FILENAME;
 use rustc::session::Session;
 
 pub struct ArchiveConfig<'a> {

src/librustc_codegen_llvm/back/link.rs

@@ -1,13 +1,15 @@
-use back::wasm;
 use super::archive::{ArchiveBuilder, ArchiveConfig};
 use super::bytecode::RLIB_BYTECODE_EXTENSION;
+use super::rpath::RPathConfig;
+use super::rpath;
+use crate::back::wasm;
+use crate::metadata::METADATA_FILENAME;
+use crate::context::get_reloc_model;
+use crate::llvm;
 use rustc_codegen_ssa::back::linker::Linker;
 use rustc_codegen_ssa::back::link::{remove, ignored_for_lto, each_linked_rlib, linker_and_flavor,
     get_linker};
 use rustc_codegen_ssa::back::command::Command;
-use super::rpath::RPathConfig;
-use super::rpath;
-use metadata::METADATA_FILENAME;
 use rustc::session::config::{self, DebugInfo, OutputFilenames, OutputType, PrintRequest};
 use rustc::session::config::{RUST_CGU_EXT, Lto, Sanitizer};
 use rustc::session::filesearch;
@@ -22,8 +24,6 @@ use rustc::hir::def_id::CrateNum;
 use tempfile::{Builder as TempFileBuilder, TempDir};
 use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor};
 use rustc_data_structures::fx::FxHashSet;
-use context::get_reloc_model;
-use llvm;
 
 use std::ascii;
 use std::char;
@@ -523,7 +523,7 @@ fn link_natively(sess: &Session,
     }
 
     {
-        let target_cpu = ::llvm_util::target_cpu(sess);
+        let target_cpu = crate::llvm_util::target_cpu(sess);
         let mut linker = codegen_results.linker_info.to_linker(cmd, &sess, flavor, target_cpu);
         link_args(&mut *linker, flavor, sess, crate_type, tmpdir,
                   out_filename, codegen_results);

src/librustc_codegen_llvm/back/lto.rs

@@ -1,12 +1,15 @@
-use back::bytecode::{DecodedBytecode, RLIB_BYTECODE_EXTENSION};
+use crate::back::bytecode::{DecodedBytecode, RLIB_BYTECODE_EXTENSION};
+use crate::back::write::{self, DiagnosticHandlers, with_llvm_pmb, save_temp_bitcode,
+    to_llvm_opt_settings};
+use crate::llvm::archive_ro::ArchiveRO;
+use crate::llvm::{self, True, False};
+use crate::time_graph::Timeline;
+use crate::{ModuleLlvm, LlvmCodegenBackend};
 use rustc_codegen_ssa::back::symbol_export;
 use rustc_codegen_ssa::back::write::{ModuleConfig, CodegenContext, FatLTOInput};
 use rustc_codegen_ssa::back::lto::{SerializedModule, LtoModuleCodegen, ThinShared, ThinModule};
 use rustc_codegen_ssa::traits::*;
-use back::write::{self, DiagnosticHandlers, with_llvm_pmb, save_temp_bitcode, to_llvm_opt_settings};
 use errors::{FatalError, Handler};
-use llvm::archive_ro::ArchiveRO;
-use llvm::{self, True, False};
 use rustc::dep_graph::WorkProduct;
 use rustc::dep_graph::cgu_reuse_tracker::CguReuse;
 use rustc::hir::def_id::LOCAL_CRATE;
@@ -14,12 +17,8 @@ use rustc::middle::exported_symbols::SymbolExportLevel;
 use rustc::session::config::{self, Lto};
 use rustc::util::common::time_ext;
 use rustc_data_structures::fx::FxHashMap;
-use time_graph::Timeline;
-use {ModuleLlvm, LlvmCodegenBackend};
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind};
 
-use libc;
-
 use std::ffi::{CStr, CString};
 use std::ptr;
 use std::slice;

src/librustc_codegen_llvm/back/write.rs

@@ -1,28 +1,27 @@
-use attributes;
+use crate::attributes;
-use back::bytecode::{self, RLIB_BYTECODE_EXTENSION};
+use crate::back::bytecode::{self, RLIB_BYTECODE_EXTENSION};
-use back::lto::ThinBuffer;
+use crate::back::lto::ThinBuffer;
+use crate::base;
+use crate::consts;
+use crate::time_graph::Timeline;
+use crate::llvm::{self, DiagnosticInfo, PassManager, SMDiagnostic};
+use crate::llvm_util;
+use crate::ModuleLlvm;
+use crate::type_::Type;
+use crate::context::{is_pie_binary, get_reloc_model};
+use crate::common;
+use crate::LlvmCodegenBackend;
 use rustc_codegen_ssa::back::write::{CodegenContext, ModuleConfig, run_assembler};
 use rustc_codegen_ssa::traits::*;
-use base;
-use consts;
 use rustc::hir::def_id::LOCAL_CRATE;
 use rustc::session::config::{self, OutputType, Passes, Lto};
 use rustc::session::Session;
 use rustc::ty::TyCtxt;
-use time_graph::Timeline;
-use llvm::{self, DiagnosticInfo, PassManager, SMDiagnostic};
-use llvm_util;
-use ModuleLlvm;
 use rustc_codegen_ssa::{ModuleCodegen, CompiledModule};
 use rustc::util::common::time_ext;
 use rustc_fs_util::{path_to_c_string, link_or_copy};
 use rustc_data_structures::small_c_str::SmallCStr;
-use errors::{self, Handler, FatalError};
+use errors::{Handler, FatalError};
-use type_::Type;
-use context::{is_pie_binary, get_reloc_model};
-use common;
-use LlvmCodegenBackend;
-use rustc_demangle;
 
 use std::ffi::{CString, CStr};
 use std::fs;

src/librustc_codegen_llvm/base.rs

@@ -18,18 +18,18 @@ use rustc_codegen_ssa::{ModuleCodegen, ModuleKind};
 use rustc_codegen_ssa::base::maybe_create_entry_wrapper;
 use super::LlvmCodegenBackend;
 
-use llvm;
+use crate::llvm;
-use metadata;
+use crate::metadata;
+use crate::builder::Builder;
+use crate::common;
+use crate::context::CodegenCx;
+use crate::monomorphize::partitioning::CodegenUnitExt;
 use rustc::dep_graph;
 use rustc::mir::mono::{Linkage, Visibility, Stats};
 use rustc::middle::cstore::{EncodedMetadata};
 use rustc::ty::TyCtxt;
 use rustc::middle::exported_symbols;
 use rustc::session::config::{self, DebugInfo};
-use builder::Builder;
-use common;
-use context::CodegenCx;
-use monomorphize::partitioning::CodegenUnitExt;
 use rustc_codegen_ssa::mono_item::MonoItemExt;
 use rustc_data_structures::small_c_str::SmallCStr;
 
@@ -41,7 +41,7 @@ use std::time::Instant;
 use syntax_pos::symbol::InternedString;
 use rustc::hir::CodegenFnAttrs;
 
-use value::Value;
+use crate::value::Value;
 
 
 pub fn write_metadata<'a, 'gcx>(

src/librustc_codegen_llvm/builder.rs

@@ -1,12 +1,12 @@
-use llvm::{AtomicRmwBinOp, AtomicOrdering, SynchronizationScope, AsmDialect};
+use crate::llvm::{AtomicRmwBinOp, AtomicOrdering, SynchronizationScope, AsmDialect};
-use llvm::{self, False, BasicBlock};
+use crate::llvm::{self, False, BasicBlock};
+use crate::common::Funclet;
+use crate::context::CodegenCx;
+use crate::type_::Type;
+use crate::type_of::LayoutLlvmExt;
+use crate::value::Value;
 use rustc_codegen_ssa::common::{IntPredicate, TypeKind, RealPredicate};
-use rustc_codegen_ssa::{self, MemFlags};
+use rustc_codegen_ssa::MemFlags;
-use common::Funclet;
-use context::CodegenCx;
-use type_::Type;
-use type_of::LayoutLlvmExt;
-use value::Value;
 use libc::{c_uint, c_char};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::ty::layout::{self, Align, Size, TyLayout};
@@ -14,7 +14,6 @@ use rustc::hir::def_id::DefId;
 use rustc::session::config;
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_codegen_ssa::traits::*;
-use syntax;
 use rustc_codegen_ssa::base::to_immediate;
 use rustc_codegen_ssa::mir::operand::{OperandValue, OperandRef};
 use rustc_codegen_ssa::mir::place::PlaceRef;

src/librustc_codegen_llvm/callee.rs

@@ -4,11 +4,11 @@
 //! and methods are represented as just a fn ptr and not a full
 //! closure.
 
-use attributes;
+use crate::attributes;
-use llvm;
+use crate::llvm;
-use monomorphize::Instance;
+use crate::monomorphize::Instance;
-use context::CodegenCx;
+use crate::context::CodegenCx;
-use value::Value;
+use crate::value::Value;
 use rustc_codegen_ssa::traits::*;
 
 use rustc::ty::TypeFoldable;

src/librustc_codegen_llvm/common.rs

@@ -2,17 +2,17 @@
 
 //! Code that is useful in various codegen modules.
 
-use llvm::{self, True, False, Bool, BasicBlock, OperandBundleDef};
+use crate::llvm::{self, True, False, Bool, BasicBlock, OperandBundleDef};
-use abi;
+use crate::abi;
-use consts;
+use crate::consts;
-use type_::Type;
+use crate::type_::Type;
-use type_of::LayoutLlvmExt;
+use crate::type_of::LayoutLlvmExt;
-use value::Value;
+use crate::value::Value;
 use rustc_codegen_ssa::traits::*;
 
+use crate::consts::const_alloc_to_llvm;
 use rustc::ty::layout::{HasDataLayout, LayoutOf, self, TyLayout, Size};
 use rustc::mir::interpret::{Scalar, AllocKind, Allocation};
-use consts::const_alloc_to_llvm;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 
 use libc::{c_uint, c_char};
@@ -20,7 +20,7 @@ use libc::{c_uint, c_char};
 use syntax::symbol::LocalInternedString;
 use syntax::ast::Mutability;
 
-pub use context::CodegenCx;
+pub use crate::context::CodegenCx;
 
 /*
 * A note on nomenclature of linking: "extern", "foreign", and "upcall".

src/librustc_codegen_llvm/consts.rs

@@ -1,20 +1,20 @@
+use crate::llvm::{self, SetUnnamedAddr, True};
+use crate::debuginfo;
+use crate::monomorphize::MonoItem;
+use crate::common::CodegenCx;
+use crate::monomorphize::Instance;
+use crate::base;
+use crate::type_::Type;
+use crate::type_of::LayoutLlvmExt;
+use crate::value::Value;
 use libc::c_uint;
-use llvm::{self, SetUnnamedAddr, True};
 use rustc::hir::def_id::DefId;
 use rustc::mir::interpret::{ConstValue, Allocation, read_target_uint,
     Pointer, ErrorHandled, GlobalId};
 use rustc::hir::Node;
-use debuginfo;
-use monomorphize::MonoItem;
-use common::CodegenCx;
-use monomorphize::Instance;
 use syntax_pos::Span;
 use rustc_target::abi::HasDataLayout;
 use syntax_pos::symbol::LocalInternedString;
-use base;
-use type_::Type;
-use type_of::LayoutLlvmExt;
-use value::Value;
 use rustc::ty::{self, Ty};
 use rustc_codegen_ssa::traits::*;
 

src/librustc_codegen_llvm/context.rs

@@ -1,14 +1,14 @@
-use attributes;
+use crate::attributes;
-use llvm;
+use crate::llvm;
+use crate::debuginfo;
+use crate::monomorphize::Instance;
+use crate::value::Value;
 use rustc::dep_graph::DepGraphSafe;
 use rustc::hir;
-use debuginfo;
-use monomorphize::Instance;
-use value::Value;
 
-use monomorphize::partitioning::CodegenUnit;
+use crate::monomorphize::partitioning::CodegenUnit;
-use type_::Type;
+use crate::type_::Type;
-use type_of::PointeeInfo;
+use crate::type_of::PointeeInfo;
 use rustc_codegen_ssa::traits::*;
 use libc::c_uint;
 
@@ -23,7 +23,7 @@ use rustc::util::nodemap::FxHashMap;
 use rustc_target::spec::{HasTargetSpec, Target};
 use rustc_codegen_ssa::callee::resolve_and_get_fn;
 use rustc_codegen_ssa::base::wants_msvc_seh;
-use callee::get_fn;
+use crate::callee::get_fn;
 
 use std::ffi::CStr;
 use std::cell::{Cell, RefCell};
@@ -31,7 +31,7 @@ use std::iter;
 use std::str;
 use std::sync::Arc;
 use syntax::symbol::LocalInternedString;
-use abi::Abi;
+use crate::abi::Abi;
 
 /// There is one `CodegenCx` per compilation unit. Each one has its own LLVM
 /// `llvm::Context` so that several compilation units may be optimized in parallel.
@@ -103,7 +103,7 @@ pub fn get_reloc_model(sess: &Session) -> llvm::RelocMode {
         None => &sess.target.target.options.relocation_model[..],
     };
 
-    match ::back::write::RELOC_MODEL_ARGS.iter().find(
+    match crate::back::write::RELOC_MODEL_ARGS.iter().find(
         |&&arg| arg.0 == reloc_model_arg) {
         Some(x) => x.1,
         _ => {
@@ -121,7 +121,7 @@ fn get_tls_model(sess: &Session) -> llvm::ThreadLocalMode {
         None => &sess.target.target.options.tls_model[..],
     };
 
-    match ::back::write::TLS_MODEL_ARGS.iter().find(
+    match crate::back::write::TLS_MODEL_ARGS.iter().find(
         |&&arg| arg.0 == tls_model_arg) {
         Some(x) => x.1,
         _ => {
@@ -154,7 +154,7 @@ pub unsafe fn create_module(
 
     // Ensure the data-layout values hardcoded remain the defaults.
     if sess.target.target.options.is_builtin {
-        let tm = ::back::write::create_target_machine(tcx, false);
+        let tm = crate::back::write::create_target_machine(tcx, false);
         llvm::LLVMRustSetDataLayoutFromTargetMachine(llmod, tm);
         llvm::LLVMRustDisposeTargetMachine(tm);
 
@@ -212,7 +212,7 @@ pub unsafe fn create_module(
 impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
     crate fn new(tcx: TyCtxt<'ll, 'tcx, 'tcx>,
                  codegen_unit: Arc<CodegenUnit<'tcx>>,
-                 llvm_module: &'ll ::ModuleLlvm)
+                 llvm_module: &'ll crate::ModuleLlvm)
                  -> Self {
         // An interesting part of Windows which MSVC forces our hand on (and
         // apparently MinGW didn't) is the usage of `dllimport` and `dllexport`
@@ -377,7 +377,7 @@ impl MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     // Returns a Value of the "eh_unwind_resume" lang item if one is defined,
     // otherwise declares it as an external function.
     fn eh_unwind_resume(&self) -> &'ll Value {
-        use attributes;
+        use crate::attributes;
         let unwresume = &self.eh_unwind_resume;
         if let Some(llfn) = unwresume.get() {
             return llfn;

src/librustc_codegen_llvm/debuginfo/create_scope_map.rs

@@ -2,9 +2,9 @@ use rustc_codegen_ssa::debuginfo::{FunctionDebugContext, FunctionDebugContextDat
 use super::metadata::file_metadata;
 use super::utils::{DIB, span_start};
 
-use llvm;
+use crate::llvm;
-use llvm::debuginfo::{DIScope, DISubprogram};
+use crate::llvm::debuginfo::{DIScope, DISubprogram};
-use common::CodegenCx;
+use crate::common::CodegenCx;
 use rustc::mir::{Mir, SourceScope};
 
 use libc::c_uint;

src/librustc_codegen_llvm/debuginfo/gdb.rs

@@ -1,11 +1,11 @@
 // .debug_gdb_scripts binary section.
 
-use llvm;
+use crate::llvm;
 
-use common::CodegenCx;
+use crate::common::CodegenCx;
-use builder::Builder;
+use crate::builder::Builder;
+use crate::value::Value;
 use rustc::session::config::DebugInfo;
-use value::Value;
 use rustc_codegen_ssa::traits::*;
 
 use syntax::attr;

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -7,15 +7,16 @@ use super::utils::{debug_context, DIB, span_start,
 use super::namespace::mangled_name_of_instance;
 use super::type_names::compute_debuginfo_type_name;
 use super::{CrateDebugContext};
+use crate::abi;
+use crate::value::Value;
 use rustc_codegen_ssa::traits::*;
-use abi;
-use value::Value;
 
-use llvm;
+use crate::llvm;
-use llvm::debuginfo::{DIArray, DIType, DIFile, DIScope, DIDescriptor,
+use crate::llvm::debuginfo::{DIArray, DIType, DIFile, DIScope, DIDescriptor,
                       DICompositeType, DILexicalBlock, DIFlags, DebugEmissionKind};
-use llvm_util;
+use crate::llvm_util;
 
+use crate::common::CodegenCx;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc::hir::CodegenFnAttrFlags;
 use rustc::hir::def::CtorKind;
@@ -23,7 +24,6 @@ use rustc::hir::def_id::{DefId, CrateNum, LOCAL_CRATE};
 use rustc::ich::NodeIdHashingMode;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc::ty::Instance;
-use common::CodegenCx;
 use rustc::ty::{self, AdtKind, ParamEnv, Ty, TyCtxt};
 use rustc::ty::layout::{self, Align, Integer, IntegerExt, LayoutOf,
                         PrimitiveExt, Size, TyLayout};

src/librustc_codegen_llvm/debuginfo/mod.rs

@@ -10,24 +10,24 @@ use self::type_names::compute_debuginfo_type_name;
 use self::metadata::{type_metadata, file_metadata, TypeMap};
 use self::source_loc::InternalDebugLocation::{self, UnknownLocation};
 
-use llvm;
+use crate::llvm;
-use llvm::debuginfo::{DIFile, DIType, DIScope, DIBuilder, DISubprogram, DIArray, DIFlags,
+use crate::llvm::debuginfo::{DIFile, DIType, DIScope, DIBuilder, DISubprogram, DIArray, DIFlags,
     DISPFlags, DILexicalBlock};
 use rustc::hir::CodegenFnAttrFlags;
 use rustc::hir::def_id::{DefId, CrateNum, LOCAL_CRATE};
 use rustc::ty::subst::{Substs, UnpackedKind};
 
-use abi::Abi;
+use crate::abi::Abi;
-use common::CodegenCx;
+use crate::common::CodegenCx;
-use builder::Builder;
+use crate::builder::Builder;
-use monomorphize::Instance;
+use crate::monomorphize::Instance;
+use crate::value::Value;
 use rustc::ty::{self, ParamEnv, Ty, InstanceDef};
 use rustc::mir;
 use rustc::session::config::{self, DebugInfo};
 use rustc::util::nodemap::{DefIdMap, FxHashMap, FxHashSet};
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_data_structures::indexed_vec::IndexVec;
-use value::Value;
 use rustc_codegen_ssa::debuginfo::{FunctionDebugContext, MirDebugScope, VariableAccess,
     VariableKind, FunctionDebugContextData};
 

src/librustc_codegen_llvm/debuginfo/namespace.rs

@@ -2,14 +2,14 @@
 
 use super::metadata::{unknown_file_metadata, UNKNOWN_LINE_NUMBER};
 use super::utils::{DIB, debug_context};
-use monomorphize::Instance;
+use crate::monomorphize::Instance;
 use rustc::ty;
 
-use llvm;
+use crate::llvm;
-use llvm::debuginfo::DIScope;
+use crate::llvm::debuginfo::DIScope;
+use crate::common::CodegenCx;
 use rustc::hir::def_id::DefId;
 use rustc::hir::map::DefPathData;
-use common::CodegenCx;
 
 use rustc_data_structures::small_c_str::SmallCStr;
 

src/librustc_codegen_llvm/debuginfo/source_loc.rs

@@ -4,9 +4,9 @@ use super::utils::{debug_context, span_start};
 use super::metadata::UNKNOWN_COLUMN_NUMBER;
 use rustc_codegen_ssa::debuginfo::FunctionDebugContext;
 
-use llvm;
+use crate::llvm;
-use llvm::debuginfo::DIScope;
+use crate::llvm::debuginfo::DIScope;
-use builder::Builder;
+use crate::builder::Builder;
 use rustc_codegen_ssa::traits::*;
 
 use libc::c_uint;

src/librustc_codegen_llvm/debuginfo/type_names.rs

@@ -1,6 +1,6 @@
 // Type Names for Debug Info.
 
-use common::CodegenCx;
+use crate::common::CodegenCx;
 use rustc::hir::def_id::DefId;
 use rustc::ty::subst::Substs;
 use rustc::ty::{self, Ty};
@@ -125,7 +125,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
             }
 
             let abi = sig.abi();
-            if abi != ::abi::Abi::Rust {
+            if abi != crate::abi::Abi::Rust {
                 output.push_str("extern \"");
                 output.push_str(abi.name());
                 output.push_str("\" ");

src/librustc_codegen_llvm/debuginfo/utils.rs

@@ -6,12 +6,12 @@ use super::namespace::item_namespace;
 use rustc::hir::def_id::DefId;
 use rustc::ty::DefIdTree;
 
-use llvm;
+use crate::llvm;
-use llvm::debuginfo::{DIScope, DIBuilder, DIDescriptor, DIArray};
+use crate::llvm::debuginfo::{DIScope, DIBuilder, DIDescriptor, DIArray};
-use common::{CodegenCx};
+use crate::common::{CodegenCx};
 use rustc_codegen_ssa::traits::*;
 
-use syntax_pos::{self, Span};
+use syntax_pos::Span;
 
 pub fn is_node_local_to_unit(cx: &CodegenCx, def_id: DefId) -> bool
 {

src/librustc_codegen_llvm/declare.rs

@@ -11,18 +11,18 @@
 //! * Use define_* family of methods when you might be defining the Value.
 //! * When in doubt, define.
 
-use llvm;
+use crate::llvm;
-use llvm::AttributePlace::Function;
+use crate::llvm::AttributePlace::Function;
+use crate::abi::{FnType, FnTypeExt};
+use crate::attributes;
+use crate::context::CodegenCx;
+use crate::type_::Type;
+use crate::value::Value;
 use rustc::ty::{self, PolyFnSig};
 use rustc::ty::layout::LayoutOf;
 use rustc::session::config::Sanitizer;
 use rustc_data_structures::small_c_str::SmallCStr;
-use abi::{FnType, FnTypeExt};
-use attributes;
-use context::CodegenCx;
-use type_::Type;
 use rustc_codegen_ssa::traits::*;
-use value::Value;
 
 /// Declare a function.
 ///

src/librustc_codegen_llvm/intrinsic.rs

@@ -1,26 +1,26 @@
 #![allow(non_upper_case_globals)]
 
-use attributes;
+use crate::attributes;
-use llvm;
+use crate::llvm;
-use llvm_util;
+use crate::llvm_util;
-use abi::{Abi, FnType, LlvmType, PassMode};
+use crate::abi::{Abi, FnType, LlvmType, PassMode};
+use crate::context::CodegenCx;
+use crate::type_::Type;
+use crate::type_of::LayoutLlvmExt;
+use crate::builder::Builder;
+use crate::value::Value;
+use crate::va_arg::emit_va_arg;
 use rustc_codegen_ssa::MemFlags;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
 use rustc_codegen_ssa::glue;
 use rustc_codegen_ssa::base::{to_immediate, wants_msvc_seh, compare_simd_types};
-use context::CodegenCx;
-use type_::Type;
-use type_of::LayoutLlvmExt;
 use rustc::ty::{self, Ty};
 use rustc::ty::layout::{self, LayoutOf, HasTyCtxt, Primitive};
 use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
 use rustc::hir;
 use syntax::ast::{self, FloatTy};
 use syntax::symbol::Symbol;
-use builder::Builder;
-use value::Value;
-use va_arg::emit_va_arg;
 
 use rustc_codegen_ssa::traits::*;
 
@@ -192,8 +192,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             "size_of_val" => {
                 let tp_ty = substs.type_at(0);
                 if let OperandValue::Pair(_, meta) = args[0].val {
-                    let (llsize, _) =
+                    let (llsize, _) = glue::size_and_align_of_dst(self, tp_ty, Some(meta));
-                        glue::size_and_align_of_dst(self, tp_ty, Some(meta));
                     llsize
                 } else {
                     self.const_usize(self.size_of(tp_ty).bytes())
@@ -206,8 +205,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             "min_align_of_val" => {
                 let tp_ty = substs.type_at(0);
                 if let OperandValue::Pair(_, meta) = args[0].val {
-                    let (_, llalign) =
+                    let (_, llalign) = glue::size_and_align_of_dst(self, tp_ty, Some(meta));
-                        glue::size_and_align_of_dst(self, tp_ty, Some(meta));
                     llalign
                 } else {
                     self.const_usize(self.align_of(tp_ty).bytes())

src/librustc_codegen_llvm/lib.rs

@@ -21,6 +21,9 @@
 #![feature(concat_idents)]
 #![feature(link_args)]
 #![feature(static_nobundle)]
+#![deny(rust_2018_idioms)]
+#![allow(explicit_outlives_requirements)]
+#![allow(elided_lifetimes_in_paths)]
 
 use back::write::create_target_machine;
 use syntax_pos::symbol::Symbol;
@@ -29,16 +32,11 @@ extern crate flate2;
 #[macro_use] extern crate bitflags;
 extern crate libc;
 #[macro_use] extern crate rustc;
-extern crate jobserver;
-extern crate num_cpus;
 extern crate rustc_mir;
 extern crate rustc_allocator;
-extern crate rustc_apfloat;
 extern crate rustc_target;
 #[macro_use] extern crate rustc_data_structures;
-extern crate rustc_demangle;
 extern crate rustc_incremental;
-extern crate rustc_llvm;
 extern crate rustc_codegen_utils;
 extern crate rustc_codegen_ssa;
 extern crate rustc_fs_util;
@@ -48,9 +46,7 @@ extern crate rustc_fs_util;
 extern crate syntax_pos;
 extern crate rustc_errors as errors;
 extern crate serialize;
-extern crate cc; // Used to locate MSVC
 extern crate tempfile;
-extern crate memmap;
 
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::back::write::{CodegenContext, ModuleConfig, FatLTOInput};

src/librustc_codegen_llvm/llvm/diagnostic.rs

@@ -4,7 +4,7 @@ pub use self::OptimizationDiagnosticKind::*;
 pub use self::Diagnostic::*;
 
 use libc::c_uint;
-use value::Value;
+use crate::value::Value;
 
 use super::{DiagnosticInfo, Twine};
 

src/librustc_codegen_llvm/llvm/ffi.rs

@@ -9,8 +9,6 @@ use libc::{c_uint, c_int, size_t, c_char};
 use libc::{c_ulonglong, c_void};
 
 use std::marker::PhantomData;
-use syntax;
-use rustc_codegen_ssa;
 
 use super::RustString;
 

src/librustc_codegen_llvm/llvm/mod.rs

@@ -16,7 +16,7 @@ use std::string::FromUtf8Error;
 use std::slice;
 use std::ffi::CStr;
 use std::cell::RefCell;
-use libc::{self, c_uint, c_char, size_t};
+use libc::{c_uint, c_char, size_t};
 use rustc_data_structures::small_c_str::SmallCStr;
 
 pub mod archive_ro;

src/librustc_codegen_llvm/llvm_util.rs

@@ -1,6 +1,6 @@
+use crate::back::write::create_informational_target_machine;
+use crate::llvm;
 use syntax_pos::symbol::Symbol;
-use back::write::create_informational_target_machine;
-use llvm;
 use rustc::session::Session;
 use rustc::session::config::PrintRequest;
 use rustc_target::spec::MergeFunctions;

src/librustc_codegen_llvm/metadata.rs

@@ -1,8 +1,8 @@
+use crate::llvm;
+use crate::llvm::{False, ObjectFile, mk_section_iter};
+use crate::llvm::archive_ro::ArchiveRO;
 use rustc::middle::cstore::MetadataLoader;
 use rustc_target::spec::Target;
-use llvm;
-use llvm::{False, ObjectFile, mk_section_iter};
-use llvm::archive_ro::ArchiveRO;
 
 use rustc_data_structures::owning_ref::OwningRef;
 use std::path::Path;

src/librustc_codegen_llvm/mono_item.rs

@@ -1,9 +1,9 @@
-use attributes;
+use crate::attributes;
-use base;
+use crate::base;
-use context::CodegenCx;
+use crate::context::CodegenCx;
-use llvm;
+use crate::llvm;
-use monomorphize::Instance;
+use crate::monomorphize::Instance;
-use type_of::LayoutLlvmExt;
+use crate::type_of::LayoutLlvmExt;
 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
 use rustc::mir::mono::{Linkage, Visibility};
 use rustc::ty::TypeFoldable;

src/librustc_codegen_llvm/type_.rs

@@ -1,22 +1,22 @@
 #![allow(non_upper_case_globals)]
 
-pub use llvm::Type;
+pub use crate::llvm::Type;
 
-use llvm;
+use crate::llvm;
-use llvm::{Bool, False, True};
+use crate::llvm::{Bool, False, True};
-use context::CodegenCx;
+use crate::context::CodegenCx;
+use crate::value::Value;
 use rustc_codegen_ssa::traits::*;
-use value::Value;
 
+use crate::common;
+use crate::type_of::LayoutLlvmExt;
+use crate::abi::{LlvmType, FnTypeExt};
 use rustc::util::nodemap::FxHashMap;
 use rustc::ty::Ty;
 use rustc::ty::layout::TyLayout;
 use rustc_target::abi::call::{CastTarget, FnType, Reg};
 use rustc_data_structures::small_c_str::SmallCStr;
-use common;
 use rustc_codegen_ssa::common::TypeKind;
-use type_of::LayoutLlvmExt;
-use abi::{LlvmType, FnTypeExt};
 
 use std::fmt;
 use std::cell::RefCell;
@@ -82,7 +82,6 @@ impl BaseTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
 
     fn type_i16(&self) -> &'ll Type {
         unsafe {
-
             llvm::LLVMInt16TypeInContext(self.llcx)
         }
     }

src/librustc_codegen_llvm/type_of.rs

@@ -1,12 +1,12 @@
-use abi::{FnType, FnTypeExt};
+use crate::abi::{FnType, FnTypeExt};
-use common::*;
+use crate::common::*;
+use crate::type_::Type;
 use rustc::hir;
 use rustc::ty::{self, Ty, TypeFoldable};
 use rustc::ty::layout::{self, Align, LayoutOf, Size, TyLayout};
 use rustc_target::abi::FloatTy;
 use rustc_mir::monomorphize::item::DefPathBasedNames;
 use rustc_codegen_ssa::traits::*;
-use type_::Type;
 
 use std::fmt::Write;
 

src/librustc_codegen_llvm/va_arg.rs

@@ -1,11 +1,11 @@
-use builder::Builder;
+use crate::builder::Builder;
+use crate::type_::Type;
+use crate::type_of::LayoutLlvmExt;
+use crate::value::Value;
 use rustc_codegen_ssa::mir::operand::OperandRef;
 use rustc_codegen_ssa::traits::{BaseTypeMethods, BuilderMethods, ConstMethods, DerivedTypeMethods};
 use rustc::ty::layout::{Align, HasDataLayout, HasTyCtxt, LayoutOf, Size};
 use rustc::ty::Ty;
-use type_::Type;
-use type_of::LayoutLlvmExt;
-use value::Value;
 
 #[allow(dead_code)]
 fn round_pointer_up_to_alignment(

src/librustc_codegen_llvm/value.rs

@@ -1,6 +1,6 @@
-pub use llvm::Value;
+pub use crate::llvm::Value;
 
-use llvm;
+use crate::llvm;
 
 use std::fmt;
 use std::hash::{Hash, Hasher};

src/librustc_driver/driver.rs

@@ -1172,7 +1172,7 @@ pub fn default_provide_extern(providers: &mut ty::query::Providers) {
     cstore::provide_extern(providers);
 }
 
-/// Runs the resolution, typec-hecking, region checking and other
+/// Runs the resolution, type-checking, region checking and other
 /// miscellaneous analysis passes on the crate. Return various
 /// structures carrying the results of the analysis.
 pub fn phase_3_run_analysis_passes<'tcx, F, R>(

src/librustc_mir/build/matches/mod.rs

@@ -338,6 +338,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 self.schedule_drop_for_binding(var, irrefutable_pat.span, OutsideGuard);
                 block.unit()
             }
+
             _ => {
                 let place = unpack!(block = self.as_place(block, initializer));
                 self.place_into_pattern(block, irrefutable_pat, &place, true)
@@ -534,6 +535,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     self.visit_bindings(subpattern, pattern_user_ty, f);
                 }
             }
+
             PatternKind::Array {
                 ref prefix,
                 ref slice,
@@ -556,10 +558,13 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     self.visit_bindings(subpattern, pattern_user_ty.clone().index(), f);
                 }
             }
+
             PatternKind::Constant { .. } | PatternKind::Range { .. } | PatternKind::Wild => {}
+
             PatternKind::Deref { ref subpattern } => {
                 self.visit_bindings(subpattern, pattern_user_ty.deref(), f);
             }
+
             PatternKind::AscribeUserType {
                 ref subpattern,
                 ascription: hair::pattern::Ascription {

src/librustc_mir/build/matches/simplify.rs

@@ -45,10 +45,10 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         }
     }
 
-    /// Tries to simplify `match_pair`, returning true if
+    /// Tries to simplify `match_pair`, returning `Ok(())` if
     /// successful. If successful, new match pairs and bindings will
     /// have been pushed into the candidate. If no simplification is
-    /// possible, Err is returned and no changes are made to
+    /// possible, `Err` is returned and no changes are made to
     /// candidate.
     fn simplify_match_pair<'pat>(&mut self,
                                  match_pair: MatchPair<'pat, 'tcx>,
@@ -174,7 +174,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 } else {
                     Err(match_pair)
                 }
-            },
+            }
 
             PatternKind::Array { ref prefix, ref slice, ref suffix } => {
                 self.prefix_slice_suffix(&mut candidate.match_pairs,

src/librustc_mir/build/matches/test.rs

@@ -35,10 +35,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 }
             }
 
-            PatternKind::Constant { .. }
+            PatternKind::Constant { .. } if is_switch_ty(match_pair.pattern.ty) => {
-            if is_switch_ty(match_pair.pattern.ty) => {
+                // For integers, we use a `SwitchInt` match, which allows
-                // for integers, we use a SwitchInt match, which allows
+                // us to handle more cases.
-                // us to handle more cases
                 Test {
                     span: match_pair.pattern.span,
                     kind: TestKind::SwitchInt {
@@ -253,12 +252,12 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             TestKind::Eq { value, mut ty } => {
                 let val = Operand::Copy(place.clone());
                 let mut expect = self.literal_operand(test.span, ty, value);
-                // Use PartialEq::eq instead of BinOp::Eq
+                // Use `PartialEq::eq` instead of `BinOp::Eq`
                 // (the binop can only handle primitives)
                 let fail = self.cfg.start_new_block();
                 if !ty.is_scalar() {
-                    // If we're using b"..." as a pattern, we need to insert an
+                    // If we're using `b"..."` as a pattern, we need to insert an
-                    // unsizing coercion, as the byte string has the type &[u8; N].
+                    // unsizing coercion, as the byte string has the type `&[u8; N]`.
                     //
                     // We want to do this even when the scrutinee is a reference to an
                     // array, so we can call `<[u8]>::eq` rather than having to find an
@@ -503,6 +502,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 resulting_candidates[variant_index.as_usize()].push(new_candidate);
                 true
             }
+
             (&TestKind::Switch { .. }, _) => false,
 
             // If we are performing a switch over integers, then this informs integer
@@ -539,7 +539,6 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
 
             (&TestKind::SwitchInt { .. }, _) => false,
 
-
             (&TestKind::Len { len: test_len, op: BinOp::Eq },
              &PatternKind::Slice { ref prefix, ref slice, ref suffix }) => {
                 let pat_len = (prefix.len() + suffix.len()) as u64;

src/librustc_mir/build/matches/util.rs

@@ -13,7 +13,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         subpatterns.iter()
                    .map(|fieldpat| {
                        let place = place.clone().field(fieldpat.field,
-                                                         fieldpat.pattern.ty);
+                                                       fieldpat.pattern.ty);
                        MatchPair::new(place, &fieldpat.pattern)
                    })
                    .collect()

src/librustc_mir/hair/pattern/_match.rs

@@ -634,8 +634,8 @@ impl<'tcx> Witness<'tcx> {
 /// but is instead bounded by the maximum fixed length of slice patterns in
 /// the column of patterns being analyzed.
 ///
-/// We make sure to omit constructors that are statically impossible. eg for
+/// We make sure to omit constructors that are statically impossible. E.g., for
-/// Option<!> we do not include Some(_) in the returned list of constructors.
+/// `Option<!>`, we do not include `Some(_)` in the returned list of constructors.
 fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                                   pcx: PatternContext<'tcx>)
                                   -> Vec<Constructor<'tcx>>
@@ -1347,7 +1347,7 @@ fn pat_constructors<'tcx>(cx: &mut MatchCheckCtxt<'_, 'tcx>,
 /// This computes the arity of a constructor. The arity of a constructor
 /// is how many subpattern patterns of that constructor should be expanded to.
 ///
-/// For instance, a tuple pattern (_, 42, Some([])) has the arity of 3.
+/// For instance, a tuple pattern `(_, 42, Some([]))` has the arity of 3.
 /// A struct pattern's arity is the number of fields it contains, etc.
 fn constructor_arity(cx: &MatchCheckCtxt<'a, 'tcx>, ctor: &Constructor<'tcx>, ty: Ty<'tcx>) -> u64 {
     debug!("constructor_arity({:#?}, {:?})", ctor, ty);
@@ -1357,7 +1357,7 @@ fn constructor_arity(cx: &MatchCheckCtxt<'a, 'tcx>, ctor: &Constructor<'tcx>, ty
             Slice(length) => length,
             ConstantValue(_) => 0,
             _ => bug!("bad slice pattern {:?} {:?}", ctor, ty)
-        },
+        }
         ty::Ref(..) => 1,
         ty::Adt(adt, _) => {
             adt.variants[ctor.variant_index_for_adt(cx, adt)].fields.len() as u64
@@ -1381,7 +1381,7 @@ fn constructor_sub_pattern_tys<'a, 'tcx: 'a>(cx: &MatchCheckCtxt<'a, 'tcx>,
             Slice(length) => (0..length).map(|_| ty).collect(),
             ConstantValue(_) => vec![],
             _ => bug!("bad slice pattern {:?} {:?}", ctor, ty)
-        },
+        }
         ty::Ref(_, rty, _) => vec![rty],
         ty::Adt(adt, substs) => {
             if adt.is_box() {

src/librustc_mir/hair/pattern/check_match.rs

@@ -375,7 +375,7 @@ fn check_arms<'a, 'tcx>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                                 },
                                 _ => bug!(),
                             }
-                        },
+                        }
 
                         hir::MatchSource::ForLoopDesugar |
                         hir::MatchSource::Normal => {
@@ -391,7 +391,7 @@ fn check_arms<'a, 'tcx>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                                 err.span_label(catchall, "matches any value");
                             }
                             err.emit();
-                        },
+                        }
 
                         // Unreachable patterns in try expressions occur when one of the arms
                         // are an uninhabited type. Which is OK.
@@ -436,7 +436,7 @@ fn check_exhaustive<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
                     let (tail, head) = witnesses.split_last().unwrap();
                     let head: Vec<_> = head.iter().map(|w| w.to_string()).collect();
                     format!("`{}` and `{}`", head.join("`, `"), tail)
-                },
+                }
                 _ => {
                     let (head, tail) = witnesses.split_at(LIMIT);
                     let head: Vec<_> = head.iter().map(|w| w.to_string()).collect();
@@ -446,7 +446,7 @@ fn check_exhaustive<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
 
             let label_text = match witnesses.len() {
                 1 => format!("pattern {} not covered", joined_patterns),
-                _ => format!("patterns {} not covered", joined_patterns)
+                _ => format!("patterns {} not covered", joined_patterns),
             };
             create_e0004(cx.tcx.sess, sp,
                             format!("non-exhaustive patterns: {} not covered",
@@ -456,7 +456,7 @@ fn check_exhaustive<'p, 'a: 'p, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
         }
         NotUseful => {
             // This is good, wildcard pattern isn't reachable
-        },
+        }
         _ => bug!()
     }
 }

src/librustc_mir/hair/pattern/mod.rs

@@ -965,7 +965,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                 PatternKind::Constant {
                     value: cv,
                 }
-            },
+            }
             ty::Adt(adt_def, _) if adt_def.is_union() => {
                 // Matching on union fields is unsafe, we can't hide it in constants
                 self.tcx.sess.span_err(span, "cannot use unions in constant patterns");
@@ -978,7 +978,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                                     self.tcx.item_path_str(adt_def.did));
                 self.tcx.sess.span_err(span, &msg);
                 PatternKind::Wild
-            },
+            }
             ty::Adt(adt_def, substs) if adt_def.is_enum() => {
                 let variant_index = const_variant_index(
                     self.tcx, self.param_env, cv
@@ -993,7 +993,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                     variant_index,
                     subpatterns,
                 }
-            },
+            }
             ty::Adt(adt_def, _) => {
                 let struct_var = adt_def.non_enum_variant();
                 PatternKind::Leaf {
@@ -1018,7 +1018,7 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                 PatternKind::Constant {
                     value: cv,
                 }
-            },
+            }
         };
 
         Pattern {
@@ -1252,19 +1252,19 @@ pub fn compare_const_vals<'a, 'gcx, 'tcx>(
                 let l = ::rustc_apfloat::ieee::Single::from_bits(a);
                 let r = ::rustc_apfloat::ieee::Single::from_bits(b);
                 l.partial_cmp(&r)
-            },
+            }
             ty::Float(ast::FloatTy::F64) => {
                 let l = ::rustc_apfloat::ieee::Double::from_bits(a);
                 let r = ::rustc_apfloat::ieee::Double::from_bits(b);
                 l.partial_cmp(&r)
-            },
+            }
             ty::Int(_) => {
                 let layout = tcx.layout_of(ty).ok()?;
                 assert!(layout.abi.is_signed());
                 let a = sign_extend(a, layout.size);
                 let b = sign_extend(b, layout.size);
                 Some((a as i128).cmp(&(b as i128)))
-            },
+            }
             _ => Some(a.cmp(&b)),
         }
     }

src/librustc_mir/interpret/operand.rs

@@ -10,6 +10,7 @@ use rustc::mir::interpret::{
     GlobalId, AllocId, InboundsCheck,
     ConstValue, Pointer, Scalar,
     EvalResult, EvalErrorKind,
+    sign_extend, truncate,
 };
 use super::{
     EvalContext, Machine, AllocMap, Allocation, AllocationExtra,
@@ -633,20 +634,17 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
                     Err(_) => return err!(InvalidDiscriminant(raw_discr.erase_tag())),
                 };
                 let real_discr = if discr_val.layout.ty.is_signed() {
-                    let i = bits_discr as i128;
                     // going from layout tag type to typeck discriminant type
                     // requires first sign extending with the layout discriminant
-                    let shift = 128 - discr_val.layout.size.bits();
+                    let sexted = sign_extend(bits_discr, discr_val.layout.size) as i128;
-                    let sexted = (i << shift) >> shift;
                     // and then zeroing with the typeck discriminant type
                     let discr_ty = rval.layout.ty
                         .ty_adt_def().expect("tagged layout corresponds to adt")
                         .repr
                         .discr_type();
-                    let discr_ty = layout::Integer::from_attr(self, discr_ty);
+                    let size = layout::Integer::from_attr(self, discr_ty).size();
-                    let shift = 128 - discr_ty.size().bits();
                     let truncatee = sexted as u128;
-                    (truncatee << shift) >> shift
+                    truncate(truncatee, size)
                 } else {
                     bits_discr
                 };

src/librustdoc/html/format.rs

@@ -49,8 +49,11 @@ pub struct AbiSpace(pub Abi);
 pub struct Function<'a> {
     /// The declaration to emit.
     pub decl: &'a clean::FnDecl,
-    /// The length of the function's "name", used to determine line-wrapping.
+    /// The length of the function header and name. In other words, the number of characters in the
-    pub name_len: usize,
+    /// function declaration up to but not including the parentheses.
+    ///
+    /// Used to determine line-wrapping.
+    pub header_len: usize,
     /// The number of spaces to indent each successive line with, if line-wrapping is necessary.
     pub indent: usize,
     /// Whether the function is async or not.
@@ -675,7 +678,11 @@ fn fmt_type(t: &clean::Type, f: &mut fmt::Formatter, use_absolute: bool) -> fmt:
             }
         }
         clean::ImplTrait(ref bounds) => {
-            write!(f, "impl {}", GenericBounds(bounds))
+            if f.alternate() {
+                write!(f, "impl {:#}", GenericBounds(bounds))
+            } else {
+                write!(f, "impl {}", GenericBounds(bounds))
+            }
         }
         clean::QPath { ref name, ref self_type, ref trait_ } => {
             let should_show_cast = match *trait_ {
@@ -844,7 +851,7 @@ impl fmt::Display for clean::FnDecl {
 
 impl<'a> fmt::Display for Function<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let &Function { decl, name_len, indent, asyncness } = self;
+        let &Function { decl, header_len, indent, asyncness } = self;
         let amp = if f.alternate() { "&" } else { "&amp;" };
         let mut args = String::new();
         let mut args_plain = String::new();
@@ -899,6 +906,8 @@ impl<'a> fmt::Display for Function<'a> {
             }
         }
 
+        let mut args_plain = format!("({})", args_plain);
+
         if decl.variadic {
             args.push_str(",<br> ...");
             args_plain.push_str(", ...");
@@ -917,13 +926,8 @@ impl<'a> fmt::Display for Function<'a> {
             output.to_string()
         };
 
-        let pad = " ".repeat(name_len);
+        let declaration_len = header_len + args_plain.len() + arrow_plain.len();
-        let plain = format!("{pad}({args}){arrow}",
+        let output = if declaration_len > 80 {
-                        pad = pad,
-                        args = args_plain,
-                        arrow = arrow_plain);
-
-        let output = if plain.len() > 80 {
             let full_pad = format!("<br>{}", "&nbsp;".repeat(indent + 4));
             let close_pad = format!("<br>{}", "&nbsp;".repeat(indent));
             format!("({args}{close}){arrow}",

src/librustdoc/html/render.rs

@@ -2787,8 +2787,7 @@ fn item_module(w: &mut fmt::Formatter, cx: &Context,
                        <tr class='{stab}{add}module-item'>\
                            <td><a class=\"{class}\" href=\"{href}\" \
                                   title='{title}'>{name}</a>{unsafety_flag}</td>\
-                           <td class='docblock-short'>{stab_tags}{docs}\
+                           <td class='docblock-short'>{stab_tags}{docs}</td>\
-                           </td>\
                        </tr>",
                        name = *myitem.name.as_ref().unwrap(),
                        stab_tags = stability_tags(myitem),
@@ -2985,14 +2984,16 @@ fn item_static(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
 
 fn item_function(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
                  f: &clean::Function) -> fmt::Result {
-    let name_len = format!("{}{}{}{}{:#}fn {}{:#}",
+    let header_len = format!(
-                           VisSpace(&it.visibility),
+        "{}{}{}{}{:#}fn {}{:#}",
-                           ConstnessSpace(f.header.constness),
+        VisSpace(&it.visibility),
-                           UnsafetySpace(f.header.unsafety),
+        ConstnessSpace(f.header.constness),
-                           AsyncSpace(f.header.asyncness),
+        UnsafetySpace(f.header.unsafety),
-                           AbiSpace(f.header.abi),
+        AsyncSpace(f.header.asyncness),
-                           it.name.as_ref().unwrap(),
+        AbiSpace(f.header.abi),
-                           f.generics).len();
+        it.name.as_ref().unwrap(),
+        f.generics
+    ).len();
     write!(w, "{}<pre class='rust fn'>", render_spotlight_traits(it)?)?;
     render_attributes(w, it)?;
     write!(w,
@@ -3008,7 +3009,7 @@ fn item_function(w: &mut fmt::Formatter, cx: &Context, it: &clean::Item,
            where_clause = WhereClause { gens: &f.generics, indent: 0, end_newline: true },
            decl = Function {
               decl: &f.decl,
-              name_len,
+              header_len,
               indent: 0,
               asyncness: f.header.asyncness,
            })?;
@@ -3423,16 +3424,18 @@ fn render_assoc_item(w: &mut fmt::Formatter,
                 href(did).map(|p| format!("{}#{}.{}", p.0, ty, name)).unwrap_or(anchor)
             }
         };
-        let mut head_len = format!("{}{}{}{}{:#}fn {}{:#}",
+        let mut header_len = format!(
-                                   VisSpace(&meth.visibility),
+            "{}{}{}{}{:#}fn {}{:#}",
-                                   ConstnessSpace(header.constness),
+            VisSpace(&meth.visibility),
-                                   UnsafetySpace(header.unsafety),
+            ConstnessSpace(header.constness),
-                                   AsyncSpace(header.asyncness),
+            UnsafetySpace(header.unsafety),
-                                   AbiSpace(header.abi),
+            AsyncSpace(header.asyncness),
-                                   name,
+            AbiSpace(header.abi),
-                                   *g).len();
+            name,
+            *g
+        ).len();
         let (indent, end_newline) = if parent == ItemType::Trait {
-            head_len += 4;
+            header_len += 4;
             (4, false)
         } else {
             (0, true)
@@ -3450,7 +3453,7 @@ fn render_assoc_item(w: &mut fmt::Formatter,
                generics = *g,
                decl = Function {
                    decl: d,
-                   name_len: head_len,
+                   header_len,
                    indent,
                    asyncness: header.asyncness,
                },

src/librustdoc/html/static/main.js

@@ -1196,7 +1196,7 @@ if (!DOMTokenList.prototype.remove) {
                 var actives = [[], [], []];
                 // "current" is used to know which tab we're looking into.
                 var current = 0;
-                onEachLazy(document.getElementsByClassName("search-results"), function(e) {
+                onEachLazy(document.getElementById("results").childNodes, function(e) {
                     onEachLazy(e.getElementsByClassName("highlighted"), function(e) {
                         actives[current].push(e);
                     });
@@ -1213,7 +1213,7 @@ if (!DOMTokenList.prototype.remove) {
                     removeClass(actives[currentTab][0], "highlighted");
                 } else if (e.which === 40) { // down
                     if (!actives[currentTab].length) {
-                        var results = document.getElementsByClassName("search-results");
+                        var results = document.getElementById("results").childNodes;
                         if (results.length > 0) {
                             var res = results[currentTab].getElementsByClassName("result");
                             if (res.length > 0) {

src/librustdoc/html/static/rustdoc.css

@@ -424,7 +424,8 @@ h4 > code, h3 > code, .invisible > code {
 
 .docblock table {
 	margin: .5em 0;
-	width: 100%;
+	width: calc(100% - 2px);
+	border: 1px dashed;
 }
 
 .docblock table td {
@@ -657,7 +658,7 @@ a {
 	transition: border-color 300ms ease;
 	transition: border-radius 300ms ease-in-out;
 	transition: box-shadow 300ms ease-in-out;
-	width: 100%;
+	width: calc(100% - 32px);
 }
 
 #crate-search + .search-input {

src/librustdoc/html/static/themes/dark.css

@@ -68,20 +68,10 @@ pre {
 	border-bottom-color: #DDD;
 }
 
-.docblock table {
+.docblock table, .docblock table td, .docblock table th {
 	border-color: #ddd;
 }
 
-.docblock table td {
-	border-top-color: #ddd;
-	border-bottom-color: #ddd;
-}
-
-.docblock table th {
-	border-top-color: #ddd;
-	border-bottom-color: #ddd;
-}
-
 .content .method .where,
 .content .fn .where,
 .content .where.fmt-newline {
@@ -190,15 +180,15 @@ a.test-arrow {
 	box-shadow: 1px 0 0 1px #000, 0 0 0 2px transparent;
 }
 
-.stab.unstable { background: #FFF5D6; border-color: #FFC600; color: #404040; }
-.stab.internal { background: #FFB9B3; border-color: #B71C1C; color: #404040; }
-.stab.deprecated { background: #F3DFFF; border-color: #7F0087;  color: #404040; }
-.stab.portability { background: #C4ECFF; border-color: #7BA5DB;  color: #404040; }
-
 .module-item .stab {
 	color: #ddd;
 }
 
+.stab.unstable {background: #FFF5D6; border-color: #FFC600; color: #2f2f2f; }
+.stab.internal { background: #FFB9B3; border-color: #B71C1C; color: #2f2f2f; }
+.stab.deprecated { background: #F3DFFF; border-color: #7F0087; color: #2f2f2f; }
+.stab.portability { background: #C4ECFF; border-color: #7BA5DB; color: #2f2f2f; }
+
 #help > div {
 	background: #4d4d4d;
 	border-color: #bfbfbf;

src/librustdoc/html/static/themes/light.css

@@ -67,23 +67,13 @@ pre {
 }
 
 .docblock h1, .docblock h2, .docblock h3, .docblock h4, .docblock h5 {
-	border-bottom-color: #DDD;
+	border-bottom-color: #ddd;
 }
 
-.docblock table {
+.docblock table, .docblock table td, .docblock table th {
 	border-color: #ddd;
 }
 
-.docblock table td {
-	border-top-color: #ddd;
-	border-bottom-color: #ddd;
-}
-
-.docblock table th {
-	border-top-color: #ddd;
-	border-bottom-color: #ddd;
-}
-
 .content .method .where,
 .content .fn .where,
 .content .where.fmt-newline {
@@ -191,15 +181,15 @@ a.test-arrow {
 	box-shadow: 1px 0 0 1px #e0e0e0, 0 0 0 2px transparent;
 }
 
+.module-item .stab {
+	color: #000;
+}
+
 .stab.unstable { background: #FFF5D6; border-color: #FFC600; }
 .stab.internal { background: #FFB9B3; border-color: #B71C1C; }
 .stab.deprecated { background: #F3DFFF; border-color: #7F0087; }
 .stab.portability { background: #C4ECFF; border-color: #7BA5DB; }
 
-.module-item .stab {
-	color: #000;
-}
-
 #help > div {
 	background: #e9e9e9;
 	border-color: #bfbfbf;

src/librustdoc/test.rs

@@ -517,13 +517,19 @@ pub fn make_test(s: &str,
         }
     }
 
-    if dont_insert_main || already_has_main {
+    // FIXME: This code cannot yet handle no_std test cases yet
+    if dont_insert_main || already_has_main || prog.contains("![no_std]") {
         prog.push_str(everything_else);
     } else {
-        prog.push_str("fn main() {\n");
+        let returns_result = everything_else.trim_end().ends_with("(())");
+        let (main_pre, main_post) = if returns_result {
+            ("fn main() { fn _inner() -> Result<(), impl core::fmt::Debug> {",
+             "}\n_inner().unwrap() }")
+        } else {
+            ("fn main() {\n", "\n}")
+        };
+        prog.extend([main_pre, everything_else, main_post].iter().cloned());
         line_offset += 1;
-        prog.push_str(everything_else);
-        prog.push_str("\n}");
     }
 
     debug!("final doctest:\n{}", prog);

src/libstd/collections/hash/map.rs

@@ -1641,7 +1641,7 @@ impl<K, V, S> Default for HashMap<K, V, S>
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S>
+impl<K, Q: ?Sized, V, S> Index<&Q> for HashMap<K, V, S>
     where K: Eq + Hash + Borrow<Q>,
           Q: Eq + Hash,
           S: BuildHasher
@@ -1673,14 +1673,14 @@ pub struct Iter<'a, K: 'a, V: 'a> {
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> Clone for Iter<'a, K, V> {
+impl<K, V> Clone for Iter<'_, K, V> {
-    fn clone(&self) -> Iter<'a, K, V> {
+    fn clone(&self) -> Self {
         Iter { inner: self.inner.clone() }
     }
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K: Debug, V: Debug> fmt::Debug for Iter<'a, K, V> {
+impl<K: Debug, V: Debug> fmt::Debug for Iter<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_list()
             .entries(self.clone())
@@ -1726,14 +1726,14 @@ pub struct Keys<'a, K: 'a, V: 'a> {
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> Clone for Keys<'a, K, V> {
+impl<K, V> Clone for Keys<'_, K, V> {
-    fn clone(&self) -> Keys<'a, K, V> {
+    fn clone(&self) -> Self {
         Keys { inner: self.inner.clone() }
     }
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K: Debug, V> fmt::Debug for Keys<'a, K, V> {
+impl<K: Debug, V> fmt::Debug for Keys<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_list()
             .entries(self.clone())
@@ -1755,14 +1755,14 @@ pub struct Values<'a, K: 'a, V: 'a> {
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> Clone for Values<'a, K, V> {
+impl<K, V> Clone for Values<'_, K, V> {
-    fn clone(&self) -> Values<'a, K, V> {
+    fn clone(&self) -> Self {
         Values { inner: self.inner.clone() }
     }
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K, V: Debug> fmt::Debug for Values<'a, K, V> {
+impl<K, V: Debug> fmt::Debug for Values<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_list()
             .entries(self.clone())
@@ -2241,7 +2241,7 @@ impl<'a, K, V, S> RawVacantEntryMut<'a, K, V, S> {
 }
 
 #[unstable(feature = "hash_raw_entry", issue = "56167")]
-impl<'a, K, V, S> Debug for RawEntryBuilderMut<'a, K, V, S> {
+impl<K, V, S> Debug for RawEntryBuilderMut<'_, K, V, S> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("RawEntryBuilder")
          .finish()
@@ -2249,7 +2249,7 @@ impl<'a, K, V, S> Debug for RawEntryBuilderMut<'a, K, V, S> {
 }
 
 #[unstable(feature = "hash_raw_entry", issue = "56167")]
-impl<'a, K: Debug, V: Debug, S> Debug for RawEntryMut<'a, K, V, S> {
+impl<K: Debug, V: Debug, S> Debug for RawEntryMut<'_, K, V, S> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             RawEntryMut::Vacant(ref v) => {
@@ -2267,7 +2267,7 @@ impl<'a, K: Debug, V: Debug, S> Debug for RawEntryMut<'a, K, V, S> {
 }
 
 #[unstable(feature = "hash_raw_entry", issue = "56167")]
-impl<'a, K: Debug, V: Debug> Debug for RawOccupiedEntryMut<'a, K, V> {
+impl<K: Debug, V: Debug> Debug for RawOccupiedEntryMut<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("RawOccupiedEntryMut")
          .field("key", self.key())
@@ -2277,7 +2277,7 @@ impl<'a, K: Debug, V: Debug> Debug for RawOccupiedEntryMut<'a, K, V> {
 }
 
 #[unstable(feature = "hash_raw_entry", issue = "56167")]
-impl<'a, K, V, S> Debug for RawVacantEntryMut<'a, K, V, S> {
+impl<K, V, S> Debug for RawVacantEntryMut<'_, K, V, S> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("RawVacantEntryMut")
          .finish()
@@ -2285,7 +2285,7 @@ impl<'a, K, V, S> Debug for RawVacantEntryMut<'a, K, V, S> {
 }
 
 #[unstable(feature = "hash_raw_entry", issue = "56167")]
-impl<'a, K, V, S> Debug for RawEntryBuilder<'a, K, V, S> {
+impl<K, V, S> Debug for RawEntryBuilder<'_, K, V, S> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("RawEntryBuilder")
          .finish()
@@ -2312,7 +2312,7 @@ pub enum Entry<'a, K: 'a, V: 'a> {
 }
 
 #[stable(feature= "debug_hash_map", since = "1.12.0")]
-impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for Entry<'a, K, V> {
+impl<K: Debug, V: Debug> Debug for Entry<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             Vacant(ref v) => {
@@ -2340,7 +2340,7 @@ pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
 }
 
 #[stable(feature= "debug_hash_map", since = "1.12.0")]
-impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for OccupiedEntry<'a, K, V> {
+impl<K: Debug, V: Debug> Debug for OccupiedEntry<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("OccupiedEntry")
             .field("key", self.key())
@@ -2361,7 +2361,7 @@ pub struct VacantEntry<'a, K: 'a, V: 'a> {
 }
 
 #[stable(feature= "debug_hash_map", since = "1.12.0")]
-impl<'a, K: 'a + Debug, V: 'a> Debug for VacantEntry<'a, K, V> {
+impl<K: Debug, V> Debug for VacantEntry<'_, K, V> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_tuple("VacantEntry")
             .field(self.key())
@@ -2448,7 +2448,7 @@ impl<'a, K, V> Iterator for Iter<'a, K, V> {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
+impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
     #[inline]
     fn len(&self) -> usize {
         self.inner.len()
@@ -2456,7 +2456,7 @@ impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K, V> FusedIterator for Iter<'a, K, V> {}
+impl<K, V> FusedIterator for Iter<'_, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K, V> Iterator for IterMut<'a, K, V> {
@@ -2472,17 +2472,17 @@ impl<'a, K, V> Iterator for IterMut<'a, K, V> {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {
+impl<K, V> ExactSizeIterator for IterMut<'_, K, V> {
     #[inline]
     fn len(&self) -> usize {
         self.inner.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K, V> FusedIterator for IterMut<'a, K, V> {}
+impl<K, V> FusedIterator for IterMut<'_, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K, V> fmt::Debug for IterMut<'a, K, V>
+impl<K, V> fmt::Debug for IterMut<'_, K, V>
     where K: fmt::Debug,
           V: fmt::Debug,
 {
@@ -2539,14 +2539,14 @@ impl<'a, K, V> Iterator for Keys<'a, K, V> {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {
+impl<K, V> ExactSizeIterator for Keys<'_, K, V> {
     #[inline]
     fn len(&self) -> usize {
         self.inner.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K, V> FusedIterator for Keys<'a, K, V> {}
+impl<K, V> FusedIterator for Keys<'_, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, K, V> Iterator for Values<'a, K, V> {
@@ -2562,14 +2562,14 @@ impl<'a, K, V> Iterator for Values<'a, K, V> {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {
+impl<K, V> ExactSizeIterator for Values<'_, K, V> {
     #[inline]
     fn len(&self) -> usize {
         self.inner.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K, V> FusedIterator for Values<'a, K, V> {}
+impl<K, V> FusedIterator for Values<'_, K, V> {}
 
 #[stable(feature = "map_values_mut", since = "1.10.0")]
 impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
@@ -2585,17 +2585,17 @@ impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
     }
 }
 #[stable(feature = "map_values_mut", since = "1.10.0")]
-impl<'a, K, V> ExactSizeIterator for ValuesMut<'a, K, V> {
+impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> {
     #[inline]
     fn len(&self) -> usize {
         self.inner.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K, V> FusedIterator for ValuesMut<'a, K, V> {}
+impl<K, V> FusedIterator for ValuesMut<'_, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K, V> fmt::Debug for ValuesMut<'a, K, V>
+impl<K, V> fmt::Debug for ValuesMut<'_, K, V>
     where K: fmt::Debug,
           V: fmt::Debug,
 {
@@ -2620,17 +2620,17 @@ impl<'a, K, V> Iterator for Drain<'a, K, V> {
     }
 }
 #[stable(feature = "drain", since = "1.6.0")]
-impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> {
+impl<K, V> ExactSizeIterator for Drain<'_, K, V> {
     #[inline]
     fn len(&self) -> usize {
         self.inner.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K, V> FusedIterator for Drain<'a, K, V> {}
+impl<K, V> FusedIterator for Drain<'_, K, V> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K, V> fmt::Debug for Drain<'a, K, V>
+impl<K, V> fmt::Debug for Drain<'_, K, V>
     where K: fmt::Debug,
           V: fmt::Debug,
 {

src/libstd/collections/hash/set.rs

@@ -1112,8 +1112,8 @@ impl<T, S> IntoIterator for HashSet<T, S>
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K> Clone for Iter<'a, K> {
+impl<K> Clone for Iter<'_, K> {
-    fn clone(&self) -> Iter<'a, K> {
+    fn clone(&self) -> Self {
         Iter { iter: self.iter.clone() }
     }
 }
@@ -1129,16 +1129,16 @@ impl<'a, K> Iterator for Iter<'a, K> {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K> ExactSizeIterator for Iter<'a, K> {
+impl<K> ExactSizeIterator for Iter<'_, K> {
     fn len(&self) -> usize {
         self.iter.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K> FusedIterator for Iter<'a, K> {}
+impl<K> FusedIterator for Iter<'_, K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K: fmt::Debug> fmt::Debug for Iter<'a, K> {
+impl<K: fmt::Debug> fmt::Debug for Iter<'_, K> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_list().entries(self.clone()).finish()
     }
@@ -1187,16 +1187,16 @@ impl<'a, K> Iterator for Drain<'a, K> {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, K> ExactSizeIterator for Drain<'a, K> {
+impl<K> ExactSizeIterator for Drain<'_, K> {
     fn len(&self) -> usize {
         self.iter.len()
     }
 }
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, K> FusedIterator for Drain<'a, K> {}
+impl<K> FusedIterator for Drain<'_, K> {}
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, K: fmt::Debug> fmt::Debug for Drain<'a, K> {
+impl<K: fmt::Debug> fmt::Debug for Drain<'_, K> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let entries_iter = self.iter
             .inner
@@ -1207,8 +1207,8 @@ impl<'a, K: fmt::Debug> fmt::Debug for Drain<'a, K> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, S> Clone for Intersection<'a, T, S> {
+impl<T, S> Clone for Intersection<'_, T, S> {
-    fn clone(&self) -> Intersection<'a, T, S> {
+    fn clone(&self) -> Self {
         Intersection { iter: self.iter.clone(), ..*self }
     }
 }
@@ -1236,7 +1236,7 @@ impl<'a, T, S> Iterator for Intersection<'a, T, S>
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, T, S> fmt::Debug for Intersection<'a, T, S>
+impl<T, S> fmt::Debug for Intersection<'_, T, S>
     where T: fmt::Debug + Eq + Hash,
           S: BuildHasher
 {
@@ -1246,15 +1246,15 @@ impl<'a, T, S> fmt::Debug for Intersection<'a, T, S>
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, T, S> FusedIterator for Intersection<'a, T, S>
+impl<T, S> FusedIterator for Intersection<'_, T, S>
     where T: Eq + Hash,
           S: BuildHasher
 {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, S> Clone for Difference<'a, T, S> {
+impl<T, S> Clone for Difference<'_, T, S> {
-    fn clone(&self) -> Difference<'a, T, S> {
+    fn clone(&self) -> Self {
         Difference { iter: self.iter.clone(), ..*self }
     }
 }
@@ -1282,14 +1282,14 @@ impl<'a, T, S> Iterator for Difference<'a, T, S>
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, T, S> FusedIterator for Difference<'a, T, S>
+impl<T, S> FusedIterator for Difference<'_, T, S>
     where T: Eq + Hash,
           S: BuildHasher
 {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, T, S> fmt::Debug for Difference<'a, T, S>
+impl<T, S> fmt::Debug for Difference<'_, T, S>
     where T: fmt::Debug + Eq + Hash,
           S: BuildHasher
 {
@@ -1299,8 +1299,8 @@ impl<'a, T, S> fmt::Debug for Difference<'a, T, S>
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, S> Clone for SymmetricDifference<'a, T, S> {
+impl<T, S> Clone for SymmetricDifference<'_, T, S> {
-    fn clone(&self) -> SymmetricDifference<'a, T, S> {
+    fn clone(&self) -> Self {
         SymmetricDifference { iter: self.iter.clone() }
     }
 }
@@ -1321,14 +1321,14 @@ impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S>
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, T, S> FusedIterator for SymmetricDifference<'a, T, S>
+impl<T, S> FusedIterator for SymmetricDifference<'_, T, S>
     where T: Eq + Hash,
           S: BuildHasher
 {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, T, S> fmt::Debug for SymmetricDifference<'a, T, S>
+impl<T, S> fmt::Debug for SymmetricDifference<'_, T, S>
     where T: fmt::Debug + Eq + Hash,
           S: BuildHasher
 {
@@ -1338,21 +1338,21 @@ impl<'a, T, S> fmt::Debug for SymmetricDifference<'a, T, S>
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, S> Clone for Union<'a, T, S> {
+impl<T, S> Clone for Union<'_, T, S> {
-    fn clone(&self) -> Union<'a, T, S> {
+    fn clone(&self) -> Self {
         Union { iter: self.iter.clone() }
     }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a, T, S> FusedIterator for Union<'a, T, S>
+impl<T, S> FusedIterator for Union<'_, T, S>
     where T: Eq + Hash,
           S: BuildHasher
 {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, T, S> fmt::Debug for Union<'a, T, S>
+impl<T, S> fmt::Debug for Union<'_, T, S>
     where T: fmt::Debug + Eq + Hash,
           S: BuildHasher
 {

src/libstd/collections/hash/table.rs

@@ -296,7 +296,7 @@ pub trait Put<K, V> {
 }
 
 
-impl<'t, K, V> Put<K, V> for &'t mut RawTable<K, V> {
+impl<K, V> Put<K, V> for &mut RawTable<K, V> {
     unsafe fn borrow_table_mut(&mut self) -> &mut RawTable<K, V> {
         *self
     }
@@ -865,8 +865,8 @@ struct RawBuckets<'a, K, V> {
 }
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
-impl<'a, K, V> Clone for RawBuckets<'a, K, V> {
+impl<K, V> Clone for RawBuckets<'_, K, V> {
-    fn clone(&self) -> RawBuckets<'a, K, V> {
+    fn clone(&self) -> Self {
         RawBuckets {
             raw: self.raw,
             elems_left: self.elems_left,
@@ -901,7 +901,7 @@ impl<'a, K, V> Iterator for RawBuckets<'a, K, V> {
     }
 }
 
-impl<'a, K, V> ExactSizeIterator for RawBuckets<'a, K, V> {
+impl<K, V> ExactSizeIterator for RawBuckets<'_, K, V> {
     fn len(&self) -> usize {
         self.elems_left
     }
@@ -912,12 +912,12 @@ pub struct Iter<'a, K: 'a, V: 'a> {
     iter: RawBuckets<'a, K, V>,
 }
 
-unsafe impl<'a, K: Sync, V: Sync> Sync for Iter<'a, K, V> {}
+unsafe impl<K: Sync, V: Sync> Sync for Iter<'_, K, V> {}
-unsafe impl<'a, K: Sync, V: Sync> Send for Iter<'a, K, V> {}
+unsafe impl<K: Sync, V: Sync> Send for Iter<'_, K, V> {}
 
 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
-impl<'a, K, V> Clone for Iter<'a, K, V> {
+impl<K, V> Clone for Iter<'_, K, V> {
-    fn clone(&self) -> Iter<'a, K, V> {
+    fn clone(&self) -> Self {
         Iter {
             iter: self.iter.clone(),
         }
@@ -931,10 +931,10 @@ pub struct IterMut<'a, K: 'a, V: 'a> {
     _marker: marker::PhantomData<&'a mut V>,
 }
 
-unsafe impl<'a, K: Sync, V: Sync> Sync for IterMut<'a, K, V> {}
+unsafe impl<K: Sync, V: Sync> Sync for IterMut<'_, K, V> {}
 // Both K: Sync and K: Send are correct for IterMut's Send impl,
 // but Send is the more useful bound
-unsafe impl<'a, K: Send, V: Send> Send for IterMut<'a, K, V> {}
+unsafe impl<K: Send, V: Send> Send for IterMut<'_, K, V> {}
 
 impl<'a, K: 'a, V: 'a> IterMut<'a, K, V> {
     pub fn iter(&self) -> Iter<K, V> {
@@ -968,8 +968,8 @@ pub struct Drain<'a, K: 'a, V: 'a> {
     marker: marker::PhantomData<&'a RawTable<K, V>>,
 }
 
-unsafe impl<'a, K: Sync, V: Sync> Sync for Drain<'a, K, V> {}
+unsafe impl<K: Sync, V: Sync> Sync for Drain<'_, K, V> {}
-unsafe impl<'a, K: Send, V: Send> Send for Drain<'a, K, V> {}
+unsafe impl<K: Send, V: Send> Send for Drain<'_, K, V> {}
 
 impl<'a, K, V> Drain<'a, K, V> {
     pub fn iter(&self) -> Iter<K, V> {
@@ -994,7 +994,7 @@ impl<'a, K, V> Iterator for Iter<'a, K, V> {
     }
 }
 
-impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
+impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
     fn len(&self) -> usize {
         self.iter.len()
     }
@@ -1015,7 +1015,7 @@ impl<'a, K, V> Iterator for IterMut<'a, K, V> {
     }
 }
 
-impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {
+impl<K, V> ExactSizeIterator for IterMut<'_, K, V> {
     fn len(&self) -> usize {
         self.iter.len()
     }
@@ -1064,13 +1064,13 @@ impl<'a, K, V> Iterator for Drain<'a, K, V> {
     }
 }
 
-impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> {
+impl<K, V> ExactSizeIterator for Drain<'_, K, V> {
     fn len(&self) -> usize {
         self.iter.len()
     }
 }
 
-impl<'a, K: 'a, V: 'a> Drop for Drain<'a, K, V> {
+impl<K, V> Drop for Drain<'_, K, V> {
     fn drop(&mut self) {
         self.for_each(drop);
     }

src/libstd/env.rs

@@ -399,7 +399,7 @@ impl<'a> Iterator for SplitPaths<'a> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for SplitPaths<'a> {
+impl fmt::Debug for SplitPaths<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("SplitPaths { .. }")
     }

src/libstd/ffi/c_str.rs

@@ -659,8 +659,8 @@ impl fmt::Debug for CStr {
 }
 
 #[stable(feature = "cstr_default", since = "1.10.0")]
-impl<'a> Default for &'a CStr {
+impl Default for &CStr {
-    fn default() -> &'a CStr {
+    fn default() -> Self {
         const SLICE: &[c_char] = &[0];
         unsafe { CStr::from_ptr(SLICE.as_ptr()) }
     }

src/libstd/ffi/os_str.rs

@@ -778,10 +778,10 @@ impl Default for Box<OsStr> {
 }
 
 #[stable(feature = "osstring_default", since = "1.9.0")]
-impl<'a> Default for &'a OsStr {
+impl Default for &OsStr {
     /// Creates an empty `OsStr`.
     #[inline]
-    fn default() -> &'a OsStr {
+    fn default() -> Self {
         OsStr::new("")
     }
 }

src/libstd/fs.rs

@@ -254,10 +254,13 @@ fn initial_buffer_size(file: &File) -> usize {
 /// ```
 #[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
 pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
-    let mut file = File::open(path)?;
+    fn inner(path: &Path) -> io::Result<Vec<u8>> {
-    let mut bytes = Vec::with_capacity(initial_buffer_size(&file));
+        let mut file = File::open(path)?;
-    file.read_to_end(&mut bytes)?;
+        let mut bytes = Vec::with_capacity(initial_buffer_size(&file));
-    Ok(bytes)
+        file.read_to_end(&mut bytes)?;
+        Ok(bytes)
+    }
+    inner(path.as_ref())
 }
 
 /// Read the entire contents of a file into a string.
@@ -296,10 +299,13 @@ pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
 /// ```
 #[stable(feature = "fs_read_write", since = "1.26.0")]
 pub fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
-    let mut file = File::open(path)?;
+    fn inner(path: &Path) -> io::Result<String> {
-    let mut string = String::with_capacity(initial_buffer_size(&file));
+        let mut file = File::open(path)?;
-    file.read_to_string(&mut string)?;
+        let mut string = String::with_capacity(initial_buffer_size(&file));
-    Ok(string)
+        file.read_to_string(&mut string)?;
+        Ok(string)
+    }
+    inner(path.as_ref())
 }
 
 /// Write a slice as the entire contents of a file.
@@ -326,7 +332,10 @@ pub fn read_to_string<P: AsRef<Path>>(path: P) -> io::Result<String> {
 /// ```
 #[stable(feature = "fs_read_write_bytes", since = "1.26.0")]
 pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result<()> {
-    File::create(path)?.write_all(contents.as_ref())
+    fn inner(path: &Path, contents: &[u8]) -> io::Result<()> {
+        File::create(path)?.write_all(contents)
+    }
+    inner(path.as_ref(), contents.as_ref())
 }
 
 impl File {
@@ -618,7 +627,7 @@ impl Seek for File {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Read for &'a File {
+impl Read for &File {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         self.inner.read(buf)
     }
@@ -629,14 +638,14 @@ impl<'a> Read for &'a File {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for &'a File {
+impl Write for &File {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.inner.write(buf)
     }
     fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Seek for &'a File {
+impl Seek for &File {
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
         self.inner.seek(pos)
     }

src/libstd/io/buffered.rs

@@ -1174,7 +1174,7 @@ mod tests {
         // Issue #32085
         struct FailFlushWriter<'a>(&'a mut Vec<u8>);
 
-        impl<'a> Write for FailFlushWriter<'a> {
+        impl Write for FailFlushWriter<'_> {
             fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
                 self.0.extend_from_slice(buf);
                 Ok(buf.len())

src/libstd/io/cursor.rs

@@ -279,7 +279,7 @@ fn vec_write(pos_mut: &mut u64, vec: &mut Vec<u8>, buf: &[u8]) -> io::Result<usi
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for Cursor<&'a mut [u8]> {
+impl Write for Cursor<&mut [u8]> {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         slice_write(&mut self.pos, self.inner, buf)
@@ -288,7 +288,7 @@ impl<'a> Write for Cursor<&'a mut [u8]> {
 }
 
 #[stable(feature = "cursor_mut_vec", since = "1.25.0")]
-impl<'a> Write for Cursor<&'a mut Vec<u8>> {
+impl Write for Cursor<&mut Vec<u8>> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         vec_write(&mut self.pos, self.inner, buf)
     }

src/libstd/io/impls.rs

@@ -7,7 +7,7 @@ use mem;
 // Forwarding implementations
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, R: Read + ?Sized> Read for &'a mut R {
+impl<R: Read + ?Sized> Read for &mut R {
     #[inline]
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         (**self).read(buf)
@@ -34,7 +34,7 @@ impl<'a, R: Read + ?Sized> Read for &'a mut R {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, W: Write + ?Sized> Write for &'a mut W {
+impl<W: Write + ?Sized> Write for &mut W {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> { (**self).write(buf) }
 
@@ -52,12 +52,12 @@ impl<'a, W: Write + ?Sized> Write for &'a mut W {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, S: Seek + ?Sized> Seek for &'a mut S {
+impl<S: Seek + ?Sized> Seek for &mut S {
     #[inline]
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { (**self).seek(pos) }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, B: BufRead + ?Sized> BufRead for &'a mut B {
+impl<B: BufRead + ?Sized> BufRead for &mut B {
     #[inline]
     fn fill_buf(&mut self) -> io::Result<&[u8]> { (**self).fill_buf() }
 
@@ -152,7 +152,7 @@ impl<B: BufRead + ?Sized> BufRead for Box<B> {
 /// Note that reading updates the slice to point to the yet unread part.
 /// The slice will be empty when EOF is reached.
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Read for &'a [u8] {
+impl Read for &[u8] {
     #[inline]
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         let amt = cmp::min(buf.len(), self.len());
@@ -207,7 +207,7 @@ impl<'a> Read for &'a [u8] {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> BufRead for &'a [u8] {
+impl BufRead for &[u8] {
     #[inline]
     fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(*self) }
 
@@ -221,7 +221,7 @@ impl<'a> BufRead for &'a [u8] {
 /// Note that writing updates the slice to point to the yet unwritten part.
 /// The slice will be empty when it has been completely overwritten.
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for &'a mut [u8] {
+impl Write for &mut [u8] {
     #[inline]
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         let amt = cmp::min(data.len(), self.len());

src/libstd/io/mod.rs

@@ -299,7 +299,7 @@ const DEFAULT_BUF_SIZE: usize = ::sys_common::io::DEFAULT_BUF_SIZE;
 
 struct Guard<'a> { buf: &'a mut Vec<u8>, len: usize }
 
-impl<'a> Drop for Guard<'a> {
+impl Drop for Guard<'_> {
     fn drop(&mut self) {
         unsafe { self.buf.set_len(self.len); }
     }
@@ -1114,7 +1114,7 @@ pub trait Write {
             error: Result<()>,
         }
 
-        impl<'a, T: Write + ?Sized> fmt::Write for Adaptor<'a, T> {
+        impl<T: Write + ?Sized> fmt::Write for Adaptor<'_, T> {
             fn write_str(&mut self, s: &str) -> fmt::Result {
                 match self.inner.write_all(s.as_bytes()) {
                     Ok(()) => Ok(()),

src/libstd/io/stdio.rs

@@ -312,7 +312,7 @@ impl Read for Stdin {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Read for StdinLock<'a> {
+impl Read for StdinLock<'_> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         self.inner.read(buf)
     }
@@ -323,13 +323,13 @@ impl<'a> Read for StdinLock<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> BufRead for StdinLock<'a> {
+impl BufRead for StdinLock<'_> {
     fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() }
     fn consume(&mut self, n: usize) { self.inner.consume(n) }
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for StdinLock<'a> {
+impl fmt::Debug for StdinLock<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("StdinLock { .. }")
     }
@@ -485,7 +485,7 @@ impl Write for Stdout {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for StdoutLock<'a> {
+impl Write for StdoutLock<'_> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.inner.borrow_mut().write(buf)
     }
@@ -495,7 +495,7 @@ impl<'a> Write for StdoutLock<'a> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for StdoutLock<'a> {
+impl fmt::Debug for StdoutLock<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("StdoutLock { .. }")
     }
@@ -638,7 +638,7 @@ impl Write for Stderr {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for StderrLock<'a> {
+impl Write for StderrLock<'_> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.inner.borrow_mut().write(buf)
     }
@@ -648,7 +648,7 @@ impl<'a> Write for StderrLock<'a> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a> fmt::Debug for StderrLock<'a> {
+impl fmt::Debug for StderrLock<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("StderrLock { .. }")
     }

src/libstd/net/addr.rs

@@ -861,7 +861,7 @@ fn resolve_socket_addr(lh: LookupHost) -> io::Result<vec::IntoIter<SocketAddr>>
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> ToSocketAddrs for (&'a str, u16) {
+impl ToSocketAddrs for (&str, u16) {
     type Iter = vec::IntoIter<SocketAddr>;
     fn to_socket_addrs(&self) -> io::Result<vec::IntoIter<SocketAddr>> {
         let (host, port) = *self;
@@ -904,7 +904,7 @@ impl<'a> ToSocketAddrs for &'a [SocketAddr] {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T: ToSocketAddrs + ?Sized> ToSocketAddrs for &'a T {
+impl<T: ToSocketAddrs + ?Sized> ToSocketAddrs for &T {
     type Iter = T::Iter;
     fn to_socket_addrs(&self) -> io::Result<T::Iter> {
         (**self).to_socket_addrs()

src/libstd/net/ip.rs

@@ -329,6 +329,8 @@ impl Ipv4Addr {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub const fn new(a: u8, b: u8, c: u8, d: u8) -> Ipv4Addr {
+        // FIXME: should just be u32::from_be_bytes([a, b, c, d]),
+        // once that method is no longer rustc_const_unstable
         Ipv4Addr {
             inner: c::in_addr {
                 s_addr: u32::to_be(
@@ -392,6 +394,7 @@ impl Ipv4Addr {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn octets(&self) -> [u8; 4] {
+        // This returns the order we want because s_addr is stored in big-endian.
         self.inner.s_addr.to_ne_bytes()
     }
 
@@ -618,9 +621,13 @@ impl Ipv4Addr {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn to_ipv6_compatible(&self) -> Ipv6Addr {
-        Ipv6Addr::new(0, 0, 0, 0, 0, 0,
+        let octets = self.octets();
-                      ((self.octets()[0] as u16) << 8) | self.octets()[1] as u16,
+        Ipv6Addr::from([
-                      ((self.octets()[2] as u16) << 8) | self.octets()[3] as u16)
+            0, 0, 0, 0,
+            0, 0, 0, 0,
+            0, 0, 0, 0,
+            octets[0], octets[1], octets[2], octets[3],
+        ])
     }
 
     /// Converts this address to an IPv4-mapped [IPv6 address].
@@ -639,9 +646,13 @@ impl Ipv4Addr {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn to_ipv6_mapped(&self) -> Ipv6Addr {
-        Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff,
+        let octets = self.octets();
-                      ((self.octets()[0] as u16) << 8) | self.octets()[1] as u16,
+        Ipv6Addr::from([
-                      ((self.octets()[2] as u16) << 8) | self.octets()[3] as u16)
+            0, 0, 0, 0,
+            0, 0, 0, 0,
+            0, 0, 0xFF, 0xFF,
+            octets[0], octets[1], octets[2], octets[3],
+        ])
     }
 }
 
@@ -784,7 +795,7 @@ impl From<Ipv4Addr> for u32 {
     /// ```
     fn from(ip: Ipv4Addr) -> u32 {
         let ip = ip.octets();
-        ((ip[0] as u32) << 24) + ((ip[1] as u32) << 16) + ((ip[2] as u32) << 8) + (ip[3] as u32)
+        u32::from_be_bytes(ip)
     }
 }
 
@@ -801,7 +812,7 @@ impl From<u32> for Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
     /// ```
     fn from(ip: u32) -> Ipv4Addr {
-        Ipv4Addr::new((ip >> 24) as u8, (ip >> 16) as u8, (ip >> 8) as u8, ip as u8)
+        Ipv4Addr::from(ip.to_be_bytes())
     }
 }
 
@@ -909,14 +920,14 @@ impl Ipv6Addr {
     pub fn segments(&self) -> [u16; 8] {
         let arr = &self.inner.s6_addr;
         [
-            (arr[0] as u16) << 8 | (arr[1] as u16),
+            u16::from_be_bytes([arr[0], arr[1]]),
-            (arr[2] as u16) << 8 | (arr[3] as u16),
+            u16::from_be_bytes([arr[2], arr[3]]),
-            (arr[4] as u16) << 8 | (arr[5] as u16),
+            u16::from_be_bytes([arr[4], arr[5]]),
-            (arr[6] as u16) << 8 | (arr[7] as u16),
+            u16::from_be_bytes([arr[6], arr[7]]),
-            (arr[8] as u16) << 8 | (arr[9] as u16),
+            u16::from_be_bytes([arr[8], arr[9]]),
-            (arr[10] as u16) << 8 | (arr[11] as u16),
+            u16::from_be_bytes([arr[10], arr[11]]),
-            (arr[12] as u16) << 8 | (arr[13] as u16),
+            u16::from_be_bytes([arr[12], arr[13]]),
-            (arr[14] as u16) << 8 | (arr[15] as u16),
+            u16::from_be_bytes([arr[14], arr[15]]),
         ]
     }
 
@@ -1382,21 +1393,43 @@ impl FromInner<c::in6_addr> for Ipv6Addr {
 
 #[stable(feature = "i128", since = "1.26.0")]
 impl From<Ipv6Addr> for u128 {
+    /// Convert an `Ipv6Addr` into a host byte order `u128`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv6Addr;
+    ///
+    /// let addr = Ipv6Addr::new(
+    ///     0x1020, 0x3040, 0x5060, 0x7080,
+    ///     0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
+    /// );
+    /// assert_eq!(0x102030405060708090A0B0C0D0E0F00D_u128, u128::from(addr));
+    /// ```
     fn from(ip: Ipv6Addr) -> u128 {
-        let ip = ip.segments();
+        let ip = ip.octets();
-        ((ip[0] as u128) << 112) + ((ip[1] as u128) << 96) + ((ip[2] as u128) << 80) +
+        u128::from_be_bytes(ip)
-            ((ip[3] as u128) << 64) + ((ip[4] as u128) << 48) + ((ip[5] as u128) << 32) +
-            ((ip[6] as u128) << 16) + (ip[7] as u128)
     }
 }
 #[stable(feature = "i128", since = "1.26.0")]
 impl From<u128> for Ipv6Addr {
+    /// Convert a host byte order `u128` into an `Ipv6Addr`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv6Addr;
+    ///
+    /// let addr = Ipv6Addr::from(0x102030405060708090A0B0C0D0E0F00D_u128);
+    /// assert_eq!(
+    ///     Ipv6Addr::new(
+    ///         0x1020, 0x3040, 0x5060, 0x7080,
+    ///         0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
+    ///     ),
+    ///     addr);
+    /// ```
     fn from(ip: u128) -> Ipv6Addr {
-        Ipv6Addr::new(
+        Ipv6Addr::from(ip.to_be_bytes())
-            (ip >> 112) as u16, (ip >> 96) as u16, (ip >> 80) as u16,
-            (ip >> 64) as u16, (ip >> 48) as u16, (ip >> 32) as u16,
-            (ip >> 16) as u16, ip as u16,
-        )
     }
 }
 

src/libstd/net/tcp.rs

@@ -580,7 +580,7 @@ impl Write for TcpStream {
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Read for &'a TcpStream {
+impl Read for &TcpStream {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { self.0.read(buf) }
 
     #[inline]
@@ -589,7 +589,7 @@ impl<'a> Read for &'a TcpStream {
     }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Write for &'a TcpStream {
+impl Write for &TcpStream {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> { self.0.write(buf) }
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }
@@ -1187,9 +1187,13 @@ mod tests {
     #[test]
     fn double_bind() {
         each_ip(&mut |addr| {
-            let _listener = t!(TcpListener::bind(&addr));
+            let listener1 = t!(TcpListener::bind(&addr));
             match TcpListener::bind(&addr) {
-                Ok(..) => panic!(),
+                Ok(listener2) => panic!(
+                    "This system (perhaps due to options set by TcpListener::bind) \
+                     permits double binding: {:?} and {:?}",
+                    listener1, listener2
+                ),
                 Err(e) => {
                     assert!(e.kind() == ErrorKind::ConnectionRefused ||
                             e.kind() == ErrorKind::Other ||

src/libstd/panic.rs

@@ -199,9 +199,9 @@ pub struct AssertUnwindSafe<T>(
 // * Our custom AssertUnwindSafe wrapper is indeed unwind safe
 
 #[stable(feature = "catch_unwind", since = "1.9.0")]
-impl<'a, T: ?Sized> !UnwindSafe for &'a mut T {}
+impl<T: ?Sized> !UnwindSafe for &mut T {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
-impl<'a, T: RefUnwindSafe + ?Sized> UnwindSafe for &'a T {}
+impl<T: RefUnwindSafe + ?Sized> UnwindSafe for &T {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T: RefUnwindSafe + ?Sized> UnwindSafe for *const T {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
@@ -320,7 +320,7 @@ impl<T: fmt::Debug> fmt::Debug for AssertUnwindSafe<T> {
 }
 
 #[unstable(feature = "futures_api", issue = "50547")]
-impl<'a, F: Future> Future for AssertUnwindSafe<F> {
+impl<F: Future> Future for AssertUnwindSafe<F> {
     type Output = F::Output;
 
     fn poll(self: Pin<&mut Self>, waker: &Waker) -> Poll<Self::Output> {

src/libstd/path.rs

@@ -457,14 +457,14 @@ impl<'a> cmp::PartialOrd for PrefixComponent<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> cmp::Ord for PrefixComponent<'a> {
+impl cmp::Ord for PrefixComponent<'_> {
-    fn cmp(&self, other: &PrefixComponent<'a>) -> cmp::Ordering {
+    fn cmp(&self, other: &Self) -> cmp::Ordering {
         cmp::Ord::cmp(&self.parsed, &other.parsed)
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> Hash for PrefixComponent<'a> {
+impl Hash for PrefixComponent<'_> {
     fn hash<H: Hasher>(&self, h: &mut H) {
         self.parsed.hash(h);
     }
@@ -561,14 +561,14 @@ impl<'a> Component<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> AsRef<OsStr> for Component<'a> {
+impl AsRef<OsStr> for Component<'_> {
     fn as_ref(&self) -> &OsStr {
         self.as_os_str()
     }
 }
 
 #[stable(feature = "path_component_asref", since = "1.25.0")]
-impl<'a> AsRef<Path> for Component<'a> {
+impl AsRef<Path> for Component<'_> {
     fn as_ref(&self) -> &Path {
         self.as_os_str().as_ref()
     }
@@ -630,11 +630,11 @@ pub struct Iter<'a> {
 }
 
 #[stable(feature = "path_components_debug", since = "1.13.0")]
-impl<'a> fmt::Debug for Components<'a> {
+impl fmt::Debug for Components<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         struct DebugHelper<'a>(&'a Path);
 
-        impl<'a> fmt::Debug for DebugHelper<'a> {
+        impl fmt::Debug for DebugHelper<'_> {
             fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                 f.debug_list()
                     .entries(self.0.components())
@@ -814,25 +814,25 @@ impl<'a> Components<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> AsRef<Path> for Components<'a> {
+impl AsRef<Path> for Components<'_> {
     fn as_ref(&self) -> &Path {
         self.as_path()
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> AsRef<OsStr> for Components<'a> {
+impl AsRef<OsStr> for Components<'_> {
     fn as_ref(&self) -> &OsStr {
         self.as_path().as_os_str()
     }
 }
 
 #[stable(feature = "path_iter_debug", since = "1.13.0")]
-impl<'a> fmt::Debug for Iter<'a> {
+impl fmt::Debug for Iter<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         struct DebugHelper<'a>(&'a Path);
 
-        impl<'a> fmt::Debug for DebugHelper<'a> {
+        impl fmt::Debug for DebugHelper<'_> {
             fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                 f.debug_list()
                     .entries(self.0.iter())
@@ -867,14 +867,14 @@ impl<'a> Iter<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> AsRef<Path> for Iter<'a> {
+impl AsRef<Path> for Iter<'_> {
     fn as_ref(&self) -> &Path {
         self.as_path()
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> AsRef<OsStr> for Iter<'a> {
+impl AsRef<OsStr> for Iter<'_> {
     fn as_ref(&self) -> &OsStr {
         self.as_path().as_os_str()
     }
@@ -897,7 +897,7 @@ impl<'a> DoubleEndedIterator for Iter<'a> {
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a> FusedIterator for Iter<'a> {}
+impl FusedIterator for Iter<'_> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> Iterator for Components<'a> {
@@ -1000,7 +1000,7 @@ impl<'a> DoubleEndedIterator for Components<'a> {
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<'a> FusedIterator for Components<'a> {}
+impl FusedIterator for Components<'_> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> cmp::PartialEq for Components<'a> {
@@ -1010,7 +1010,7 @@ impl<'a> cmp::PartialEq for Components<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> cmp::Eq for Components<'a> {}
+impl cmp::Eq for Components<'_> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> cmp::PartialOrd for Components<'a> {
@@ -1020,8 +1020,8 @@ impl<'a> cmp::PartialOrd for Components<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> cmp::Ord for Components<'a> {
+impl cmp::Ord for Components<'_> {
-    fn cmp(&self, other: &Components<'a>) -> cmp::Ordering {
+    fn cmp(&self, other: &Self) -> cmp::Ordering {
         Iterator::cmp(self.clone(), other.clone())
     }
 }
@@ -1063,7 +1063,7 @@ impl<'a> Iterator for Ancestors<'a> {
 }
 
 #[stable(feature = "path_ancestors", since = "1.28.0")]
-impl<'a> FusedIterator for Ancestors<'a> {}
+impl FusedIterator for Ancestors<'_> {}
 
 ////////////////////////////////////////////////////////////////////////////////
 // Basic types and traits
@@ -1145,6 +1145,33 @@ impl PathBuf {
         PathBuf { inner: OsString::new() }
     }
 
+    /// Creates a new `PathBuf` with a given capacity used to create the
+    /// internal [`OsString`]. See [`with_capacity`] defined on [`OsString`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_buf_capacity)]
+    /// use std::path::PathBuf;
+    ///
+    /// let mut path = PathBuf::with_capacity(10);
+    /// let capacity = path.capacity();
+    ///
+    /// // This push is done without reallocating
+    /// path.push(r"C:\");
+    ///
+    /// assert_eq!(capacity, path.capacity());
+    /// ```
+    ///
+    /// [`with_capacity`]: ../ffi/struct.OsString.html#method.with_capacity
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn with_capacity(capacity: usize) -> PathBuf {
+        PathBuf {
+            inner: OsString::with_capacity(capacity)
+        }
+    }
+
     /// Coerces to a [`Path`] slice.
     ///
     /// [`Path`]: struct.Path.html
@@ -1373,6 +1400,60 @@ impl PathBuf {
         let rw = Box::into_raw(self.inner.into_boxed_os_str()) as *mut Path;
         unsafe { Box::from_raw(rw) }
     }
+
+    /// Invokes [`capacity`] on the underlying instance of [`OsString`].
+    ///
+    /// [`capacity`]: ../ffi/struct.OsString.html#method.capacity
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn capacity(&self) -> usize {
+        self.inner.capacity()
+    }
+
+    /// Invokes [`clear`] on the underlying instance of [`OsString`].
+    ///
+    /// [`clear`]: ../ffi/struct.OsString.html#method.clear
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn clear(&mut self) {
+        self.inner.clear()
+    }
+
+    /// Invokes [`reserve`] on the underlying instance of [`OsString`].
+    ///
+    /// [`reserve`]: ../ffi/struct.OsString.html#method.reserve
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn reserve(&mut self, additional: usize) {
+        self.inner.reserve(additional)
+    }
+
+    /// Invokes [`reserve_exact`] on the underlying instance of [`OsString`].
+    ///
+    /// [`reserve_exact`]: ../ffi/struct.OsString.html#method.reserve_exact
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn reserve_exact(&mut self, additional: usize) {
+        self.inner.reserve_exact(additional)
+    }
+
+    /// Invokes [`shrink_to_fit`] on the underlying instance of [`OsString`].
+    ///
+    /// [`shrink_to_fit`]: ../ffi/struct.OsString.html#method.shrink_to_fit
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn shrink_to_fit(&mut self) {
+        self.inner.shrink_to_fit()
+    }
+
+    /// Invokes [`shrink_to`] on the underlying instance of [`OsString`].
+    ///
+    /// [`shrink_to`]: ../ffi/struct.OsString.html#method.shrink_to
+    /// [`OsString`]: ../ffi/struct.OsString.html
+    #[unstable(feature = "path_buf_capacity", issue = "58234")]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.inner.shrink_to(min_capacity)
+    }
 }
 
 #[stable(feature = "box_from_path", since = "1.17.0")]
@@ -2529,14 +2610,14 @@ pub struct Display<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> fmt::Debug for Display<'a> {
+impl fmt::Debug for Display<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(&self.path, f)
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a> fmt::Display for Display<'a> {
+impl fmt::Display for Display<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.path.inner.display(f)
     }
@@ -2590,7 +2671,7 @@ impl AsRef<Path> for OsStr {
 }
 
 #[stable(feature = "cow_os_str_as_ref_path", since = "1.8.0")]
-impl<'a> AsRef<Path> for Cow<'a, OsStr> {
+impl AsRef<Path> for Cow<'_, OsStr> {
     fn as_ref(&self) -> &Path {
         Path::new(self)
     }

src/libstd/sync/mpsc/select.rs

@@ -321,7 +321,7 @@ impl Drop for Select {
     }
 }
 
-impl<'rx, T: Send> Drop for Handle<'rx, T> {
+impl<T: Send> Drop for Handle<'_, T> {
     fn drop(&mut self) {
         unsafe { self.remove() }
     }
@@ -347,7 +347,7 @@ impl fmt::Debug for Select {
     }
 }
 
-impl<'rx, T:Send+'rx> fmt::Debug for Handle<'rx, T> {
+impl<T: Send> fmt::Debug for Handle<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("Handle").finish()
     }

src/libstd/sync/mutex.rs

@@ -150,9 +150,9 @@ pub struct MutexGuard<'a, T: ?Sized + 'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T: ?Sized> !Send for MutexGuard<'a, T> { }
+impl<T: ?Sized> !Send for MutexGuard<'_, T> { }
 #[stable(feature = "mutexguard", since = "1.19.0")]
-unsafe impl<'a, T: ?Sized + Sync> Sync for MutexGuard<'a, T> { }
+unsafe impl<T: ?Sized + Sync> Sync for MutexGuard<'_, T> { }
 
 impl<T> Mutex<T> {
     /// Creates a new mutex in an unlocked state ready for use.
@@ -421,7 +421,7 @@ impl<'mutex, T: ?Sized> MutexGuard<'mutex, T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'mutex, T: ?Sized> Deref for MutexGuard<'mutex, T> {
+impl<T: ?Sized> Deref for MutexGuard<'_, T> {
     type Target = T;
 
     fn deref(&self) -> &T {
@@ -430,14 +430,14 @@ impl<'mutex, T: ?Sized> Deref for MutexGuard<'mutex, T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'mutex, T: ?Sized> DerefMut for MutexGuard<'mutex, T> {
+impl<T: ?Sized> DerefMut for MutexGuard<'_, T> {
     fn deref_mut(&mut self) -> &mut T {
         unsafe { &mut *self.__lock.data.get() }
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T: ?Sized> Drop for MutexGuard<'a, T> {
+impl<T: ?Sized> Drop for MutexGuard<'_, T> {
     #[inline]
     fn drop(&mut self) {
         unsafe {
@@ -448,14 +448,14 @@ impl<'a, T: ?Sized> Drop for MutexGuard<'a, T> {
 }
 
 #[stable(feature = "std_debug", since = "1.16.0")]
-impl<'a, T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'a, T> {
+impl<T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(&**self, f)
     }
 }
 
 #[stable(feature = "std_guard_impls", since = "1.20.0")]
-impl<'a, T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'a, T> {
+impl<T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         (**self).fmt(f)
     }