Rollup of 25 pull requests

src/bootstrap/bootstrap.py

@@ -678,10 +678,10 @@ def update_submodule(self, module, checked_out, recorded_submodules):
 
         print("Updating submodule", module)
 
-        run(["git", "submodule", "-q", "sync", module],
+        run(["git", "submodule", "-q", "sync", "--progress", module],
             cwd=self.rust_root, verbose=self.verbose)
         run(["git", "submodule", "update",
-            "--init", "--recursive", module],
+            "--init", "--recursive", "--progress", module],
             cwd=self.rust_root, verbose=self.verbose)
         run(["git", "reset", "-q", "--hard"],
             cwd=module_path, verbose=self.verbose)

src/doc/rustdoc/src/unstable-features.md

@@ -402,3 +402,18 @@ Using `index-page` option enables `enable-index-page` option as well.
 ### `--enable-index-page`: generate a default index page for docs
 
 This feature allows the generation of a default index-page which lists the generated crates.
+
+### `--static-root-path`: control how static files are loaded in HTML output
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --static-root-path '/cache/'
+```
+
+This flag controls how rustdoc links to its static files on HTML pages. If you're hosting a lot of
+crates' docs generated by the same version of rustdoc, you can use this flag to cache rustdoc's CSS,
+JavaScript, and font files in a single location, rather than duplicating it once per "doc root"
+(grouping of crate docs generated into the same output directory, like with `cargo doc`). Per-crate
+files like the search index will still load from the documentation root, but anything that gets
+renamed with `--resource-suffix` will load from the given path.

src/liballoc/collections/vec_deque.rs

@@ -1897,8 +1897,6 @@ impl<T> VecDeque<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vec_resize_with)]
-    ///
     /// use std::collections::VecDeque;
     ///
     /// let mut buf = VecDeque::new();
@@ -1917,7 +1915,7 @@ impl<T> VecDeque<T> {
     /// buf.resize_with(5, || { state += 1; state });
     /// assert_eq!(buf, [5, 10, 101, 102, 103]);
     /// ```
-    #[unstable(feature = "vec_resize_with", issue = "41758")]
+    #[stable(feature = "vec_resize_with", since = "1.33.0")]
     pub fn resize_with(&mut self, new_len: usize, generator: impl FnMut()->T) {
         let len = self.len();
 

src/liballoc/lib.rs

@@ -72,6 +72,8 @@
        test(no_crate_inject, attr(allow(unused_variables), deny(warnings))))]
 #![no_std]
 #![needs_allocator]
+
+#![deny(intra_doc_link_resolution_failure)]
 #![deny(missing_debug_implementations)]
 
 #![cfg_attr(not(test), feature(fn_traits))]

src/liballoc/rc.rs

@@ -843,6 +843,8 @@ unsafe impl<#[may_dangle] T: ?Sized> Drop for Rc<T> {
     /// drop(foo);    // Doesn't print anything
     /// drop(foo2);   // Prints "dropped!"
     /// ```
+    ///
+    /// [`Weak`]: ../../std/rc/struct.Weak.html
     fn drop(&mut self) {
         unsafe {
             self.dec_strong();
@@ -1422,9 +1424,10 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for Weak<T> {
 #[stable(feature = "downgraded_weak", since = "1.10.0")]
 impl<T> Default for Weak<T> {
     /// Constructs a new `Weak<T>`, allocating memory for `T` without initializing
-    /// it. Calling [`upgrade`][Weak::upgrade] on the return value always gives [`None`].
+    /// it. Calling [`upgrade`] on the return value always gives [`None`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html
+    /// [`upgrade`]: ../../std/rc/struct.Weak.html#method.upgrade
     ///
     /// # Examples
     ///

src/liballoc/sync.rs

@@ -955,6 +955,8 @@ unsafe impl<#[may_dangle] T: ?Sized> Drop for Arc<T> {
     /// drop(foo);    // Doesn't print anything
     /// drop(foo2);   // Prints "dropped!"
     /// ```
+    ///
+    /// [`Weak`]: ../../std/sync/struct.Weak.html
     #[inline]
     fn drop(&mut self) {
         // Because `fetch_sub` is already atomic, we do not need to synchronize
@@ -1222,10 +1224,11 @@ impl<T: ?Sized> Clone for Weak<T> {
 #[stable(feature = "downgraded_weak", since = "1.10.0")]
 impl<T> Default for Weak<T> {
     /// Constructs a new `Weak<T>`, without allocating memory.
-    /// Calling [`upgrade`][Weak::upgrade] on the return value always
+    /// Calling [`upgrade`] on the return value always
     /// gives [`None`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`upgrade`]: ../../std/sync/struct.Weak.html#method.upgrade
     ///
     /// # Examples
     ///

src/liballoc/vec.rs

@@ -1241,8 +1241,6 @@ impl<T> Vec<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vec_resize_with)]
-    ///
     /// let mut vec = vec![1, 2, 3];
     /// vec.resize_with(5, Default::default);
     /// assert_eq!(vec, [1, 2, 3, 0, 0]);
@@ -1255,7 +1253,7 @@ impl<T> Vec<T> {
     ///
     /// [`resize`]: #method.resize
     /// [`Clone`]: ../../std/clone/trait.Clone.html
-    #[unstable(feature = "vec_resize_with", issue = "41758")]
+    #[stable(feature = "vec_resize_with", since = "1.33.0")]
     pub fn resize_with<F>(&mut self, new_len: usize, f: F)
         where F: FnMut() -> T
     {

src/libcore/iter/mod.rs

@@ -429,6 +429,9 @@ impl<I> Iterator for Rev<I> where I: DoubleEndedIterator {
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 
+    #[inline]
+    fn nth(&mut self, n: usize) -> Option<<I as Iterator>::Item> { self.iter.nth_back(n) }
+
     fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
         Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
     {
@@ -461,6 +464,9 @@ impl<I> DoubleEndedIterator for Rev<I> where I: DoubleEndedIterator {
     #[inline]
     fn next_back(&mut self) -> Option<<I as Iterator>::Item> { self.iter.next() }
 
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> { self.iter.nth(n) }
+
     fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R where
         Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
     {

src/libcore/iter/traits.rs

@@ -427,6 +427,62 @@ pub trait DoubleEndedIterator: Iterator {
     #[stable(feature = "rust1", since = "1.0.0")]
     fn next_back(&mut self) -> Option<Self::Item>;
 
+    /// Returns the `n`th element from the end of the iterator.
+    ///
+    /// This is essentially the reversed version of [`nth`]. Although like most indexing
+    /// operations, the count starts from zero, so `nth_back(0)` returns the first value fro
+    /// the end, `nth_back(1)` the second, and so on.
+    ///
+    /// Note that all elements between the end and the returned element will be
+    /// consumed, including the returned element. This also means that calling
+    /// `nth_back(0)` multiple times on the same iterator will return different
+    /// elements.
+    ///
+    /// `nth_back()` will return [`None`] if `n` is greater than or equal to the length of the
+    /// iterator.
+    ///
+    /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`nth`]: ../../std/iter/trait.Iterator.html#method.nth
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// #![feature(iter_nth_back)]
+    /// let a = [1, 2, 3];
+    /// assert_eq!(a.iter().nth_back(2), Some(&1));
+    /// ```
+    ///
+    /// Calling `nth_back()` multiple times doesn't rewind the iterator:
+    ///
+    /// ```
+    /// #![feature(iter_nth_back)]
+    /// let a = [1, 2, 3];
+    ///
+    /// let mut iter = a.iter();
+    ///
+    /// assert_eq!(iter.nth_back(1), Some(&2));
+    /// assert_eq!(iter.nth_back(1), None);
+    /// ```
+    ///
+    /// Returning `None` if there are less than `n + 1` elements:
+    ///
+    /// ```
+    /// #![feature(iter_nth_back)]
+    /// let a = [1, 2, 3];
+    /// assert_eq!(a.iter().nth_back(10), None);
+    /// ```
+    #[inline]
+    #[unstable(feature = "iter_nth_back", issue = "56995")]
+    fn nth_back(&mut self, mut n: usize) -> Option<Self::Item> {
+        for x in self.rev() {
+            if n == 0 { return Some(x) }
+            n -= 1;
+        }
+        None
+    }
+
     /// This is the reverse version of [`try_fold()`]: it takes elements
     /// starting from the back of the iterator.
     ///
@@ -461,8 +517,11 @@ pub trait DoubleEndedIterator: Iterator {
     /// ```
     #[inline]
     #[stable(feature = "iterator_try_fold", since = "1.27.0")]
-    fn try_rfold<B, F, R>(&mut self, init: B, mut f: F) -> R where
-        Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
+    fn try_rfold<B, F, R>(&mut self, init: B, mut f: F) -> R
+    where
+        Self: Sized,
+        F: FnMut(B, Self::Item) -> R,
+        R: Try<Ok=B>
     {
         let mut accum = init;
         while let Some(x) = self.next_back() {
@@ -524,8 +583,10 @@ pub trait DoubleEndedIterator: Iterator {
     /// ```
     #[inline]
     #[stable(feature = "iter_rfold", since = "1.27.0")]
-    fn rfold<B, F>(mut self, accum: B, mut f: F) -> B where
-        Self: Sized, F: FnMut(B, Self::Item) -> B,
+    fn rfold<B, F>(mut self, accum: B, mut f: F) -> B
+    where
+        Self: Sized,
+        F: FnMut(B, Self::Item) -> B,
     {
         self.try_rfold(accum, move |acc, x| Ok::<B, !>(f(acc, x))).unwrap()
     }
@@ -574,7 +635,8 @@ pub trait DoubleEndedIterator: Iterator {
     /// ```
     #[inline]
     #[stable(feature = "iter_rfind", since = "1.27.0")]
-    fn rfind<P>(&mut self, mut predicate: P) -> Option<Self::Item> where
+    fn rfind<P>(&mut self, mut predicate: P) -> Option<Self::Item>
+    where
         Self: Sized,
         P: FnMut(&Self::Item) -> bool
     {
@@ -587,7 +649,12 @@ pub trait DoubleEndedIterator: Iterator {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, I: DoubleEndedIterator + ?Sized> DoubleEndedIterator for &'a mut I {
-    fn next_back(&mut self) -> Option<I::Item> { (**self).next_back() }
+    fn next_back(&mut self) -> Option<I::Item> {
+        (**self).next_back()
+    }
+    fn nth_back(&mut self, n: usize) -> Option<I::Item> {
+        (**self).nth_back(n)
+    }
 }
 
 /// An iterator that knows its exact length.

src/libcore/lib.rs

@@ -71,6 +71,7 @@
 
 #![no_core]
 #![deny(missing_docs)]
+#![deny(intra_doc_link_resolution_failure)]
 #![deny(missing_debug_implementations)]
 
 #![feature(allow_internal_unstable)]

src/libcore/mem.rs

@@ -530,6 +530,12 @@ pub unsafe fn zeroed<T>() -> T {
 /// it goes out of scope (and therefore would be dropped). Note that this
 /// includes a `panic` occurring and unwinding the stack suddenly.
 ///
+/// If you partially initialize an array, you may need to use
+/// [`ptr::drop_in_place`][drop_in_place] to remove the elements you have fully
+/// initialized followed by [`mem::forget`][mem_forget] to prevent drop running
+/// on the array. If a partially allocated array is dropped this will lead to
+/// undefined behaviour.
+///
 /// # Examples
 ///
 /// Here's how to safely initialize an array of [`Vec`]s.
@@ -583,11 +589,44 @@ pub unsafe fn zeroed<T>() -> T {
 /// println!("{:?}", &data[0]);
 /// ```
 ///
+/// This example shows how to handle partially initialized arrays, which could
+/// be found in low-level datastructures.
+///
+/// ```
+/// use std::mem;
+/// use std::ptr;
+///
+/// // Count the number of elements we have assigned.
+/// let mut data_len: usize = 0;
+/// let mut data: [String; 1000];
+///
+/// unsafe {
+///     data = mem::uninitialized();
+///
+///     for elem in &mut data[0..500] {
+///         ptr::write(elem, String::from("hello"));
+///         data_len += 1;
+///     }
+///
+///     // For each item in the array, drop if we allocated it.
+///     for i in &mut data[0..data_len] {
+///         ptr::drop_in_place(i);
+///     }
+/// }
+/// // Forget the data. If this is allowed to drop, you may see a crash such as:
+/// // 'mem_uninit_test(2457,0x7fffb55dd380) malloc: *** error for object
+/// // 0x7ff3b8402920: pointer being freed was not allocated'
+/// mem::forget(data);
+/// ```
+///
 /// [`Vec`]: ../../std/vec/struct.Vec.html
 /// [`vec!`]: ../../std/macro.vec.html
 /// [`Clone`]: ../../std/clone/trait.Clone.html
 /// [ub]: ../../reference/behavior-considered-undefined.html
 /// [write]: ../ptr/fn.write.html
+/// [drop_in_place]: ../ptr/fn.drop_in_place.html
+/// [mem_zeroed]: fn.zeroed.html
+/// [mem_forget]: fn.forget.html
 /// [copy]: ../intrinsics/fn.copy.html
 /// [copy_no]: ../intrinsics/fn.copy_nonoverlapping.html
 /// [`Drop`]: ../ops/trait.Drop.html
@@ -984,6 +1023,9 @@ impl<T> ManuallyDrop<T> {
     ///
     /// This function semantically moves out the contained value without preventing further usage.
     /// It is up to the user of this method to ensure that this container is not used again.
+    ///
+    /// [`ManuallyDrop::drop`]: #method.drop
+    /// [`ManuallyDrop::into_inner`]: #method.into_inner
     #[must_use = "if you don't need the value, you can use `ManuallyDrop::drop` instead"]
     #[unstable(feature = "manually_drop_take", issue = "55422")]
     #[inline]