Auto merge of #49642 - kennytm:rollup, r=kennytm

Rollup of 25 pull requests

Successful merges:

 - #49179 (Handle future deprecation annotations )
 - #49512 (Add support for variant and types fields for intra links)
 - #49515 (fix targetted value background)
 - #49516 (Add missing anchor for union type fields)
 - #49532 (Add test for rustdoc ignore test)
 - #49533 (Add #[must_use] to a few standard library methods)
 - #49540 (Fix miri Discriminant() for non-ADT)
 - #49559 (Introduce Vec::resize_with method (see #41758))
 - #49570 (avoid IdxSets containing garbage above the universe length)
 - #49577 (Stabilize String::replace_range)
 - #49599 (Fix typo)
 - #49603 (Fix url for intra link provided method)
 - #49607 (Stabilize iterator methods in 1.27)
 - #49609 (run-pass/attr-stmt-expr: expand test cases)
 - #49612 (Fix "since" version for getpid feature.)
 - #49618 (Fix build error when compiling libcore for 16bit targets)
 - #49619 (tweak core::fmt docs)
 - #49637 (Stabilize parent_id())
 - #49639 (Update Cargo)
 - #49628 (Re-write the documentation index)
 - #49594 (Add some performance guidance to std::fs and std::io docs)
 - #49625 (miri: add public alloc_kind accessor)
 - #49634 (Add a test for the fix to issue #43058)
 - #49641 (Regression test for #46314)
 - #49547 (Unignore borrowck test)

Failed merges:

5 files changed, 78 insertions, 29 deletions

diff --git a/src/liballoc/borrow.rs b/src/liballoc/borrow.rs
index acae0daa86b..c6741ddb822 100644
--- a/src/liballoc/borrow.rs
+++ b/src/liballoc/borrow.rs
@@ -59,6 +59,7 @@ pub trait ToOwned {
     /// let vv: Vec<i32> = v.to_owned();
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[must_use = "cloning is often expensive and is not expected to have side effects"]
     fn to_owned(&self) -> Self::Owned;
 
     /// Uses borrowed data to replace owned data, usually by cloning.
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 2fad3b0bad4..51a78025401 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -99,7 +99,6 @@
 #![feature(fundamental)]
 #![feature(generic_param_attrs)]
 #![cfg_attr(stage0, feature(i128_type))]
-#![feature(iter_rfold)]
 #![feature(lang_items)]
 #![feature(needs_allocator)]
 #![feature(nonzero)]
diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index aa202e23628..b95aae02894 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -1517,7 +1517,7 @@ impl String {
         }
     }
 
-    /// Creates a splicing iterator that removes the specified range in the string,
+    /// Removes the specified range in the string,
     /// and replaces it with the given string.
     /// The given string doesn't need to be the same length as the range.
     ///
@@ -1537,21 +1537,20 @@ impl String {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(splice)]
     /// let mut s = String::from("α is alpha, β is beta");
     /// let beta_offset = s.find('β').unwrap_or(s.len());
     ///
     /// // Replace the range up until the β from the string
-    /// s.splice(..beta_offset, "Α is capital alpha; ");
+    /// s.replace_range(..beta_offset, "Α is capital alpha; ");
     /// assert_eq!(s, "Α is capital alpha; β is beta");
     /// ```
-    #[unstable(feature = "splice", reason = "recently added", issue = "44643")]
-    pub fn splice<R>(&mut self, range: R, replace_with: &str)
+    #[stable(feature = "splice", since = "1.27.0")]
+    pub fn replace_range<R>(&mut self, range: R, replace_with: &str)
         where R: RangeBounds<usize>
     {
         // Memory safety
         //
-        // The String version of Splice does not have the memory safety issues
+        // Replace_range does not have the memory safety issues of a vector Splice.
         // of the vector version. The data is just plain bytes.
 
         match range.start() {
diff --git a/src/liballoc/tests/string.rs b/src/liballoc/tests/string.rs
index d1e746ea43b..cb4a17a22d8 100644
--- a/src/liballoc/tests/string.rs
+++ b/src/liballoc/tests/string.rs
@@ -443,53 +443,53 @@ fn test_drain() {
 }
 
 #[test]
-fn test_splice() {
+fn test_replace_range() {
     let mut s = "Hello, world!".to_owned();
-    s.splice(7..12, "世界");
+    s.replace_range(7..12, "世界");
     assert_eq!(s, "Hello, 世界!");
 }
 
 #[test]
 #[should_panic]
-fn test_splice_char_boundary() {
+fn test_replace_range_char_boundary() {
     let mut s = "Hello, 世界!".to_owned();
-    s.splice(..8, "");
+    s.replace_range(..8, "");
 }
 
 #[test]
-fn test_splice_inclusive_range() {
+fn test_replace_range_inclusive_range() {
     let mut v = String::from("12345");
-    v.splice(2..=3, "789");
+    v.replace_range(2..=3, "789");
     assert_eq!(v, "127895");
-    v.splice(1..=2, "A");
+    v.replace_range(1..=2, "A");
     assert_eq!(v, "1A895");
 }
 
 #[test]
 #[should_panic]
-fn test_splice_out_of_bounds() {
+fn test_replace_range_out_of_bounds() {
     let mut s = String::from("12345");
-    s.splice(5..6, "789");
+    s.replace_range(5..6, "789");
 }
 
 #[test]
 #[should_panic]
-fn test_splice_inclusive_out_of_bounds() {
+fn test_replace_range_inclusive_out_of_bounds() {
     let mut s = String::from("12345");
-    s.splice(5..=5, "789");
+    s.replace_range(5..=5, "789");
 }
 
 #[test]
-fn test_splice_empty() {
+fn test_replace_range_empty() {
     let mut s = String::from("12345");
-    s.splice(1..2, "");
+    s.replace_range(1..2, "");
     assert_eq!(s, "1345");
 }
 
 #[test]
-fn test_splice_unbounded() {
+fn test_replace_range_unbounded() {
     let mut s = String::from("12345");
-    s.splice(.., "");
+    s.replace_range(.., "");
     assert_eq!(s, "");
 }
 
diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index 47c92028b14..02008310b81 100644
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -1283,6 +1283,49 @@ impl<T> Vec<T> {
         }
         other
     }
+
+    /// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
+    ///
+    /// If `new_len` is greater than `len`, the `Vec` is extended by the
+    /// difference, with each additional slot filled with the result of
+    /// calling the closure `f`. The return values from `f` will end up
+    /// in the `Vec` in the order they have been generated.
+    ///
+    /// If `new_len` is less than `len`, the `Vec` is simply truncated.
+    ///
+    /// This method uses a closure to create new values on every push. If
+    /// you'd rather [`Clone`] a given value, use [`resize`]. If you want
+    /// to use the [`Default`] trait to generate values, you can pass
+    /// [`Default::default()`] as the second argument..
+    ///
+    /// # 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]);
+    ///
+    /// let mut vec = vec![];
+    /// let mut p = 1;
+    /// vec.resize_with(4, || { p *= 2; p });
+    /// assert_eq!(vec, [2, 4, 8, 16]);
+    /// ```
+    ///
+    /// [`resize`]: #method.resize
+    /// [`Clone`]: ../../std/clone/trait.Clone.html
+    #[unstable(feature = "vec_resize_with", issue = "41758")]
+    pub fn resize_with<F>(&mut self, new_len: usize, f: F)
+        where F: FnMut() -> T
+    {
+        let len = self.len();
+        if new_len > len {
+            self.extend_with(new_len - len, ExtendFunc(f));
+        } else {
+            self.truncate(new_len);
+        }
+    }
 }
 
 impl<T: Clone> Vec<T> {
@@ -1293,8 +1336,8 @@ impl<T: Clone> Vec<T> {
     /// If `new_len` is less than `len`, the `Vec` is simply truncated.
     ///
     /// This method requires [`Clone`] to be able clone the passed value. If
-    /// you'd rather create a value with [`Default`] instead, see
-    /// [`resize_default`].
+    /// you need more flexibility (or want to rely on [`Default`] instead of
+    /// [`Clone`]), use [`resize_with`].
     ///
     /// # Examples
     ///
@@ -1310,7 +1353,7 @@ impl<T: Clone> Vec<T> {
     ///
     /// [`Clone`]: ../../std/clone/trait.Clone.html
     /// [`Default`]: ../../std/default/trait.Default.html
-    /// [`resize_default`]: #method.resize_default
+    /// [`resize_with`]: #method.resize_with
     #[stable(feature = "vec_resize", since = "1.5.0")]
     pub fn resize(&mut self, new_len: usize, value: T) {
         let len = self.len();
@@ -1389,24 +1432,31 @@ impl<T: Default> Vec<T> {
 
 // This code generalises `extend_with_{element,default}`.
 trait ExtendWith<T> {
-    fn next(&self) -> T;
+    fn next(&mut self) -> T;
     fn last(self) -> T;
 }
 
 struct ExtendElement<T>(T);
 impl<T: Clone> ExtendWith<T> for ExtendElement<T> {
-    fn next(&self) -> T { self.0.clone() }
+    fn next(&mut self) -> T { self.0.clone() }
     fn last(self) -> T { self.0 }
 }
 
 struct ExtendDefault;
 impl<T: Default> ExtendWith<T> for ExtendDefault {
-    fn next(&self) -> T { Default::default() }
+    fn next(&mut self) -> T { Default::default() }
     fn last(self) -> T { Default::default() }
 }
+
+struct ExtendFunc<F>(F);
+impl<T, F: FnMut() -> T> ExtendWith<T> for ExtendFunc<F> {
+    fn next(&mut self) -> T { (self.0)() }
+    fn last(mut self) -> T { (self.0)() }
+}
+
 impl<T> Vec<T> {
     /// Extend the vector by `n` values, using the given generator.
-    fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, value: E) {
+    fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, mut value: E) {
         self.reserve(n);
 
         unsafe {