Auto merge of #44585 - frewsxcv:rollup, r=frewsxcv

Rollup of 23 pull requests

- Successful merges: #44131, #44254, #44368, #44374, #44378, #44388, #44430, #44450, #44453, #44472, #44476, #44477, #44485, #44497, #44521, #44534, #44536, #44541, #44552, #44559, #44563, #44569, #44572
- Failed merges:

CONTRIBUTING.md

@@ -400,30 +400,53 @@ labels to triage issues:
 
 * Magenta, **B**-prefixed labels identify bugs which are **blockers**.
 
+* Dark blue, **beta-** labels track changes which need to be backported into
+  the beta branches.
+
+* Light purple, **C**-prefixed labels represent the **category** of an issue.
+
 * Green, **E**-prefixed labels explain the level of **experience** necessary
   to fix the issue.
 
+* The dark blue **final-comment-period** label marks bugs that are using the
+  RFC signoff functionality of [rfcbot][rfcbot] and are currenty in the final
+  comment period.
+
 * Red, **I**-prefixed labels indicate the **importance** of the issue. The
   [I-nominated][inom] label indicates that an issue has been nominated for
   prioritizing at the next triage meeting.
 
+* The purple **metabug** label marks lists of bugs collected by other
+  categories.
+
+* Purple gray, **O**-prefixed labels are the **operating system** or platform
+  that this issue is specific to.
+
 * Orange, **P**-prefixed labels indicate a bug's **priority**. These labels
   are only assigned during triage meetings, and replace the [I-nominated][inom]
   label.
 
-* Blue, **T**-prefixed bugs denote which **team** the issue belongs to.
+* The gray **proposed-final-comment-period** label marks bugs that are using
+  the RFC signoff functionality of [rfcbot][rfcbot] and are currently awaiting
+  signoff of all team members in order to enter the final comment period.
 
-* Dark blue, **beta-** labels track changes which need to be backported into
-  the beta branches.
+* Pink, **regression**-prefixed labels track regressions from stable to the
+  release channels.
 
-* The purple **metabug** label marks lists of bugs collected by other
-  categories.
+* The light orange **relnotes** label marks issues that should be documented in
+  the release notes of the next release.
+
+* Gray, **S**-prefixed labels are used for tracking the **status** of pull
+  requests.
+
+* Blue, **T**-prefixed bugs denote which **team** the issue belongs to.
 
 If you're looking for somewhere to start, check out the [E-easy][eeasy] tag.
 
 [inom]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AI-nominated
 [eeasy]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy
 [lru]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
+[rfcbot]: https://github.com/dikaiosune/rust-dashboard/blob/master/RFCBOT.md
 
 ## Out-of-tree Contributions
 

src/bootstrap/native.rs

@@ -389,7 +389,8 @@ impl Step for Openssl {
         drop(fs::remove_dir_all(&dst));
         build.run(Command::new("tar").arg("xf").arg(&tarball).current_dir(&out));
 
-        let mut configure = Command::new(obj.join("Configure"));
+        let mut configure = Command::new("perl");
+        configure.arg(obj.join("Configure"));
         configure.arg(format!("--prefix={}", dst.display()));
         configure.arg("no-dso");
         configure.arg("no-ssl2");

src/liballoc/btree/set.rs

@@ -1110,15 +1110,13 @@ impl<'a, T: Ord> Iterator for Union<'a, T> {
     type Item = &'a T;
 
     fn next(&mut self) -> Option<&'a T> {
-        loop {
-            match cmp_opt(self.a.peek(), self.b.peek(), Greater, Less) {
-                Less => return self.a.next(),
-                Equal => {
-                    self.b.next();
-                    return self.a.next();
-                }
-                Greater => return self.b.next(),
+        match cmp_opt(self.a.peek(), self.b.peek(), Greater, Less) {
+            Less => self.a.next(),
+            Equal => {
+                self.b.next();
+                self.a.next()
             }
+            Greater => self.b.next(),
         }
     }
 

src/liballoc/str.rs

@@ -855,6 +855,19 @@ impl str {
     }
 
     /// Returns an iterator of `u16` over the string encoded as UTF-16.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// let text = "Zażółć gęślą jaźń";
+    ///
+    /// let utf8_len = text.len();
+    /// let utf16_len = text.encode_utf16().count();
+    ///
+    /// assert!(utf16_len <= utf8_len);
+    /// ```
     #[stable(feature = "encode_utf16", since = "1.8.0")]
     pub fn encode_utf16(&self) -> EncodeUtf16 {
         EncodeUtf16 { encoder: Utf16Encoder::new(self[..].chars()) }
@@ -1783,6 +1796,17 @@ impl str {
     }
 
     /// Converts a `Box<str>` into a `Box<[u8]>` without copying or allocating.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// let s = "this is a string";
+    /// let boxed_str = s.to_owned().into_boxed_str();
+    /// let boxed_bytes = boxed_str.into_boxed_bytes();
+    /// assert_eq!(*boxed_bytes, *s.as_bytes());
+    /// ```
     #[stable(feature = "str_box_extras", since = "1.20.0")]
     pub fn into_boxed_bytes(self: Box<str>) -> Box<[u8]> {
         self.into()
@@ -2050,6 +2074,17 @@ impl str {
 
 /// Converts a boxed slice of bytes to a boxed string slice without checking
 /// that the string contains valid UTF-8.
+///
+/// # Examples
+///
+/// Basic usage:
+///
+/// ```
+/// let smile_utf8 = Box::new([226, 152, 186]);
+/// let smile = unsafe { std::str::from_boxed_utf8_unchecked(smile_utf8) };
+///
+/// assert_eq!("☺", &*smile);
+/// ```
 #[stable(feature = "str_box_extras", since = "1.20.0")]
 pub unsafe fn from_boxed_utf8_unchecked(v: Box<[u8]>) -> Box<str> {
     mem::transmute(v)

src/liballoc/string.rs

@@ -622,6 +622,13 @@ impl String {
     /// Decode a UTF-16 encoded slice `v` into a `String`, replacing
     /// invalid data with the replacement character (U+FFFD).
     ///
+    /// Unlike [`from_utf8_lossy`] which returns a [`Cow<'a, str>`],
+    /// `from_utf16_lossy` returns a `String` since the UTF-16 to UTF-8
+    /// conversion requires a memory allocation.
+    ///
+    /// [`from_utf8_lossy`]: #method.from_utf8_lossy
+    /// [`Cow<'a, str>`]: ../borrow/enum.Cow.html
+    ///
     /// # Examples
     ///
     /// Basic usage:
@@ -759,7 +766,22 @@ impl String {
         self
     }
 
-    /// Extracts a string slice containing the entire string.
+    /// Converts a `String` into a mutable string slice.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use std::ascii::AsciiExt;
+    ///
+    /// let mut s = String::from("foobar");
+    /// let s_mut_str = s.as_mut_str();
+    ///
+    /// s_mut_str.make_ascii_uppercase();
+    ///
+    /// assert_eq!("FOOBAR", s_mut_str);
+    /// ```
     #[inline]
     #[stable(feature = "string_as_str", since = "1.7.0")]
     pub fn as_mut_str(&mut self) -> &mut str {

src/liballoc/vec.rs

@@ -370,6 +370,7 @@ impl<T> Vec<T> {
     ///
     /// * `ptr` needs to have been previously allocated via [`String`]/`Vec<T>`
     ///   (at least, it's highly likely to be incorrect if it wasn't).
+    /// * `ptr`'s `T` needs to have the same size and alignment as it was allocated with.
     /// * `length` needs to be less than or equal to `capacity`.
     /// * `capacity` needs to be the capacity that the pointer was allocated with.
     ///
@@ -1969,16 +1970,19 @@ impl<T> Vec<T> {
     /// Using this method is equivalent to the following code:
     ///
     /// ```
-    /// # let some_predicate = |x: &mut i32| { *x == 2 };
-    /// # let mut vec = vec![1, 2, 3, 4, 5];
+    /// # let some_predicate = |x: &mut i32| { *x == 2 || *x == 3 || *x == 6 };
+    /// # let mut vec = vec![1, 2, 3, 4, 5, 6];
     /// let mut i = 0;
     /// while i != vec.len() {
     ///     if some_predicate(&mut vec[i]) {
     ///         let val = vec.remove(i);
     ///         // your code here
+    ///     } else {
+    ///         i += 1;
     ///     }
-    ///     i += 1;
     /// }
+    ///
+    /// # assert_eq!(vec, vec![1, 4, 5]);
     /// ```
     ///
     /// But `drain_filter` is easier to use. `drain_filter` is also more efficient,

src/libcore/intrinsics.rs

@@ -848,12 +848,12 @@ extern "rust-intrinsic" {
     /// // The no-copy, unsafe way, still using transmute, but not UB.
     /// // This is equivalent to the original, but safer, and reuses the
     /// // same Vec internals. Therefore the new inner type must have the
-    /// // exact same size, and the same or lesser alignment, as the old
-    /// // type. The same caveats exist for this method as transmute, for
+    /// // exact same size, and the same alignment, as the old type.
+    /// // The same caveats exist for this method as transmute, for
     /// // the original inner type (`&i32`) to the converted inner type
     /// // (`Option<&i32>`), so read the nomicon pages linked above.
     /// let v_from_raw = unsafe {
-    ///     Vec::from_raw_parts(v_orig.as_mut_ptr(),
+    ///     Vec::from_raw_parts(v_orig.as_mut_ptr() as *mut Option<&i32>,
     ///                         v_orig.len(),
     ///                         v_orig.capacity())
     /// };

src/libcore/mem.rs

@@ -712,39 +712,39 @@ pub unsafe fn transmute_copy<T, U>(src: &T) -> U {
 /// Opaque type representing the discriminant of an enum.
 ///
 /// See the `discriminant` function in this module for more information.
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 pub struct Discriminant<T>(u64, PhantomData<*const T>);
 
 // N.B. These trait implementations cannot be derived because we don't want any bounds on T.
 
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 impl<T> Copy for Discriminant<T> {}
 
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 impl<T> clone::Clone for Discriminant<T> {
     fn clone(&self) -> Self {
         *self
     }
 }
 
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 impl<T> cmp::PartialEq for Discriminant<T> {
     fn eq(&self, rhs: &Self) -> bool {
         self.0 == rhs.0
     }
 }
 
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 impl<T> cmp::Eq for Discriminant<T> {}
 
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 impl<T> hash::Hash for Discriminant<T> {
     fn hash<H: hash::Hasher>(&self, state: &mut H) {
         self.0.hash(state);
     }
 }
 
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 impl<T> fmt::Debug for Discriminant<T> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         fmt.debug_tuple("Discriminant")
@@ -777,7 +777,7 @@ impl<T> fmt::Debug for Discriminant<T> {
 /// assert!(mem::discriminant(&Foo::B(1))     == mem::discriminant(&Foo::B(2)));
 /// assert!(mem::discriminant(&Foo::B(3))     != mem::discriminant(&Foo::C(3)));
 /// ```
-#[stable(feature = "discriminant_value", since = "1.22.0")]
+#[stable(feature = "discriminant_value", since = "1.21.0")]
 pub fn discriminant<T>(v: &T) -> Discriminant<T> {
     unsafe {
         Discriminant(intrinsics::discriminant_value(v), PhantomData)