Rollup of 14 pull requests

compiler/rustc_borrowck/src/member_constraints.rs

@@ -144,7 +144,7 @@ impl<R> MemberConstraintSet<'tcx, R>
 where
     R: Copy + Hash + Eq,
 {
-    crate fn all_indices(&self) -> impl Iterator<Item = NllMemberConstraintIndex> {
+    crate fn all_indices(&self) -> impl Iterator<Item = NllMemberConstraintIndex> + '_ {
         self.constraints.indices()
     }
 

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -497,7 +497,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     }
 
     /// Returns an iterator over all the region indices.
-    pub fn regions(&self) -> impl Iterator<Item = RegionVid> {
+    pub fn regions(&self) -> impl Iterator<Item = RegionVid> + '_ {
         self.definitions.indices()
     }
 

compiler/rustc_data_structures/src/lib.rs

@@ -7,7 +7,6 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![feature(allow_internal_unstable)]
 #![feature(array_windows)]
 #![feature(associated_type_bounds)]
 #![feature(auto_traits)]

compiler/rustc_index/src/lib.rs

@@ -2,9 +2,8 @@
 #![feature(bench_black_box)]
 #![feature(extend_one)]
 #![feature(iter_zip)]
-#![feature(unboxed_closures)]
+#![feature(min_specialization)]
 #![feature(test)]
-#![feature(fn_traits)]
 
 pub mod bit_set;
 pub mod vec;

compiler/rustc_index/src/vec.rs

@@ -3,9 +3,9 @@ use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use std::fmt;
 use std::fmt::Debug;
 use std::hash::Hash;
-use std::iter::{self, FromIterator};
+use std::iter::FromIterator;
 use std::marker::PhantomData;
-use std::ops::{Index, IndexMut, Range, RangeBounds};
+use std::ops::{Index, IndexMut, RangeBounds};
 use std::slice;
 use std::vec;
 
@@ -518,8 +518,6 @@ impl<I: Idx, T: fmt::Debug> fmt::Debug for IndexVec<I, T> {
     }
 }
 
-pub type Enumerated<I, J> = iter::Map<iter::Enumerate<J>, IntoIdx<I>>;
-
 impl<I: Idx, T> IndexVec<I, T> {
     #[inline]
     pub fn new() -> Self {
@@ -596,8 +594,10 @@ impl<I: Idx, T> IndexVec<I, T> {
     }
 
     #[inline]
-    pub fn into_iter_enumerated(self) -> Enumerated<I, vec::IntoIter<T>> {
-        self.raw.into_iter().enumerate().map(IntoIdx { _marker: PhantomData })
+    pub fn into_iter_enumerated(
+        self,
+    ) -> impl DoubleEndedIterator<Item = (I, T)> + ExactSizeIterator {
+        self.raw.into_iter().enumerate().map(|(n, t)| (I::new(n), t))
     }
 
     #[inline]
@@ -606,13 +606,15 @@ impl<I: Idx, T> IndexVec<I, T> {
     }
 
     #[inline]
-    pub fn iter_enumerated(&self) -> Enumerated<I, slice::Iter<'_, T>> {
-        self.raw.iter().enumerate().map(IntoIdx { _marker: PhantomData })
+    pub fn iter_enumerated(
+        &self,
+    ) -> impl DoubleEndedIterator<Item = (I, &T)> + ExactSizeIterator + '_ {
+        self.raw.iter().enumerate().map(|(n, t)| (I::new(n), t))
     }
 
     #[inline]
-    pub fn indices(&self) -> iter::Map<Range<usize>, IntoIdx<I>> {
-        (0..self.len()).map(IntoIdx { _marker: PhantomData })
+    pub fn indices(&self) -> impl DoubleEndedIterator<Item = I> + ExactSizeIterator + 'static {
+        (0..self.len()).map(|n| I::new(n))
     }
 
     #[inline]
@@ -621,8 +623,10 @@ impl<I: Idx, T> IndexVec<I, T> {
     }
 
     #[inline]
-    pub fn iter_enumerated_mut(&mut self) -> Enumerated<I, slice::IterMut<'_, T>> {
-        self.raw.iter_mut().enumerate().map(IntoIdx { _marker: PhantomData })
+    pub fn iter_enumerated_mut(
+        &mut self,
+    ) -> impl DoubleEndedIterator<Item = (I, &mut T)> + ExactSizeIterator + '_ {
+        self.raw.iter_mut().enumerate().map(|(n, t)| (I::new(n), t))
     }
 
     #[inline]
@@ -638,7 +642,7 @@ impl<I: Idx, T> IndexVec<I, T> {
         &'a mut self,
         range: R,
     ) -> impl Iterator<Item = (I, T)> + 'a {
-        self.raw.drain(range).enumerate().map(IntoIdx { _marker: PhantomData })
+        self.raw.drain(range).enumerate().map(|(n, t)| (I::new(n), t))
     }
 
     #[inline]
@@ -832,36 +836,5 @@ impl<'a, I: Idx, T> IntoIterator for &'a mut IndexVec<I, T> {
     }
 }
 
-pub struct IntoIdx<I: Idx> {
-    _marker: PhantomData<fn(&I)>,
-}
-impl<I: Idx, T> FnOnce<((usize, T),)> for IntoIdx<I> {
-    type Output = (I, T);
-
-    extern "rust-call" fn call_once(self, ((n, t),): ((usize, T),)) -> Self::Output {
-        (I::new(n), t)
-    }
-}
-
-impl<I: Idx, T> FnMut<((usize, T),)> for IntoIdx<I> {
-    extern "rust-call" fn call_mut(&mut self, ((n, t),): ((usize, T),)) -> Self::Output {
-        (I::new(n), t)
-    }
-}
-
-impl<I: Idx> FnOnce<(usize,)> for IntoIdx<I> {
-    type Output = I;
-
-    extern "rust-call" fn call_once(self, (n,): (usize,)) -> Self::Output {
-        I::new(n)
-    }
-}
-
-impl<I: Idx> FnMut<(usize,)> for IntoIdx<I> {
-    extern "rust-call" fn call_mut(&mut self, (n,): (usize,)) -> Self::Output {
-        I::new(n)
-    }
-}
-
 #[cfg(test)]
 mod tests;

compiler/rustc_lint/src/lib.rs

@@ -26,7 +26,6 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![cfg_attr(test, feature(test))]
 #![feature(array_windows)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]

compiler/rustc_middle/src/lib.rs

@@ -41,13 +41,11 @@
 #![feature(once_cell)]
 #![feature(min_specialization)]
 #![feature(trusted_len)]
-#![feature(test)]
 #![feature(in_band_lifetimes)]
 #![feature(crate_visibility_modifier)]
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
 #![feature(half_open_range_patterns)]
-#![feature(exclusive_range_pattern)]
 #![feature(control_flow_enum)]
 #![feature(associated_type_defaults)]
 #![feature(iter_zip)]

compiler/rustc_middle/src/ty/codec.rs

@@ -1,10 +1,10 @@
-// This module contains some shared code for encoding and decoding various
-// things from the `ty` module, and in particular implements support for
-// "shorthands" which allow to have pointers back into the already encoded
-// stream instead of re-encoding the same thing twice.
-//
-// The functionality in here is shared between persisting to crate metadata and
-// persisting to incr. comp. caches.
+//! This module contains some shared code for encoding and decoding various
+//! things from the `ty` module, and in particular implements support for
+//! "shorthands" which allow to have pointers back into the already encoded
+//! stream instead of re-encoding the same thing twice.
+//!
+//! The functionality in here is shared between persisting to crate metadata and
+//! persisting to incr. comp. caches.
 
 use crate::arena::ArenaAllocatable;
 use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos};

compiler/rustc_mir_dataflow/src/move_paths/mod.rs

@@ -1,6 +1,5 @@
-use core::slice::Iter;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_index::vec::{Enumerated, IndexVec};
+use rustc_index::vec::IndexVec;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
 use rustc_span::Span;
@@ -337,7 +336,9 @@ impl MovePathLookup {
 
     /// An enumerated iterator of `local`s and their associated
     /// `MovePathIndex`es.
-    pub fn iter_locals_enumerated(&self) -> Enumerated<Local, Iter<'_, MovePathIndex>> {
+    pub fn iter_locals_enumerated(
+        &self,
+    ) -> impl DoubleEndedIterator<Item = (Local, &MovePathIndex)> + ExactSizeIterator {
         self.locals.iter_enumerated()
     }
 }

compiler/rustc_target/src/lib.rs

@@ -15,7 +15,6 @@
 #![feature(exhaustive_patterns)]
 #![feature(min_specialization)]
 #![feature(step_trait)]
-#![feature(unchecked_math)]
 
 use std::path::{Path, PathBuf};
 

compiler/rustc_ty_utils/src/lib.rs

@@ -6,8 +6,6 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(control_flow_enum)]
-#![feature(half_open_range_patterns)]
-#![feature(exclusive_range_pattern)]
 #![feature(nll)]
 #![recursion_limit = "256"]
 

library/alloc/src/collections/btree/map.rs

@@ -19,16 +19,16 @@ mod entry;
 pub use entry::{Entry, OccupiedEntry, OccupiedError, VacantEntry};
 use Entry::*;
 
-/// Minimum number of elements in nodes that are not a root.
+/// Minimum number of elements in a node that is not a root.
 /// We might temporarily have fewer elements during methods.
 pub(super) const MIN_LEN: usize = node::MIN_LEN_AFTER_SPLIT;
 
 // A tree in a `BTreeMap` is a tree in the `node` module with additional invariants:
 // - Keys must appear in ascending order (according to the key's type).
-// - If the root node is internal, it must contain at least 1 element.
+// - Every non-leaf node contains at least 1 element (has at least 2 children).
 // - Every non-root node contains at least MIN_LEN elements.
 //
-// An empty map may be represented both by the absence of a root node or by a
+// An empty map is represented either by the absence of a root node or by a
 // root node that is an empty leaf.
 
 /// A map based on a [B-Tree].
@@ -1735,8 +1735,8 @@ impl<'a, K: 'a, V: 'a> DrainFilterInner<'a, K, V> {
     pub(super) fn size_hint(&self) -> (usize, Option<usize>) {
         // In most of the btree iterators, `self.length` is the number of elements
         // yet to be visited. Here, it includes elements that were visited and that
-        // the predicate decided not to drain. Making this upper bound more accurate
-        // requires maintaining an extra field and is not worth while.
+        // the predicate decided not to drain. Making this upper bound more tight
+        // during iteration would require an extra field.
         (0, Some(*self.length))
     }
 }

library/alloc/src/collections/btree/navigate.rs

@@ -440,8 +440,7 @@ impl<K, V> Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge> {
     /// - The given edge must not have been previously returned by counterpart
     ///   `deallocating_next_back`.
     /// - The returned KV handle is only valid to access the key and value,
-    ///   and only valid until the next call to this method or counterpart
-    ///   `deallocating_next_back`.
+    ///   and only valid until the next call to a `deallocating_` method.
     unsafe fn deallocating_next(
         self,
     ) -> Option<(Self, Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV>)>
@@ -470,8 +469,7 @@ impl<K, V> Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge> {
     /// - The given edge must not have been previously returned by counterpart
     ///   `deallocating_next`.
     /// - The returned KV handle is only valid to access the key and value,
-    ///   and only valid until the next call to this method or counterpart
-    ///   `deallocating_next`.
+    ///   and only valid until the next call to a `deallocating_` method.
     unsafe fn deallocating_next_back(
         self,
     ) -> Option<(Self, Handle<NodeRef<marker::Dying, K, V, marker::LeafOrInternal>, marker::KV>)>

library/alloc/src/collections/btree/node.rs

@@ -574,7 +574,7 @@ impl<K, V> NodeRef<marker::Owned, K, V, marker::LeafOrInternal> {
     /// no cleanup is done on any of the keys, values and other children.
     /// This decreases the height by 1 and is the opposite of `push_internal_level`.
     ///
-    /// Requires exclusive access to the `Root` object but not to the root node;
+    /// Requires exclusive access to the `NodeRef` object but not to the root node;
     /// it will not invalidate other handles or references to the root node.
     ///
     /// Panics if there is no internal level, i.e., if the root node is a leaf.

library/alloc/src/vec/mod.rs

@@ -2137,6 +2137,7 @@ impl<T: Clone, A: Allocator> Vec<T, A> {
     /// in order to be able to clone the passed value.
     /// If you need more flexibility (or want to rely on [`Default`] instead of
     /// [`Clone`]), use [`Vec::resize_with`].
+    /// If you only need to resize to a smaller size, use [`Vec::truncate`].
     ///
     /// # Examples
     ///
@@ -2188,7 +2189,12 @@ impl<T: Clone, A: Allocator> Vec<T, A> {
 
     /// Copies elements from `src` range to the end of the vector.
     ///
-    /// ## Examples
+    /// # Panics
+    ///
+    /// Panics if the starting point is greater than the end point or if
+    /// the end point is greater than the length of the vector.
+    ///
+    /// # Examples
     ///
     /// ```
     /// let mut vec = vec![0, 1, 2, 3, 4];

library/core/src/array/mod.rs

@@ -368,14 +368,14 @@ impl<T, const N: usize> [T; N] {
     }
 
     /// Returns a slice containing the entire array. Equivalent to `&s[..]`.
-    #[unstable(feature = "array_methods", issue = "76118")]
-    pub fn as_slice(&self) -> &[T] {
+    #[stable(feature = "array_as_slice", since = "1.57.0")]
+    pub const fn as_slice(&self) -> &[T] {
         self
     }
 
     /// Returns a mutable slice containing the entire array. Equivalent to
     /// `&mut s[..]`.
-    #[unstable(feature = "array_methods", issue = "76118")]
+    #[stable(feature = "array_as_slice", since = "1.57.0")]
     pub fn as_mut_slice(&mut self) -> &mut [T] {
         self
     }

library/core/src/lib.rs

@@ -91,6 +91,7 @@
 #![feature(const_maybe_uninit_assume_init)]
 #![feature(const_option)]
 #![feature(const_pin)]
+#![feature(const_replace)]
 #![feature(const_ptr_offset)]
 #![feature(const_ptr_offset_from)]
 #![feature(const_ptr_read)]

library/core/src/num/nonzero.rs

@@ -379,7 +379,7 @@ macro_rules! nonzero_unsigned_operations {
                 /// ```
                 #[unstable(feature = "nonzero_ops", issue = "84186")]
                 #[inline]
-                pub unsafe fn unchecked_add(self, other: $Int) -> $Ty {
+                pub const unsafe fn unchecked_add(self, other: $Int) -> $Ty {
                     // SAFETY: The caller ensures there is no overflow.
                     unsafe { $Ty::new_unchecked(self.get().unchecked_add(other)) }
                 }
@@ -750,7 +750,7 @@ macro_rules! nonzero_unsigned_signed_operations {
                 /// ```
                 #[unstable(feature = "nonzero_ops", issue = "84186")]
                 #[inline]
-                pub unsafe fn unchecked_mul(self, other: $Ty) -> $Ty {
+                pub const unsafe fn unchecked_mul(self, other: $Ty) -> $Ty {
                     // SAFETY: The caller ensures there is no overflow.
                     unsafe { $Ty::new_unchecked(self.get().unchecked_mul(other.get())) }
                 }