Auto merge of #58644 - Centril:rollup, r=Centril

Rollup of 17 pull requests

Successful merges:

 - #57656 (Deprecate the unstable Vec::resize_default)
 - #58059 (deprecate before_exec in favor of unsafe pre_exec)
 - #58064 (override `VecDeque::try_rfold`, also update iterator)
 - #58198 (Suggest removing parentheses surrounding lifetimes)
 - #58431 (fix overlapping references in BTree)
 - #58555 (Add a note about 2018e if someone uses `try {` in 2015e)
 - #58588 (remove a bit of dead code)
 - #58589 (cleanup macro after 2018 transition)
 - #58591 (Dedup a rustdoc diagnostic construction)
 - #58600 (fix small documentation typo)
 - #58601 (Search for target_triple.json only if builtin target not found)
 - #58606 (Docs: put Future trait into spotlight)
 - #58607 (Fixes #58586: Make E0505 erronous example fail for the 2018 edition)
 - #58615 (miri: explain why we use static alignment in ref-to-place conversion)
 - #58620 (introduce benchmarks of BTreeSet.intersection)
 - #58621 (Update miri links)
 - #58632 (Make std feature list sorted)

Failed merges:

r? @ghost

Author: bors

CONTRIBUTING.md

@@ -161,10 +161,10 @@ it can be found [here][rctd].
 
 Currently building Rust will also build the following external projects:
 
-* [clippy](https://github.com/rust-lang-nursery/rust-clippy)
-* [miri](https://github.com/solson/miri)
-* [rustfmt](https://github.com/rust-lang-nursery/rustfmt)
-* [rls](https://github.com/rust-lang-nursery/rls/)
+* [clippy](https://github.com/rust-lang/rust-clippy)
+* [miri](https://github.com/rust-lang/miri)
+* [rustfmt](https://github.com/rust-lang/rustfmt)
+* [rls](https://github.com/rust-lang/rls/)
 
 We allow breakage of these tools in the nightly channel. Maintainers of these
 projects will be notified of the breakages and should fix them as soon as
@@ -191,9 +191,9 @@ before the PR is merged.
 
 Rust's build system builds a number of tools that make use of the
 internals of the compiler. This includes 
-[Clippy](https://github.com/rust-lang-nursery/rust-clippy),
-[RLS](https://github.com/rust-lang-nursery/rls) and
-[rustfmt](https://github.com/rust-lang-nursery/rustfmt). If these tools
+[Clippy](https://github.com/rust-lang/rust-clippy),
+[RLS](https://github.com/rust-lang/rls) and
+[rustfmt](https://github.com/rust-lang/rustfmt). If these tools
 break because of your changes, you may run into a sort of "chicken and egg"
 problem. These tools rely on the latest compiler to be built so you can't update
 them to reflect your changes to the compiler until those changes are merged into
@@ -253,10 +253,10 @@ to complete a few more steps which are outlined with their rationale below.
 
 *(This error may change in the future to include more information.)*
 ```
-error: failed to resolve patches for `https://github.com/rust-lang-nursery/rustfmt`
+error: failed to resolve patches for `https://github.com/rust-lang/rustfmt`
 
 Caused by:
-  patch for `rustfmt-nightly` in `https://github.com/rust-lang-nursery/rustfmt` did not resolve to any crates
+  patch for `rustfmt-nightly` in `https://github.com/rust-lang/rustfmt` did not resolve to any crates
 failed to run: ~/rust/build/x86_64-unknown-linux-gnu/stage0/bin/cargo build --manifest-path ~/rust/src/bootstrap/Cargo.toml
 ```
 

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

@@ -244,7 +244,7 @@ disambiguate the error type:
 /// use std::io;
 /// let mut input = String::new();
 /// io::stdin().read_line(&mut input)?;
-/// # Ok::<(), io:Error>(())
+/// # Ok::<(), io::Error>(())
 /// ```
 ```
 

src/liballoc/benches/btree/mod.rs

@@ -1 +1,2 @@
 mod map;
+mod set;

src/liballoc/benches/btree/set.rs

@@ -0,0 +1,88 @@
+use std::collections::BTreeSet;
+
+use rand::{thread_rng, Rng};
+use test::{black_box, Bencher};
+
+fn random(n1: u32, n2: u32) -> [BTreeSet<usize>; 2] {
+    let mut rng = thread_rng();
+    let mut set1 = BTreeSet::new();
+    let mut set2 = BTreeSet::new();
+    for _ in 0..n1 {
+        let i = rng.gen::<usize>();
+        set1.insert(i);
+    }
+    for _ in 0..n2 {
+        let i = rng.gen::<usize>();
+        set2.insert(i);
+    }
+    [set1, set2]
+}
+
+fn staggered(n1: u32, n2: u32) -> [BTreeSet<u32>; 2] {
+    let mut even = BTreeSet::new();
+    let mut odd = BTreeSet::new();
+    for i in 0..n1 {
+        even.insert(i * 2);
+    }
+    for i in 0..n2 {
+        odd.insert(i * 2 + 1);
+    }
+    [even, odd]
+}
+
+fn neg_vs_pos(n1: u32, n2: u32) -> [BTreeSet<i32>; 2] {
+    let mut neg = BTreeSet::new();
+    let mut pos = BTreeSet::new();
+    for i in -(n1 as i32)..=-1 {
+        neg.insert(i);
+    }
+    for i in 1..=(n2 as i32) {
+        pos.insert(i);
+    }
+    [neg, pos]
+}
+
+fn pos_vs_neg(n1: u32, n2: u32) -> [BTreeSet<i32>; 2] {
+    let mut neg = BTreeSet::new();
+    let mut pos = BTreeSet::new();
+    for i in -(n1 as i32)..=-1 {
+        neg.insert(i);
+    }
+    for i in 1..=(n2 as i32) {
+        pos.insert(i);
+    }
+    [pos, neg]
+}
+
+macro_rules! set_intersection_bench {
+    ($name: ident, $sets: expr) => {
+        #[bench]
+        pub fn $name(b: &mut Bencher) {
+            // setup
+            let sets = $sets;
+
+            // measure
+            b.iter(|| {
+                let x = sets[0].intersection(&sets[1]).count();
+                black_box(x);
+            })
+        }
+    };
+}
+
+set_intersection_bench! {intersect_random_100,          random(100, 100)}
+set_intersection_bench! {intersect_random_10k,          random(10_000, 10_000)}
+set_intersection_bench! {intersect_random_10_vs_10k,    random(10, 10_000)}
+set_intersection_bench! {intersect_random_10k_vs_10,    random(10_000, 10)}
+set_intersection_bench! {intersect_staggered_100,       staggered(100, 100)}
+set_intersection_bench! {intersect_staggered_10k,       staggered(10_000, 10_000)}
+set_intersection_bench! {intersect_staggered_10_vs_10k, staggered(10, 10_000)}
+set_intersection_bench! {intersect_staggered_10k_vs_10, staggered(10_000, 10)}
+set_intersection_bench! {intersect_neg_vs_pos_100,      neg_vs_pos(100, 100)}
+set_intersection_bench! {intersect_neg_vs_pos_10k,      neg_vs_pos(10_000, 10_000)}
+set_intersection_bench! {intersect_neg_vs_pos_10_vs_10k,neg_vs_pos(10, 10_000)}
+set_intersection_bench! {intersect_neg_vs_pos_10k_vs_10,neg_vs_pos(10_000, 10)}
+set_intersection_bench! {intersect_pos_vs_neg_100,      pos_vs_neg(100, 100)}
+set_intersection_bench! {intersect_pos_vs_neg_10k,      pos_vs_neg(10_000, 10_000)}
+set_intersection_bench! {intersect_pos_vs_neg_10_vs_10k,pos_vs_neg(10, 10_000)}
+set_intersection_bench! {intersect_pos_vs_neg_10k_vs_10,pos_vs_neg(10_000, 10)}

src/liballoc/benches/vec_deque.rs

@@ -45,3 +45,10 @@ fn bench_mut_iter_1000(b: &mut Bencher) {
         black_box(sum);
     })
 }
+
+#[bench]
+fn bench_try_fold(b: &mut Bencher) {
+    let ring: VecDeque<_> = (0..1000).collect();
+
+    b.iter(|| black_box(ring.iter().try_fold(0, |a, b| Some(a + b))))
+}

src/liballoc/collections/btree/map.rs

@@ -1634,9 +1634,11 @@ impl<'a, K, V> RangeMut<'a, K, V> {
 
         let mut cur_handle = match handle.right_kv() {
             Ok(kv) => {
-                let (k, v) = ptr::read(&kv).into_kv_mut();
-                self.front = kv.right_edge();
-                return (k, v);
+                self.front = ptr::read(&kv).right_edge();
+                // Doing the descend invalidates the references returned by `into_kv_mut`,
+                // so we have to do this last.
+                let (k, v) = kv.into_kv_mut();
+                return (k, v); // coerce k from `&mut K` to `&K`
             }
             Err(last_edge) => {
                 let next_level = last_edge.into_node().ascend().ok();
@@ -1647,9 +1649,11 @@ impl<'a, K, V> RangeMut<'a, K, V> {
         loop {
             match cur_handle.right_kv() {
                 Ok(kv) => {
-                    let (k, v) = ptr::read(&kv).into_kv_mut();
-                    self.front = first_leaf_edge(kv.right_edge().descend());
-                    return (k, v);
+                    self.front = first_leaf_edge(ptr::read(&kv).right_edge().descend());
+                    // Doing the descend invalidates the references returned by `into_kv_mut`,
+                    // so we have to do this last.
+                    let (k, v) = kv.into_kv_mut();
+                    return (k, v); // coerce k from `&mut K` to `&K`
                 }
                 Err(last_edge) => {
                     let next_level = last_edge.into_node().ascend().ok();
@@ -1680,9 +1684,11 @@ impl<'a, K, V> RangeMut<'a, K, V> {
 
         let mut cur_handle = match handle.left_kv() {
             Ok(kv) => {
-                let (k, v) = ptr::read(&kv).into_kv_mut();
-                self.back = kv.left_edge();
-                return (k, v);
+                self.back = ptr::read(&kv).left_edge();
+                // Doing the descend invalidates the references returned by `into_kv_mut`,
+                // so we have to do this last.
+                let (k, v) = kv.into_kv_mut();
+                return (k, v); // coerce k from `&mut K` to `&K`
             }
             Err(last_edge) => {
                 let next_level = last_edge.into_node().ascend().ok();
@@ -1693,9 +1699,11 @@ impl<'a, K, V> RangeMut<'a, K, V> {
         loop {
             match cur_handle.left_kv() {
                 Ok(kv) => {
-                    let (k, v) = ptr::read(&kv).into_kv_mut();
-                    self.back = last_leaf_edge(kv.left_edge().descend());
-                    return (k, v);
+                    self.back = last_leaf_edge(ptr::read(&kv).left_edge().descend());
+                    // Doing the descend invalidates the references returned by `into_kv_mut`,
+                    // so we have to do this last.
+                    let (k, v) = kv.into_kv_mut();
+                    return (k, v); // coerce k from `&mut K` to `&K`
                 }
                 Err(last_edge) => {
                     let next_level = last_edge.into_node().ascend().ok();

src/liballoc/collections/btree/node.rs

@@ -645,6 +645,8 @@ impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
     }
 
     fn into_key_slice_mut(mut self) -> &'a mut [K] {
+        // Same as for `into_key_slice` above, we try to avoid a run-time check
+        // (the alignment comparison will usually be performed at compile-time).
         if mem::align_of::<K>() > mem::align_of::<LeafNode<(), ()>>() && self.is_shared_root() {
             &mut []
         } else {
@@ -667,9 +669,26 @@ impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
         }
     }
 
-    fn into_slices_mut(self) -> (&'a mut [K], &'a mut [V]) {
-        let k = unsafe { ptr::read(&self) };
-        (k.into_key_slice_mut(), self.into_val_slice_mut())
+    fn into_slices_mut(mut self) -> (&'a mut [K], &'a mut [V]) {
+        debug_assert!(!self.is_shared_root());
+        // We cannot use the getters here, because calling the second one
+        // invalidates the reference returned by the first.
+        // More precisely, it is the call to `len` that is the culprit,
+        // because that creates a shared reference to the header, which *can*
+        // overlap with the keys (and even the values, for ZST keys).
+        unsafe {
+            let len = self.len();
+            let leaf = self.as_leaf_mut();
+            let keys = slice::from_raw_parts_mut(
+                MaybeUninit::first_ptr_mut(&mut (*leaf).keys),
+                len
+            );
+            let vals = slice::from_raw_parts_mut(
+                MaybeUninit::first_ptr_mut(&mut (*leaf).vals),
+                len
+            );
+            (keys, vals)
+        }
     }
 }
 

src/liballoc/collections/vec_deque.rs

@@ -2170,12 +2170,29 @@ impl<'a, T> Iterator for Iter<'a, T> {
         back.iter().fold(accum, &mut f)
     }
 
-    fn try_fold<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_fold<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 (front, back) = RingSlices::ring_slices(self.ring, self.head, self.tail);
-        let accum = front.iter().try_fold(init, &mut f)?;
-        back.iter().try_fold(accum, &mut f)
+        let (mut iter, final_res);
+        if self.tail <= self.head {
+            // single slice self.ring[self.tail..self.head]
+            iter = self.ring[self.tail..self.head].iter();
+            final_res = iter.try_fold(init, &mut f);
+        } else {
+            // two slices: self.ring[self.tail..], self.ring[..self.head]
+            let (front, back) = self.ring.split_at(self.tail);
+            let mut back_iter = back.iter();
+            let res = back_iter.try_fold(init, &mut f);
+            let len = self.ring.len();
+            self.tail = (self.ring.len() - back_iter.len()) & (len - 1);
+            iter = front[..self.head].iter();
+            final_res = iter.try_fold(res?, &mut f);
+        }
+        self.tail = self.head - iter.len();
+        final_res
     }
 }
 
@@ -2197,6 +2214,30 @@ impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
         accum = back.iter().rfold(accum, &mut f);
         front.iter().rfold(accum, &mut f)
     }
+
+    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 iter, final_res);
+        if self.tail <= self.head {
+            // single slice self.ring[self.tail..self.head]
+            iter = self.ring[self.tail..self.head].iter();
+            final_res = iter.try_rfold(init, &mut f);
+        } else {
+            // two slices: self.ring[self.tail..], self.ring[..self.head]
+            let (front, back) = self.ring.split_at(self.tail);
+            let mut front_iter = front[..self.head].iter();
+            let res = front_iter.try_rfold(init, &mut f);
+            self.head = front_iter.len();
+            iter = back.iter();
+            final_res = iter.try_rfold(res?, &mut f);
+        }
+        self.head = self.tail + iter.len();
+        final_res
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

src/liballoc/tests/vec_deque.rs

@@ -1465,6 +1465,15 @@ fn test_try_fold_unit() {
     assert_eq!(Some(()), v.into_iter().try_fold((), |(), ()| Some(())));
 }
 
+
+#[test]
+fn test_try_fold_unit_none() {
+    let v: std::collections::VecDeque<()> = [(); 10].iter().cloned().collect();
+    let mut iter = v.into_iter();
+    assert!(iter.try_fold((), |_, _| None).is_none());
+    assert_eq!(iter.len(), 9);
+}
+
 #[test]
 fn test_try_fold_rotated() {
     let mut v: VecDeque<_> = (0..12).collect();
@@ -1477,3 +1486,58 @@ fn test_try_fold_rotated() {
         assert_eq!(Ok::<_, ()>(66), v.iter().try_fold(0, |a, b| Ok(a + b)));
     }
 }
+
+#[test]
+fn test_try_fold_moves_iter() {
+    let v: VecDeque<_> = [10, 20, 30, 40, 100, 60, 70, 80, 90].iter().collect();
+    let mut iter = v.into_iter();
+    assert_eq!(iter.try_fold(0_i8, |acc, &x| acc.checked_add(x)), None);
+    assert_eq!(iter.next(), Some(&60));
+}
+
+#[test]
+fn test_try_fold_exhaust_wrap() {
+    let mut v = VecDeque::with_capacity(7);
+    v.push_back(1);
+    v.push_back(1);
+    v.push_back(1);
+    v.pop_front();
+    v.pop_front();
+    let mut iter = v.iter();
+    let _ = iter.try_fold(0, |_, _| Some(1));
+    assert!(iter.is_empty());
+}
+
+#[test]
+fn test_try_fold_wraparound() {
+    let mut v = VecDeque::with_capacity(8);
+    v.push_back(7);
+    v.push_back(8);
+    v.push_back(9);
+    v.push_front(2);
+    v.push_front(1);
+    let mut iter = v.iter();
+    let _ = iter.find(|&&x| x == 2);
+    assert_eq!(Some(&7), iter.next());
+}
+
+#[test]
+fn test_try_rfold_rotated() {
+    let mut v: VecDeque<_> = (0..12).collect();
+    for n in 0..10 {
+        if n & 1 == 0 {
+            v.rotate_left(n);
+        } else {
+            v.rotate_right(n);
+        }
+        assert_eq!(Ok::<_, ()>(66), v.iter().try_rfold(0, |a, b| Ok(a + b)));
+    }
+}
+
+#[test]
+fn test_try_rfold_moves_iter() {
+    let v : VecDeque<_> = [10, 20, 30, 40, 100, 60, 70, 80, 90].iter().collect();
+    let mut iter = v.into_iter();
+    assert_eq!(iter.try_rfold(0_i8, |acc, &x| acc.checked_add(x)), None);
+    assert_eq!(iter.next_back(), Some(&70));
+}