Rollup of 12 pull requests

.gitignore

@@ -31,6 +31,7 @@ __pycache__/
 /inst/
 /llvm/
 /mingw-build/
+/src/tools/x/target
 # Created by default with `src/ci/docker/run.sh`:
 /obj/
 /unicode-downloads

Cargo.toml

@@ -29,11 +29,17 @@ members = [
   "src/tools/unicode-table-generator",
   "src/tools/expand-yaml-anchors",
 ]
+
 exclude = [
   "build",
   "compiler/rustc_codegen_cranelift",
   # HACK(eddyb) This hardcodes the fact that our CI uses `/checkout/obj`.
   "obj",
+  # The `x` binary is a thin wrapper that calls `x.py`, which initializes
+  # submodules, before which workspace members cannot be invoked because
+  # not all `Cargo.toml` files are available, so we exclude the `x` binary,
+  # so it can be invoked before the current checkout is set up.
+  "src/tools/x",
 ]
 
 [profile.release.package.compiler_builtins]

compiler/rustc_lint_defs/src/builtin.rs

@@ -2801,6 +2801,7 @@ declare_lint_pass! {
         UNSTABLE_NAME_COLLISIONS,
         IRREFUTABLE_LET_PATTERNS,
         BROKEN_INTRA_DOC_LINKS,
+        PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
         MISSING_CRATE_LEVEL_DOCS,
         MISSING_DOC_CODE_EXAMPLES,

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

@@ -42,7 +42,7 @@ fn test_all_refs<'a, T: 'a>(dummy: &mut T, iter: impl Iterator<Item = &'a mut T>
     }
 }
 
-impl<'a, K: 'a, V: 'a> BTreeMap<K, V> {
+impl<K, V> BTreeMap<K, V> {
     /// Panics if the map (or the code navigating it) is corrupted.
     fn check(&self)
     where
@@ -54,14 +54,14 @@ impl<'a, K: 'a, V: 'a> BTreeMap<K, V> {
             assert!(root_node.ascend().is_err());
             root_node.assert_back_pointers();
 
-            let counted = root_node.assert_ascending();
-            assert_eq!(self.length, counted);
             assert_eq!(self.length, root_node.calc_length());
 
             root_node.assert_min_len(if root_node.height() > 0 { 1 } else { 0 });
         } else {
             assert_eq!(self.length, 0);
         }
+
+        self.assert_ascending();
     }
 
     /// Returns the height of the root, if any.
@@ -79,10 +79,28 @@ impl<'a, K: 'a, V: 'a> BTreeMap<K, V> {
             String::from("not yet allocated")
         }
     }
+
+    /// Asserts that the keys are in strictly ascending order.
+    fn assert_ascending(&self)
+    where
+        K: Copy + Debug + Ord,
+    {
+        let mut num_seen = 0;
+        let mut keys = self.keys();
+        if let Some(mut previous) = keys.next() {
+            num_seen = 1;
+            for next in keys {
+                assert!(previous < next, "{:?} >= {:?}", previous, next);
+                previous = next;
+                num_seen += 1;
+            }
+        }
+        assert_eq!(num_seen, self.len());
+    }
 }
 
 impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal> {
-    pub fn assert_min_len(self, min_len: usize) {
+    fn assert_min_len(self, min_len: usize) {
         assert!(self.len() >= min_len, "{} < {}", self.len(), min_len);
         if let node::ForceResult::Internal(node) = self.force() {
             for idx in 0..=node.len() {

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

@@ -1608,15 +1608,19 @@ pub mod marker {
 
 unsafe fn slice_insert<T>(slice: &mut [T], idx: usize, val: T) {
     unsafe {
-        ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
-        ptr::write(slice.get_unchecked_mut(idx), val);
+        let len = slice.len();
+        let slice_ptr = slice.as_mut_ptr();
+        ptr::copy(slice_ptr.add(idx), slice_ptr.add(idx + 1), len - idx);
+        ptr::write(slice_ptr.add(idx), val);
     }
 }
 
 unsafe fn slice_remove<T>(slice: &mut [T], idx: usize) -> T {
     unsafe {
-        let ret = ptr::read(slice.get_unchecked(idx));
-        ptr::copy(slice.as_ptr().add(idx + 1), slice.as_mut_ptr().add(idx), slice.len() - idx - 1);
+        let len = slice.len();
+        let slice_ptr = slice.as_mut_ptr();
+        let ret = ptr::read(slice_ptr.add(idx));
+        ptr::copy(slice_ptr.add(idx + 1), slice_ptr.add(idx), len - idx - 1);
         ret
     }
 }

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

@@ -17,43 +17,6 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal>
         }
     }
 
-    /// Asserts that the keys are in strictly ascending order.
-    /// Returns how many keys it encountered.
-    pub fn assert_ascending(self) -> usize
-    where
-        K: Copy + Debug + Ord,
-    {
-        struct SeriesChecker<T> {
-            num_seen: usize,
-            previous: Option<T>,
-        }
-        impl<T: Copy + Debug + Ord> SeriesChecker<T> {
-            fn is_ascending(&mut self, next: T) {
-                if let Some(previous) = self.previous {
-                    assert!(previous < next, "{:?} >= {:?}", previous, next);
-                }
-                self.previous = Some(next);
-                self.num_seen += 1;
-            }
-        }
-
-        let mut checker = SeriesChecker { num_seen: 0, previous: None };
-        self.visit_nodes_in_order(|pos| match pos {
-            navigate::Position::Leaf(node) => {
-                for idx in 0..node.len() {
-                    let key = *unsafe { node.key_at(idx) };
-                    checker.is_ascending(key);
-                }
-            }
-            navigate::Position::InternalKV(kv) => {
-                let key = *kv.into_kv().0;
-                checker.is_ascending(key);
-            }
-            navigate::Position::Internal(_) => {}
-        });
-        checker.num_seen
-    }
-
     pub fn dump_keys(self) -> String
     where
         K: Debug,

library/alloc/src/lib.rs

@@ -119,7 +119,6 @@
 #![feature(raw_ref_op)]
 #![feature(rustc_attrs)]
 #![feature(receiver_trait)]
-#![feature(renamed_spin_loop)]
 #![feature(min_specialization)]
 #![feature(slice_ptr_get)]
 #![feature(slice_ptr_len)]

library/core/src/cell.rs

@@ -406,7 +406,8 @@ impl<T> Cell<T> {
     /// assert_eq!(five, 5);
     /// ```
     #[stable(feature = "move_cell", since = "1.17.0")]
-    pub fn into_inner(self) -> T {
+    #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
+    pub const fn into_inner(self) -> T {
         self.value.into_inner()
     }
 }
@@ -668,12 +669,11 @@ impl<T> RefCell<T> {
     /// let five = c.into_inner();
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
     #[inline]
-    pub fn into_inner(self) -> T {
+    pub const fn into_inner(self) -> T {
         // Since this function takes `self` (the `RefCell`) by value, the
         // compiler statically verifies that it is not currently borrowed.
-        // Therefore the following assertion is just a `debug_assert!`.
-        debug_assert!(self.borrow.get() == UNUSED);
         self.value.into_inner()
     }
 
@@ -1682,7 +1682,8 @@ impl<T> UnsafeCell<T> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn into_inner(self) -> T {
+    #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
+    pub const fn into_inner(self) -> T {
         self.value
     }
 }

library/core/src/hint.rs

@@ -1,6 +1,7 @@
 #![stable(feature = "core_hint", since = "1.27.0")]
 
 //! Hints to compiler that affects how code should be emitted or optimized.
+//! Hints may be compile time or runtime.
 
 use crate::intrinsics;
 
@@ -24,7 +25,6 @@ use crate::intrinsics;
 /// Otherwise, consider using the [`unreachable!`] macro, which does not allow
 /// optimizations but will panic when executed.
 ///
-///
 /// # Example
 ///
 /// ```
@@ -51,18 +51,62 @@ pub const unsafe fn unreachable_unchecked() -> ! {
     unsafe { intrinsics::unreachable() }
 }
 
-/// Emits a machine instruction hinting to the processor that it is running in busy-wait
-/// spin-loop ("spin lock").
+/// Emits a machine instruction to signal the processor that it is running in
+/// a busy-wait spin-loop ("spin lock").
+///
+/// Upon receiving the spin-loop signal the processor can optimize its behavior by,
+/// for example, saving power or switching hyper-threads.
+///
+/// This function is different from [`thread::yield_now`] which directly
+/// yields to the system's scheduler, whereas `spin_loop` does not interact
+/// with the operating system.
+///
+/// A common use case for `spin_loop` is implementing bounded optimistic
+/// spinning in a CAS loop in synchronization primitives. To avoid problems
+/// like priority inversion, it is strongly recommended that the spin loop is
+/// terminated after a finite amount of iterations and an appropriate blocking
+/// syscall is made.
+///
+/// **Note**: On platforms that do not support receiving spin-loop hints this
+/// function does not do anything at all.
+///
+/// # Examples
 ///
-/// For a discussion of different locking strategies and their trade-offs, see
-/// [`core::sync::atomic::spin_loop_hint`].
+/// ```
+/// use std::sync::atomic::{AtomicBool, Ordering};
+/// use std::sync::Arc;
+/// use std::{hint, thread};
+///
+/// // A shared atomic value that threads will use to coordinate
+/// let live = Arc::new(AtomicBool::new(false));
+///
+/// // In a background thread we'll eventually set the value
+/// let bg_work = {
+///     let live = live.clone();
+///     thread::spawn(move || {
+///         // Do some work, then make the value live
+///         do_some_work();
+///         live.store(true, Ordering::Release);
+///     })
+/// };
 ///
-/// **Note**: On platforms that do not support receiving spin-loop hints this function does not
-/// do anything at all.
+/// // Back on our current thread, we wait for the value to be set
+/// while live.load(Ordering::Acquire) {
+///     // The spin loop is a hint to the CPU that we're waiting, but probably
+///     // not for very long
+///     hint::spin_loop();
+/// }
+///
+/// // The value is now set
+/// # fn do_some_work() {}
+/// do_some_work();
+/// bg_work.join()?;
+/// # Ok::<(), Box<dyn core::any::Any + Send + 'static>>(())
+/// ```
 ///
-/// [`core::sync::atomic::spin_loop_hint`]: crate::sync::atomic::spin_loop_hint
+/// [`thread::yield_now`]: ../../std/thread/fn.yield_now.html
 #[inline]
-#[unstable(feature = "renamed_spin_loop", issue = "55002")]
+#[stable(feature = "renamed_spin_loop", since = "1.49.0")]
 pub fn spin_loop() {
     #[cfg(all(any(target_arch = "x86", target_arch = "x86_64"), target_feature = "sse2"))]
     {

library/core/src/lib.rs

@@ -70,6 +70,7 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(const_alloc_layout)]
 #![feature(const_discriminant)]
+#![feature(const_cell_into_inner)]
 #![feature(const_checked_int_methods)]
 #![feature(const_euclidean_int_methods)]
 #![feature(const_float_classify)]

library/core/src/sync/atomic.rs

@@ -115,23 +115,13 @@ use crate::hint::spin_loop;
 
 /// Signals the processor that it is inside a busy-wait spin-loop ("spin lock").
 ///
-/// Upon receiving spin-loop signal the processor can optimize its behavior by, for example, saving
-/// power or switching hyper-threads.
-///
-/// This function is different from [`std::thread::yield_now`] which directly yields to the
-/// system's scheduler, whereas `spin_loop_hint` does not interact with the operating system.
-///
-/// A common use case for `spin_loop_hint` is implementing bounded optimistic spinning in a CAS
-/// loop in synchronization primitives. To avoid problems like priority inversion, it is strongly
-/// recommended that the spin loop is terminated after a finite amount of iterations and an
-/// appropriate blocking syscall is made.
+/// This function is expected to be deprecated in favor of
+/// [`hint::spin_loop`].
 ///
 /// **Note**: On platforms that do not support receiving spin-loop hints this function does not
 /// do anything at all.
 ///
-/// [`std::thread::yield_now`]: ../../../std/thread/fn.yield_now.html
-/// [`std::thread::sleep`]: ../../../std/thread/fn.sleep.html
-/// [`std::sync::Mutex`]: ../../../std/sync/struct.Mutex.html
+/// [`hint::spin_loop`]: crate::hint::spin_loop
 #[inline]
 #[stable(feature = "spin_loop_hint", since = "1.24.0")]
 pub fn spin_loop_hint() {
@@ -365,7 +355,8 @@ impl AtomicBool {
     /// ```
     #[inline]
     #[stable(feature = "atomic_access", since = "1.15.0")]
-    pub fn into_inner(self) -> bool {
+    #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
+    pub const fn into_inner(self) -> bool {
         self.v.into_inner() != 0
     }
 
@@ -941,7 +932,8 @@ impl<T> AtomicPtr<T> {
     /// ```
     #[inline]
     #[stable(feature = "atomic_access", since = "1.15.0")]
-    pub fn into_inner(self) -> *mut T {
+    #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
+    pub const fn into_inner(self) -> *mut T {
         self.p.into_inner()
     }
 
@@ -1462,7 +1454,8 @@ assert_eq!(some_var.into_inner(), 5);
 ```"),
                 #[inline]
                 #[$stable_access]
-                pub fn into_inner(self) -> $int_type {
+                #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
+                pub const fn into_inner(self) -> $int_type {
                     self.v.into_inner()
                 }
             }

library/core/src/task/poll.rs

@@ -39,15 +39,17 @@ impl<T> Poll<T> {
 
     /// Returns `true` if this is `Poll::Ready`
     #[inline]
+    #[rustc_const_stable(feature = "const_poll", since = "1.49.0")]
     #[stable(feature = "futures_api", since = "1.36.0")]
-    pub fn is_ready(&self) -> bool {
+    pub const fn is_ready(&self) -> bool {
         matches!(*self, Poll::Ready(_))
     }
 
     /// Returns `true` if this is `Poll::Pending`
     #[inline]
+    #[rustc_const_stable(feature = "const_poll", since = "1.49.0")]
     #[stable(feature = "futures_api", since = "1.36.0")]
-    pub fn is_pending(&self) -> bool {
+    pub const fn is_pending(&self) -> bool {
         !self.is_ready()
     }
 }

library/core/tests/cell.rs

@@ -422,3 +422,15 @@ fn refcell_format() {
     let msg = format!("{name} {}", &*what.borrow(), name = &*name.borrow());
     assert_eq!(msg, "rust rocks".to_string());
 }
+
+#[allow(dead_code)]
+fn const_cells() {
+    const UNSAFE_CELL: UnsafeCell<i32> = UnsafeCell::new(3);
+    const _: i32 = UNSAFE_CELL.into_inner();
+
+    const REF_CELL: RefCell<i32> = RefCell::new(3);
+    const _: i32 = REF_CELL.into_inner();
+
+    const CELL: Cell<i32> = Cell::new(3);
+    const _: i32 = CELL.into_inner();
+}