Auto merge of #81113 - m-ou-se:rollup-a1unz4x, r=m-ou-se

Rollup of 13 pull requests

Successful merges:

 - #79298 (correctly deal with late-bound lifetimes in anon consts)
 - #80031 (resolve: Reject ambiguity built-in attr vs different built-in attr)
 - #80201 (Add benchmark and fast path for BufReader::read_exact)
 - #80635 (Improve diagnostics when closure doesn't meet trait bound)
 - #80765 (resolve: Simplify collection of traits in scope)
 - #80932 (Allow downloading LLVM on Windows and MacOS)
 - #80983 (Remove is_dllimport_foreign_item definition from cg_ssa)
 - #81064 (Support non-stage0 check)
 - #81080 (Force vec![] to expression position only)
 - #81082 (BTreeMap: clean up a few more comments)
 - #81084 (Use Option::map instead of open-coding it)
 - #81095 (Use Option::unwrap_or instead of open-coding it)
 - #81107 (Add NonZeroUn::is_power_of_two)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

4 files changed, 20 insertions, 10 deletions

diff --git a/library/alloc/src/collections/btree/node.rs b/library/alloc/src/collections/btree/node.rs
index 220c98b294c..928c6f9a3a8 100644
--- a/library/alloc/src/collections/btree/node.rs
+++ b/library/alloc/src/collections/btree/node.rs
@@ -184,7 +184,7 @@ impl<K, V> NodeRef<marker::Owned, K, V, marker::LeafOrInternal> {
 
     /// Removes the internal root node, using its first child as the new root node.
     /// As it is intended only to be called when the root node has only one child,
-    /// no cleanup is done on any of the other children.
+    /// 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;
@@ -225,7 +225,7 @@ impl<K, V> NodeRef<marker::Owned, K, V, marker::LeafOrInternal> {
 ///    - When this is `Owned`, the `NodeRef` acts roughly like `Box<Node>`,
 ///      but does not have a destructor, and must be cleaned up manually.
 ///   Since any `NodeRef` allows navigating through the tree, `BorrowType`
-///   effectively applies to the entire tree, not just the node itself.
+///   effectively applies to the entire tree, not just to the node itself.
 /// - `K` and `V`: These are the types of keys and values stored in the nodes.
 /// - `Type`: This can be `Leaf`, `Internal`, or `LeafOrInternal`. When this is
 ///   `Leaf`, the `NodeRef` points to a leaf node, when this is `Internal` the
@@ -425,7 +425,7 @@ impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Immut<'a>, K, V, Type> {
 
 impl<K, V> NodeRef<marker::Owned, K, V, marker::LeafOrInternal> {
     /// Similar to `ascend`, gets a reference to a node's parent node, but also
-    /// deallocate the current node in the process. This is unsafe because the
+    /// deallocates the current node in the process. This is unsafe because the
     /// current node will still be accessible despite being deallocated.
     pub unsafe fn deallocate_and_ascend(
         self,
@@ -661,7 +661,10 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
     /// Removes a key-value pair from the end of the node and returns the pair.
     /// Also removes the edge that was to the right of that pair and, if the node
     /// is internal, returns the orphaned subtree that this edge owned.
-    fn pop(&mut self) -> (K, V, Option<Root<K, V>>) {
+    ///
+    /// # Safety
+    /// The node must not be empty.
+    unsafe fn pop(&mut self) -> (K, V, Option<Root<K, V>>) {
         debug_assert!(self.len() > 0);
 
         let idx = self.len() - 1;
diff --git a/library/alloc/src/collections/btree/search.rs b/library/alloc/src/collections/btree/search.rs
index ed7f95fe632..efe94ef175c 100644
--- a/library/alloc/src/collections/btree/search.rs
+++ b/library/alloc/src/collections/btree/search.rs
@@ -12,8 +12,7 @@ pub enum SearchResult<BorrowType, K, V, FoundType, GoDownType> {
 
 /// Looks up a given key in a (sub)tree headed by the given node, recursively.
 /// Returns a `Found` with the handle of the matching KV, if any. Otherwise,
-/// returns a `GoDown` with the handle of the possible leaf edge where the key
-/// belongs.
+/// returns a `GoDown` with the handle of the leaf edge where the key belongs.
 ///
 /// The result is meaningful only if the tree is ordered by key, like the tree
 /// in a `BTreeMap` is.
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index d0bfa038aa1..14a10aac061 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -140,6 +140,7 @@
 #![feature(type_alias_impl_trait)]
 #![feature(associated_type_bounds)]
 #![feature(slice_group_by)]
+#![feature(decl_macro)]
 // Allow testing this library
 
 #[cfg(test)]
@@ -193,4 +194,11 @@ mod std {
 #[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
 pub mod __export {
     pub use core::format_args;
+
+    /// Force AST node to an expression to improve diagnostics in pattern position.
+    #[rustc_macro_transparency = "semitransparent"]
+    #[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
+    pub macro force_expr($e:expr) {
+        $e
+    }
 }
diff --git a/library/alloc/src/macros.rs b/library/alloc/src/macros.rs
index 7d4eff6185d..3a46763c3f6 100644
--- a/library/alloc/src/macros.rs
+++ b/library/alloc/src/macros.rs
@@ -37,16 +37,16 @@
 #[cfg(not(test))]
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable(box_syntax)]
+#[allow_internal_unstable(box_syntax, liballoc_internals)]
 macro_rules! vec {
     () => (
-        $crate::vec::Vec::new()
+        $crate::__export::force_expr!($crate::vec::Vec::new())
     );
     ($elem:expr; $n:expr) => (
-        $crate::vec::from_elem($elem, $n)
+        $crate::__export::force_expr!($crate::vec::from_elem($elem, $n))
     );
     ($($x:expr),+ $(,)?) => (
-        <[_]>::into_vec(box [$($x),+])
+        $crate::__export::force_expr!(<[_]>::into_vec(box [$($x),+]))
     );
 }