Rollup of 5 pull requests

compiler/rustc_ast_lowering/src/index.rs

@@ -192,9 +192,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     }
 
     fn visit_pat(&mut self, pat: &'hir Pat<'hir>) {
-        let node =
-            if let PatKind::Binding(..) = pat.kind { Node::Binding(pat) } else { Node::Pat(pat) };
-        self.insert(pat.span, pat.hir_id, node);
+        self.insert(pat.span, pat.hir_id, Node::Pat(pat));
 
         self.with_parent(pat.hir_id, |this| {
             intravisit::walk_pat(this, pat);

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -362,7 +362,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
                 let upvar_hir_id = captured_place.get_root_variable();
 
-                if let Some(Node::Binding(pat)) = self.infcx.tcx.hir().find(upvar_hir_id)
+                if let Some(Node::Pat(pat)) = self.infcx.tcx.hir().find(upvar_hir_id)
                     && let hir::PatKind::Binding(
                         hir::BindingAnnotation::Unannotated,
                         _,

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -244,7 +244,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                         // for a generator).
                         let var_hir_id = captured_place.get_root_variable();
                         let node = self.ecx.tcx.hir().get(var_hir_id);
-                        if let hir::Node::Binding(pat) = node {
+                        if let hir::Node::Pat(pat) = node {
                             if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
                                 name = Some(ident.name);
                             }

compiler/rustc_errors/src/lib.rs

@@ -1447,7 +1447,7 @@ impl HandlerInner {
                 self.flags.treat_err_as_bug.map(|c| c.get()).unwrap_or(0),
             ) {
                 (1, 1) => panic!("aborting due to `-Z treat-err-as-bug=1`"),
-                (0, _) | (1, _) => {}
+                (0 | 1, _) => {}
                 (count, as_bug) => panic!(
                     "aborting after {} errors due to `-Z treat-err-as-bug={}`",
                     count, as_bug,

compiler/rustc_hir/src/hir.rs

@@ -3326,7 +3326,6 @@ pub enum Node<'hir> {
     Ty(&'hir Ty<'hir>),
     TypeBinding(&'hir TypeBinding<'hir>),
     TraitRef(&'hir TraitRef<'hir>),
-    Binding(&'hir Pat<'hir>),
     Pat(&'hir Pat<'hir>),
     Arm(&'hir Arm<'hir>),
     Block(&'hir Block<'hir>),
@@ -3378,7 +3377,6 @@ impl<'hir> Node<'hir> {
             | Node::Block(..)
             | Node::Ctor(..)
             | Node::Pat(..)
-            | Node::Binding(..)
             | Node::Arm(..)
             | Node::Local(..)
             | Node::Crate(..)

compiler/rustc_hir_pretty/src/lib.rs

@@ -87,7 +87,7 @@ impl<'a> State<'a> {
             Node::Ty(a) => self.print_type(&a),
             Node::TypeBinding(a) => self.print_type_binding(&a),
             Node::TraitRef(a) => self.print_trait_ref(&a),
-            Node::Binding(a) | Node::Pat(a) => self.print_pat(&a),
+            Node::Pat(a) => self.print_pat(&a),
             Node::Arm(a) => self.print_arm(&a),
             Node::Infer(_) => self.word("_"),
             Node::Block(a) => {

compiler/rustc_middle/src/hir/map/mod.rs

@@ -302,7 +302,6 @@ impl<'hir> Map<'hir> {
             | Node::Infer(_)
             | Node::TraitRef(_)
             | Node::Pat(_)
-            | Node::Binding(_)
             | Node::Local(_)
             | Node::Param(_)
             | Node::Arm(_)
@@ -901,7 +900,7 @@ impl<'hir> Map<'hir> {
     #[inline]
     fn opt_ident(self, id: HirId) -> Option<Ident> {
         match self.get(id) {
-            Node::Binding(&Pat { kind: PatKind::Binding(_, _, ident, _), .. }) => Some(ident),
+            Node::Pat(&Pat { kind: PatKind::Binding(_, _, ident, _), .. }) => Some(ident),
             // A `Ctor` doesn't have an identifier itself, but its parent
             // struct/variant does. Compare with `hir::Map::opt_span`.
             Node::Ctor(..) => match self.find(self.get_parent_node(id))? {
@@ -969,7 +968,6 @@ impl<'hir> Map<'hir> {
             Node::Ty(ty) => ty.span,
             Node::TypeBinding(tb) => tb.span,
             Node::TraitRef(tr) => tr.path.span,
-            Node::Binding(pat) => pat.span,
             Node::Pat(pat) => pat.span,
             Node::Arm(arm) => arm.span,
             Node::Block(block) => block.span,
@@ -1203,7 +1201,6 @@ fn hir_id_to_string(map: Map<'_>, id: HirId) -> String {
         Some(Node::Ty(_)) => node_str("type"),
         Some(Node::TypeBinding(_)) => node_str("type binding"),
         Some(Node::TraitRef(_)) => node_str("trait ref"),
-        Some(Node::Binding(_)) => node_str("local"),
         Some(Node::Pat(_)) => node_str("pat"),
         Some(Node::Param(_)) => node_str("param"),
         Some(Node::Arm(_)) => node_str("arm"),

compiler/rustc_mir_build/src/build/mod.rs

@@ -997,7 +997,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 continue;
             };
             let pat = match tcx.hir().get(arg.pat.hir_id) {
-                Node::Pat(pat) | Node::Binding(pat) => pat,
+                Node::Pat(pat) => pat,
                 node => bug!("pattern became {:?}", node),
             };
             let pattern = pat_from_hir(tcx, self.param_env, self.typeck_results, pat);

compiler/rustc_mir_build/src/thir/cx/mod.rs

@@ -101,7 +101,7 @@ impl<'tcx> Cx<'tcx> {
     #[tracing::instrument(level = "debug", skip(self))]
     pub(crate) fn pattern_from_hir(&mut self, p: &hir::Pat<'_>) -> Pat<'tcx> {
         let p = match self.tcx.hir().get(p.hir_id) {
-            Node::Pat(p) | Node::Binding(p) => p,
+            Node::Pat(p) => p,
             node => bug!("pattern became {:?}", node),
         };
         pat_from_hir(self.tcx, self.param_env, self.typeck_results(), p)

compiler/rustc_save_analysis/src/lib.rs

@@ -623,9 +623,9 @@ impl<'tcx> SaveContext<'tcx> {
                 }
             },
 
-            Node::Binding(&hir::Pat {
-                kind: hir::PatKind::Binding(_, canonical_id, ..), ..
-            }) => Res::Local(canonical_id),
+            Node::Pat(&hir::Pat { kind: hir::PatKind::Binding(_, canonical_id, ..), .. }) => {
+                Res::Local(canonical_id)
+            }
 
             _ => Res::Err,
         }

compiler/rustc_typeck/src/check/demand.rs

@@ -223,7 +223,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         None,
                         hir::Path { res: hir::def::Res::Local(hir_id), .. },
                     )) => {
-                        if let Some(hir::Node::Binding(pat)) = self.tcx.hir().find(*hir_id) {
+                        if let Some(hir::Node::Pat(pat)) = self.tcx.hir().find(*hir_id) {
                             let parent = self.tcx.hir().get_parent_node(pat.hir_id);
                             primary_span = pat.span;
                             secondary_span = pat.span;

compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs

@@ -251,7 +251,6 @@ impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> {
                 | hir::Node::Ty(..)
                 | hir::Node::TypeBinding(..)
                 | hir::Node::TraitRef(..)
-                | hir::Node::Binding(..)
                 | hir::Node::Pat(..)
                 | hir::Node::Arm(..)
                 | hir::Node::Local(..)

library/core/src/sync/exclusive.rs

@@ -0,0 +1,173 @@
+//! Defines [`Exclusive`].
+
+use core::fmt;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+/// `Exclusive` provides only _mutable_ access, also referred to as _exclusive_
+/// access to the underlying value. It provides no _immutable_, or _shared_
+/// access to the underlying value.
+///
+/// While this may seem not very useful, it allows `Exclusive` to _unconditionally_
+/// implement [`Sync`]. Indeed, the safety requirements of `Sync` state that for `Exclusive`
+/// to be `Sync`, it must be sound to _share_ across threads, that is, it must be sound
+/// for `&Exclusive` to cross thread boundaries. By design, a `&Exclusive` has no API
+/// whatsoever, making it useless, thus harmless, thus memory safe.
+///
+/// Certain constructs like [`Future`]s can only be used with _exclusive_ access,
+/// and are often `Send` but not `Sync`, so `Exclusive` can be used as hint to the
+/// rust compiler that something is `Sync` in practice.
+///
+/// ## Examples
+/// Using a non-`Sync` future prevents the wrapping struct from being `Sync`
+/// ```compile_fail
+/// use core::cell::Cell;
+///
+/// async fn other() {}
+/// fn assert_sync<T: Sync>(t: T) {}
+/// struct State<F> {
+///     future: F
+/// }
+///
+/// assert_sync(State {
+///     future: async {
+///         let cell = Cell::new(1);
+///         let cell_ref = &cell;
+///         other().await;
+///         let value = cell_ref.get();
+///     }
+/// });
+/// ```
+///
+/// `Exclusive` ensures the struct is `Sync` without stripping the future of its
+/// functionality.
+/// ```
+/// #![feature(exclusive_wrapper)]
+/// use core::cell::Cell;
+/// use core::sync::Exclusive;
+///
+/// async fn other() {}
+/// fn assert_sync<T: Sync>(t: T) {}
+/// struct State<F> {
+///     future: Exclusive<F>
+/// }
+///
+/// assert_sync(State {
+///     future: Exclusive::new(async {
+///         let cell = Cell::new(1);
+///         let cell_ref = &cell;
+///         other().await;
+///         let value = cell_ref.get();
+///     })
+/// });
+/// ```
+///
+/// ## Parallels with a mutex
+/// In some sense, `Exclusive` can be thought of as a _compile-time_ version of
+/// a mutex, as the borrow-checker guarantees that only one `&mut` can exist
+/// for any value. This is a parallel with the fact that
+/// `&` and `&mut` references together can be thought of as a _compile-time_
+/// version of a read-write lock.
+///
+///
+/// [`Sync`]: core::marker::Sync
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+#[doc(alias = "SyncWrapper")]
+#[doc(alias = "SyncCell")]
+#[doc(alias = "Unique")]
+// `Exclusive` can't have `PartialOrd`, `Clone`, etc. impls as they would
+// use `&` access to the inner value, violating the `Sync` impl's safety
+// requirements.
+#[derive(Default)]
+#[repr(transparent)]
+pub struct Exclusive<T: ?Sized> {
+    inner: T,
+}
+
+// See `Exclusive`'s docs for justification.
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+unsafe impl<T: ?Sized> Sync for Exclusive<T> {}
+
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+impl<T: ?Sized> fmt::Debug for Exclusive<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        f.debug_struct("Exclusive").finish_non_exhaustive()
+    }
+}
+
+impl<T: Sized> Exclusive<T> {
+    /// Wrap a value in an `Exclusive`
+    #[unstable(feature = "exclusive_wrapper", issue = "98407")]
+    #[must_use]
+    pub const fn new(t: T) -> Self {
+        Self { inner: t }
+    }
+
+    /// Unwrap the value contained in the `Exclusive`
+    #[unstable(feature = "exclusive_wrapper", issue = "98407")]
+    #[must_use]
+    pub const fn into_inner(self) -> T {
+        self.inner
+    }
+}
+
+impl<T: ?Sized> Exclusive<T> {
+    /// Get exclusive access to the underlying value.
+    #[unstable(feature = "exclusive_wrapper", issue = "98407")]
+    #[must_use]
+    pub const fn get_mut(&mut self) -> &mut T {
+        &mut self.inner
+    }
+
+    /// Get pinned exclusive access to the underlying value.
+    ///
+    /// `Exclusive` is considered to _structurally pin_ the underlying
+    /// value, which means _unpinned_ `Exclusive`s can produce _unpinned_
+    /// access to the underlying value, but _pinned_ `Exclusive`s only
+    /// produce _pinned_ access to the underlying value.
+    #[unstable(feature = "exclusive_wrapper", issue = "98407")]
+    #[must_use]
+    pub const fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
+        // SAFETY: `Exclusive` can only produce `&mut T` if itself is unpinned
+        // `Pin::map_unchecked_mut` is not const, so we do this conversion manually
+        unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().inner) }
+    }
+
+    /// Build a _mutable_ references to an `Exclusive<T>` from
+    /// a _mutable_ reference to a `T`. This allows you to skip
+    /// building an `Exclusive` with [`Exclusive::new`].
+    #[unstable(feature = "exclusive_wrapper", issue = "98407")]
+    #[must_use]
+    pub const fn from_mut(r: &'_ mut T) -> &'_ mut Exclusive<T> {
+        // SAFETY: repr is ≥ C, so refs have the same layout; and `Exclusive` properties are `&mut`-agnostic
+        unsafe { &mut *(r as *mut T as *mut Exclusive<T>) }
+    }
+
+    /// Build a _pinned mutable_ references to an `Exclusive<T>` from
+    /// a _pinned mutable_ reference to a `T`. This allows you to skip
+    /// building an `Exclusive` with [`Exclusive::new`].
+    #[unstable(feature = "exclusive_wrapper", issue = "98407")]
+    #[must_use]
+    pub const fn from_pin_mut(r: Pin<&'_ mut T>) -> Pin<&'_ mut Exclusive<T>> {
+        // SAFETY: `Exclusive` can only produce `&mut T` if itself is unpinned
+        // `Pin::map_unchecked_mut` is not const, so we do this conversion manually
+        unsafe { Pin::new_unchecked(Self::from_mut(r.get_unchecked_mut())) }
+    }
+}
+
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+impl<T> From<T> for Exclusive<T> {
+    fn from(t: T) -> Self {
+        Self::new(t)
+    }
+}
+
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+impl<T: Future + ?Sized> Future for Exclusive<T> {
+    type Output = T::Output;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.get_pin_mut().poll(cx)
+    }
+}

library/core/src/sync/mod.rs

@@ -3,3 +3,6 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 pub mod atomic;
+mod exclusive;
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+pub use exclusive::Exclusive;

library/std/src/lib.rs

@@ -270,6 +270,7 @@
 #![feature(duration_checked_float)]
 #![feature(duration_constants)]
 #![feature(exact_size_is_empty)]
+#![feature(exclusive_wrapper)]
 #![feature(extend_one)]
 #![feature(float_minimum_maximum)]
 #![feature(hasher_prefixfree_extras)]

library/std/src/sync/mod.rs

@@ -155,6 +155,8 @@
 pub use alloc_crate::sync::{Arc, Weak};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::sync::atomic;
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+pub use core::sync::Exclusive;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::barrier::{Barrier, BarrierWaitResult};