5 files changed, 49 insertions, 8 deletions
diff --git a/compiler/rustc_middle/src/ty/adjustment.rs b/compiler/rustc_middle/src/ty/adjustment.rs
index 3425da48559..a61a6c571a2 100644
--- a/compiler/rustc_middle/src/ty/adjustment.rs
+++ b/compiler/rustc_middle/src/ty/adjustment.rs
@@ -214,3 +214,25 @@ pub enum CustomCoerceUnsized {
     /// Records the index of the field being coerced.
     Struct(FieldIdx),
 }
+
+/// Represents an implicit coercion applied to the scrutinee of a match before testing a pattern
+/// against it. Currently, this is used only for implicit dereferences.
+#[derive(Clone, Copy, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
+pub struct PatAdjustment<'tcx> {
+    pub kind: PatAdjust,
+    /// The type of the scrutinee before the adjustment is applied, or the "adjusted type" of the
+    /// pattern.
+    pub source: Ty<'tcx>,
+}
+
+/// Represents implicit coercions of patterns' types, rather than values' types.
+#[derive(Clone, Copy, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)]
+#[derive(TypeFoldable, TypeVisitable)]
+pub enum PatAdjust {
+    /// An implicit dereference before matching, such as when matching the pattern `0` against a
+    /// scrutinee of type `&u8` or `&mut u8`.
+    BuiltinDeref,
+    /// An implicit call to `Deref(Mut)::deref(_mut)` before matching, such as when matching the
+    /// pattern `[..]` against a scrutinee of type `Vec<T>`.
+    OverloadedDeref,
+}
diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs
index 66517c97a68..d92b4f9c06b 100644
--- a/compiler/rustc_middle/src/ty/adt.rs
+++ b/compiler/rustc_middle/src/ty/adt.rs
@@ -55,8 +55,6 @@ bitflags::bitflags! {
         const IS_UNSAFE_CELL              = 1 << 9;
         /// Indicates whether the type is `UnsafePinned`.
         const IS_UNSAFE_PINNED              = 1 << 10;
-        /// Indicates whether the type is anonymous.
-        const IS_ANONYMOUS                = 1 << 11;
     }
 }
 rustc_data_structures::external_bitflags_debug! { AdtFlags }
diff --git a/compiler/rustc_middle/src/ty/assoc.rs b/compiler/rustc_middle/src/ty/assoc.rs
index 0c44fd2758d..78b2e265b48 100644
--- a/compiler/rustc_middle/src/ty/assoc.rs
+++ b/compiler/rustc_middle/src/ty/assoc.rs
@@ -246,6 +246,8 @@ impl AssocItems {
     }
 
     /// Returns an iterator over all associated items with the given name, ignoring hygiene.
+    ///
+    /// Panics if `name.is_empty()` returns `true`.
     pub fn filter_by_name_unhygienic(
         &self,
         name: Symbol,
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 40eef541423..26861666c1d 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -60,6 +60,12 @@ impl<'tcx> fmt::Debug for ty::adjustment::Adjustment<'tcx> {
     }
 }
 
+impl<'tcx> fmt::Debug for ty::adjustment::PatAdjustment<'tcx> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{} -> {:?}", self.source, self.kind)
+    }
+}
+
 impl fmt::Debug for ty::BoundRegionKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
diff --git a/compiler/rustc_middle/src/ty/typeck_results.rs b/compiler/rustc_middle/src/ty/typeck_results.rs
index 90c6ef67fb8..4c5c669771f 100644
--- a/compiler/rustc_middle/src/ty/typeck_results.rs
+++ b/compiler/rustc_middle/src/ty/typeck_results.rs
@@ -77,8 +77,8 @@ pub struct TypeckResults<'tcx> {
     /// to a form valid in all Editions, either as a lint diagnostic or hard error.
     rust_2024_migration_desugared_pats: ItemLocalMap<Rust2024IncompatiblePatInfo>,
 
-    /// Stores the types which were implicitly dereferenced in pattern binding modes
-    /// for later usage in THIR lowering. For example,
+    /// Stores the types which were implicitly dereferenced in pattern binding modes or deref
+    /// patterns for later usage in THIR lowering. For example,
     ///
     /// ```
     /// match &&Some(5i32) {
@@ -86,11 +86,20 @@ pub struct TypeckResults<'tcx> {
     ///     _ => {},
     /// }
     /// ```
-    /// leads to a `vec![&&Option<i32>, &Option<i32>]`. Empty vectors are not stored.
+    /// leads to a `vec![&&Option<i32>, &Option<i32>]` and
+    ///
+    /// ```
+    /// #![feature(deref_patterns)]
+    /// match &Box::new(Some(5i32)) {
+    ///     Some(n) => {},
+    ///     _ => {},
+    /// }
+    /// ```
+    /// leads to a `vec![&Box<Option<i32>>, Box<Option<i32>>]`. Empty vectors are not stored.
     ///
     /// See:
     /// <https://github.com/rust-lang/rfcs/blob/master/text/2005-match-ergonomics.md#definitions>
-    pat_adjustments: ItemLocalMap<Vec<Ty<'tcx>>>,
+    pat_adjustments: ItemLocalMap<Vec<ty::adjustment::PatAdjustment<'tcx>>>,
 
     /// Set of reference patterns that match against a match-ergonomics inserted reference
     /// (as opposed to against a reference in the scrutinee type).
@@ -403,11 +412,15 @@ impl<'tcx> TypeckResults<'tcx> {
         LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.pat_binding_modes }
     }
 
-    pub fn pat_adjustments(&self) -> LocalTableInContext<'_, Vec<Ty<'tcx>>> {
+    pub fn pat_adjustments(
+        &self,
+    ) -> LocalTableInContext<'_, Vec<ty::adjustment::PatAdjustment<'tcx>>> {
         LocalTableInContext { hir_owner: self.hir_owner, data: &self.pat_adjustments }
     }
 
-    pub fn pat_adjustments_mut(&mut self) -> LocalTableInContextMut<'_, Vec<Ty<'tcx>>> {
+    pub fn pat_adjustments_mut(
+        &mut self,
+    ) -> LocalTableInContextMut<'_, Vec<ty::adjustment::PatAdjustment<'tcx>>> {
         LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.pat_adjustments }
     }