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-rw-r--r--compiler/rustc_middle/src/mir/mod.rs8
-rw-r--r--compiler/rustc_middle/src/mir/syntax.rs7
-rw-r--r--compiler/rustc_middle/src/mir/tcx.rs4
-rw-r--r--compiler/rustc_middle/src/mir/type_foldable.rs1
-rw-r--r--compiler/rustc_middle/src/mir/visit.rs7
-rw-r--r--compiler/rustc_middle/src/traits/mod.rs10
-rw-r--r--compiler/rustc_middle/src/ty/layout.rs4
-rw-r--r--compiler/rustc_middle/src/ty/print/pretty.rs12
8 files changed, 33 insertions, 20 deletions
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index f61cb7e8c47..0b5d23be58d 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -1397,6 +1397,7 @@ impl<V, T> ProjectionElem<V, T> {
 
             Self::Field(_, _)
             | Self::Index(_)
+            | Self::OpaqueCast(_)
             | Self::ConstantIndex { .. }
             | Self::Subslice { .. }
             | Self::Downcast(_, _) => false,
@@ -1574,7 +1575,9 @@ impl Debug for Place<'_> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         for elem in self.projection.iter().rev() {
             match elem {
-                ProjectionElem::Downcast(_, _) | ProjectionElem::Field(_, _) => {
+                ProjectionElem::OpaqueCast(_)
+                | ProjectionElem::Downcast(_, _)
+                | ProjectionElem::Field(_, _) => {
                     write!(fmt, "(").unwrap();
                 }
                 ProjectionElem::Deref => {
@@ -1590,6 +1593,9 @@ impl Debug for Place<'_> {
 
         for elem in self.projection.iter() {
             match elem {
+                ProjectionElem::OpaqueCast(ty) => {
+                    write!(fmt, " as {})", ty)?;
+                }
                 ProjectionElem::Downcast(Some(name), _index) => {
                     write!(fmt, " as {})", name)?;
                 }
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index 510316c778b..263c2ca3c70 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -754,6 +754,9 @@ pub type AssertMessage<'tcx> = AssertKind<Operand<'tcx>>;
 ///    generator has more than one variant, the parent place's variant index must be set, indicating
 ///    which variant is being used. If it has just one variant, the variant index may or may not be
 ///    included - the single possible variant is inferred if it is not included.
+///  - [`OpaqueCast`](ProjectionElem::OpaqueCast): This projection changes the place's type to the
+///    given one, and makes no other changes. A `OpaqueCast` projection on any type other than an
+///    opaque type from the current crate is not well-formed.
 ///  - [`ConstantIndex`](ProjectionElem::ConstantIndex): Computes an offset in units of `T` into the
 ///    place as described in the documentation for the `ProjectionElem`. The resulting address is
 ///    the parent's address plus that offset, and the type is `T`. This is only legal if the parent
@@ -856,6 +859,10 @@ pub enum ProjectionElem<V, T> {
     ///
     /// The included Symbol is the name of the variant, used for printing MIR.
     Downcast(Option<Symbol>, VariantIdx),
+
+    /// Like an explicit cast from an opaque type to a concrete type, but without
+    /// requiring an intermediate variable.
+    OpaqueCast(T),
 }
 
 /// Alias for projections as they appear in places, where the base is a place
diff --git a/compiler/rustc_middle/src/mir/tcx.rs b/compiler/rustc_middle/src/mir/tcx.rs
index fd3359ea80f..c6975df45ef 100644
--- a/compiler/rustc_middle/src/mir/tcx.rs
+++ b/compiler/rustc_middle/src/mir/tcx.rs
@@ -57,7 +57,7 @@ impl<'tcx> PlaceTy<'tcx> {
     /// `PlaceElem`, where we can just use the `Ty` that is already
     /// stored inline on field projection elems.
     pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: PlaceElem<'tcx>) -> PlaceTy<'tcx> {
-        self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty)
+        self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty, |_, ty| ty)
     }
 
     /// `place_ty.projection_ty_core(tcx, elem, |...| { ... })`
@@ -71,6 +71,7 @@ impl<'tcx> PlaceTy<'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         elem: &ProjectionElem<V, T>,
         mut handle_field: impl FnMut(&Self, Field, T) -> Ty<'tcx>,
+        mut handle_opaque_cast: impl FnMut(&Self, T) -> Ty<'tcx>,
     ) -> PlaceTy<'tcx>
     where
         V: ::std::fmt::Debug,
@@ -109,6 +110,7 @@ impl<'tcx> PlaceTy<'tcx> {
                 PlaceTy { ty: self.ty, variant_index: Some(index) }
             }
             ProjectionElem::Field(f, fty) => PlaceTy::from_ty(handle_field(&self, f, fty)),
+            ProjectionElem::OpaqueCast(ty) => PlaceTy::from_ty(handle_opaque_cast(&self, ty)),
         };
         debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer);
         answer
diff --git a/compiler/rustc_middle/src/mir/type_foldable.rs b/compiler/rustc_middle/src/mir/type_foldable.rs
index 82a6b0c506f..a73ef23e281 100644
--- a/compiler/rustc_middle/src/mir/type_foldable.rs
+++ b/compiler/rustc_middle/src/mir/type_foldable.rs
@@ -182,6 +182,7 @@ impl<'tcx> TypeFoldable<'tcx> for PlaceElem<'tcx> {
         Ok(match self {
             Deref => Deref,
             Field(f, ty) => Field(f, ty.try_fold_with(folder)?),
+            OpaqueCast(ty) => OpaqueCast(ty.try_fold_with(folder)?),
             Index(v) => Index(v.try_fold_with(folder)?),
             Downcast(symbol, variantidx) => Downcast(symbol, variantidx),
             ConstantIndex { offset, min_length, from_end } => {
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index d285728ec07..e5599fb15ad 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -1064,6 +1064,11 @@ macro_rules! visit_place_fns {
                     self.visit_ty(&mut new_ty, TyContext::Location(location));
                     if ty != new_ty { Some(PlaceElem::Field(field, new_ty)) } else { None }
                 }
+                PlaceElem::OpaqueCast(ty) => {
+                    let mut new_ty = ty;
+                    self.visit_ty(&mut new_ty, TyContext::Location(location));
+                    if ty != new_ty { Some(PlaceElem::OpaqueCast(new_ty)) } else { None }
+                }
                 PlaceElem::Deref
                 | PlaceElem::ConstantIndex { .. }
                 | PlaceElem::Subslice { .. }
@@ -1133,7 +1138,7 @@ macro_rules! visit_place_fns {
             location: Location,
         ) {
             match elem {
-                ProjectionElem::Field(_field, ty) => {
+                ProjectionElem::OpaqueCast(ty) | ProjectionElem::Field(_, ty) => {
                     self.visit_ty(ty, TyContext::Location(location));
                 }
                 ProjectionElem::Index(local) => {
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 945cdfbb0e9..75559d4f8b8 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -542,17 +542,9 @@ pub enum SelectionError<'tcx> {
     ErrorReporting,
     /// Multiple applicable `impl`s where found. The `DefId`s correspond to
     /// all the `impl`s' Items.
-    Ambiguous(Vec<AmbiguousSelection>),
+    Ambiguous(Vec<DefId>),
 }
 
-#[derive(Copy, Clone, Debug)]
-pub enum AmbiguousSelection {
-    Impl(DefId),
-    ParamEnv(Span),
-}
-
-TrivialTypeTraversalAndLiftImpls! { AmbiguousSelection, }
-
 /// When performing resolution, it is typically the case that there
 /// can be one of three outcomes:
 ///
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 71c93d05792..c41a8318ec5 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1975,7 +1975,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                         min_size = field_end;
                     }
                     FieldInfo {
-                        name: name.to_string(),
+                        name,
                         offset: offset.bytes(),
                         size: field_layout.size.bytes(),
                         align: field_layout.align.abi.bytes(),
@@ -1984,7 +1984,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                 .collect();
 
             VariantInfo {
-                name: n.map(|n| n.to_string()),
+                name: n,
                 kind: if layout.is_unsized() { SizeKind::Min } else { SizeKind::Exact },
                 align: layout.align.abi.bytes(),
                 size: if min_size.bytes() == 0 { layout.size.bytes() } else { min_size.bytes() },
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 81c4d2ae346..96e84bc8f0a 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1030,11 +1030,11 @@ pub trait PrettyPrinter<'tcx>:
         }
     }
 
-    fn ty_infer_name(&self, _: ty::TyVid) -> Option<String> {
+    fn ty_infer_name(&self, _: ty::TyVid) -> Option<Symbol> {
         None
     }
 
-    fn const_infer_name(&self, _: ty::ConstVid<'tcx>) -> Option<String> {
+    fn const_infer_name(&self, _: ty::ConstVid<'tcx>) -> Option<Symbol> {
         None
     }
 
@@ -1550,8 +1550,8 @@ pub struct FmtPrinterData<'a, 'tcx> {
 
     pub region_highlight_mode: RegionHighlightMode<'tcx>,
 
-    pub ty_infer_name_resolver: Option<Box<dyn Fn(ty::TyVid) -> Option<String> + 'a>>,
-    pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid<'tcx>) -> Option<String> + 'a>>,
+    pub ty_infer_name_resolver: Option<Box<dyn Fn(ty::TyVid) -> Option<Symbol> + 'a>>,
+    pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid<'tcx>) -> Option<Symbol> + 'a>>,
 }
 
 impl<'a, 'tcx> Deref for FmtPrinter<'a, 'tcx> {
@@ -1841,11 +1841,11 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
 }
 
 impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
-    fn ty_infer_name(&self, id: ty::TyVid) -> Option<String> {
+    fn ty_infer_name(&self, id: ty::TyVid) -> Option<Symbol> {
         self.0.ty_infer_name_resolver.as_ref().and_then(|func| func(id))
     }
 
-    fn const_infer_name(&self, id: ty::ConstVid<'tcx>) -> Option<String> {
+    fn const_infer_name(&self, id: ty::ConstVid<'tcx>) -> Option<Symbol> {
         self.0.const_infer_name_resolver.as_ref().and_then(|func| func(id))
     }
generated by cgit-pink 1.4.1-3-g733a5 (git 2.37.1) at 2025-11-03 05:18:17 +0000