Rollup of 9 pull requests

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -557,8 +557,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         // for the branching codepaths that aren't covered, to point at them.
         let map = self.infcx.tcx.hir();
         let body = map.body_owned_by(self.mir_def_id());
-
-        let mut visitor = ConditionVisitor { spans: &spans, name: &name, errors: vec![] };
+        let mut visitor =
+            ConditionVisitor { tcx: self.infcx.tcx, spans: &spans, name: &name, errors: vec![] };
         visitor.visit_body(&body);
 
         let mut show_assign_sugg = false;
@@ -4372,13 +4372,14 @@ impl<'hir> Visitor<'hir> for BreakFinder {
 
 /// Given a set of spans representing statements initializing the relevant binding, visit all the
 /// function expressions looking for branching code paths that *do not* initialize the binding.
-struct ConditionVisitor<'b> {
+struct ConditionVisitor<'b, 'tcx> {
+    tcx: TyCtxt<'tcx>,
     spans: &'b [Span],
     name: &'b str,
     errors: Vec<(Span, String)>,
 }
 
-impl<'b, 'v> Visitor<'v> for ConditionVisitor<'b> {
+impl<'b, 'v, 'tcx> Visitor<'v> for ConditionVisitor<'b, 'tcx> {
     fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) {
         match ex.kind {
             hir::ExprKind::If(cond, body, None) => {
@@ -4464,6 +4465,12 @@ impl<'b, 'v> Visitor<'v> for ConditionVisitor<'b> {
                                     ),
                                 ));
                             } else if let Some(guard) = &arm.guard {
+                                if matches!(
+                                    self.tcx.hir_node(arm.body.hir_id),
+                                    hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Ret(_), .. })
+                                ) {
+                                    continue;
+                                }
                                 self.errors.push((
                                     arm.pat.span.to(guard.span),
                                     format!(
@@ -4473,6 +4480,12 @@ impl<'b, 'v> Visitor<'v> for ConditionVisitor<'b> {
                                     ),
                                 ));
                             } else {
+                                if matches!(
+                                    self.tcx.hir_node(arm.body.hir_id),
+                                    hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Ret(_), .. })
+                                ) {
+                                    continue;
+                                }
                                 self.errors.push((
                                     arm.pat.span,
                                     format!(

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -387,7 +387,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         match (&src_pointee_ty.kind(), &dest_pointee_ty.kind()) {
             (&ty::Array(_, length), &ty::Slice(_)) => {
                 let ptr = self.read_pointer(src)?;
-                // u64 cast is from usize to u64, which is always good
                 let val = Immediate::new_slice(
                     ptr,
                     length.eval_target_usize(*self.tcx, self.param_env),
@@ -405,13 +404,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let (old_data, old_vptr) = val.to_scalar_pair();
                 let old_data = old_data.to_pointer(self)?;
                 let old_vptr = old_vptr.to_pointer(self)?;
-                let (ty, old_trait) = self.get_ptr_vtable(old_vptr)?;
-                if old_trait != data_a.principal() {
-                    throw_ub!(InvalidVTableTrait {
-                        expected_trait: data_a,
-                        vtable_trait: old_trait,
-                    });
-                }
+                let ty = self.get_ptr_vtable_ty(old_vptr, Some(data_a))?;
                 let new_vptr = self.get_vtable_ptr(ty, data_b.principal())?;
                 self.write_immediate(Immediate::new_dyn_trait(old_data, new_vptr, self), dest)
             }

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -765,10 +765,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 }
                 Ok(Some((full_size, full_align)))
             }
-            ty::Dynamic(_, _, ty::Dyn) => {
+            ty::Dynamic(expected_trait, _, ty::Dyn) => {
                 let vtable = metadata.unwrap_meta().to_pointer(self)?;
                 // Read size and align from vtable (already checks size).
-                Ok(Some(self.get_vtable_size_and_align(vtable)?))
+                Ok(Some(self.get_vtable_size_and_align(vtable, Some(expected_trait))?))
             }
 
             ty::Slice(_) | ty::Str => {

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -432,12 +432,14 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
             sym::vtable_size => {
                 let ptr = self.read_pointer(&args[0])?;
-                let (size, _align) = self.get_vtable_size_and_align(ptr)?;
+                // `None` because we don't know which trait to expect here; any vtable is okay.
+                let (size, _align) = self.get_vtable_size_and_align(ptr, None)?;
                 self.write_scalar(Scalar::from_target_usize(size.bytes(), self), dest)?;
             }
             sym::vtable_align => {
                 let ptr = self.read_pointer(&args[0])?;
-                let (_size, align) = self.get_vtable_size_and_align(ptr)?;
+                // `None` because we don't know which trait to expect here; any vtable is okay.
+                let (_size, align) = self.get_vtable_size_and_align(ptr, None)?;
                 self.write_scalar(Scalar::from_target_usize(align.bytes(), self), dest)?;
             }
 

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -867,19 +867,26 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             .ok_or_else(|| err_ub!(InvalidFunctionPointer(Pointer::new(alloc_id, offset))).into())
     }
 
-    pub fn get_ptr_vtable(
+    /// Get the dynamic type of the given vtable pointer.
+    /// If `expected_trait` is `Some`, it must be a vtable for the given trait.
+    pub fn get_ptr_vtable_ty(
         &self,
         ptr: Pointer<Option<M::Provenance>>,
-    ) -> InterpResult<'tcx, (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>)> {
+        expected_trait: Option<&'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>>,
+    ) -> InterpResult<'tcx, Ty<'tcx>> {
         trace!("get_ptr_vtable({:?})", ptr);
         let (alloc_id, offset, _tag) = self.ptr_get_alloc_id(ptr)?;
         if offset.bytes() != 0 {
             throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset)))
         }
-        match self.tcx.try_get_global_alloc(alloc_id) {
-            Some(GlobalAlloc::VTable(ty, trait_ref)) => Ok((ty, trait_ref)),
-            _ => throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset))),
+        let Some(GlobalAlloc::VTable(ty, vtable_trait)) = self.tcx.try_get_global_alloc(alloc_id)
+        else {
+            throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset)))
+        };
+        if let Some(expected_trait) = expected_trait {
+            self.check_vtable_for_type(vtable_trait, expected_trait)?;
         }
+        Ok(ty)
     }
 
     pub fn alloc_mark_immutable(&mut self, id: AllocId) -> InterpResult<'tcx> {

compiler/rustc_const_eval/src/interpret/place.rs

@@ -9,7 +9,6 @@ use tracing::{instrument, trace};
 
 use rustc_ast::Mutability;
 use rustc_middle::mir;
-use rustc_middle::ty;
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
 use rustc_middle::ty::Ty;
 use rustc_middle::{bug, span_bug};
@@ -1018,54 +1017,6 @@ where
         let layout = self.layout_of(raw.ty)?;
         Ok(self.ptr_to_mplace(ptr.into(), layout))
     }
-
-    /// Turn a place with a `dyn Trait` type into a place with the actual dynamic type.
-    /// Aso returns the vtable.
-    pub(super) fn unpack_dyn_trait(
-        &self,
-        mplace: &MPlaceTy<'tcx, M::Provenance>,
-        expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
-    ) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, Pointer<Option<M::Provenance>>)> {
-        assert!(
-            matches!(mplace.layout.ty.kind(), ty::Dynamic(_, _, ty::Dyn)),
-            "`unpack_dyn_trait` only makes sense on `dyn*` types"
-        );
-        let vtable = mplace.meta().unwrap_meta().to_pointer(self)?;
-        let (ty, vtable_trait) = self.get_ptr_vtable(vtable)?;
-        if expected_trait.principal() != vtable_trait {
-            throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
-        }
-        // This is a kind of transmute, from a place with unsized type and metadata to
-        // a place with sized type and no metadata.
-        let layout = self.layout_of(ty)?;
-        let mplace =
-            MPlaceTy { mplace: MemPlace { meta: MemPlaceMeta::None, ..mplace.mplace }, layout };
-        Ok((mplace, vtable))
-    }
-
-    /// Turn a `dyn* Trait` type into an value with the actual dynamic type.
-    /// Also returns the vtable.
-    pub(super) fn unpack_dyn_star<P: Projectable<'tcx, M::Provenance>>(
-        &self,
-        val: &P,
-        expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
-    ) -> InterpResult<'tcx, (P, Pointer<Option<M::Provenance>>)> {
-        assert!(
-            matches!(val.layout().ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
-            "`unpack_dyn_star` only makes sense on `dyn*` types"
-        );
-        let data = self.project_field(val, 0)?;
-        let vtable = self.project_field(val, 1)?;
-        let vtable = self.read_pointer(&vtable.to_op(self)?)?;
-        let (ty, vtable_trait) = self.get_ptr_vtable(vtable)?;
-        if expected_trait.principal() != vtable_trait {
-            throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
-        }
-        // `data` is already the right thing but has the wrong type. So we transmute it.
-        let layout = self.layout_of(ty)?;
-        let data = data.transmute(layout, self)?;
-        Ok((data, vtable))
-    }
 }
 
 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.

compiler/rustc_const_eval/src/interpret/terminator.rs

@@ -1,6 +1,7 @@
 use std::borrow::Cow;
 
 use either::Either;
+use rustc_middle::ty::TyCtxt;
 use tracing::trace;
 
 use rustc_middle::span_bug;
@@ -827,20 +828,19 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 };
 
                 // Obtain the underlying trait we are working on, and the adjusted receiver argument.
-                let (vptr, dyn_ty, adjusted_receiver) = if let ty::Dynamic(data, _, ty::DynStar) =
+                let (dyn_trait, dyn_ty, adjusted_recv) = if let ty::Dynamic(data, _, ty::DynStar) =
                     receiver_place.layout.ty.kind()
                 {
-                    let (recv, vptr) = self.unpack_dyn_star(&receiver_place, data)?;
-                    let (dyn_ty, _dyn_trait) = self.get_ptr_vtable(vptr)?;
+                    let recv = self.unpack_dyn_star(&receiver_place, data)?;
 
-                    (vptr, dyn_ty, recv.ptr())
+                    (data.principal(), recv.layout.ty, recv.ptr())
                 } else {
                     // Doesn't have to be a `dyn Trait`, but the unsized tail must be `dyn Trait`.
                     // (For that reason we also cannot use `unpack_dyn_trait`.)
                     let receiver_tail = self
                         .tcx
                         .struct_tail_erasing_lifetimes(receiver_place.layout.ty, self.param_env);
-                    let ty::Dynamic(data, _, ty::Dyn) = receiver_tail.kind() else {
+                    let ty::Dynamic(receiver_trait, _, ty::Dyn) = receiver_tail.kind() else {
                         span_bug!(
                             self.cur_span(),
                             "dynamic call on non-`dyn` type {}",
@@ -851,25 +851,24 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
                     // Get the required information from the vtable.
                     let vptr = receiver_place.meta().unwrap_meta().to_pointer(self)?;
-                    let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
-                    if dyn_trait != data.principal() {
-                        throw_ub!(InvalidVTableTrait {
-                            expected_trait: data,
-                            vtable_trait: dyn_trait,
-                        });
-                    }
+                    let dyn_ty = self.get_ptr_vtable_ty(vptr, Some(receiver_trait))?;
 
                     // It might be surprising that we use a pointer as the receiver even if this
                     // is a by-val case; this works because by-val passing of an unsized `dyn
                     // Trait` to a function is actually desugared to a pointer.
-                    (vptr, dyn_ty, receiver_place.ptr())
+                    (receiver_trait.principal(), dyn_ty, receiver_place.ptr())
                 };
 
                 // Now determine the actual method to call. We can do that in two different ways and
                 // compare them to ensure everything fits.
-                let Some(ty::VtblEntry::Method(fn_inst)) =
-                    self.get_vtable_entries(vptr)?.get(idx).copied()
-                else {
+                let vtable_entries = if let Some(dyn_trait) = dyn_trait {
+                    let trait_ref = dyn_trait.with_self_ty(*self.tcx, dyn_ty);
+                    let trait_ref = self.tcx.erase_regions(trait_ref);
+                    self.tcx.vtable_entries(trait_ref)
+                } else {
+                    TyCtxt::COMMON_VTABLE_ENTRIES
+                };
+                let Some(ty::VtblEntry::Method(fn_inst)) = vtable_entries.get(idx).copied() else {
                     // FIXME(fee1-dead) these could be variants of the UB info enum instead of this
                     throw_ub_custom!(fluent::const_eval_dyn_call_not_a_method);
                 };
@@ -898,7 +897,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let receiver_ty = Ty::new_mut_ptr(self.tcx.tcx, dyn_ty);
                 args[0] = FnArg::Copy(
                     ImmTy::from_immediate(
-                        Scalar::from_maybe_pointer(adjusted_receiver, self).into(),
+                        Scalar::from_maybe_pointer(adjusted_recv, self).into(),
                         self.layout_of(receiver_ty)?,
                     )
                     .into(),
@@ -974,11 +973,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let place = match place.layout.ty.kind() {
             ty::Dynamic(data, _, ty::Dyn) => {
                 // Dropping a trait object. Need to find actual drop fn.
-                self.unpack_dyn_trait(&place, data)?.0
+                self.unpack_dyn_trait(&place, data)?
             }
             ty::Dynamic(data, _, ty::DynStar) => {
                 // Dropping a `dyn*`. Need to find actual drop fn.
-                self.unpack_dyn_star(&place, data)?.0
+                self.unpack_dyn_star(&place, data)?
             }
             _ => {
                 debug_assert_eq!(