Merge from rustc

8 files changed, 85 insertions, 47 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
index 9447d18fe8c..76e59ea9055 100644
--- a/compiler/rustc_const_eval/src/interpret/cast.rs
+++ b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -393,6 +393,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let val = self.read_immediate(src)?;
                 if data_a.principal() == data_b.principal() {
                     // A NOP cast that doesn't actually change anything, should be allowed even with mismatching vtables.
+                    // (But currently mismatching vtables violate the validity invariant so UB is triggered anyway.)
                     return self.write_immediate(*val, dest);
                 }
                 let (old_data, old_vptr) = val.to_scalar_pair();
@@ -400,7 +401,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 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_custom!(fluent::const_eval_upcast_mismatch);
+                    throw_ub!(InvalidVTableTrait {
+                        expected_trait: data_a,
+                        vtable_trait: old_trait,
+                    });
                 }
                 let new_vptr = self.get_vtable_ptr(ty, data_b.principal())?;
                 self.write_immediate(Immediate::new_dyn_trait(old_data, new_vptr, self), dest)
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 62d169db628..126d64329f8 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -822,15 +822,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         self.stack_mut().push(frame);
 
         // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
-        if M::POST_MONO_CHECKS {
-            for &const_ in &body.required_consts {
-                let c = self
-                    .instantiate_from_current_frame_and_normalize_erasing_regions(const_.const_)?;
-                c.eval(*self.tcx, self.param_env, const_.span).map_err(|err| {
-                    err.emit_note(*self.tcx);
-                    err
-                })?;
-            }
+        for &const_ in &body.required_consts {
+            let c =
+                self.instantiate_from_current_frame_and_normalize_erasing_regions(const_.const_)?;
+            c.eval(*self.tcx, self.param_env, const_.span).map_err(|err| {
+                err.emit_note(*self.tcx);
+                err
+            })?;
         }
 
         // done
@@ -1181,8 +1179,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
         M::eval_mir_constant(self, *val, span, layout, |ecx, val, span, layout| {
             let const_val = val.eval(*ecx.tcx, ecx.param_env, span).map_err(|err| {
-                // FIXME: somehow this is reachable even when POST_MONO_CHECKS is on.
-                // Are we not always populating `required_consts`?
+                if M::ALL_CONSTS_ARE_PRECHECKED && !matches!(err, ErrorHandled::TooGeneric(..)) {
+                    // Looks like the const is not captued by `required_consts`, that's bad.
+                    bug!("interpret const eval failure of {val:?} which is not in required_consts");
+                }
                 err.emit_note(*ecx.tcx);
                 err
             })?;
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index 63c709d8aed..4d37c3c22cd 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -173,7 +173,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let ty = instance_args.type_at(0);
                 let layout = self.layout_of(ty)?;
                 let val = self.read_scalar(&args[0])?;
-                let out_val = self.numeric_intrinsic(intrinsic_name, val, layout)?;
+
+                let out_val = self.numeric_intrinsic(intrinsic_name, val, layout, dest.layout)?;
                 self.write_scalar(out_val, dest)?;
             }
             sym::saturating_add | sym::saturating_sub => {
@@ -200,12 +201,15 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             sym::rotate_left | sym::rotate_right => {
                 // rotate_left: (X << (S % BW)) | (X >> ((BW - S) % BW))
                 // rotate_right: (X << ((BW - S) % BW)) | (X >> (S % BW))
-                let layout = self.layout_of(instance_args.type_at(0))?;
+                let layout_val = self.layout_of(instance_args.type_at(0))?;
                 let val = self.read_scalar(&args[0])?;
-                let val_bits = val.to_bits(layout.size)?;
+                let val_bits = val.to_bits(layout_val.size)?;
+
+                let layout_raw_shift = self.layout_of(self.tcx.types.u32)?;
                 let raw_shift = self.read_scalar(&args[1])?;
-                let raw_shift_bits = raw_shift.to_bits(layout.size)?;
-                let width_bits = u128::from(layout.size.bits());
+                let raw_shift_bits = raw_shift.to_bits(layout_raw_shift.size)?;
+
+                let width_bits = u128::from(layout_val.size.bits());
                 let shift_bits = raw_shift_bits % width_bits;
                 let inv_shift_bits = (width_bits - shift_bits) % width_bits;
                 let result_bits = if intrinsic_name == sym::rotate_left {
@@ -213,8 +217,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 } else {
                     (val_bits >> shift_bits) | (val_bits << inv_shift_bits)
                 };
-                let truncated_bits = self.truncate(result_bits, layout);
-                let result = Scalar::from_uint(truncated_bits, layout.size);
+                let truncated_bits = self.truncate(result_bits, layout_val);
+                let result = Scalar::from_uint(truncated_bits, layout_val.size);
                 self.write_scalar(result, dest)?;
             }
             sym::copy => {
@@ -472,6 +476,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         name: Symbol,
         val: Scalar<M::Provenance>,
         layout: TyAndLayout<'tcx>,
+        ret_layout: TyAndLayout<'tcx>,
     ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
         assert!(layout.ty.is_integral(), "invalid type for numeric intrinsic: {}", layout.ty);
         let bits = val.to_bits(layout.size)?;
@@ -483,11 +488,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
             sym::ctlz | sym::ctlz_nonzero => u128::from(bits.leading_zeros()) - extra,
             sym::cttz | sym::cttz_nonzero => u128::from((bits << extra).trailing_zeros()) - extra,
-            sym::bswap => (bits << extra).swap_bytes(),
-            sym::bitreverse => (bits << extra).reverse_bits(),
+            sym::bswap => {
+                assert_eq!(layout, ret_layout);
+                (bits << extra).swap_bytes()
+            }
+            sym::bitreverse => {
+                assert_eq!(layout, ret_layout);
+                (bits << extra).reverse_bits()
+            }
             _ => bug!("not a numeric intrinsic: {}", name),
         };
-        Ok(Scalar::from_uint(bits_out, layout.size))
+        Ok(Scalar::from_uint(bits_out, ret_layout.size))
     }
 
     pub fn exact_div(
diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index 7617cb57b3c..8bc569bed54 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -140,8 +140,9 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
     /// Should the machine panic on allocation failures?
     const PANIC_ON_ALLOC_FAIL: bool;
 
-    /// Should post-monomorphization checks be run when a stack frame is pushed?
-    const POST_MONO_CHECKS: bool = true;
+    /// Determines whether `eval_mir_constant` can never fail because all required consts have
+    /// already been checked before.
+    const ALL_CONSTS_ARE_PRECHECKED: bool = true;
 
     /// Whether memory accesses should be alignment-checked.
     fn enforce_alignment(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool;
diff --git a/compiler/rustc_const_eval/src/interpret/place.rs b/compiler/rustc_const_eval/src/interpret/place.rs
index 8364a5a8d18..e5241f1ba19 100644
--- a/compiler/rustc_const_eval/src/interpret/place.rs
+++ b/compiler/rustc_const_eval/src/interpret/place.rs
@@ -1020,16 +1020,20 @@ where
     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, _) = self.get_ptr_vtable(vtable)?;
-        let layout = self.layout_of(ty)?;
+        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))
@@ -1040,6 +1044,7 @@ where
     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)),
@@ -1048,10 +1053,12 @@ where
         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, _) = self.get_ptr_vtable(vtable)?;
+        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)?;
-        // `data` is already the right thing but has the wrong type. So we transmute it, by
-        // projecting with offset 0.
         let data = data.transmute(layout, self)?;
         Ok((data, vtable))
     }
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index 908c4da71f1..9c31532a9ce 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -803,11 +803,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let (vptr, dyn_ty, adjusted_receiver) = if let ty::Dynamic(data, _, ty::DynStar) =
                     receiver_place.layout.ty.kind()
                 {
-                    let (recv, vptr) = self.unpack_dyn_star(&receiver_place)?;
-                    let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
-                    if dyn_trait != data.principal() {
-                        throw_ub_custom!(fluent::const_eval_dyn_star_call_vtable_mismatch);
-                    }
+                    let (recv, vptr) = self.unpack_dyn_star(&receiver_place, data)?;
+                    let (dyn_ty, _dyn_trait) = self.get_ptr_vtable(vptr)?;
 
                     (vptr, dyn_ty, recv.ptr())
                 } else {
@@ -829,7 +826,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     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_custom!(fluent::const_eval_dyn_call_vtable_mismatch);
+                        throw_ub!(InvalidVTableTrait {
+                            expected_trait: data,
+                            vtable_trait: dyn_trait,
+                        });
                     }
 
                     // It might be surprising that we use a pointer as the receiver even if this
@@ -939,13 +939,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let place = self.force_allocation(place)?;
 
         let place = match place.layout.ty.kind() {
-            ty::Dynamic(_, _, ty::Dyn) => {
+            ty::Dynamic(data, _, ty::Dyn) => {
                 // Dropping a trait object. Need to find actual drop fn.
-                self.unpack_dyn_trait(&place)?.0
+                self.unpack_dyn_trait(&place, data)?.0
             }
-            ty::Dynamic(_, _, ty::DynStar) => {
+            ty::Dynamic(data, _, ty::DynStar) => {
                 // Dropping a `dyn*`. Need to find actual drop fn.
-                self.unpack_dyn_star(&place)?.0
+                self.unpack_dyn_star(&place, data)?.0
             }
             _ => {
                 debug_assert_eq!(
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index b8a1733e45a..14566719ccd 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -339,16 +339,22 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
     ) -> InterpResult<'tcx> {
         let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(pointee.ty, self.ecx.param_env);
         match tail.kind() {
-            ty::Dynamic(_, _, ty::Dyn) => {
+            ty::Dynamic(data, _, ty::Dyn) => {
                 let vtable = meta.unwrap_meta().to_pointer(self.ecx)?;
                 // Make sure it is a genuine vtable pointer.
-                let (_ty, _trait) = try_validation!(
+                let (_dyn_ty, dyn_trait) = try_validation!(
                     self.ecx.get_ptr_vtable(vtable),
                     self.path,
                     Ub(DanglingIntPointer(..) | InvalidVTablePointer(..)) =>
                         InvalidVTablePtr { value: format!("{vtable}") }
                 );
-                // FIXME: check if the type/trait match what ty::Dynamic says?
+                // Make sure it is for the right trait.
+                if dyn_trait != data.principal() {
+                    throw_validation_failure!(
+                        self.path,
+                        InvalidMetaWrongTrait { expected_trait: data, vtable_trait: dyn_trait }
+                    );
+                }
             }
             ty::Slice(..) | ty::Str => {
                 let _len = meta.unwrap_meta().to_target_usize(self.ecx)?;
@@ -933,7 +939,16 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 }
             }
             _ => {
-                self.walk_value(op)?; // default handler
+                // default handler
+                try_validation!(
+                    self.walk_value(op),
+                    self.path,
+                    // It's not great to catch errors here, since we can't give a very good path,
+                    // but it's better than ICEing.
+                    Ub(InvalidVTableTrait { expected_trait, vtable_trait }) => {
+                        InvalidMetaWrongTrait { expected_trait, vtable_trait: *vtable_trait }
+                    },
+                );
             }
         }
 
diff --git a/compiler/rustc_const_eval/src/interpret/visitor.rs b/compiler/rustc_const_eval/src/interpret/visitor.rs
index 0e824f3f592..84557b8e2d6 100644
--- a/compiler/rustc_const_eval/src/interpret/visitor.rs
+++ b/compiler/rustc_const_eval/src/interpret/visitor.rs
@@ -88,22 +88,22 @@ pub trait ValueVisitor<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>: Sized {
         // Special treatment for special types, where the (static) layout is not sufficient.
         match *ty.kind() {
             // If it is a trait object, switch to the real type that was used to create it.
-            ty::Dynamic(_, _, ty::Dyn) => {
+            ty::Dynamic(data, _, ty::Dyn) => {
                 // Dyn types. This is unsized, and the actual dynamic type of the data is given by the
                 // vtable stored in the place metadata.
                 // unsized values are never immediate, so we can assert_mem_place
                 let op = v.to_op(self.ecx())?;
                 let dest = op.assert_mem_place();
-                let inner_mplace = self.ecx().unpack_dyn_trait(&dest)?.0;
+                let inner_mplace = self.ecx().unpack_dyn_trait(&dest, data)?.0;
                 trace!("walk_value: dyn object layout: {:#?}", inner_mplace.layout);
                 // recurse with the inner type
                 return self.visit_field(v, 0, &inner_mplace.into());
             }
-            ty::Dynamic(_, _, ty::DynStar) => {
+            ty::Dynamic(data, _, ty::DynStar) => {
                 // DynStar types. Very different from a dyn type (but strangely part of the
                 // same variant in `TyKind`): These are pairs where the 2nd component is the
                 // vtable, and the first component is the data (which must be ptr-sized).
-                let data = self.ecx().unpack_dyn_star(v)?.0;
+                let data = self.ecx().unpack_dyn_star(v, data)?.0;
                 return self.visit_field(v, 0, &data);
             }
             // Slices do not need special handling here: they have `Array` field