Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 228 insertions, 115 deletions

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index 54213d55a..79f1737e3 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -242,7 +242,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
             // impl trait is gone in MIR, so check the return type of a const fn by its signature
             // instead of the type of the return place.
             self.span = body.local_decls[RETURN_PLACE].source_info.span;
-            let return_ty = tcx.fn_sig(def_id).output();
+            let return_ty = self.ccx.fn_sig().output();
             self.check_local_or_return_ty(return_ty.skip_binder(), RETURN_PLACE);
         }
 
@@ -442,7 +442,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
         self.super_rvalue(rvalue, location);
 
-        match *rvalue {
+        match rvalue {
             Rvalue::ThreadLocalRef(_) => self.check_op(ops::ThreadLocalAccess),
 
             Rvalue::Use(_)
@@ -451,18 +451,15 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
             | Rvalue::Discriminant(..)
             | Rvalue::Len(_) => {}
 
-            Rvalue::Aggregate(ref kind, ..) => {
-                if let AggregateKind::Generator(def_id, ..) = kind.as_ref() {
-                    if let Some(generator_kind) = self.tcx.generator_kind(def_id.to_def_id()) {
-                        if matches!(generator_kind, hir::GeneratorKind::Async(..)) {
-                            self.check_op(ops::Generator(generator_kind));
-                        }
-                    }
+            Rvalue::Aggregate(kind, ..) => {
+                if let AggregateKind::Generator(def_id, ..) = kind.as_ref()
+                    && let Some(generator_kind @ hir::GeneratorKind::Async(..)) = self.tcx.generator_kind(def_id.to_def_id())
+                {
+                    self.check_op(ops::Generator(generator_kind));
                 }
             }
 
-            Rvalue::Ref(_, kind @ BorrowKind::Mut { .. }, ref place)
-            | Rvalue::Ref(_, kind @ BorrowKind::Unique, ref place) => {
+            Rvalue::Ref(_, kind @ (BorrowKind::Mut { .. } | BorrowKind::Unique), place) => {
                 let ty = place.ty(self.body, self.tcx).ty;
                 let is_allowed = match ty.kind() {
                     // Inside a `static mut`, `&mut [...]` is allowed.
@@ -491,12 +488,12 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 }
             }
 
-            Rvalue::AddressOf(Mutability::Mut, ref place) => {
+            Rvalue::AddressOf(Mutability::Mut, place) => {
                 self.check_mut_borrow(place.local, hir::BorrowKind::Raw)
             }
 
-            Rvalue::Ref(_, BorrowKind::Shared | BorrowKind::Shallow, ref place)
-            | Rvalue::AddressOf(Mutability::Not, ref place) => {
+            Rvalue::Ref(_, BorrowKind::Shared | BorrowKind::Shallow, place)
+            | Rvalue::AddressOf(Mutability::Not, place) => {
                 let borrowed_place_has_mut_interior = qualifs::in_place::<HasMutInterior, _>(
                     &self.ccx,
                     &mut |local| self.qualifs.has_mut_interior(self.ccx, local, location),
@@ -564,7 +561,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
             Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => {}
             Rvalue::ShallowInitBox(_, _) => {}
 
-            Rvalue::UnaryOp(_, ref operand) => {
+            Rvalue::UnaryOp(_, operand) => {
                 let ty = operand.ty(self.body, self.tcx);
                 if is_int_bool_or_char(ty) {
                     // Int, bool, and char operations are fine.
@@ -575,8 +572,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 }
             }
 
-            Rvalue::BinaryOp(op, box (ref lhs, ref rhs))
-            | Rvalue::CheckedBinaryOp(op, box (ref lhs, ref rhs)) => {
+            Rvalue::BinaryOp(op, box (lhs, rhs))
+            | Rvalue::CheckedBinaryOp(op, box (lhs, rhs)) => {
                 let lhs_ty = lhs.ty(self.body, self.tcx);
                 let rhs_ty = rhs.ty(self.body, self.tcx);
 
@@ -585,13 +582,16 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 } else if lhs_ty.is_fn_ptr() || lhs_ty.is_unsafe_ptr() {
                     assert_eq!(lhs_ty, rhs_ty);
                     assert!(
-                        op == BinOp::Eq
-                            || op == BinOp::Ne
-                            || op == BinOp::Le
-                            || op == BinOp::Lt
-                            || op == BinOp::Ge
-                            || op == BinOp::Gt
-                            || op == BinOp::Offset
+                        matches!(
+                            op,
+                            BinOp::Eq
+                            | BinOp::Ne
+                            | BinOp::Le
+                            | BinOp::Lt
+                            | BinOp::Ge
+                            | BinOp::Gt
+                            | BinOp::Offset
+                        )
                     );
 
                     self.check_op(ops::RawPtrComparison);
@@ -730,6 +730,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                             substs,
                             span: *fn_span,
                             from_hir_call: *from_hir_call,
+                            feature: Some(sym::const_trait_impl),
                         });
                         return;
                     }
@@ -782,6 +783,20 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                             );
                             return;
                         }
+                        Ok(Some(ImplSource::Closure(data))) => {
+                            if !tcx.is_const_fn_raw(data.closure_def_id) {
+                                self.check_op(ops::FnCallNonConst {
+                                    caller,
+                                    callee,
+                                    substs,
+                                    span: *fn_span,
+                                    from_hir_call: *from_hir_call,
+                                    feature: None,
+                                });
+
+                                return;
+                            }
+                        }
                         Ok(Some(ImplSource::UserDefined(data))) => {
                             let callee_name = tcx.item_name(callee);
                             if let Some(&did) = tcx
@@ -802,6 +817,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                                     substs,
                                     span: *fn_span,
                                     from_hir_call: *from_hir_call,
+                                    feature: None,
                                 });
                                 return;
                             }
@@ -844,6 +860,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                                     substs,
                                     span: *fn_span,
                                     from_hir_call: *from_hir_call,
+                                    feature: None,
                                 });
                                 return;
                             }
@@ -903,6 +920,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                             substs,
                             span: *fn_span,
                             from_hir_call: *from_hir_call,
+                            feature: None,
                         });
                         return;
                     }
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
index 655ec345e..54868e418 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
@@ -8,7 +8,7 @@ use rustc_attr as attr;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::mir;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::{self, PolyFnSig, TyCtxt};
 use rustc_span::Symbol;
 
 pub use self::qualifs::Qualif;
@@ -64,6 +64,17 @@ impl<'mir, 'tcx> ConstCx<'mir, 'tcx> {
     fn is_async(&self) -> bool {
         self.tcx.asyncness(self.def_id()).is_async()
     }
+
+    pub fn fn_sig(&self) -> PolyFnSig<'tcx> {
+        let did = self.def_id().to_def_id();
+        if self.tcx.is_closure(did) {
+            let ty = self.tcx.type_of(did);
+            let ty::Closure(_, substs) = ty.kind() else { bug!("type_of closure not ty::Closure") };
+            substs.as_closure().sig()
+        } else {
+            self.tcx.fn_sig(did)
+        }
+    }
 }
 
 pub fn rustc_allow_const_fn_unstable(
@@ -115,7 +126,7 @@ fn is_parent_const_stable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
     let local_def_id = def_id.expect_local();
     let hir_id = tcx.local_def_id_to_hir_id(local_def_id);
 
-    let Some(parent) = tcx.hir().find_parent_node(hir_id) else { return false };
+    let Some(parent) = tcx.hir().opt_parent_id(hir_id) else { return false };
     let parent_def = tcx.hir().get(parent);
 
     if !matches!(
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/ops.rs b/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
index b19d270e6..0cb5d2ff8 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
@@ -111,6 +111,7 @@ pub struct FnCallNonConst<'tcx> {
     pub substs: SubstsRef<'tcx>,
     pub span: Span,
     pub from_hir_call: bool,
+    pub feature: Option<Symbol>,
 }
 
 impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
@@ -119,7 +120,7 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
         ccx: &ConstCx<'_, 'tcx>,
         _: Span,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        let FnCallNonConst { caller, callee, substs, span, from_hir_call } = *self;
+        let FnCallNonConst { caller, callee, substs, span, from_hir_call, feature } = *self;
         let ConstCx { tcx, param_env, .. } = *ccx;
 
         let diag_trait = |err, self_ty: Ty<'_>, trait_id| {
@@ -318,6 +319,13 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
             ccx.const_kind(),
         ));
 
+        if let Some(feature) = feature && ccx.tcx.sess.is_nightly_build() {
+            err.help(&format!(
+                "add `#![feature({})]` to the crate attributes to enable",
+                feature,
+            ));
+        }
+
         if let ConstContext::Static(_) = ccx.const_kind() {
             err.note("consider wrapping this expression in `Lazy::new(|| ...)` from the `once_cell` crate: https://crates.io/crates/once_cell");
         }
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs b/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
index d4570c598..cf4e875c9 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
@@ -95,7 +95,7 @@ impl<'tcx> Visitor<'tcx> for CheckLiveDrops<'_, 'tcx> {
                 }
 
                 // Drop elaboration is not precise enough to accept code like
-                // `src/test/ui/consts/control-flow/drop-pass.rs`; e.g., when an `Option<Vec<T>>` is
+                // `tests/ui/consts/control-flow/drop-pass.rs`; e.g., when an `Option<Vec<T>>` is
                 // initialized with `None` and never changed, it still emits drop glue.
                 // Hence we additionally check the qualifs here to allow more code to pass.
                 if self.qualifs.needs_non_const_drop(self.ccx, dropped_place.local, location) {
diff --git a/compiler/rustc_const_eval/src/transform/promote_consts.rs b/compiler/rustc_const_eval/src/transform/promote_consts.rs
index 6777fae74..fae6117f8 100644
--- a/compiler/rustc_const_eval/src/transform/promote_consts.rs
+++ b/compiler/rustc_const_eval/src/transform/promote_consts.rs
@@ -133,7 +133,7 @@ impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> {
                 }
                 _ => { /* mark as unpromotable below */ }
             }
-        } else if let TempState::Defined { ref mut uses, .. } = *temp {
+        } else if let TempState::Defined { uses, .. } = temp {
             // We always allow borrows, even mutable ones, as we need
             // to promote mutable borrows of some ZSTs e.g., `&mut []`.
             let allowed_use = match context {
@@ -216,12 +216,6 @@ impl<'tcx> Validator<'_, 'tcx> {
                     return Err(Unpromotable);
                 }
 
-                // We cannot promote things that need dropping, since the promoted value
-                // would not get dropped.
-                if self.qualif_local::<qualifs::NeedsDrop>(place.local) {
-                    return Err(Unpromotable);
-                }
-
                 Ok(())
             }
             _ => bug!(),
@@ -262,13 +256,17 @@ impl<'tcx> Validator<'_, 'tcx> {
                 }
             }
         } else {
-            let span = self.body.local_decls[local].source_info.span;
-            span_bug!(span, "{:?} not promotable, qualif_local shouldn't have been called", local);
+            false
         }
     }
 
     fn validate_local(&mut self, local: Local) -> Result<(), Unpromotable> {
         if let TempState::Defined { location: loc, uses, valid } = self.temps[local] {
+            // We cannot promote things that need dropping, since the promoted value
+            // would not get dropped.
+            if self.qualif_local::<qualifs::NeedsDrop>(local) {
+                return Err(Unpromotable);
+            }
             valid.or_else(|_| {
                 let ok = {
                     let block = &self.body[loc.block];
@@ -750,7 +748,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
         if loc.statement_index < num_stmts {
             let (mut rvalue, source_info) = {
                 let statement = &mut self.source[loc.block].statements[loc.statement_index];
-                let StatementKind::Assign(box (_, ref mut rhs)) = statement.kind else {
+                let StatementKind::Assign(box (_, rhs)) = &mut statement.kind else {
                     span_bug!(
                         statement.source_info.span,
                         "{:?} is not an assignment",
@@ -780,9 +778,9 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                 self.source[loc.block].terminator().clone()
             } else {
                 let terminator = self.source[loc.block].terminator_mut();
-                let target = match terminator.kind {
-                    TerminatorKind::Call { target: Some(target), .. } => target,
-                    ref kind => {
+                let target = match &terminator.kind {
+                    TerminatorKind::Call { target: Some(target), .. } => *target,
+                    kind => {
                         span_bug!(terminator.source_info.span, "{:?} not promotable", kind);
                     }
                 };
@@ -816,7 +814,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                         ..terminator
                     };
                 }
-                ref kind => {
+                kind => {
                     span_bug!(terminator.source_info.span, "{:?} not promotable", kind);
                 }
             };
@@ -849,54 +847,50 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
             let local_decls = &mut self.source.local_decls;
             let loc = candidate.location;
             let statement = &mut blocks[loc.block].statements[loc.statement_index];
-            match statement.kind {
-                StatementKind::Assign(box (
-                    _,
-                    Rvalue::Ref(ref mut region, borrow_kind, ref mut place),
-                )) => {
-                    // Use the underlying local for this (necessarily interior) borrow.
-                    let ty = local_decls[place.local].ty;
-                    let span = statement.source_info.span;
-
-                    let ref_ty = tcx.mk_ref(
-                        tcx.lifetimes.re_erased,
-                        ty::TypeAndMut { ty, mutbl: borrow_kind.to_mutbl_lossy() },
-                    );
+            let StatementKind::Assign(box (_, Rvalue::Ref(region, borrow_kind, place))) = &mut statement.kind else {
+                bug!()
+            };
 
-                    *region = tcx.lifetimes.re_erased;
-
-                    let mut projection = vec![PlaceElem::Deref];
-                    projection.extend(place.projection);
-                    place.projection = tcx.intern_place_elems(&projection);
-
-                    // Create a temp to hold the promoted reference.
-                    // This is because `*r` requires `r` to be a local,
-                    // otherwise we would use the `promoted` directly.
-                    let mut promoted_ref = LocalDecl::new(ref_ty, span);
-                    promoted_ref.source_info = statement.source_info;
-                    let promoted_ref = local_decls.push(promoted_ref);
-                    assert_eq!(self.temps.push(TempState::Unpromotable), promoted_ref);
-
-                    let promoted_ref_statement = Statement {
-                        source_info: statement.source_info,
-                        kind: StatementKind::Assign(Box::new((
-                            Place::from(promoted_ref),
-                            Rvalue::Use(promoted_operand(ref_ty, span)),
-                        ))),
-                    };
-                    self.extra_statements.push((loc, promoted_ref_statement));
-
-                    Rvalue::Ref(
-                        tcx.lifetimes.re_erased,
-                        borrow_kind,
-                        Place {
-                            local: mem::replace(&mut place.local, promoted_ref),
-                            projection: List::empty(),
-                        },
-                    )
-                }
-                _ => bug!(),
-            }
+            // Use the underlying local for this (necessarily interior) borrow.
+            let ty = local_decls[place.local].ty;
+            let span = statement.source_info.span;
+
+            let ref_ty = tcx.mk_ref(
+                tcx.lifetimes.re_erased,
+                ty::TypeAndMut { ty, mutbl: borrow_kind.to_mutbl_lossy() },
+            );
+
+            *region = tcx.lifetimes.re_erased;
+
+            let mut projection = vec![PlaceElem::Deref];
+            projection.extend(place.projection);
+            place.projection = tcx.intern_place_elems(&projection);
+
+            // Create a temp to hold the promoted reference.
+            // This is because `*r` requires `r` to be a local,
+            // otherwise we would use the `promoted` directly.
+            let mut promoted_ref = LocalDecl::new(ref_ty, span);
+            promoted_ref.source_info = statement.source_info;
+            let promoted_ref = local_decls.push(promoted_ref);
+            assert_eq!(self.temps.push(TempState::Unpromotable), promoted_ref);
+
+            let promoted_ref_statement = Statement {
+                source_info: statement.source_info,
+                kind: StatementKind::Assign(Box::new((
+                    Place::from(promoted_ref),
+                    Rvalue::Use(promoted_operand(ref_ty, span)),
+                ))),
+            };
+            self.extra_statements.push((loc, promoted_ref_statement));
+
+            Rvalue::Ref(
+                tcx.lifetimes.re_erased,
+                *borrow_kind,
+                Place {
+                    local: mem::replace(&mut place.local, promoted_ref),
+                    projection: List::empty(),
+                },
+            )
         };
 
         assert_eq!(self.new_block(), START_BLOCK);
diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs
index 5c9263dc5..dd168a9ac 100644
--- a/compiler/rustc_const_eval/src/transform/validate.rs
+++ b/compiler/rustc_const_eval/src/transform/validate.rs
@@ -1,7 +1,8 @@
 //! Validates the MIR to ensure that invariants are upheld.
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_index::bit_set::BitSet;
+use rustc_index::vec::IndexVec;
 use rustc_infer::traits::Reveal;
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::mir::visit::NonUseContext::VarDebugInfo;
@@ -9,8 +10,8 @@ use rustc_middle::mir::visit::{PlaceContext, Visitor};
 use rustc_middle::mir::{
     traversal, AggregateKind, BasicBlock, BinOp, Body, BorrowKind, CastKind, CopyNonOverlapping,
     Local, Location, MirPass, MirPhase, NonDivergingIntrinsic, Operand, Place, PlaceElem, PlaceRef,
-    ProjectionElem, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind, Terminator,
-    TerminatorKind, UnOp, START_BLOCK,
+    ProjectionElem, RetagKind, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind,
+    Terminator, TerminatorKind, UnOp, START_BLOCK,
 };
 use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitable};
 use rustc_mir_dataflow::impls::MaybeStorageLive;
@@ -18,7 +19,7 @@ use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_mir_dataflow::{Analysis, ResultsCursor};
 use rustc_target::abi::{Size, VariantIdx};
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 enum EdgeKind {
     Unwind,
     Normal,
@@ -52,23 +53,25 @@ impl<'tcx> MirPass<'tcx> for Validator {
         };
 
         let always_live_locals = always_storage_live_locals(body);
-        let storage_liveness = MaybeStorageLive::new(always_live_locals)
+        let storage_liveness = MaybeStorageLive::new(std::borrow::Cow::Owned(always_live_locals))
             .into_engine(tcx, body)
             .iterate_to_fixpoint()
             .into_results_cursor(body);
 
-        TypeChecker {
+        let mut checker = TypeChecker {
             when: &self.when,
             body,
             tcx,
             param_env,
             mir_phase,
+            unwind_edge_count: 0,
             reachable_blocks: traversal::reachable_as_bitset(body),
             storage_liveness,
             place_cache: Vec::new(),
             value_cache: Vec::new(),
-        }
-        .visit_body(body);
+        };
+        checker.visit_body(body);
+        checker.check_cleanup_control_flow();
     }
 }
 
@@ -78,8 +81,9 @@ struct TypeChecker<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     param_env: ParamEnv<'tcx>,
     mir_phase: MirPhase,
+    unwind_edge_count: usize,
     reachable_blocks: BitSet<BasicBlock>,
-    storage_liveness: ResultsCursor<'a, 'tcx, MaybeStorageLive>,
+    storage_liveness: ResultsCursor<'a, 'tcx, MaybeStorageLive<'static>>,
     place_cache: Vec<PlaceRef<'tcx>>,
     value_cache: Vec<u128>,
 }
@@ -102,7 +106,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         );
     }
 
-    fn check_edge(&self, location: Location, bb: BasicBlock, edge_kind: EdgeKind) {
+    fn check_edge(&mut self, location: Location, bb: BasicBlock, edge_kind: EdgeKind) {
         if bb == START_BLOCK {
             self.fail(location, "start block must not have predecessors")
         }
@@ -111,10 +115,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             match (src.is_cleanup, bb.is_cleanup, edge_kind) {
                 // Non-cleanup blocks can jump to non-cleanup blocks along non-unwind edges
                 (false, false, EdgeKind::Normal)
-                // Non-cleanup blocks can jump to cleanup blocks along unwind edges
-                | (false, true, EdgeKind::Unwind)
                 // Cleanup blocks can jump to cleanup blocks along non-unwind edges
                 | (true, true, EdgeKind::Normal) => {}
+                // Non-cleanup blocks can jump to cleanup blocks along unwind edges
+                (false, true, EdgeKind::Unwind) => {
+                    self.unwind_edge_count += 1;
+                }
                 // All other jumps are invalid
                 _ => {
                     self.fail(
@@ -134,6 +140,88 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    fn check_cleanup_control_flow(&self) {
+        if self.unwind_edge_count <= 1 {
+            return;
+        }
+        let doms = self.body.basic_blocks.dominators();
+        let mut post_contract_node = FxHashMap::default();
+        // Reusing the allocation across invocations of the closure
+        let mut dom_path = vec![];
+        let mut get_post_contract_node = |mut bb| {
+            let root = loop {
+                if let Some(root) = post_contract_node.get(&bb) {
+                    break *root;
+                }
+                let parent = doms.immediate_dominator(bb);
+                dom_path.push(bb);
+                if !self.body.basic_blocks[parent].is_cleanup {
+                    break bb;
+                }
+                bb = parent;
+            };
+            for bb in dom_path.drain(..) {
+                post_contract_node.insert(bb, root);
+            }
+            root
+        };
+
+        let mut parent = IndexVec::from_elem(None, &self.body.basic_blocks);
+        for (bb, bb_data) in self.body.basic_blocks.iter_enumerated() {
+            if !bb_data.is_cleanup || !self.reachable_blocks.contains(bb) {
+                continue;
+            }
+            let bb = get_post_contract_node(bb);
+            for s in bb_data.terminator().successors() {
+                let s = get_post_contract_node(s);
+                if s == bb {
+                    continue;
+                }
+                let parent = &mut parent[bb];
+                match parent {
+                    None => {
+                        *parent = Some(s);
+                    }
+                    Some(e) if *e == s => (),
+                    Some(e) => self.fail(
+                        Location { block: bb, statement_index: 0 },
+                        format!(
+                            "Cleanup control flow violation: The blocks dominated by {:?} have edges to both {:?} and {:?}",
+                            bb,
+                            s,
+                            *e
+                        )
+                    ),
+                }
+            }
+        }
+
+        // Check for cycles
+        let mut stack = FxHashSet::default();
+        for i in 0..parent.len() {
+            let mut bb = BasicBlock::from_usize(i);
+            stack.clear();
+            stack.insert(bb);
+            loop {
+                let Some(parent)= parent[bb].take() else {
+                    break
+                };
+                let no_cycle = stack.insert(parent);
+                if !no_cycle {
+                    self.fail(
+                        Location { block: bb, statement_index: 0 },
+                        format!(
+                            "Cleanup control flow violation: Cycle involving edge {:?} -> {:?}",
+                            bb, parent,
+                        ),
+                    );
+                    break;
+                }
+                bb = parent;
+            }
+        }
+    }
+
     /// Check if src can be assigned into dest.
     /// This is not precise, it will accept some incorrect assignments.
     fn mir_assign_valid_types(&self, src: Ty<'tcx>, dest: Ty<'tcx>) -> bool {
@@ -241,7 +329,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 };
 
                 let kind = match parent_ty.ty.kind() {
-                    &ty::Opaque(def_id, substs) => {
+                    &ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
                         self.tcx.bound_type_of(def_id).subst(self.tcx, substs).kind()
                     }
                     kind => kind,
@@ -652,7 +740,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     self.fail(location, "`SetDiscriminant`is not allowed until deaggregation");
                 }
                 let pty = place.ty(&self.body.local_decls, self.tcx).ty.kind();
-                if !matches!(pty, ty::Adt(..) | ty::Generator(..) | ty::Opaque(..)) {
+                if !matches!(pty, ty::Adt(..) | ty::Generator(..) | ty::Alias(ty::Opaque, ..)) {
                     self.fail(
                         location,
                         format!(
@@ -667,10 +755,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     self.fail(location, "`Deinit`is not allowed until deaggregation");
                 }
             }
-            StatementKind::Retag(_, _) => {
+            StatementKind::Retag(kind, _) => {
                 // FIXME(JakobDegen) The validator should check that `self.mir_phase <
                 // DropsLowered`. However, this causes ICEs with generation of drop shims, which
                 // seem to fail to set their `MirPhase` correctly.
+                if *kind == RetagKind::Raw || *kind == RetagKind::TwoPhase {
+                    self.fail(location, format!("explicit `{:?}` is forbidden", kind));
+                }
             }
             StatementKind::StorageLive(..)
             | StatementKind::StorageDead(..)
@@ -686,17 +777,8 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             TerminatorKind::Goto { target } => {
                 self.check_edge(location, *target, EdgeKind::Normal);
             }
-            TerminatorKind::SwitchInt { targets, switch_ty, discr } => {
-                let ty = discr.ty(&self.body.local_decls, self.tcx);
-                if ty != *switch_ty {
-                    self.fail(
-                        location,
-                        format!(
-                            "encountered `SwitchInt` terminator with type mismatch: {:?} != {:?}",
-                            ty, switch_ty,
-                        ),
-                    );
-                }
+            TerminatorKind::SwitchInt { targets, discr } => {
+                let switch_ty = discr.ty(&self.body.local_decls, self.tcx);
 
                 let target_width = self.tcx.sess.target.pointer_width;