remove DerefTemp and CopyFromDeref from runtime mir

beepster4096 · beepster4096 · commit 8d66edcb0082 · 2025-09-18T14:24:17.000-07:00
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
@@ -1539,24 +1539,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                 self.consume_operand(location, (operand, span), state)
             }
 
-            &Rvalue::CopyForDeref(place) => {
-                self.access_place(
-                    location,
-                    (place, span),
-                    (Deep, Read(ReadKind::Copy)),
-                    LocalMutationIsAllowed::No,
-                    state,
-                );
-
-                // Finally, check if path was already moved.
-                self.check_if_path_or_subpath_is_moved(
-                    location,
-                    InitializationRequiringAction::Use,
-                    (place.as_ref(), span),
-                    state,
-                );
-            }
-
             &Rvalue::Discriminant(place) => {
                 let af = match *rvalue {
                     Rvalue::Discriminant(..) => None,
@@ -1618,6 +1600,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
             Rvalue::WrapUnsafeBinder(op, _) => {
                 self.consume_operand(location, (op, span), state);
             }
+
+            Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in borrowck"),
         }
     }
 
diff --git a/compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs b/compiler/rustc_borrowck/src/polonius/legacy/loan_invalidations.rs
@@ -301,11 +301,6 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
             | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/)
             | Rvalue::ShallowInitBox(operand, _ /*ty*/) => self.consume_operand(location, operand),
 
-            &Rvalue::CopyForDeref(place) => {
-                let op = &Operand::Copy(place);
-                self.consume_operand(location, op);
-            }
-
             &Rvalue::Discriminant(place) => {
                 self.access_place(
                     location,
@@ -331,6 +326,8 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {
             Rvalue::WrapUnsafeBinder(op, _) => {
                 self.consume_operand(location, op);
             }
+
+            Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in borrowck"),
         }
     }
 
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -600,11 +600,6 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:
                     let val = codegen_operand(fx, operand);
                     lval.write_cvalue(fx, val);
                 }
-                Rvalue::CopyForDeref(place) => {
-                    let cplace = codegen_place(fx, place);
-                    let val = cplace.to_cvalue(fx);
-                    lval.write_cvalue(fx, val)
-                }
                 Rvalue::Ref(_, _, place) | Rvalue::RawPtr(_, place) => {
                     let place = codegen_place(fx, place);
                     let ref_ = place.place_ref(fx, lval.layout());
@@ -928,6 +923,7 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:
                     let operand = codegen_operand(fx, operand);
                     lval.write_cvalue_transmute(fx, operand);
                 }
+                Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in codegen"),
             }
         }
         StatementKind::StorageLive(_)
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -500,9 +500,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 self.codegen_place_to_pointer(bx, place, mk_ref)
             }
 
-            mir::Rvalue::CopyForDeref(place) => {
-                self.codegen_operand(bx, &mir::Operand::Copy(place))
-            }
             mir::Rvalue::RawPtr(kind, place) => {
                 let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| {
                     Ty::new_ptr(tcx, ty, kind.to_mutbl_lossy())
@@ -738,6 +735,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let layout = bx.cx().layout_of(binder_ty);
                 OperandRef { val: operand.val, layout }
             }
+            mir::Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in codegen"),
         }
     }
 
diff --git a/compiler/rustc_const_eval/src/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
@@ -234,7 +234,7 @@ where
 
         Rvalue::Discriminant(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
 
-        Rvalue::CopyForDeref(place) => in_place::<Q, _>(cx, in_local, place.as_ref()),
+        Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
 
         Rvalue::Use(operand)
         | Rvalue::Repeat(operand, _)
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -188,10 +188,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 self.copy_op(&op, &dest)?;
             }
 
-            CopyForDeref(place) => {
-                let op = self.eval_place_to_op(place, Some(dest.layout))?;
-                self.copy_op(&op, &dest)?;
-            }
+            CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
 
             BinaryOp(bin_op, box (ref left, ref right)) => {
                 let layout = util::binop_left_homogeneous(bin_op).then_some(dest.layout);
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
@@ -1065,7 +1065,11 @@ pub enum LocalInfo<'tcx> {
     /// A temporary created during evaluating `if` predicate, possibly for pattern matching for `let`s,
     /// and subject to Edition 2024 temporary lifetime rules
     IfThenRescopeTemp { if_then: HirId },
-    /// A temporary created during the pass `Derefer` to avoid it's retagging
+    /// A temporary created during the pass `Derefer` treated as a transparent alias
+    /// for the place its copied from by analysis passes such as `AddRetag` and `ElaborateDrops`.
+    ///
+    /// It may only be written to by a `CopyForDeref` and otherwise only accessed through a deref.
+    /// In runtime MIR, it is replaced with a normal `Boring` local.
     DerefTemp,
     /// A temporary created for borrow checking.
     FakeBorrow,
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
@@ -130,7 +130,9 @@ pub enum RuntimePhase {
     /// * [`TerminatorKind::Yield`]
     /// * [`TerminatorKind::CoroutineDrop`]
     /// * [`Rvalue::Aggregate`] for any `AggregateKind` except `Array`
+    /// * [`Rvalue::CopyForDeref`]
     /// * [`PlaceElem::OpaqueCast`]
+    /// * [`LocalInfo::DerefTemp`](super::LocalInfo::DerefTemp)
     ///
     /// And the following variants are allowed:
     /// * [`StatementKind::Retag`]
@@ -1472,11 +1474,13 @@ pub enum Rvalue<'tcx> {
     /// A CopyForDeref is equivalent to a read from a place at the
     /// codegen level, but is treated specially by drop elaboration. When such a read happens, it
     /// is guaranteed (via nature of the mir_opt `Derefer` in rustc_mir_transform/src/deref_separator)
-    /// that the only use of the returned value is a deref operation, immediately
-    /// followed by one or more projections. Drop elaboration treats this rvalue as if the
+    /// that the returned value is written into a `DerefTemp` local and that its only use is a deref operation,
+    /// immediately followed by one or more projections. Drop elaboration treats this rvalue as if the
     /// read never happened and just projects further. This allows simplifying various MIR
     /// optimizations and codegen backends that previously had to handle deref operations anywhere
     /// in a place.
+    ///
+    /// Disallowed in runtime MIR and is replaced by normal copies.
     CopyForDeref(Place<'tcx>),
 
     /// Wraps a value in an unsafe binder.
diff --git a/compiler/rustc_mir_transform/src/copy_prop.rs b/compiler/rustc_mir_transform/src/copy_prop.rs
@@ -74,9 +74,7 @@ fn fully_moved_locals(ssa: &SsaLocals, body: &Body<'_>) -> DenseBitSet<Local> {
     let mut fully_moved = DenseBitSet::new_filled(body.local_decls.len());
 
     for (_, rvalue, _) in ssa.assignments(body) {
-        let (Rvalue::Use(Operand::Copy(place) | Operand::Move(place))
-        | Rvalue::CopyForDeref(place)) = rvalue
-        else {
+        let Rvalue::Use(Operand::Copy(place) | Operand::Move(place)) = rvalue else {
             continue;
         };
 
@@ -85,7 +83,7 @@ fn fully_moved_locals(ssa: &SsaLocals, body: &Body<'_>) -> DenseBitSet<Local> {
             continue;
         }
 
-        if let Rvalue::Use(Operand::Copy(_)) | Rvalue::CopyForDeref(_) = rvalue {
+        if let Rvalue::Use(Operand::Copy(_)) = rvalue {
             fully_moved.remove(rhs);
         }
     }
@@ -146,8 +144,7 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {
 
         // Do not leave tautological assignments around.
         if let StatementKind::Assign(box (lhs, ref rhs)) = stmt.kind
-            && let Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)) | Rvalue::CopyForDeref(rhs) =
-                *rhs
+            && let Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)) = *rhs
             && lhs == rhs
         {
             stmt.make_nop();
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -309,12 +309,7 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
                     self.assign_operand(state, target, operand);
                 }
             }
-            Rvalue::CopyForDeref(rhs) => {
-                state.flood(target.as_ref(), &self.map);
-                if let Some(target) = self.map.find(target.as_ref()) {
-                    self.assign_operand(state, target, &Operand::Copy(*rhs));
-                }
-            }
+            Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
             Rvalue::Aggregate(kind, operands) => {
                 // If we assign `target = Enum::Variant#0(operand)`,
                 // we must make sure that all `target as Variant#i` are `Top`.
@@ -488,9 +483,7 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
             }
             Rvalue::Discriminant(place) => state.get_discr(place.as_ref(), &self.map),
             Rvalue::Use(operand) => return self.handle_operand(operand, state),
-            Rvalue::CopyForDeref(place) => {
-                return self.handle_operand(&Operand::Copy(*place), state);
-            }
+            Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
             Rvalue::Ref(..) | Rvalue::RawPtr(..) => {
                 // We don't track such places.
                 return ValueOrPlace::TOP;
diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs
@@ -285,8 +285,7 @@ impl<'tcx> MutVisitor<'tcx> for Merger<'tcx> {
         match &statement.kind {
             StatementKind::Assign(box (dest, rvalue)) => {
                 match rvalue {
-                    Rvalue::CopyForDeref(place)
-                    | Rvalue::Use(Operand::Copy(place) | Operand::Move(place)) => {
+                    Rvalue::Use(Operand::Copy(place) | Operand::Move(place)) => {
                         // These might've been turned into self-assignments by the replacement
                         // (this includes the original statement we wanted to eliminate).
                         if dest == place {
@@ -400,7 +399,7 @@ impl<'tcx> Visitor<'tcx> for FindAssignments<'_, 'tcx> {
     fn visit_statement(&mut self, statement: &Statement<'tcx>, _: Location) {
         if let StatementKind::Assign(box (
             lhs,
-            Rvalue::CopyForDeref(rhs) | Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)),
+            Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)),
         )) = &statement.kind
             && let Some(src) = lhs.as_local()
             && let Some(dest) = rhs.as_local()
diff --git a/compiler/rustc_mir_transform/src/erase_deref_temps.rs b/compiler/rustc_mir_transform/src/erase_deref_temps.rs
@@ -0,0 +1,41 @@
+//! This pass converts all `DerefTemp` locals into normal temporaries
+//! and turns their `CopyForDeref` rvalues into normal copies.
+
+use rustc_middle::mir::visit::MutVisitor;
+use rustc_middle::mir::*;
+use rustc_middle::ty::TyCtxt;
+
+struct EraseDerefTempsVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'tcx> MutVisitor<'tcx> for EraseDerefTempsVisitor<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>, _: Location) {
+        if let &mut Rvalue::CopyForDeref(place) = rvalue {
+            *rvalue = Rvalue::Use(Operand::Copy(place))
+        }
+    }
+
+    fn visit_local_decl(&mut self, _: Local, local_decl: &mut LocalDecl<'tcx>) {
+        if local_decl.is_deref_temp() {
+            let info = local_decl.local_info.as_mut().unwrap_crate_local();
+            **info = LocalInfo::Boring;
+        }
+    }
+}
+
+pub(super) struct EraseDerefTemps;
+
+impl<'tcx> crate::MirPass<'tcx> for EraseDerefTemps {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        EraseDerefTempsVisitor { tcx }.visit_body_preserves_cfg(body);
+    }
+
+    fn is_required(&self) -> bool {
+        true
+    }
+}
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
@@ -806,12 +806,6 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
         let value = match *rvalue {
             // Forward values.
             Rvalue::Use(ref mut operand) => return self.simplify_operand(operand, location),
-            Rvalue::CopyForDeref(place) => {
-                let mut operand = Operand::Copy(place);
-                let val = self.simplify_operand(&mut operand, location);
-                *rvalue = Rvalue::Use(operand);
-                return val;
-            }
 
             // Roots.
             Rvalue::Repeat(ref mut op, amount) => {
@@ -853,6 +847,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
 
             // Unsupported values.
             Rvalue::ThreadLocalRef(..) | Rvalue::ShallowInitBox(..) => return None,
+            Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in runtime MIR"),
         };
         let ty = rvalue.ty(self.local_decls, self.tcx);
         Some(self.insert(ty, value))
diff --git a/compiler/rustc_mir_transform/src/jump_threading.rs b/compiler/rustc_mir_transform/src/jump_threading.rs
@@ -455,7 +455,6 @@ impl<'a, 'tcx> TOFinder<'a, 'tcx> {
         match rhs {
             Rvalue::Use(operand) => self.process_operand(bb, lhs, operand, state),
             // Transfer the conditions on the copy rhs.
-            Rvalue::CopyForDeref(rhs) => self.process_operand(bb, lhs, &Operand::Copy(*rhs), state),
             Rvalue::Discriminant(rhs) => {
                 let Some(rhs) = self.map.find_discr(rhs.as_ref()) else { return };
                 state.insert_place_idx(rhs, lhs, &self.map);
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
@@ -139,6 +139,7 @@ declare_passes! {
     mod dest_prop : DestinationPropagation;
     pub mod dump_mir : Marker;
     mod early_otherwise_branch : EarlyOtherwiseBranch;
+    mod erase_deref_temps : EraseDerefTemps;
     mod elaborate_box_derefs : ElaborateBoxDerefs;
     mod elaborate_drops : ElaborateDrops;
     mod function_item_references : FunctionItemReferences;
@@ -619,6 +620,7 @@ fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         // `AddRetag` needs to run after `ElaborateDrops` but before `ElaborateBoxDerefs`.
         // Otherwise it should run fairly late, but before optimizations begin.
         &add_retag::AddRetag,
+        &erase_deref_temps::EraseDerefTemps,
         &elaborate_box_derefs::ElaborateBoxDerefs,
         &coroutine::StateTransform,
         &Lint(known_panics_lint::KnownPanicsLint),
diff --git a/compiler/rustc_mir_transform/src/ref_prop.rs b/compiler/rustc_mir_transform/src/ref_prop.rs
@@ -247,8 +247,7 @@ fn compute_replacement<'tcx>(
             // This is a copy, just use the value we have in store for the previous one.
             // As we are visiting in `assignment_order`, ie. reverse postorder, `rhs` should
             // have been visited before.
-            Rvalue::Use(Operand::Copy(place) | Operand::Move(place))
-            | Rvalue::CopyForDeref(place) => {
+            Rvalue::Use(Operand::Copy(place) | Operand::Move(place)) => {
                 if let Some(rhs) = place.as_local()
                     && ssa.is_ssa(rhs)
                 {
diff --git a/compiler/rustc_mir_transform/src/shim/async_destructor_ctor.rs b/compiler/rustc_mir_transform/src/shim/async_destructor_ctor.rs
@@ -240,7 +240,7 @@ fn build_adrop_for_coroutine_shim<'tcx>(
                 source_info,
                 StatementKind::Assign(Box::new((
                     Place::from(proxy_ref_local),
-                    Rvalue::CopyForDeref(proxy_ref_place),
+                    Rvalue::Use(Operand::Copy(proxy_ref_place)),
                 ))),
             ),
         );
@@ -261,7 +261,7 @@ fn build_adrop_for_coroutine_shim<'tcx>(
                         source_info,
                         StatementKind::Assign(Box::new((
                             Place::from(cor_ptr_local),
-                            Rvalue::CopyForDeref(impl_ptr_place),
+                            Rvalue::Use(Operand::Copy(impl_ptr_place)),
                         ))),
                     ),
                 );
@@ -334,7 +334,7 @@ fn build_adrop_for_adrop_shim<'tcx>(
         source_info,
         StatementKind::Assign(Box::new((
             Place::from(proxy_ref_local),
-            Rvalue::CopyForDeref(proxy_ref_place),
+            Rvalue::Use(Operand::Copy(proxy_ref_place)),
         ))),
     ));
 
@@ -350,7 +350,7 @@ fn build_adrop_for_adrop_shim<'tcx>(
                 source_info,
                 StatementKind::Assign(Box::new((
                     Place::from(cor_ptr_local),
-                    Rvalue::CopyForDeref(impl_ptr_place),
+                    Rvalue::Use(Operand::Copy(impl_ptr_place)),
                 ))),
             ));
         }
diff --git a/compiler/rustc_mir_transform/src/ssa.rs b/compiler/rustc_mir_transform/src/ssa.rs
@@ -297,9 +297,7 @@ fn compute_copy_classes(ssa: &mut SsaLocals, body: &Body<'_>) {
     let mut copies = IndexVec::from_fn_n(|l| l, body.local_decls.len());
 
     for (local, rvalue, _) in ssa.assignments(body) {
-        let (Rvalue::Use(Operand::Copy(place) | Operand::Move(place))
-        | Rvalue::CopyForDeref(place)) = rvalue
-        else {
+        let Rvalue::Use(Operand::Copy(place) | Operand::Move(place)) = rvalue else {
             continue;
         };
 
diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs

Original file line number	Diff line number	Diff line change
`@@ -301,11 +301,6 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {`
`301`	`301`	`\| Rvalue::Cast(_ /cast_kind/, operand, _ /ty/)`
`302`	`302`	`\| Rvalue::ShallowInitBox(operand, _ /ty/) => self.consume_operand(location, operand),`
`303`	`303`
`304`		`- &Rvalue::CopyForDeref(place) => {`
`305`		`- let op = &Operand::Copy(place);`
`306`		`- self.consume_operand(location, op);`
`307`		`- }`
`308`		`-`
`309`	`304`	`&Rvalue::Discriminant(place) => {`
`310`	`305`	`self.access_place(`
`311`	`306`	`location,`
`@@ -331,6 +326,8 @@ impl<'a, 'tcx> LoanInvalidationsGenerator<'a, 'tcx> {`
`331`	`326`	`Rvalue::WrapUnsafeBinder(op, _) => {`
`332`	`327`	`self.consume_operand(location, op);`
`333`	`328`	`}`
	`329`	`+`
	`330`	+ Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in borrowck"),
`334`	`331`	`}`
`335`	`332`	`}`
`336`	`333`
Original file line number	Diff line number	Diff line change
`@@ -600,11 +600,6 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:`
`600`	`600`	`let val = codegen_operand(fx, operand);`
`601`	`601`	`lval.write_cvalue(fx, val);`
`602`	`602`	`}`
`603`		`- Rvalue::CopyForDeref(place) => {`
`604`		`- let cplace = codegen_place(fx, place);`
`605`		`- let val = cplace.to_cvalue(fx);`
`606`		`- lval.write_cvalue(fx, val)`
`607`		`- }`
`608`	`603`	`Rvalue::Ref(_, _, place) \| Rvalue::RawPtr(_, place) => {`
`609`	`604`	`let place = codegen_place(fx, place);`
`610`	`605`	`let ref_ = place.place_ref(fx, lval.layout());`
`@@ -928,6 +923,7 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:`
`928`	`923`	`let operand = codegen_operand(fx, operand);`
`929`	`924`	`lval.write_cvalue_transmute(fx, operand);`
`930`	`925`	`}`
	`926`	+ Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in codegen"),
`931`	`927`	`}`
`932`	`928`	`}`
`933`	`929`	`StatementKind::StorageLive(_)`
Original file line number	Diff line number	Diff line change
`@@ -500,9 +500,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {`
`500`	`500`	`self.codegen_place_to_pointer(bx, place, mk_ref)`
`501`	`501`	`}`
`502`	`502`
`503`		`- mir::Rvalue::CopyForDeref(place) => {`
`504`		`- self.codegen_operand(bx, &mir::Operand::Copy(place))`
`505`		`- }`
`506`	`503`	`mir::Rvalue::RawPtr(kind, place) => {`
`507`	`504`	`let mk_ptr = move \|tcx: TyCtxt<'tcx>, ty: Ty<'tcx>\| {`
`508`	`505`	`Ty::new_ptr(tcx, ty, kind.to_mutbl_lossy())`
`@@ -738,6 +735,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {`
`738`	`735`	`let layout = bx.cx().layout_of(binder_ty);`
`739`	`736`	`OperandRef { val: operand.val, layout }`
`740`	`737`	`}`
	`738`	+ mir::Rvalue::CopyForDeref(_) => bug!("`CopyForDeref` in codegen"),
`741`	`739`	`}`
`742`	`740`	`}`
`743`	`741`
Original file line number	Diff line number	Diff line change
`@@ -74,9 +74,7 @@ fn fully_moved_locals(ssa: &SsaLocals, body: &Body<'_>) -> DenseBitSet<Local> {`
`74`	`74`	`let mut fully_moved = DenseBitSet::new_filled(body.local_decls.len());`
`75`	`75`
`76`	`76`	`for (_, rvalue, _) in ssa.assignments(body) {`
`77`		`- let (Rvalue::Use(Operand::Copy(place) \| Operand::Move(place))`
`78`		`- \| Rvalue::CopyForDeref(place)) = rvalue`
`79`		`- else {`
	`77`	`+ let Rvalue::Use(Operand::Copy(place) \| Operand::Move(place)) = rvalue else {`
`80`	`78`	`continue;`
`81`	`79`	`};`
`82`	`80`
`@@ -85,7 +83,7 @@ fn fully_moved_locals(ssa: &SsaLocals, body: &Body<'_>) -> DenseBitSet<Local> {`
`85`	`83`	`continue;`
`86`	`84`	`}`
`87`	`85`
`88`		`- if let Rvalue::Use(Operand::Copy(_)) \| Rvalue::CopyForDeref(_) = rvalue {`
	`86`	`+ if let Rvalue::Use(Operand::Copy(_)) = rvalue {`
`89`	`87`	`fully_moved.remove(rhs);`
`90`	`88`	`}`
`91`	`89`	`}`
`@@ -146,8 +144,7 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {`
`146`	`144`
`147`	`145`	`// Do not leave tautological assignments around.`
`148`	`146`	`if let StatementKind::Assign(box (lhs, ref rhs)) = stmt.kind`
`149`		`- && let Rvalue::Use(Operand::Copy(rhs) \| Operand::Move(rhs)) \| Rvalue::CopyForDeref(rhs) =`
`150`		`- *rhs`
	`147`	`+ && let Rvalue::Use(Operand::Copy(rhs) \| Operand::Move(rhs)) = *rhs`
`151`	`148`	`&& lhs == rhs`
`152`	`149`	`{`
`153`	`150`	`stmt.make_nop();`