Remove DesugaringKind::Replace.

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1635,34 +1635,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             })
     }
 
-    /// Reports StorageDeadOrDrop of `place` conflicts with `borrow`.
-    ///
-    /// Depending on the origin of the StorageDeadOrDrop, this may be
-    /// reported as either a drop or an illegal mutation of a borrowed value.
-    /// The latter is preferred when the this is a drop triggered by a
-    /// reassignment, as it's more user friendly to report a problem with the
-    /// explicit assignment than the implicit drop.
-    #[instrument(level = "debug", skip(self))]
-    pub(crate) fn report_storage_dead_or_drop_of_borrowed(
-        &mut self,
-        location: Location,
-        place_span: (Place<'tcx>, Span),
-        borrow: &BorrowData<'tcx>,
-    ) {
-        // It's sufficient to check the last desugaring as Replace is the last
-        // one to be applied.
-        if let Some(DesugaringKind::Replace) = place_span.1.desugaring_kind() {
-            self.report_illegal_mutation_of_borrowed(location, place_span, borrow)
-        } else {
-            self.report_borrowed_value_does_not_live_long_enough(
-                location,
-                borrow,
-                place_span,
-                Some(WriteKind::StorageDeadOrDrop),
-            )
-        }
-    }
-
     /// This means that some data referenced by `borrow` needs to live
     /// past the point where the StorageDeadOrDrop of `place` occurs.
     /// This is usually interpreted as meaning that `place` has too

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -641,13 +641,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             let Some(hir::Node::Item(item)) = node else { return; };
             let hir::ItemKind::Fn(.., body_id) = item.kind else { return; };
             let body = self.infcx.tcx.hir().body(body_id);
-            let mut assign_span = span;
-            // Drop desugaring is done at MIR build so it's not in the HIR
-            if let Some(DesugaringKind::Replace) = span.desugaring_kind() {
-                assign_span.remove_mark();
-            }
 
-            let mut v = V { assign_span, err, ty, suggested: false };
+            let mut v = V { assign_span: span, err, ty, suggested: false };
             v.visit_body(body);
             if !v.suggested {
                 err.help(format!(

compiler/rustc_borrowck/src/invalidation.rs

@@ -112,11 +112,13 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
             TerminatorKind::SwitchInt { discr, targets: _ } => {
                 self.consume_operand(location, discr);
             }
-            TerminatorKind::Drop { place: drop_place, target: _, unwind: _ } => {
+            TerminatorKind::Drop { place: drop_place, target: _, unwind: _, replace } => {
+                let write_kind =
+                    if *replace { WriteKind::Replace } else { WriteKind::StorageDeadOrDrop };
                 self.access_place(
                     location,
                     *drop_place,
-                    (AccessDepth::Drop, Write(WriteKind::StorageDeadOrDrop)),
+                    (AccessDepth::Drop, Write(write_kind)),
                     LocalMutationIsAllowed::Yes,
                 );
             }

compiler/rustc_borrowck/src/lib.rs

@@ -685,17 +685,19 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
             TerminatorKind::SwitchInt { discr, targets: _ } => {
                 self.consume_operand(loc, (discr, span), flow_state);
             }
-            TerminatorKind::Drop { place, target: _, unwind: _ } => {
+            TerminatorKind::Drop { place, target: _, unwind: _, replace } => {
                 debug!(
                     "visit_terminator_drop \
                      loc: {:?} term: {:?} place: {:?} span: {:?}",
                     loc, term, place, span
                 );
 
+                let write_kind =
+                    if *replace { WriteKind::Replace } else { WriteKind::StorageDeadOrDrop };
                 self.access_place(
                     loc,
                     (*place, span),
-                    (AccessDepth::Drop, Write(WriteKind::StorageDeadOrDrop)),
+                    (AccessDepth::Drop, Write(write_kind)),
                     LocalMutationIsAllowed::Yes,
                     flow_state,
                 );
@@ -885,6 +887,7 @@ enum ReadKind {
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 enum WriteKind {
     StorageDeadOrDrop,
+    Replace,
     MutableBorrow(BorrowKind),
     Mutate,
     Move,
@@ -1132,13 +1135,21 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             this.buffer_error(err);
                         }
                         WriteKind::StorageDeadOrDrop => this
-                            .report_storage_dead_or_drop_of_borrowed(location, place_span, borrow),
+                            .report_borrowed_value_does_not_live_long_enough(
+                                location,
+                                borrow,
+                                place_span,
+                                Some(WriteKind::StorageDeadOrDrop),
+                            ),
                         WriteKind::Mutate => {
                             this.report_illegal_mutation_of_borrowed(location, place_span, borrow)
                         }
                         WriteKind::Move => {
                             this.report_move_out_while_borrowed(location, place_span, borrow)
                         }
+                        WriteKind::Replace => {
+                            this.report_illegal_mutation_of_borrowed(location, place_span, borrow)
+                        }
                     }
                     Control::Break
                 }
@@ -1982,12 +1993,14 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
             Reservation(
                 WriteKind::Move
+                | WriteKind::Replace
                 | WriteKind::StorageDeadOrDrop
                 | WriteKind::MutableBorrow(BorrowKind::Shared)
                 | WriteKind::MutableBorrow(BorrowKind::Shallow),
             )
             | Write(
                 WriteKind::Move
+                | WriteKind::Replace
                 | WriteKind::StorageDeadOrDrop
                 | WriteKind::MutableBorrow(BorrowKind::Shared)
                 | WriteKind::MutableBorrow(BorrowKind::Shallow),