Avoid cloning Place in describe_place_for_conflicting_borrow

Author: spastorino

src/librustc_mir/borrow_check/conflict_errors.rs

@@ -275,11 +275,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             "report_move_out_while_borrowed: location={:?} place={:?} span={:?} borrow={:?}",
             location, place, span, borrow
         );
-        let value_msg = match self.describe_place(place) {
+        let value_msg = match self.describe_place(place.as_place_ref()) {
             Some(name) => format!("`{}`", name),
             None => "value".to_owned(),
         };
-        let borrow_msg = match self.describe_place(&borrow.borrowed_place) {
+        let borrow_msg = match self.describe_place(borrow.borrowed_place.as_place_ref()) {
             Some(name) => format!("`{}`", name),
             None => "value".to_owned(),
         };
@@ -292,7 +292,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
         let mut err = self.cannot_move_when_borrowed(
             span,
-            &self.describe_place(place).unwrap_or_else(|| "_".to_owned()),
+            &self.describe_place(place.as_place_ref()).unwrap_or_else(|| "_".to_owned()),
         );
         err.span_label(borrow_span, format!("borrow of {} occurs here", borrow_msg));
         err.span_label(span, format!("move out of {} occurs here", value_msg));
@@ -331,15 +331,16 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
         let mut err = self.cannot_use_when_mutably_borrowed(
             span,
-            &self.describe_place(place).unwrap_or_else(|| "_".to_owned()),
+            &self.describe_place(place.as_place_ref()).unwrap_or_else(|| "_".to_owned()),
             borrow_span,
-            &self.describe_place(&borrow.borrowed_place)
+            &self.describe_place(borrow.borrowed_place.as_place_ref())
                 .unwrap_or_else(|| "_".to_owned()),
         );
 
         borrow_spans.var_span_label(&mut err, {
             let place = &borrow.borrowed_place;
-            let desc_place = self.describe_place(place).unwrap_or_else(|| "_".to_owned());
+            let desc_place =
+                self.describe_place(place.as_place_ref()).unwrap_or_else(|| "_".to_owned());
 
             format!("borrow occurs due to use of `{}`{}", desc_place, borrow_spans.describe())
         });
@@ -516,7 +517,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             );
         } else {
             let borrow_place = &issued_borrow.borrowed_place;
-            let borrow_place_desc = self.describe_place(borrow_place)
+            let borrow_place_desc = self.describe_place(borrow_place.as_place_ref())
                                         .unwrap_or_else(|| "_".to_owned());
             issued_spans.var_span_label(
                 &mut err,
@@ -615,9 +616,9 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 while let Some(box Projection { base: base_proj, elem }) = current {
                     match elem {
                         ProjectionElem::Field(field, _) if union_ty(base, base_proj).is_some() => {
-                            return Some((Place {
-                                base: base.clone(),
-                                projection: base_proj.clone(),
+                            return Some((PlaceRef {
+                                base: base,
+                                projection: base_proj,
                             }, field));
                         },
                         _ => current = base_proj,
@@ -639,18 +640,18 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     if let ProjectionElem::Field(field, _) = elem {
                         if let Some(union_ty) = union_ty(base, proj_base) {
                             if field != target_field
-                                && *base == target_base.base
-                                && *proj_base == target_base.projection {
+                                && base == target_base.base
+                                && proj_base == target_base.projection {
                                 // FIXME when we avoid clone reuse describe_place closure
-                                let describe_base_place =  self.describe_place(&Place {
-                                    base: base.clone(),
-                                    projection: proj_base.clone(),
+                                let describe_base_place =  self.describe_place(PlaceRef {
+                                    base: base,
+                                    projection: proj_base,
                                 }).unwrap_or_else(|| "_".to_owned());
 
                                 return Some((
                                     describe_base_place,
-                                    describe_place(first_borrowed_place),
-                                    describe_place(second_borrowed_place),
+                                    describe_place(first_borrowed_place.as_place_ref()),
+                                    describe_place(second_borrowed_place.as_place_ref()),
                                     union_ty.to_string(),
                                 ));
                             }
@@ -665,7 +666,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 // If we didn't find a field access into a union, or both places match, then
                 // only return the description of the first place.
                 (
-                    describe_place(first_borrowed_place),
+                    describe_place(first_borrowed_place.as_place_ref()),
                     "".to_string(),
                     "".to_string(),
                     "".to_string(),
@@ -743,7 +744,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             }
         }
 
-        let place_desc = self.describe_place(&borrow.borrowed_place);
+        let place_desc = self.describe_place(borrow.borrowed_place.as_place_ref());
 
         let kind_place = kind.filter(|_| place_desc.is_some()).map(|k| (k, place_span.0));
         let explanation = self.explain_why_borrow_contains_point(location, &borrow, kind_place);
@@ -950,12 +951,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
         let mut err = self.cannot_borrow_across_destructor(borrow_span);
 
-        let what_was_dropped = match self.describe_place(place) {
+        let what_was_dropped = match self.describe_place(place.as_place_ref()) {
             Some(name) => format!("`{}`", name.as_str()),
             None => String::from("temporary value"),
         };
 
-        let label = match self.describe_place(&borrow.borrowed_place) {
+        let label = match self.describe_place(borrow.borrowed_place.as_place_ref()) {
             Some(borrowed) => format!(
                 "here, drop of {D} needs exclusive access to `{B}`, \
                  because the type `{T}` implements the `Drop` trait",
@@ -1389,7 +1390,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             let mut err = self.cannot_mutate_in_match_guard(
                 span,
                 loan_span,
-                &self.describe_place(place).unwrap_or_else(|| "_".to_owned()),
+                &self.describe_place(place.as_place_ref()).unwrap_or_else(|| "_".to_owned()),
                 "assign",
             );
             loan_spans.var_span_label(
@@ -1405,7 +1406,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let mut err = self.cannot_assign_to_borrowed(
             span,
             loan_span,
-            &self.describe_place(place).unwrap_or_else(|| "_".to_owned()),
+            &self.describe_place(place.as_place_ref()).unwrap_or_else(|| "_".to_owned()),
         );
 
         loan_spans.var_span_label(
@@ -1465,8 +1466,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 is_user_variable: None,
                 ..
             })
-            | None => (self.describe_place(place), assigned_span),
-            Some(decl) => (self.describe_place(err_place), decl.source_info.span),
+            | None => (self.describe_place(place.as_place_ref()), assigned_span),
+            Some(decl) => (self.describe_place(err_place.as_place_ref()), decl.source_info.span),
         };
 
         let mut err = self.cannot_reassign_immutable(

src/librustc_mir/borrow_check/error_reporting.rs

@@ -121,8 +121,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
     /// End-user visible description of `place` if one can be found. If the
     /// place is a temporary for instance, None will be returned.
-    pub(super) fn describe_place(&self, place: &Place<'tcx>) -> Option<String> {
-        self.describe_place_with_options(place.as_place_ref(), IncludingDowncast(false))
+    pub(super) fn describe_place(&self, place_ref: PlaceRef<'cx, 'tcx>) -> Option<String> {
+        self.describe_place_with_options(place_ref, IncludingDowncast(false))
     }
 
     /// End-user visible description of `place` if one can be found. If the

src/librustc_mir/borrow_check/move_errors.rs

@@ -277,7 +277,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         span: Span
     ) -> DiagnosticBuilder<'a> {
         let description = if place.projection.is_none() {
-            format!("static item `{}`", self.describe_place(place).unwrap())
+            format!("static item `{}`", self.describe_place(place.as_place_ref()).unwrap())
         } else {
             let mut base_static = &place.projection;
             while let Some(box Projection { base: Some(ref proj), .. }) = base_static {
@@ -290,8 +290,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
             format!(
                 "`{:?}` as `{:?}` is a static item",
-                self.describe_place(place).unwrap(),
-                self.describe_place(&base_static).unwrap(),
+                self.describe_place(place.as_place_ref()).unwrap(),
+                self.describe_place(base_static.as_place_ref()).unwrap(),
             )
         };
 
@@ -363,7 +363,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 let upvar_name = upvar.name;
                 let upvar_span = self.infcx.tcx.hir().span(upvar_hir_id);
 
-                let place_name = self.describe_place(move_place).unwrap();
+                let place_name = self.describe_place(move_place.as_place_ref()).unwrap();
 
                 let place_description = if self
                     .is_upvar_field_projection(move_place.as_place_ref())
@@ -392,7 +392,10 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             }
             _ => {
                 let source = self.borrowed_content_source(&deref_base);
-                match (self.describe_place(move_place), source.describe_for_named_place()) {
+                match (
+                    self.describe_place(move_place.as_place_ref()),
+                    source.describe_for_named_place(),
+                ) {
                     (Some(place_desc), Some(source_desc)) => {
                         self.cannot_move_out_of(
                             span,
@@ -452,7 +455,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
                 if binds_to.is_empty() {
                     let place_ty = move_from.ty(self.body, self.infcx.tcx).ty;
-                    let place_desc = match self.describe_place(&move_from) {
+                    let place_desc = match self.describe_place(move_from.as_place_ref()) {
                         Some(desc) => format!("`{}`", desc),
                         None => format!("value"),
                     };
@@ -480,7 +483,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             GroupedMoveError::OtherIllegalMove { ref original_path, use_spans, .. } => {
                 let span = use_spans.var_or_use();
                 let place_ty = original_path.ty(self.body, self.infcx.tcx).ty;
-                let place_desc = match self.describe_place(original_path) {
+                let place_desc = match self.describe_place(original_path.as_place_ref()) {
                     Some(desc) => format!("`{}`", desc),
                     None => format!("value"),
                 };

src/librustc_mir/borrow_check/mutability_errors.rs

@@ -40,7 +40,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         let item_msg;
         let reason;
         let mut opt_source = None;
-        let access_place_desc = self.describe_place(access_place);
+        let access_place_desc = self.describe_place(access_place.as_place_ref());
         debug!("report_mutability_error: access_place_desc={:?}", access_place_desc);
 
         match the_place_err {
@@ -236,7 +236,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     format!(
                         "mutable borrow occurs due to use of `{}` in closure",
                         // always Some() if the message is printed.
-                        self.describe_place(access_place).unwrap_or_default(),
+                        self.describe_place(access_place.as_place_ref()).unwrap_or_default(),
                     )
                 );
                 borrow_span

src/librustc_mir/borrow_check/nll/explain_borrow/mod.rs

@@ -304,7 +304,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             region,
                         );
                     if let Some(region_name) = region_name {
-                        let opt_place_desc = self.describe_place(&borrow.borrowed_place);
+                        let opt_place_desc =
+                            self.describe_place(borrow.borrowed_place.as_place_ref());
                         BorrowExplanation::MustBeValidFor {
                             category,
                             from_closure,