Avoid &Rc<T> arguments.

Either `&T` or `Rc<T>` is preferable.

compiler/rustc_borrowck/src/nll.rs

@@ -98,7 +98,7 @@ pub(crate) fn compute_regions<'a, 'tcx>(
 
     let universal_regions = Rc::new(universal_regions);
 
-    let elements = &Rc::new(DenseLocationMap::new(body));
+    let elements = Rc::new(DenseLocationMap::new(body));
 
     // Run the MIR type-checker.
     let MirTypeckResults { constraints, universal_region_relations, opaque_type_values } =
@@ -107,13 +107,13 @@ pub(crate) fn compute_regions<'a, 'tcx>(
             param_env,
             body,
             promoted,
-            &universal_regions,
+            universal_regions.clone(),
             location_table,
             borrow_set,
             &mut all_facts,
             flow_inits,
             move_data,
-            elements,
+            elements.clone(),
             upvars,
         );
 
@@ -165,7 +165,7 @@ pub(crate) fn compute_regions<'a, 'tcx>(
         universe_causes,
         type_tests,
         liveness_constraints,
-        elements,
+        elements.clone(),
     );
 
     // If requested: dump NLL facts, and run legacy polonius analysis.

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -407,7 +407,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         universe_causes: FxIndexMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
         type_tests: Vec<TypeTest<'tcx>>,
         liveness_constraints: LivenessValues,
-        elements: &Rc<DenseLocationMap>,
+        elements: Rc<DenseLocationMap>,
     ) -> Self {
         debug!("universal_regions: {:#?}", universal_regions);
         debug!("outlives constraints: {:#?}", outlives_constraints);
@@ -430,7 +430,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         }
 
         let mut scc_values =
-            RegionValues::new(elements, universal_regions.len(), &placeholder_indices);
+            RegionValues::new(elements, universal_regions.len(), placeholder_indices);
 
         for region in liveness_constraints.regions() {
             let scc = constraint_sccs.scc(region);

compiler/rustc_borrowck/src/region_infer/values.rs

@@ -275,15 +275,16 @@ impl<N: Idx> RegionValues<N> {
     /// Each of the regions in num_region_variables will be initialized with an
     /// empty set of points and no causal information.
     pub(crate) fn new(
-        elements: &Rc<DenseLocationMap>,
+        elements: Rc<DenseLocationMap>,
         num_universal_regions: usize,
-        placeholder_indices: &Rc<PlaceholderIndices>,
+        placeholder_indices: Rc<PlaceholderIndices>,
     ) -> Self {
+        let num_points = elements.num_points();
         let num_placeholders = placeholder_indices.len();
         Self {
-            elements: elements.clone(),
-            points: SparseIntervalMatrix::new(elements.num_points()),
-            placeholder_indices: placeholder_indices.clone(),
+            elements,
+            points: SparseIntervalMatrix::new(num_points),
+            placeholder_indices,
             free_regions: SparseBitMatrix::new(num_universal_regions),
             placeholders: SparseBitMatrix::new(num_placeholders),
         }

compiler/rustc_borrowck/src/type_check/free_region_relations.rs

@@ -54,15 +54,15 @@ pub(crate) fn create<'tcx>(
     infcx: &InferCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     implicit_region_bound: ty::Region<'tcx>,
-    universal_regions: &Rc<UniversalRegions<'tcx>>,
+    universal_regions: Rc<UniversalRegions<'tcx>>,
     constraints: &mut MirTypeckRegionConstraints<'tcx>,
 ) -> CreateResult<'tcx> {
     UniversalRegionRelationsBuilder {
         infcx,
         param_env,
         implicit_region_bound,
         constraints,
-        universal_regions: universal_regions.clone(),
+        universal_regions,
         region_bound_pairs: Default::default(),
         outlives: Default::default(),
         inverse_outlives: Default::default(),

compiler/rustc_borrowck/src/type_check/liveness/mod.rs

@@ -1,5 +1,3 @@
-use std::rc::Rc;
-
 use itertools::{Either, Itertools};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::mir::visit::{TyContext, Visitor};
@@ -33,7 +31,7 @@ mod trace;
 pub(super) fn generate<'a, 'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     body: &Body<'tcx>,
-    elements: &Rc<DenseLocationMap>,
+    elements: &DenseLocationMap,
     flow_inits: &mut ResultsCursor<'a, 'tcx, MaybeInitializedPlaces<'a, 'tcx>>,
     move_data: &MoveData<'tcx>,
 ) {

compiler/rustc_borrowck/src/type_check/liveness/trace.rs

@@ -1,5 +1,3 @@
-use std::rc::Rc;
-
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_index::bit_set::BitSet;
 use rustc_index::interval::IntervalSet;
@@ -40,7 +38,7 @@ use crate::type_check::{NormalizeLocation, TypeChecker};
 pub(super) fn trace<'a, 'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     body: &Body<'tcx>,
-    elements: &Rc<DenseLocationMap>,
+    elements: &DenseLocationMap,
     flow_inits: &mut ResultsCursor<'a, 'tcx, MaybeInitializedPlaces<'a, 'tcx>>,
     move_data: &MoveData<'tcx>,
     relevant_live_locals: Vec<Local>,

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -121,13 +121,13 @@ pub(crate) fn type_check<'a, 'tcx>(
     param_env: ty::ParamEnv<'tcx>,
     body: &Body<'tcx>,
     promoted: &IndexSlice<Promoted, Body<'tcx>>,
-    universal_regions: &Rc<UniversalRegions<'tcx>>,
+    universal_regions: Rc<UniversalRegions<'tcx>>,
     location_table: &LocationTable,
     borrow_set: &BorrowSet<'tcx>,
     all_facts: &mut Option<AllFacts>,
     flow_inits: &mut ResultsCursor<'a, 'tcx, MaybeInitializedPlaces<'a, 'tcx>>,
     move_data: &MoveData<'tcx>,
-    elements: &Rc<DenseLocationMap>,
+    elements: Rc<DenseLocationMap>,
     upvars: &[&ty::CapturedPlace<'tcx>],
 ) -> MirTypeckResults<'tcx> {
     let implicit_region_bound = ty::Region::new_var(infcx.tcx, universal_regions.fr_fn_body);
@@ -150,14 +150,14 @@ pub(crate) fn type_check<'a, 'tcx>(
         infcx,
         param_env,
         implicit_region_bound,
-        universal_regions,
+        universal_regions.clone(),
         &mut constraints,
     );
 
     debug!(?normalized_inputs_and_output);
 
     let mut borrowck_context = BorrowCheckContext {
-        universal_regions,
+        universal_regions: &universal_regions,
         location_table,
         borrow_set,
         all_facts,
@@ -181,10 +181,10 @@ pub(crate) fn type_check<'a, 'tcx>(
     verifier.visit_body(body);
 
     checker.typeck_mir(body);
-    checker.equate_inputs_and_outputs(body, universal_regions, &normalized_inputs_and_output);
+    checker.equate_inputs_and_outputs(body, &universal_regions, &normalized_inputs_and_output);
     checker.check_signature_annotation(body);
 
-    liveness::generate(&mut checker, body, elements, flow_inits, move_data);
+    liveness::generate(&mut checker, body, &elements, flow_inits, move_data);
 
     translate_outlives_facts(&mut checker);
     let opaque_type_values = infcx.take_opaque_types();