Avoid Rc in BodyWithBorrowckFacts.

It can own these two fields.

compiler/rustc_borrowck/src/consumers.rs

@@ -1,7 +1,5 @@
 //! This file provides API for compiler consumers.
 
-use std::rc::Rc;
-
 use rustc_hir::def_id::LocalDefId;
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::mir::{Body, Promoted};
@@ -65,10 +63,10 @@ pub struct BodyWithBorrowckFacts<'tcx> {
     /// The mir bodies of promoteds.
     pub promoted: IndexVec<Promoted, Body<'tcx>>,
     /// The set of borrows occurring in `body` with data about them.
-    pub borrow_set: Rc<BorrowSet<'tcx>>,
+    pub borrow_set: BorrowSet<'tcx>,
     /// Context generated during borrowck, intended to be passed to
     /// [`calculate_borrows_out_of_scope_at_location`].
-    pub region_inference_context: Rc<RegionInferenceContext<'tcx>>,
+    pub region_inference_context: RegionInferenceContext<'tcx>,
     /// The table that maps Polonius points to locations in the table.
     /// Populated when using [`ConsumerOptions::PoloniusInputFacts`]
     /// or [`ConsumerOptions::PoloniusOutputFacts`].

compiler/rustc_borrowck/src/lib.rs

@@ -20,7 +20,6 @@ use std::cell::RefCell;
 use std::collections::BTreeMap;
 use std::marker::PhantomData;
 use std::ops::Deref;
-use std::rc::Rc;
 
 use consumers::{BodyWithBorrowckFacts, ConsumerOptions};
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -420,8 +419,8 @@ fn do_mir_borrowck<'tcx>(
         Some(Box::new(BodyWithBorrowckFacts {
             body: body_owned,
             promoted,
-            borrow_set: Rc::new(borrow_set),
-            region_inference_context: Rc::new(regioncx),
+            borrow_set,
+            region_inference_context: regioncx,
             location_table: polonius_input.as_ref().map(|_| location_table),
             input_facts: polonius_input,
             output_facts,