use Rc to store nonlexical_regioncx in Borrows

src/librustc_mir/borrow_check/mod.rs

@@ -25,6 +25,8 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::indexed_set::IdxSetBuf;
 use rustc_data_structures::indexed_vec::Idx;
 
+use std::rc::Rc;
+
 use syntax::ast;
 use syntax_pos::Span;
 
@@ -202,7 +204,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
             &mut flow_inits,
             &mdpe.move_data,
         );
-        (Some(regioncx), opt_closure_req)
+        (Some(Rc::new(regioncx)), opt_closure_req)
     } else {
         assert!(!tcx.sess.opts.debugging_opts.nll);
         (None, None)

src/librustc_mir/dataflow/impls/borrows.rs

@@ -66,7 +66,7 @@ pub struct Borrows<'a, 'gcx: 'tcx, 'tcx: 'a> {
     region_map: FxHashMap<Region<'tcx>, FxHashSet<BorrowIndex>>,
     local_map: FxHashMap<mir::Local, FxHashSet<BorrowIndex>>,
     region_span_map: FxHashMap<RegionKind, Span>,
-    nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>,
+    nonlexical_regioncx: Option<Rc<RegionInferenceContext<'tcx>>>,
 }
 
 // Two-phase borrows actually requires two flow analyses; they need
@@ -147,7 +147,7 @@ impl ReserveOrActivateIndex {
 impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
     pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>,
                mir: &'a Mir<'tcx>,
-               nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>,
+               nonlexical_regioncx: Option<Rc<RegionInferenceContext<'tcx>>>,
                def_id: DefId,
                body_id: Option<hir::BodyId>)
                -> Self {