construct the BorrowSet outside of borrows

src/librustc_mir/borrow_check/mod.rs

@@ -46,7 +46,7 @@ use util::collect_writes::FindAssignments;
 
 use std::iter;
 
-use self::borrow_set::BorrowData;
+use self::borrow_set::{BorrowSet, BorrowData};
 use self::flows::Flows;
 use self::prefixes::PrefixSet;
 use self::MutateMode::{JustWrite, WriteAndRead};
@@ -192,6 +192,8 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
         |bd, i| DebugFormatted::new(&bd.move_data().inits[i]),
     ));
 
+    let borrow_set = BorrowSet::build(tcx, mir);
+
     // If we are in non-lexical mode, compute the non-lexical lifetimes.
     let (opt_regioncx, opt_closure_req) = if let Some(free_regions) = free_regions {
         let (regioncx, opt_closure_req) = nll::compute_regions(
@@ -216,7 +218,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
         id,
         &attributes,
         &dead_unwinds,
-        Borrows::new(tcx, mir, opt_regioncx.clone(), def_id, body_id),
+        Borrows::new(tcx, mir, opt_regioncx.clone(), def_id, body_id, borrow_set),
         |rs, i| {
             DebugFormatted::new(&(i.kind(), rs.location(i.borrow_index())))
         }

src/librustc_mir/dataflow/impls/borrows.rs

@@ -69,17 +69,18 @@ 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<Rc<RegionInferenceContext<'tcx>>>,
-               def_id: DefId,
-               body_id: Option<hir::BodyId>)
-               -> Self {
+    crate fn new(
+        tcx: TyCtxt<'a, 'gcx, 'tcx>,
+        mir: &'a Mir<'tcx>,
+        nonlexical_regioncx: Option<Rc<RegionInferenceContext<'tcx>>>,
+        def_id: DefId,
+        body_id: Option<hir::BodyId>,
+        borrow_set: BorrowSet<'tcx>
+    ) -> Self {
         let scope_tree = tcx.region_scope_tree(def_id);
         let root_scope = body_id.map(|body_id| {
             region::Scope::CallSite(tcx.hir.body(body_id).value.hir_id.local_id)
         });
-        let borrow_set = BorrowSet::build(tcx, mir);
 
         Borrows {
             tcx: tcx,

src/librustc_mir/dataflow/impls/mod.rs

@@ -38,7 +38,6 @@ mod borrowed_locals;
 
 pub use self::borrowed_locals::*;
 
-#[allow(dead_code)]
 pub(super) mod borrows;
 
 /// `MaybeInitializedPlaces` tracks all places that might be