Take ownership of RegionInferenceContext in Borrows struct

Author: Nashenas88

src/librustc_mir/borrow_check/mod.rs

@@ -84,7 +84,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
     let mir = &mut mir;
 
     // Replace all regions with fresh inference variables.
-    let num_region_variables = nll::renumber::renumber_mir(infcx, mir);
+    let free_regions = nll::replace_regions_in_mir(infcx, src, mir);
 
     let move_data: MoveData<'tcx> = match MoveData::gather_moves(mir, tcx, param_env) {
         Ok(move_data) => move_data,
@@ -127,7 +127,13 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
     let opt_regioncx = if !tcx.sess.opts.debugging_opts.nll {
         None
     } else {
-        Some(nll::compute_regions(infcx, src, param_env, mir, num_region_variables, &flow_inits, &mdpe.move_data))
+        Some(nll::compute_regions(infcx,
+                                  src,
+                                  &free_regions,
+                                  mir,
+                                  param_env,
+                                  &flow_inits,
+                                  &mdpe.move_data))
     };
 
     let mut mbcx = MirBorrowckCtxt {
@@ -139,7 +145,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
     };
 
     let flow_borrows = FlowInProgress::new(do_dataflow(tcx, mir, id, &attributes, &dead_unwinds,
-                                   Borrows::new(tcx, mir, opt_regioncx.as_ref()),
+                                   Borrows::new(tcx, mir, opt_regioncx),
                                    |bd, i| bd.location(i)));
 
     let mut state = InProgress::new(flow_borrows,

src/librustc_mir/transform/nll/free_regions.rs renamed to src/librustc_mir/borrow_check/nll/free_regions.rs

@@ -26,24 +26,53 @@ use self::mir_util::PassWhere;
 mod constraint_generation;
 mod subtype_constraint_generation;
 mod free_regions;
+use self::free_regions::FreeRegions;
 
 pub(crate) mod region_infer;
 use self::region_infer::RegionInferenceContext;
 
-pub(super) mod renumber;
+mod renumber;
+
+/// Rewrites the regions in the MIR to use NLL variables, also
+/// scraping out the set of free regions (e.g., region parameters)
+/// declared on the function. That set will need to be given to
+/// `compute_regions`.
+pub(super) fn replace_regions_in_mir<'a, 'gcx, 'tcx>(
+    infcx: &InferCtxt<'a, 'gcx, 'tcx>,
+    source: MirSource,
+    mir: &mut Mir<'tcx>
+) -> FreeRegions<'tcx> {
+    // Compute named region information.
+    let free_regions = free_regions::free_regions(infcx, source);
+
+    // Replace all regions with fresh inference variables.
+    renumber::renumber_mir(infcx, &free_regions, mir);
+
+    free_regions
+}
 
 /// Computes the (non-lexical) regions from the input MIR.
 ///
 /// This may result in errors being reported.
 pub(super) fn compute_regions<'a, 'gcx, 'tcx>(
     infcx: &InferCtxt<'a, 'gcx, 'tcx>,
     source: MirSource,
+    free_regions: &FreeRegions<'tcx>,
     mir: &Mir<'tcx>,
     param_env: ty::ParamEnv<'gcx>,
-    num_region_variables: usize,
     flow_inits: &FlowInProgress<MaybeInitializedLvals<'a, 'gcx, 'tcx>>,
     move_data: &MoveData<'tcx>,
-) -> RegionInferenceContext {
+) -> RegionInferenceContext<'tcx> {
+    // Run the MIR type-checker.
+    let body_id = source.item_id();
+    let constraint_sets = &type_check::type_check(infcx, body_id, param_env, mir);
+
+    // Create the region inference context, taking ownership of the region inference
+    // data that was contained in `infcx`.
+    let var_origins = infcx.take_region_var_origins();
+    let mut regioncx = RegionInferenceContext::new(var_origins, free_regions, mir);
+    subtype_constraint_generation::generate(&mut regioncx, free_regions, mir, constraint_sets);
+
     // Compute what is live where.
     let liveness = &LivenessResults {
         regular: liveness::liveness_of_locals(

src/librustc_mir/borrow_check/nll/mod.rs

@@ -38,7 +38,7 @@ pub struct Borrows<'a, 'gcx: 'tcx, 'tcx: 'a> {
     location_map: FxHashMap<Location, BorrowIndex>,
     region_map: FxHashMap<Region<'tcx>, FxHashSet<BorrowIndex>>,
     region_span_map: FxHashMap<RegionKind, Span>,
-    nonlexical_regioncx: Option<&'a RegionInferenceContext<'tcx>>,
+    nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>,
 }
 
 // temporarily allow some dead fields: `kind` and `region` will be
@@ -69,7 +69,7 @@ impl<'tcx> fmt::Display for BorrowData<'tcx> {
 impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
     pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>,
                mir: &'a Mir<'tcx>,
-               nonlexical_regioncx: Option<&'a RegionInferenceContext<'tcx>>)
+               nonlexical_regioncx: Option<RegionInferenceContext<'tcx>>)
                -> Self {
         let mut visitor = GatherBorrows { idx_vec: IndexVec::new(),
                                           location_map: FxHashMap(),
@@ -137,7 +137,7 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
     fn kill_loans_out_of_scope_at_location(&self,
                                            sets: &mut BlockSets<BorrowIndex>,
                                            location: Location) {
-        if let Some(regioncx) = self.nonlexical_regioncx {
+        if let Some(ref regioncx) = self.nonlexical_regioncx {
             for (borrow_index, borrow_data) in self.borrows.iter_enumerated() {
                 let borrow_region = borrow_data.region.to_region_vid();
                 if !regioncx.region_contains_point(borrow_region, location) {