move PlaceholderIndices into MirTypeckRegionConstraints struct

src/librustc_mir/borrow_check/nll/mod.rs

@@ -107,7 +107,6 @@ pub(in borrow_check) fn compute_regions<'cx, 'gcx, 'tcx>(
     // Run the MIR type-checker.
     let MirTypeckResults {
         constraints,
-        placeholder_indices,
         universal_region_relations,
     } = type_check::type_check(
         infcx,
@@ -123,8 +122,6 @@ pub(in borrow_check) fn compute_regions<'cx, 'gcx, 'tcx>(
         elements,
     );
 
-    let placeholder_indices = Rc::new(placeholder_indices);
-
     if let Some(all_facts) = &mut all_facts {
         all_facts
             .universal_region
@@ -136,11 +133,13 @@ pub(in borrow_check) fn compute_regions<'cx, 'gcx, 'tcx>(
     // base constraints generated by the type-check.
     let var_origins = infcx.take_region_var_origins();
     let MirTypeckRegionConstraints {
+        placeholder_indices,
         mut liveness_constraints,
         outlives_constraints,
         closure_bounds_mapping,
         type_tests,
     } = constraints;
+    let placeholder_indices = Rc::new(placeholder_indices);
 
     constraint_generation::generate_constraints(
         infcx,

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -126,12 +126,12 @@ pub(crate) fn type_check<'gcx, 'tcx>(
 ) -> MirTypeckResults<'tcx> {
     let implicit_region_bound = infcx.tcx.mk_region(ty::ReVar(universal_regions.fr_fn_body));
     let mut constraints = MirTypeckRegionConstraints {
+        placeholder_indices: PlaceholderIndices::default(),
         liveness_constraints: LivenessValues::new(elements),
         outlives_constraints: ConstraintSet::default(),
         closure_bounds_mapping: Default::default(),
         type_tests: Vec::default(),
     };
-    let mut placeholder_indices = PlaceholderIndices::default();
 
     let CreateResult {
         universal_region_relations,
@@ -151,7 +151,6 @@ pub(crate) fn type_check<'gcx, 'tcx>(
         borrow_set,
         all_facts,
         constraints: &mut constraints,
-        placeholder_indices: &mut placeholder_indices,
     };
 
     type_check_internal(
@@ -175,7 +174,6 @@ pub(crate) fn type_check<'gcx, 'tcx>(
 
     MirTypeckResults {
         constraints,
-        placeholder_indices,
         universal_region_relations,
     }
 }
@@ -730,18 +728,18 @@ struct BorrowCheckContext<'a, 'tcx: 'a> {
     all_facts: &'a mut Option<AllFacts>,
     borrow_set: &'a BorrowSet<'tcx>,
     constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
-    placeholder_indices: &'a mut PlaceholderIndices,
 }
 
 crate struct MirTypeckResults<'tcx> {
     crate constraints: MirTypeckRegionConstraints<'tcx>,
-    crate placeholder_indices: PlaceholderIndices,
     crate universal_region_relations: Rc<UniversalRegionRelations<'tcx>>,
 }
 
 /// A collection of region constraints that must be satisfied for the
 /// program to be considered well-typed.
 crate struct MirTypeckRegionConstraints<'tcx> {
+    crate placeholder_indices: PlaceholderIndices,
+
     /// In general, the type-checker is not responsible for enforcing
     /// liveness constraints; this job falls to the region inferencer,
     /// which performs a liveness analysis. However, in some limited

src/librustc_mir/borrow_check/nll/type_check/relate_tys.rs

@@ -83,7 +83,7 @@ impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, '_, 'tcx> {
     fn next_placeholder_region(&mut self, placeholder: ty::Placeholder) -> ty::Region<'tcx> {
         let origin = NLLRegionVariableOrigin::Placeholder(placeholder);
         if let Some(borrowck_context) = &mut self.borrowck_context {
-            borrowck_context.placeholder_indices.insert(placeholder);
+            borrowck_context.constraints.placeholder_indices.insert(placeholder);
         }
         self.infcx.next_nll_region_var(origin)
     }