Strong type FreeRegion

gcc/rust/ChangeLog:

	* checks/errors/borrowck/rust-bir-builder-internal.h: Use
	STATIC_FREE_REGION, use value of FreeRegion for origin.
	* checks/errors/borrowck/rust-bir-builder.h: Use free region
	value.
	* checks/errors/borrowck/rust-bir-dump.cc (Dump::visit_scope):
	Likewise.
	* checks/errors/borrowck/rust-bir-fact-collector.h (points):
	Likewise.
	* checks/errors/borrowck/rust-bir-free-region.h (struct FreeRegion):
	Make FreeRegion a struct.
	* checks/errors/borrowck/rust-bir-place.h: Use FreeRegion
	instead of Origin in PlaceDB.
	* typecheck/rust-tyty-variance-analysis.cc (FieldVisitorCtx::add_constraints_from_region):
	Use value of FreeRegion for origin.
	(FieldVisitorCtx::add_constrints_from_param): Likewise.
	(Term::make_transform): Likewise.

Signed-off-by: Kushal Pal <kushalpal109@gmail.com>

7 files changed, 68 insertions, 37 deletions

diff --git a/gcc/rust/checks/errors/borrowck/rust-bir-builder-internal.h b/gcc/rust/checks/errors/borrowck/rust-bir-builder-internal.h
index 38a0449..ac93714 100644
--- a/gcc/rust/checks/errors/borrowck/rust-bir-builder-internal.h
+++ b/gcc/rust/checks/errors/borrowck/rust-bir-builder-internal.h
@@ -215,7 +215,7 @@ protected:
 	  }
 	else if (region.is_static ())
 	  {
-	    free_regions.push_back (0);
+	    free_regions.push_back (STATIC_FREE_REGION);
 	  }
 	else if (region.is_anonymous ())
 	  {
@@ -314,9 +314,10 @@ protected: // Helpers to add BIR statements
   {
     auto mutability = ty->as<const TyTy::ReferenceType> ()->mutability ();
     auto loan = ctx.place_db.add_loan ({mutability, place_id, location});
-    push_tmp_assignment (new BorrowExpr (place_id, loan,
-					 ctx.place_db.get_next_free_region ()),
-			 ty, location);
+    push_tmp_assignment (
+      new BorrowExpr (place_id, loan,
+		      ctx.place_db.get_next_free_region ().value),
+      ty, location);
     return translated;
   }
 
@@ -609,7 +610,7 @@ protected:
       {ty->as<const TyTy::ReferenceType> ()->mutability (), place_id,
        location});
     return_expr (new BorrowExpr (place_id, loan,
-				 ctx.place_db.get_next_free_region ()),
+				 ctx.place_db.get_next_free_region ().value),
 		 ty, location);
     return translated;
   }
diff --git a/gcc/rust/checks/errors/borrowck/rust-bir-builder.h b/gcc/rust/checks/errors/borrowck/rust-bir-builder.h
index 3a92872..9509e00 100644
--- a/gcc/rust/checks/errors/borrowck/rust-bir-builder.h
+++ b/gcc/rust/checks/errors/borrowck/rust-bir-builder.h
@@ -94,8 +94,8 @@ private:
 	  ctx.fn_free_regions[bound.second.get_index ()]);
 
 	auto last_bound = universal_region_bounds.back ();
-	rust_debug ("\t\t %lu: %lu", (unsigned long) last_bound.first,
-		    (unsigned long) last_bound.second);
+	rust_debug ("\t\t %lu: %lu", (unsigned long) last_bound.first.value,
+		    (unsigned long) last_bound.second.value);
       }
 
     // TODO: handle type_region constraints
@@ -178,7 +178,7 @@ private:
 	if (generic_param->get_kind ()
 	    == HIR::GenericParam::GenericKind::LIFETIME)
 	  {
-	    result[regions[region_index++]]
+	    result[regions[region_index++].value]
 	      = static_cast<HIR::LifetimeParam *> (generic_param.get ());
 	  }
       }
diff --git a/gcc/rust/checks/errors/borrowck/rust-bir-dump.cc b/gcc/rust/checks/errors/borrowck/rust-bir-dump.cc
index f9478a9..8d6b2bb 100644
--- a/gcc/rust/checks/errors/borrowck/rust-bir-dump.cc
+++ b/gcc/rust/checks/errors/borrowck/rust-bir-dump.cc
@@ -380,7 +380,7 @@ Dump::visit_scope (ScopeId id, size_t depth)
       print_comma_separated (stream,
 			     func.place_db[local].regions.get_regions (),
 			     [this] (FreeRegion region_id) {
-			       stream << "'?" << region_id;
+			       stream << "'?" << region_id.value;
 			     });
       stream << "]\n";
     }
diff --git a/gcc/rust/checks/errors/borrowck/rust-bir-fact-collector.h b/gcc/rust/checks/errors/borrowck/rust-bir-fact-collector.h
index 466e643..6ca5404 100644
--- a/gcc/rust/checks/errors/borrowck/rust-bir-fact-collector.h
+++ b/gcc/rust/checks/errors/borrowck/rust-bir-fact-collector.h
@@ -107,14 +107,15 @@ protected: // Main collection entry points (for different categories).
 
     for (auto &region : universal_regions)
       {
-	facts.universal_region.emplace_back (region);
-	facts.placeholder.emplace_back (region, next_loan++);
-	facts.known_placeholder_subset.emplace_back (0, region);
+	facts.universal_region.emplace_back (region.value);
+	facts.placeholder.emplace_back (region.value, next_loan++);
+	facts.known_placeholder_subset.emplace_back (0, region.value);
       }
 
     // Copy already collected subset facts, that are universally valid.
     for (auto &bound : universal_region_bounds)
-      facts.known_placeholder_subset.emplace_back (bound.first, bound.second);
+      facts.known_placeholder_subset.emplace_back (bound.first.value,
+						   bound.second.value);
   }
 
   void visit_places (const std::vector<PlaceId> &args)
@@ -131,7 +132,7 @@ protected: // Main collection entry points (for different categories).
 	    facts.path_is_var.emplace_back (place_id.value, place_id.value);
 	    for (auto &region : place.regions)
 	      facts.use_of_var_derefs_origin.emplace_back (place_id.value,
-							   region);
+							   region.value);
 
 	    // TODO: drop_of_var_derefs_origin
 	    break;
@@ -178,10 +179,11 @@ protected: // Main collection entry points (for different categories).
 
     rust_debug ("\tSanitize deref of %s", base.tyty->as_string ().c_str ());
 
-    std::vector<Polonius::Origin> regions;
+    std::vector<FreeRegion> regions;
     regions.insert (regions.end (), base.regions.begin () + 1,
 		    base.regions.end ());
-    FreeRegions r (std::move (regions));
+    FreeRegions r;
+    r.set_from (std::move (regions));
     push_subset_all (place.tyty, r, place.regions);
   }
   void sanizite_field (PlaceId place_id)
@@ -199,7 +201,8 @@ protected: // Main collection entry points (for different categories).
 	       .query_field_regions (base.tyty->as<TyTy::ADTType> (), 0,
 				     place.variable_or_field_index,
 				     base.regions); // FIXME
-    FreeRegions f (std::move (r));
+    FreeRegions f;
+    f.set_from (std::move (r));
     push_subset_all (place.tyty, f, place.regions);
   }
 
@@ -326,14 +329,14 @@ protected: // Main collection entry points (for different categories).
 	    issue_loan (expr.get_origin (), expr.get_loan ());
 	  }
 
-	push_subset (main_loan_place.regions[0], expr.get_origin ());
+	push_subset (main_loan_place.regions[0], {expr.get_origin ()});
       }
     else
       {
 	issue_loan (expr.get_origin (), expr.get_loan ());
       }
 
-    auto loan_regions = base_place.regions.prepend (expr.get_origin ());
+    auto loan_regions = base_place.regions.prepend ({expr.get_origin ()});
     push_subset (ref_place.tyty, loan_regions, ref_place.regions);
   }
 
@@ -632,19 +635,20 @@ protected: // Generic BIR operations.
 protected: // Subset helpers.
   void push_subset (FreeRegion lhs, FreeRegion rhs)
   {
-    rust_debug ("\t\tpush_subset: '?%lu: '?%lu", (unsigned long) lhs,
-		(unsigned long) rhs);
+    rust_debug ("\t\tpush_subset: '?%lu: '?%lu", (unsigned long) lhs.value,
+		(unsigned long) rhs.value);
 
-    facts.subset_base.emplace_back (lhs, rhs, get_current_point_mid ());
+    facts.subset_base.emplace_back (lhs.value, rhs.value,
+				    get_current_point_mid ());
   }
 
   void push_subset_all (FreeRegion lhs, FreeRegion rhs)
   {
-    rust_debug ("\t\tpush_subset_all: '?%lu: '?%lu", (unsigned long) lhs,
-		(unsigned long) rhs);
+    rust_debug ("\t\tpush_subset_all: '?%lu: '?%lu", (unsigned long) lhs.value,
+		(unsigned long) rhs.value);
 
     for (auto point : cfg_points_all)
-      facts.subset_base.emplace_back (lhs, rhs, point);
+      facts.subset_base.emplace_back (lhs.value, rhs.value, point);
   }
 
   void push_subset (Variance variance, FreeRegion lhs, FreeRegion rhs)
diff --git a/gcc/rust/checks/errors/borrowck/rust-bir-free-region.h b/gcc/rust/checks/errors/borrowck/rust-bir-free-region.h
index b8d73c9..95d4e11 100644
--- a/gcc/rust/checks/errors/borrowck/rust-bir-free-region.h
+++ b/gcc/rust/checks/errors/borrowck/rust-bir-free-region.h
@@ -24,7 +24,19 @@
 
 namespace Rust {
 
-using FreeRegion = size_t;
+struct FreeRegion
+{
+  size_t value;
+  // some overloads for comparision
+  bool operator== (const FreeRegion &rhs) const { return value == rhs.value; }
+  bool operator!= (const FreeRegion &rhs) const { return !(operator== (rhs)); }
+  bool operator< (const FreeRegion &rhs) const { return value < rhs.value; }
+  bool operator> (const FreeRegion &rhs) const { return value > rhs.value; }
+  bool operator<= (const FreeRegion &rhs) const { return !(operator> (rhs)); }
+  bool operator>= (const FreeRegion &rhs) const { return !(operator< (rhs)); }
+};
+
+static constexpr FreeRegion STATIC_FREE_REGION = {0};
 
 class FreeRegions
 {
@@ -46,6 +58,14 @@ public:
 	this->regions.push_back ({region});
       }
   }
+  void set_from (std::vector<FreeRegion> &&regions)
+  {
+    this->regions.clear ();
+    for (auto &region : regions)
+      {
+	this->regions.push_back (region);
+      }
+  }
 
   WARN_UNUSED_RESULT FreeRegions prepend (FreeRegion region) const
   {
@@ -55,13 +75,14 @@ public:
   }
 
   FreeRegions (std::vector<FreeRegion> &&regions) : regions (regions) {}
+  FreeRegions () {}
 
   WARN_UNUSED_RESULT std::string to_string () const
   {
     std::stringstream result;
     for (auto &region : regions)
       {
-	result << region;
+	result << region.value;
 	result << ", ";
       }
     // Remove the last ", " from the string.
@@ -83,7 +104,8 @@ public:
 
   WARN_UNUSED_RESULT FreeRegion get_next_free_region () const
   {
-    return next_free_region++;
+    ++next_free_region.value;
+    return {next_free_region.value - 1};
   }
 
   FreeRegions bind_regions (std::vector<TyTy::Region> regions,
@@ -95,7 +117,7 @@ public:
 	if (region.is_early_bound ())
 	  free_regions.push_back (parent_free_regions[region.get_index ()]);
 	else if (region.is_static ())
-	  free_regions.push_back (0);
+	  free_regions.push_back (STATIC_FREE_REGION);
 	else if (region.is_anonymous ())
 	  free_regions.push_back (get_next_free_region ());
 	else if (region.is_named ())
diff --git a/gcc/rust/checks/errors/borrowck/rust-bir-place.h b/gcc/rust/checks/errors/borrowck/rust-bir-place.h
index 3b0fad2..589aaf0 100644
--- a/gcc/rust/checks/errors/borrowck/rust-bir-place.h
+++ b/gcc/rust/checks/errors/borrowck/rust-bir-place.h
@@ -187,7 +187,7 @@ private:
 
   std::vector<Loan> loans;
 
-  Polonius::Origin next_free_region = 1;
+  FreeRegion next_free_region = {1};
 
 public:
   PlaceDB ()
@@ -216,7 +216,11 @@ public:
 
   const Scope &get_scope (ScopeId id) const { return scopes[id]; }
 
-  FreeRegion get_next_free_region () { return next_free_region++; }
+  FreeRegion get_next_free_region ()
+  {
+    ++next_free_region.value;
+    return {next_free_region.value - 1};
+  }
 
   FreeRegion peek_next_free_region () const { return next_free_region; }
 
@@ -256,8 +260,8 @@ public:
 		       ->get_variance_analysis_ctx ()
 		       .query_type_variances (new_place_ref.tyty);
     std::vector<Polonius::Origin> regions;
-    for (size_t i = 0; i < variances.size (); i++)
-      regions.push_back (next_free_region++);
+    for (size_t i = 0; i < variances.size (); ++i)
+      regions.push_back (next_free_region.value++);
 
     new_place_ref.regions.set_from (std::move (regions));
 
@@ -352,7 +356,7 @@ public:
 
   void set_next_free_region (Polonius::Origin next_free_region)
   {
-    this->next_free_region = next_free_region;
+    this->next_free_region.value = next_free_region;
   }
 
   PlaceId lookup_or_add_variable (NodeId id, TyTy::BaseType *tyty)
diff --git a/gcc/rust/typecheck/rust-tyty-variance-analysis.cc b/gcc/rust/typecheck/rust-tyty-variance-analysis.cc
index d7116f5..15c16db 100644
--- a/gcc/rust/typecheck/rust-tyty-variance-analysis.cc
+++ b/gcc/rust/typecheck/rust-tyty-variance-analysis.cc
@@ -570,7 +570,7 @@ FieldVisitorCtx::add_constraints_from_region (const Region &region,
 {
   if (region.is_early_bound ())
     {
-      regions.push_back (parent_regions[region.get_index ()]);
+      regions.push_back (parent_regions[region.get_index ()].value);
     }
   else if (region.is_late_bound ())
     {
@@ -585,7 +585,7 @@ FieldVisitorCtx::add_constrints_from_param (ParamType &param, Variance variance)
   for (size_t i = type_param_ranges[param_i];
        i < type_param_ranges[param_i + 1]; i++)
     {
-      regions.push_back (parent_regions[i]);
+      regions.push_back (parent_regions[i].value);
     }
 }
 
@@ -621,4 +621,4 @@ Term::make_transform (Term lhs, Term rhs)
 
 } // namespace VarianceAnalysis
 } // namespace TyTy
-} // namespace Rust
\ No newline at end of file
+} // namespace Rust