Reference Types can be mutable

We need to track mutability on Reference Types and check wether they
actually match up.

Addresses #576

5 files changed, 25 insertions, 11 deletions

diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index dd10d42..0749839 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -547,8 +547,9 @@ public:
 	  auto ok = context->lookup_builtin ("str", &base);
 	  rust_assert (ok);
 
-	  infered = new TyTy::ReferenceType (expr.get_mappings ().get_hirid (),
-					     TyTy::TyVar (base->get_ref ()));
+	  infered
+	    = new TyTy::ReferenceType (expr.get_mappings ().get_hirid (),
+				       TyTy::TyVar (base->get_ref ()), false);
 	}
 	break;
 
@@ -1088,7 +1089,8 @@ public:
     // FIXME double_reference
 
     infered = new TyTy::ReferenceType (expr.get_mappings ().get_hirid (),
-				       TyTy::TyVar (resolved_base->get_ref ()));
+				       TyTy::TyVar (resolved_base->get_ref ()),
+				       expr.get_is_mut ());
   }
 
   void visit (HIR::DereferenceExpr &expr) override
diff --git a/gcc/rust/typecheck/rust-hir-type-check-type.h b/gcc/rust/typecheck/rust-hir-type-check-type.h
index e9a3bde..567d482 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-type.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-type.h
@@ -190,7 +190,8 @@ public:
     TyTy::BaseType *base
       = TypeCheckType::Resolve (type.get_base_type ().get ());
     translated = new TyTy::ReferenceType (type.get_mappings ().get_hirid (),
-					  TyTy::TyVar (base->get_ref ()));
+					  TyTy::TyVar (base->get_ref ()),
+					  type.get_has_mut ());
   }
 
   void visit (HIR::InferredType &type) override
diff --git a/gcc/rust/typecheck/rust-tyty-rules.h b/gcc/rust/typecheck/rust-tyty-rules.h
index 5db005b..31d7191 100644
--- a/gcc/rust/typecheck/rust-tyty-rules.h
+++ b/gcc/rust/typecheck/rust-tyty-rules.h
@@ -1081,8 +1081,15 @@ public:
 	return;
       }
 
+    if (base->is_mutable () != type.is_mutable ())
+      {
+	BaseRules::visit (type);
+	return;
+      }
+
     resolved = new ReferenceType (base->get_ref (), base->get_ty_ref (),
-				  TyVar (base_resolved->get_ref ()));
+				  TyVar (base_resolved->get_ref ()),
+				  base->is_mutable ());
   }
 
 private:
diff --git a/gcc/rust/typecheck/rust-tyty.cc b/gcc/rust/typecheck/rust-tyty.cc
index e2c5f71..0eceaef 100644
--- a/gcc/rust/typecheck/rust-tyty.cc
+++ b/gcc/rust/typecheck/rust-tyty.cc
@@ -1355,7 +1355,8 @@ ReferenceType::accept_vis (TyConstVisitor &vis) const
 std::string
 ReferenceType::as_string () const
 {
-  return "&" + get_base ()->as_string ();
+  return std::string ("&") + (is_mutable () ? "mut" : "") + " "
+	 + get_base ()->as_string ();
 }
 
 BaseType *
@@ -1391,7 +1392,7 @@ ReferenceType::get_base () const
 BaseType *
 ReferenceType::clone ()
 {
-  return new ReferenceType (get_ref (), get_ty_ref (), base,
+  return new ReferenceType (get_ref (), get_ty_ref (), base, is_mutable (),
 			    get_combined_refs ());
 }
 
diff --git a/gcc/rust/typecheck/rust-tyty.h b/gcc/rust/typecheck/rust-tyty.h
index 7f0ad35..e8db032 100644
--- a/gcc/rust/typecheck/rust-tyty.h
+++ b/gcc/rust/typecheck/rust-tyty.h
@@ -1364,14 +1364,14 @@ public:
 class ReferenceType : public BaseType
 {
 public:
-  ReferenceType (HirId ref, TyVar base,
+  ReferenceType (HirId ref, TyVar base, bool is_mut,
 		 std::set<HirId> refs = std::set<HirId> ())
-    : BaseType (ref, ref, TypeKind::REF, refs), base (base)
+    : BaseType (ref, ref, TypeKind::REF, refs), base (base), is_mut (is_mut)
   {}
 
-  ReferenceType (HirId ref, HirId ty_ref, TyVar base,
+  ReferenceType (HirId ref, HirId ty_ref, TyVar base, bool is_mut,
 		 std::set<HirId> refs = std::set<HirId> ())
-    : BaseType (ref, ty_ref, TypeKind::REF, refs), base (base)
+    : BaseType (ref, ty_ref, TypeKind::REF, refs), base (base), is_mut (is_mut)
   {}
 
   BaseType *get_base () const;
@@ -1397,8 +1397,11 @@ public:
 
   ReferenceType *handle_substitions (SubstitutionArgumentMappings mappings);
 
+  bool is_mutable () const { return is_mut; }
+
 private:
   TyVar base;
+  bool is_mut;
 };
 
 class StrType : public BaseType