Fix out-of-bound-array-access in type checking

1 files changed, 18 insertions, 5 deletions

diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index 836328f..a734dcf 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -35,6 +35,9 @@ class TypeCheckExpr : public TypeCheckBase
   using Rust::Resolver::TypeCheckBase::visit;
 
 public:
+  /* Perform type checking on expr. Also runs type unification algorithm.
+     Returns the unified type of expr.
+     `inside_loop` acts as a context for BreakExpr, etc. May change later. */
   static TyTy::BaseType *Resolve (HIR::Expr *expr, bool inside_loop)
   {
     TypeCheckExpr resolver (inside_loop);
@@ -686,6 +689,7 @@ public:
     HIR::ArrayElems *elements = expr.get_internal_elements ();
     size_t num_elems = elements->get_num_elements ();
 
+    // Check the type of array elements
     elements->accept_vis (*this);
     rust_assert (infered_array_elems != nullptr);
 
@@ -702,14 +706,19 @@ public:
       return true;
     });
 
-    infered_array_elems = types[0];
-    for (size_t i = 1; i < types.size (); i++)
+    // Create an infer type and register its hir_id
+    infered_array_elems
+      = new TyTy::InferType (mappings->get_next_hir_id (),
+			     TyTy::InferType::InferTypeKind::GENERAL);
+
+    for (auto &type : types)
       {
-	infered_array_elems = infered_array_elems->unify (types.at (i));
+	infered_array_elems = infered_array_elems->unify (type);
       }
-
     for (auto &elem : types)
-      infered_array_elems->append_reference (elem->get_ref ());
+      {
+	infered_array_elems->append_reference (elem->get_ref ());
+      }
   }
 
   void visit (HIR::ArrayElemsCopied &elems) override
@@ -995,7 +1004,11 @@ private:
     gcc_unreachable ();
   }
 
+  /* The return value of TypeCheckExpr::Resolve */
   TyTy::BaseType *infered;
+
+  /* The return value of visit(ArrayElemsValues&) and visit(ArrayElemsCopied&)
+     Stores the type of array elements, if `expr` is ArrayExpr. */
   TyTy::BaseType *infered_array_elems;
 
   bool inside_loop;