Allow references to arrays for ArrayIndexExpr accessor's

When we have an array-index expr rust allows the array reference to be a
reference and the compiler is meant to add in the required implicit
indirection. This checks for this senario and injects the indirection
during code-generation.

Fixes #815

1 files changed, 24 insertions, 2 deletions

diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index 2bf969b..46d501a 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -390,10 +390,32 @@ public:
 
   void visit (HIR::ArrayIndexExpr &expr) override
   {
-    tree array = CompileExpr::Compile (expr.get_array_expr (), ctx);
+    tree array_reference = CompileExpr::Compile (expr.get_array_expr (), ctx);
     tree index = CompileExpr::Compile (expr.get_index_expr (), ctx);
+
+    // lets check if the array is a reference type then we can add an
+    // indirection if required
+    TyTy::BaseType *array_expr_ty = nullptr;
+    bool ok = ctx->get_tyctx ()->lookup_type (
+      expr.get_array_expr ()->get_mappings ().get_hirid (), &array_expr_ty);
+    rust_assert (ok);
+
+    // do we need to add an indirect reference
+    if (array_expr_ty->get_kind () == TyTy::TypeKind::REF)
+      {
+	TyTy::ReferenceType *r
+	  = static_cast<TyTy::ReferenceType *> (array_expr_ty);
+	TyTy::BaseType *tuple_type = r->get_base ();
+	tree array_tyty = TyTyResolveCompile::compile (ctx, tuple_type);
+
+	array_reference
+	  = ctx->get_backend ()->indirect_expression (array_tyty,
+						      array_reference, true,
+						      expr.get_locus ());
+      }
+
     translated
-      = ctx->get_backend ()->array_index_expression (array, index,
+      = ctx->get_backend ()->array_index_expression (array_reference, index,
 						     expr.get_locus ());
   }