Added check that the object being stored as a return value in the NativeArguments array is a Dart i…

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
===================================================================
--- runtime/vm/dart_api_impl.cc	(revision 19928)
+++ runtime/vm/dart_api_impl.cc	(working copy)
@@ -4,6 +4,7 @@
 
 #include "include/dart_api.h"
 
+#include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
@@ -4192,20 +4193,19 @@
 }
 
 
-// This function has friend access to SetReturnUnsafe.
-void SetReturnValueHelper(Dart_NativeArguments args, Dart_Handle retval) {
+DART_EXPORT void Dart_SetReturnValue(Dart_NativeArguments args,
+                                     Dart_Handle retval) {
+  const Object& ret_obj = Object::Handle(Api::UnwrapHandle(retval));
+  if (!ret_obj.IsNull() && !ret_obj.IsInstance()) {
+    FATAL1("Return value check failed: saw '%s' expected a dart Instance.",
+           ret_obj.ToCString());
+  }
   NoGCScope no_gc_scope;
   NativeArguments* arguments = reinterpret_cast<NativeArguments*>(args);
-  arguments->SetReturnUnsafe(Api::UnwrapHandle(retval));
+  arguments->SetReturn(ret_obj);
 }
 
 
-DART_EXPORT void Dart_SetReturnValue(Dart_NativeArguments args,
-                                     Dart_Handle retval) {
-  SetReturnValueHelper(args, retval);
-}
-
-
 // --- Scripts and Libraries ---