Fix for bug 23484 (obscure error when a compilation error happens during Object::Init())

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index bf2dfd144eece2a4c5d9e1fe4595526dcdab8de2..8dd7c2d5fbca796868e51b8dfa51b27212679270 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -1301,23 +1301,28 @@ DART_EXPORT Dart_Isolate Dart_CreateIsolate(const char* script_uri,
   Thread::EnsureInit();
   Isolate* isolate = Dart::CreateIsolate(isolate_name);
   free(isolate_name);
-  {
-    StackZone zone(isolate);
-    HANDLESCOPE(isolate);
-    const Error& error_obj =
-        Error::Handle(isolate,
-                      Dart::InitializeIsolate(snapshot, callback_data));
-    if (error_obj.IsNull()) {
+  StackZone zone(isolate);
+  HANDLESCOPE(isolate);
+  // We enter an API scope here as InitializeIsolate could compile some
+  // bootstrap library files which call out to a tag handler that may create
+  // Api Handles when an error is encountered.
+  Dart_EnterScope();
+  const Error& error_obj =
+      Error::Handle(isolate, Dart::InitializeIsolate(snapshot, callback_data));
+  if (error_obj.IsNull()) {
 #if defined(DART_NO_SNAPSHOT)
-      if (FLAG_check_function_fingerprints) {
-        Library::CheckFunctionFingerprints();
-      }
-#endif  // defined(DART_NO_SNAPSHOT).
-      START_TIMER(isolate, time_total_runtime);
-      return Api::CastIsolate(isolate);
+    if (FLAG_check_function_fingerprints) {
+      Library::CheckFunctionFingerprints();
     }
-    *error = strdup(error_obj.ToErrorCString());
-  }
+#endif  // defined(DART_NO_SNAPSHOT).
+    // We exit the API scope entered above.
+    Dart_ExitScope();
+    START_TIMER(isolate, time_total_runtime);
+    return Api::CastIsolate(isolate);
+  }
+  *error = strdup(error_obj.ToErrorCString());
+  // We exit the API scope entered above.
+  Dart_ExitScope();
   Dart::ShutdownIsolate();
   return DART_ILLEGAL_ISOLATE;
 }