module: always decorate thrown errors

This provides more information when encountering a syntax or similar
error when executing a file with require().

Fixes: https://github.com/nodejs/node/issues/4286
PR-URL: https://github.com/nodejs/node/pull/4287
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

3 files changed, 30 insertions, 3 deletions

diff --git a/src/env.h b/src/env.h
index 6151c57069..743bf057e8 100644
--- a/src/env.h
+++ b/src/env.h
@@ -51,7 +51,7 @@ namespace node {
   V(alpn_buffer_string, "alpnBuffer")                                         \
   V(args_string, "args")                                                      \
   V(argv_string, "argv")                                                      \
-  V(arrow_message_string, "arrowMessage")                                     \
+  V(arrow_message_string, "node:arrowMessage")                                \
   V(async, "async")                                                           \
   V(async_queue_string, "_asyncQueue")                                        \
   V(atime_string, "atime")                                                    \
@@ -71,6 +71,7 @@ namespace node {
   V(cwd_string, "cwd")                                                        \
   V(debug_port_string, "debugPort")                                           \
   V(debug_string, "debug")                                                    \
+  V(decorated_string, "node:decorated")                                       \
   V(dest_string, "dest")                                                      \
   V(detached_string, "detached")                                              \
   V(dev_string, "dev")                                                        \
diff --git a/src/node.cc b/src/node.cc
index f9797e664e..894c8f7641 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -1399,6 +1399,15 @@ ssize_t DecodeWrite(Isolate* isolate,
   return StringBytes::Write(isolate, buf, buflen, val, encoding, nullptr);
 }
 
+bool IsExceptionDecorated(Environment* env, Local<Value> er) {
+  if (!er.IsEmpty() && er->IsObject()) {
+    Local<Object> err_obj = er.As<Object>();
+    Local<Value> decorated = err_obj->GetHiddenValue(env->decorated_string());
+    return !decorated.IsEmpty() && decorated->IsTrue();
+  }
+  return false;
+}
+
 void AppendExceptionLine(Environment* env,
                          Local<Value> er,
                          Local<Message> message) {
@@ -1508,6 +1517,7 @@ static void ReportException(Environment* env,
 
   Local<Value> trace_value;
   Local<Value> arrow;
+  const bool decorated = IsExceptionDecorated(env, er);
 
   if (er->IsUndefined() || er->IsNull()) {
     trace_value = Undefined(env->isolate());
@@ -1522,7 +1532,7 @@ static void ReportException(Environment* env,
 
   // range errors have a trace member set to undefined
   if (trace.length() > 0 && !trace_value->IsUndefined()) {
-    if (arrow.IsEmpty() || !arrow->IsString()) {
+    if (arrow.IsEmpty() || !arrow->IsString() || decorated) {
       PrintErrorString("%s\n", *trace);
     } else {
       node::Utf8Value arrow_string(env->isolate(), arrow);
@@ -1554,7 +1564,7 @@ static void ReportException(Environment* env,
       node::Utf8Value name_string(env->isolate(), name);
       node::Utf8Value message_string(env->isolate(), message);
 
-      if (arrow.IsEmpty() || !arrow->IsString()) {
+      if (arrow.IsEmpty() || !arrow->IsString() || decorated) {
         PrintErrorString("%s: %s\n", *name_string, *message_string);
       } else {
         node::Utf8Value arrow_string(env->isolate(), arrow);
diff --git a/src/node_util.cc b/src/node_util.cc
index 1e0f214ae4..8475468c1f 100644
--- a/src/node_util.cc
+++ b/src/node_util.cc
@@ -52,6 +52,21 @@ static void GetHiddenValue(const FunctionCallbackInfo<Value>& args) {
   args.GetReturnValue().Set(obj->GetHiddenValue(name));
 }
 
+static void SetHiddenValue(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+
+  if (!args[0]->IsObject())
+    return env->ThrowTypeError("obj must be an object");
+
+  if (!args[1]->IsString())
+    return env->ThrowTypeError("name must be a string");
+
+  Local<Object> obj = args[0].As<Object>();
+  Local<String> name = args[1].As<String>();
+
+  args.GetReturnValue().Set(obj->SetHiddenValue(name, args[2]));
+}
+
 
 void Initialize(Local<Object> target,
                 Local<Value> unused,
@@ -63,6 +78,7 @@ void Initialize(Local<Object> target,
 #undef V
 
   env->SetMethod(target, "getHiddenValue", GetHiddenValue);
+  env->SetMethod(target, "setHiddenValue", SetHiddenValue);
 }
 
 }  // namespace util