console.warn goes to stderr (#810)

2 files changed, 10 insertions, 4 deletions

diff --git a/libdeno/binding.cc b/libdeno/binding.cc
index bc155b6db..b3c59c3ec 100644
--- a/libdeno/binding.cc
+++ b/libdeno/binding.cc
@@ -141,13 +141,19 @@ void ExitOnPromiseRejectCallback(
 }
 
 void Print(const v8::FunctionCallbackInfo<v8::Value>& args) {
-  CHECK_EQ(args.Length(), 1);
+  CHECK_GE(args.Length(), 1);
+  CHECK_LE(args.Length(), 2);
   auto* isolate = args.GetIsolate();
+  Deno* d = static_cast<Deno*>(isolate->GetData(0));
+  auto context = d->context.Get(d->isolate);
   v8::HandleScope handle_scope(isolate);
   v8::String::Utf8Value str(isolate, args[0]);
+  bool is_err =
+      args.Length() >= 2 ? args[1]->BooleanValue(context).ToChecked() : false;
   const char* cstr = ToCString(str);
-  printf("%s\n", cstr);
-  fflush(stdout);
+  auto stream = is_err ? stderr : stdout;
+  fprintf(stream, "%s\n", cstr);
+  fflush(stream);
 }
 
 static v8::Local<v8::Uint8Array> ImportBuf(v8::Isolate* isolate, deno_buf buf) {
diff --git a/libdeno/libdeno_test.js b/libdeno/libdeno_test.js
index ec8e4c752..e0d1d7252 100644
--- a/libdeno/libdeno_test.js
+++ b/libdeno/libdeno_test.js
@@ -112,7 +112,7 @@ global.SnapshotBug = () => {
 
 global.GlobalErrorHandling = () => {
   libdeno.setGlobalErrorHandler((message, source, line, col, error) => {
-    libdeno.print(`line ${line} col ${col}`);
+    libdeno.print(`line ${line} col ${col}`, true);
     assert("ReferenceError: notdefined is not defined" === message);
     assert(source === "helloworld.js");
     assert(line === 3);