From 750a822430afa8055cd28792ed7ec2d3854b7c00 Mon Sep 17 00:00:00 2001
From: Ryan Dahl <ry@tinyclouds.org>
Date: Thu, 1 Aug 2019 11:29:11 -0400
Subject: [PATCH 1/2] WIP Add test for #2703 ...

---
 core/libdeno/libdeno_test.cc | 21 +++++++++++++++++++++
 core/libdeno/libdeno_test.js | 10 ++++++++++
 2 files changed, 31 insertions(+)

diff --git a/core/libdeno/libdeno_test.cc b/core/libdeno/libdeno_test.cc
index 16a4a11f61a7c1..7f6402e7a51fb1 100644
--- a/core/libdeno/libdeno_test.cc
+++ b/core/libdeno/libdeno_test.cc
@@ -281,3 +281,24 @@ TEST(LibDenoTest, WasmInstantiate) {
 
   deno_delete(d);
 }
+
+/*
+
+ To run this test:
+
+ ./tools/build.py libdeno_test && ./target/debug/libdeno_test
+ --gtest_filter=LibDenoTest.AsyncException
+
+*/
+TEST(LibDenoTest, AsyncException) {
+  Deno* d = deno_new(deno_config{0, snapshot, empty, nullptr, nullptr});
+  EXPECT_EQ(deno_last_exception(d), nullptr);
+  deno_execute(d, nullptr, "a.js", "AsyncException()");
+
+  deno_check_promise_errors(d);
+
+  // Note that there is only one frame in the JSON output....
+  printf("deno_last_exception %s\n", deno_last_exception(d));
+
+  deno_delete(d);
+}
diff --git a/core/libdeno/libdeno_test.js b/core/libdeno/libdeno_test.js
index 006c71666a570b..97200479a2d913 100644
--- a/core/libdeno/libdeno_test.js
+++ b/core/libdeno/libdeno_test.js
@@ -253,3 +253,13 @@ global.WasmInstantiate = () => {
     Deno.core.send(new Uint8Array([42]));
   })();
 };
+
+global.AsyncException = () => {
+  (async () => {
+    await Promise.resolve().then(() => {
+      const error = new Error;
+      Deno.core.print(error.stack + "\n");
+      throw error;
+    });
+  })()
+};

From a3c898e3f3abf9525ce781ab6777aad7f8aaa348 Mon Sep 17 00:00:00 2001
From: Ryan Dahl <ry@tinyclouds.org>
Date: Thu, 1 Aug 2019 12:30:20 -0400
Subject: [PATCH 2/2] DEBUG PromiseRejectCallback

---
 core/libdeno/api.cc     | 4 ++--
 core/libdeno/binding.cc | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/core/libdeno/api.cc b/core/libdeno/api.cc
index 61eeb43ca46703..54dacbc7ca1fc7 100644
--- a/core/libdeno/api.cc
+++ b/core/libdeno/api.cc
@@ -120,8 +120,8 @@ void deno_init() {
     // remove this to make it work asynchronously too. But that requires getting
     // PumpMessageLoop and RunMicrotasks setup correctly.
     // See https://github.com/denoland/deno/issues/2544
-    const char* argv[2] = {"", "--no-wasm-async-compilation"};
-    int argc = 2;
+    const char* argv[3] = {"", "--no-wasm-async-compilation", "--async-stack-traces"};
+    int argc = 3;
     v8::V8::SetFlagsFromCommandLine(&argc, const_cast<char**>(argv), false);
   }
 }
diff --git a/core/libdeno/binding.cc b/core/libdeno/binding.cc
index da582a3bfa9d1d..d9fcc4ab50a72d 100644
--- a/core/libdeno/binding.cc
+++ b/core/libdeno/binding.cc
@@ -69,6 +69,12 @@ void PromiseRejectCallback(v8::PromiseRejectMessage promise_reject_message) {
 
   v8::Context::Scope context_scope(context);
 
+  auto message = v8::Exception::CreateMessage(isolate, error);
+  auto stack_trace = message->GetStackTrace();
+  uint32_t count = static_cast<uint32_t>(stack_trace->GetFrameCount());
+  printf("FRAME COUNT %d\n", count);
+
+
   int promise_id = promise->GetIdentityHash();
   switch (promise_reject_message.GetEvent()) {
     case v8::kPromiseRejectWithNoHandler: