Make PromiseRejectCallback fire after end-of-turn.

src/promise.js

Index: src/promise.js
diff --git a/src/promise.js b/src/promise.js
index e402a18532647b96b6b07268858f95c4aa627064..350eef4eb8e6ca583f5a95ecd44a6e2c55a19f77 100644
--- a/src/promise.js
+++ b/src/promise.js
@@ -18,7 +18,9 @@ var PromiseReject;
 var PromiseChain;
 var PromiseCatch;
 var PromiseThen;
-var PromiseHasRejectHandler;
+var PromiseScheduleUnhandledRejectMessage;
+var PromiseScheduleRevokeRejectMessage;
+var PromiseDispatchUnhandledRejectMessages;
 var PromiseHasUserDefinedRejectHandler;
 
 // mirror-debugger.js currently uses builtins.promiseStatus. It would be nice
@@ -31,8 +33,12 @@ var promiseValue = GLOBAL_PRIVATE("Promise#value");
 var promiseOnResolve = GLOBAL_PRIVATE("Promise#onResolve");
 var promiseOnReject = GLOBAL_PRIVATE("Promise#onReject");
 var promiseRaw = GLOBAL_PRIVATE("Promise#raw");
-var promiseHasHandler = %PromiseHasHandlerSymbol();
+var promiseHasHandler = GLOBAL_PRIVATE("Promise#hasHandler");
+// Enqueued promise message: true = revoke reject, false = unhandled reject
+var promiseMessage = GLOBAL_PRIVATE("Promise#message");
 var lastMicrotaskId = 0;
+var promiseMicrotasksCount = 0;
+var enqueuedPromiseMessages;
 
 
 (function() {
@@ -119,16 +125,18 @@ var lastMicrotaskId = 0;
 
   function PromiseEnqueue(value, tasks, status) {
     var id, name, instrumenting = DEBUG_IS_ACTIVE;
+    ++promiseMicrotasksCount;
     %EnqueueMicrotask(function() {
       if (instrumenting) {
         %DebugAsyncTaskEvent({ type: "willHandle", id: id, name: name });
       }
       for (var i = 0; i < tasks.length; i += 2) {
-        PromiseHandle(value, tasks[i], tasks[i + 1])
+        PromiseHandle(value, tasks[i], tasks[i + 1]);
       }
       if (instrumenting) {
         %DebugAsyncTaskEvent({ type: "didHandle", id: id, name: name });
       }
+      --promiseMicrotasksCount;
     });
     if (instrumenting) {
       id = ++lastMicrotaskId;
@@ -163,9 +171,11 @@ var lastMicrotaskId = 0;
     // Check promise status to confirm that this reject has an effect.
     // Call runtime for callbacks to the debugger or for unhandled reject.
     if (GET_PRIVATE(promise, promiseStatus) == 0) {
-      var debug_is_active = DEBUG_IS_ACTIVE;
-      if (debug_is_active || !HAS_DEFINED_PRIVATE(promise, promiseHasHandler)) {
-        %PromiseRejectEvent(promise, r, debug_is_active);
+      if (DEBUG_IS_ACTIVE) {
+        %DebugPromiseRejectEvent(promise, r);
+      }
+      if (!HAS_DEFINED_PRIVATE(promise, promiseHasHandler)) {
+        PromiseScheduleUnhandledRejectMessage(promise, r, false);
       }
     }
     PromiseDone(promise, -1, r, promiseOnReject)
@@ -206,9 +216,7 @@ var lastMicrotaskId = 0;
     if (this === $Promise) {
       // Optimized case, avoid extra closure.
       promise = PromiseSet(new $Promise(promiseRaw), -1, r);
-      // The debug event for this would always be an uncaught promise reject,
-      // which is usually simply noise. Do not trigger that debug event.
-      %PromiseRejectEvent(promise, r, false);
+      PromiseScheduleUnhandledRejectMessage(promise, r, false);
     } else {
       promise = new this(function(resolve, reject) { reject(r) });
     }
@@ -237,8 +245,8 @@ var lastMicrotaskId = 0;
       case -1:  // Rejected
         if (!HAS_DEFINED_PRIVATE(this, promiseHasHandler)) {
           // Promise has already been rejected, but had no handler.
-          // Revoke previously triggered reject event.
-          %PromiseRevokeReject(this);
+          // Revoke previously triggered reject message.
+          PromiseScheduleRevokeRejectMessage(this);
         }
         PromiseEnqueue(GET_PRIVATE(this, promiseValue),
                        [onReject, deferred],
@@ -340,6 +348,41 @@ var lastMicrotaskId = 0;
 
   // Utility for debugger
 
+  function PromiseScheduleUnhandledRejectMessage(promise, r, revoke) {
+    if (!enqueuedPromiseMessages) {
+      enqueuedPromiseMessages = new InternalArray;
+      %EnqueueMicrotask(PromiseDispatchUnhandledRejectMessages);
+    }
+    SET_PRIVATE(promise, promiseMessage, revoke);
+    enqueuedPromiseMessages.push(promise, r);
+  }
+
+  function PromiseScheduleRevokeRejectMessage(promise) {
+    if (HAS_DEFINED_PRIVATE(promise, promiseMessage)) {
+      DELETE_PRIVATE(promise, promiseMessage);
+    } else {
+      PromiseScheduleUnhandledRejectMessage(promise, UNDEFINED, true);
+    }
+  }
+
+  function PromiseDispatchUnhandledRejectMessages() {
+    if (promiseMicrotasksCount || %PendingMicrotaskCount()) {
+      %EnqueueMicrotask(PromiseDispatchUnhandledRejectMessages);
+      return;
+    }
+    var queue = enqueuedPromiseMessages;
+    enqueuedPromiseMessages = UNDEFINED;
+    for (var i = 0; i < queue.length; i += 2) {
+      var promise = queue[i];
+      if (HAS_DEFINED_PRIVATE(promise, promiseMessage)) {
+        var revoke = GET_PRIVATE(promise, promiseMessage);
+        DELETE_PRIVATE(promise, promiseMessage);
+        if (revoke) %PromiseRevokeRejectMessage(promise);
+        else %PromiseRejectMessage(promise, queue[i + 1]);
+      }
+    }
+  }
+
   function PromiseHasUserDefinedRejectHandlerRecursive(promise) {
     var queue = GET_PRIVATE(promise, promiseOnReject);
     if (IS_UNDEFINED(queue)) return false;