Bug 1379525 - Part 1: Await on the value before yielding or returning inside async generator.

Tag #1287

2 files changed, 88 insertions, 97 deletions

diff --git a/js/src/vm/AsyncIteration.cpp b/js/src/vm/AsyncIteration.cpp
index 74f6389c10..256f247b09 100644
--- a/js/src/vm/AsyncIteration.cpp
+++ b/js/src/vm/AsyncIteration.cpp
@@ -26,7 +26,7 @@ using namespace js::gc;
 #define UNWRAPPED_ASYNC_WRAPPED_SLOT 1
 #define WRAPPED_ASYNC_UNWRAPPED_SLOT 0
 
-// Async Iteration proposal 2.3.10 Runtime Semantics: EvaluateBody.
+// Async Iteration proposal 8.3.10 Runtime Semantics: EvaluateBody.
 static bool
 WrappedAsyncGenerator(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -128,11 +128,7 @@ js::GetUnwrappedAsyncGenerator(JSFunction* wrapped)
     return unwrapped;
 }
 
-static MOZ_MUST_USE bool
-AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
-                     CompletionKind completionKind, HandleValue argument);
-
-// Async Iteration proposal 5.1.1 Await Fulfilled Functions.
+// Async Iteration proposal 4.1.1 Await Fulfilled Functions.
 MOZ_MUST_USE bool
 js::AsyncGeneratorAwaitedFulfilled(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
                                    HandleValue value)
@@ -140,7 +136,7 @@ js::AsyncGeneratorAwaitedFulfilled(JSContext* cx, Handle<AsyncGeneratorObject*>
     return AsyncGeneratorResume(cx, asyncGenObj, CompletionKind::Normal, value);
 }
 
-// Async Iteration proposal 5.1.2 Await Rejected Functions.
+// Async Iteration proposal 4.1.2 Await Rejected Functions.
 MOZ_MUST_USE bool
 js::AsyncGeneratorAwaitedRejected(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
                                   HandleValue reason)
@@ -148,12 +144,30 @@ js::AsyncGeneratorAwaitedRejected(JSContext* cx, Handle<AsyncGeneratorObject*> a
     return AsyncGeneratorResume(cx, asyncGenObj, CompletionKind::Throw, reason);
 }
 
+// Async Iteration proposal 11.4.3.7 step 8.d-e.
+MOZ_MUST_USE bool
+js::AsyncGeneratorYieldReturnAwaitedFulfilled(JSContext* cx,
+                                              Handle<AsyncGeneratorObject*> asyncGenObj,
+                                              HandleValue value)
+{
+    return AsyncGeneratorResume(cx, asyncGenObj, CompletionKind::Return, value);
+}
+
+// Async Iteration proposal 11.4.3.7 step 8.d-e.
+MOZ_MUST_USE bool
+js::AsyncGeneratorYieldReturnAwaitedRejected(JSContext* cx,
+                                             Handle<AsyncGeneratorObject*> asyncGenObj,
+                                             HandleValue reason)
+{
+    return AsyncGeneratorResume(cx, asyncGenObj, CompletionKind::Throw, reason);
+}
+
 const Class AsyncFromSyncIteratorObject::class_ = {
     "AsyncFromSyncIteratorObject",
     JSCLASS_HAS_RESERVED_SLOTS(AsyncFromSyncIteratorObject::Slots)
 };
 
-// Async Iteration proposal 6.1.3.1.
+// Async Iteration proposal 11.1.3.1.
 JSObject*
 js::CreateAsyncFromSyncIterator(JSContext* cx, HandleObject iter)
 {
@@ -164,7 +178,7 @@ js::CreateAsyncFromSyncIterator(JSContext* cx, HandleObject iter)
     return AsyncFromSyncIteratorObject::create(cx, iter);
 }
 
-// Async Iteration proposal 6.1.3.1 steps 2-4.
+// Async Iteration proposal 11.1.3.1 steps 2-4.
 /* static */ JSObject*
 AsyncFromSyncIteratorObject::create(JSContext* cx, HandleObject iter)
 {
@@ -187,7 +201,7 @@ AsyncFromSyncIteratorObject::create(JSContext* cx, HandleObject iter)
     return asyncIter;
 }
 
-// Async Iteration proposal 6.1.3.2.1 %AsyncFromSyncIteratorPrototype%.next.
+// Async Iteration proposal 11.1.3.2.1 %AsyncFromSyncIteratorPrototype%.next.
 static bool
 AsyncFromSyncIteratorNext(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -195,7 +209,7 @@ AsyncFromSyncIteratorNext(JSContext* cx, unsigned argc, Value* vp)
     return AsyncFromSyncIteratorMethod(cx, args, CompletionKind::Normal);
 }
 
-// Async Iteration proposal 6.1.3.2.2 %AsyncFromSyncIteratorPrototype%.return.
+// Async Iteration proposal 11.1.3.2.2 %AsyncFromSyncIteratorPrototype%.return.
 static bool
 AsyncFromSyncIteratorReturn(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -203,7 +217,7 @@ AsyncFromSyncIteratorReturn(JSContext* cx, unsigned argc, Value* vp)
     return AsyncFromSyncIteratorMethod(cx, args, CompletionKind::Return);
 }
 
-// Async Iteration proposal 6.1.3.2.3 %AsyncFromSyncIteratorPrototype%.throw.
+// Async Iteration proposal 11.1.3.2.3 %AsyncFromSyncIteratorPrototype%.throw.
 static bool
 AsyncFromSyncIteratorThrow(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -211,7 +225,7 @@ AsyncFromSyncIteratorThrow(JSContext* cx, unsigned argc, Value* vp)
     return AsyncFromSyncIteratorMethod(cx, args, CompletionKind::Throw);
 }
 
-// Async Iteration proposal 6.4.1.2 AsyncGenerator.prototype.next.
+// Async Iteration proposal 11.4.1.2 AsyncGenerator.prototype.next.
 static bool
 AsyncGeneratorNext(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -222,7 +236,7 @@ AsyncGeneratorNext(JSContext* cx, unsigned argc, Value* vp)
                                  args.rval());
 }
 
-// Async Iteration proposal 6.4.1.3 AsyncGenerator.prototype.return.
+// Async Iteration proposal 11.4.1.3 AsyncGenerator.prototype.return.
 static bool
 AsyncGeneratorReturn(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -233,7 +247,7 @@ AsyncGeneratorReturn(JSContext* cx, unsigned argc, Value* vp)
                                  args.rval());
 }
 
-// Async Iteration proposal 6.4.1.4 AsyncGenerator.prototype.throw.
+// Async Iteration proposal 11.4.1.4 AsyncGenerator.prototype.throw.
 static bool
 AsyncGeneratorThrow(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -371,7 +385,7 @@ const Class AsyncGeneratorRequest::class_ = {
     JSCLASS_HAS_RESERVED_SLOTS(AsyncGeneratorRequest::Slots)
 };
 
-// Async Iteration proposal 6.4.3.1.
+// Async Iteration proposal 11.4.3.1.
 /* static */ AsyncGeneratorRequest*
 AsyncGeneratorRequest::create(JSContext* cx, CompletionKind completionKind_,
                               HandleValue completionValue_, HandleObject promise_)
@@ -387,7 +401,7 @@ AsyncGeneratorRequest::create(JSContext* cx, CompletionKind completionKind_,
     return request;
 }
 
-// Async Iteration proposal 6.4.3.2 steps 5.d-g.
+// Async Iteration proposal 11.4.3.2 AsyncGeneratorStart steps 5.d-g.
 static MOZ_MUST_USE bool
 AsyncGeneratorReturned(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
                        HandleValue value)
@@ -402,7 +416,7 @@ AsyncGeneratorReturned(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
     return AsyncGeneratorResolve(cx, asyncGenObj, value, true);
 }
 
-// Async Iteration proposal 6.4.3.2 steps 5.d, f.
+// Async Iteration proposal 11.4.3.2 AsyncGeneratorStart steps 5.d, f.
 static MOZ_MUST_USE bool
 AsyncGeneratorThrown(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj)
 {
@@ -422,85 +436,33 @@ AsyncGeneratorThrown(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj)
     return AsyncGeneratorReject(cx, asyncGenObj, value);
 }
 
-// Async Iteration proposal 6.4.3.5.
-MOZ_MUST_USE bool
-js::AsyncGeneratorResumeNext(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj)
-{
-    // Step 1 (implicit).
-
-    // Steps 2-3.
-    MOZ_ASSERT(!asyncGenObj->isExecuting());
-
-    // Steps 4-5.
-    if (asyncGenObj->isQueueEmpty())
-        return true;
-
-    // Steps 6-7.
-    Rooted<AsyncGeneratorRequest*> request(
-        cx, AsyncGeneratorObject::peekRequest(cx, asyncGenObj));
-    if (!request)
-        return false;
-
-    // Step 8.
-    CompletionKind completionKind = request->completionKind();
-
-    // Step 9.
-    if (completionKind != CompletionKind::Normal) {
-        // Step 9.a.
-        if (asyncGenObj->isSuspendedStart())
-            asyncGenObj->setCompleted();
-
-        // Step 9.b.
-        if (asyncGenObj->isCompleted()) {
-            // Step 9.b.i.
-            RootedValue value(cx, request->completionValue());
-            if (completionKind == CompletionKind::Return)
-                return AsyncGeneratorResolve(cx, asyncGenObj, value, true);
-            // Step 9.b.ii.
-            return AsyncGeneratorReject(cx, asyncGenObj, value);
-        }
-    } else if (asyncGenObj->isCompleted()) {
-        // Step 10.
-        return AsyncGeneratorResolve(cx, asyncGenObj, UndefinedHandleValue, true);
-    }
-
-    // Step 11.
-    MOZ_ASSERT(asyncGenObj->isSuspendedStart() || asyncGenObj->isSuspendedYield());
-
-    // Step 15 (reordered).
-    asyncGenObj->setExecuting();
-
-    RootedValue argument(cx, request->completionValue());
-
-    // Steps 12-14, 16-20.
-    return AsyncGeneratorResume(cx, asyncGenObj, completionKind, argument);
-}
-
-// Async Iteration proposal 6.2.1.3 (partially).
+// Async Iteration proposal 11.4.3.7 (partially).
 // Most steps are done in generator.
 static MOZ_MUST_USE bool
-AsyncGeneratorYield(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
-                    HandleValue value)
+AsyncGeneratorYield(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj, HandleValue value)
 {
-    // Step 5.
+    // Step 5 is done in bytecode.
+
+    // Step 6.
     asyncGenObj->setSuspendedYield();
 
-    // Step 8.
+    // Step 9.
     return AsyncGeneratorResolve(cx, asyncGenObj, value, false);
 }
 
-// Async Iteration proposal 6.4.3.5 steps 12-14, 16-20.
-// Async Iteration proposal 6.2.1.2 step 10.
-// Async Iteration proposal 6.4.3.2 step 5.f-g.
-// Async Iteration proposal 5.1 steps 2-9.
+// Async Iteration proposal 4.1 Await steps 2-9.
+// Async Iteration proposal 8.2.1 yield* steps 6.a.vii, 6.b.ii.7, 6.c.ix.
+// Async Iteration proposal 11.4.3.2 AsyncGeneratorStart step 5.f-g.
+// Async Iteration proposal 11.4.3.5 AsyncGeneratorResumeNext
+//   steps 12-14, 16-20.
 // Execution context switching is handled in generator.
-static MOZ_MUST_USE bool
-AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
-                     CompletionKind completionKind, HandleValue argument)
+MOZ_MUST_USE bool
+js::AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
+                         CompletionKind completionKind, HandleValue argument)
 {
     RootedValue generatorVal(cx, asyncGenObj->generatorVal());
 
-    // 6.4.3.5 steps 12-14, 16-20.
+    // 11.4.3.5 steps 12-14, 16-20.
     HandlePropertyName funName = completionKind == CompletionKind::Normal
                                  ? cx->names().StarGeneratorNext
                                  : completionKind == CompletionKind::Throw
@@ -510,10 +472,11 @@ AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
     args[0].set(argument);
     RootedValue result(cx);
     if (!CallSelfHostedFunction(cx, funName, generatorVal, args, &result)) {
-        // 6.4.3.2 step 5.d, f.
+        // 11.4.3.2 step 5.d, f.
         return AsyncGeneratorThrown(cx, asyncGenObj);
     }
 
+    // 4.1 steps 2-9.
     if (asyncGenObj->generatorObj()->isAfterAwait())
         return AsyncGeneratorAwait(cx, asyncGenObj, result);
 
@@ -525,8 +488,10 @@ AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
     // object and it's not observable.
     // For yield*, it's done on a possibly user-provided result object, and
     // it's observable.
+    //
+    // Note that IteratorComplete steps in 8.2.1 are done in bytecode.
 
-    // 2.2.1 yield* steps 6.a.vii, 6.b.ii.7, 6.c.ix.
+    // 8.2.1 yield* steps 6.a.vii, 6.b.ii.7, 6.c.ix.
     RootedObject resultObj(cx, &result.toObject());
     RootedValue value(cx);
 
@@ -536,7 +501,7 @@ AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
     if (asyncGenObj->generatorObj()->isAfterYield())
         return AsyncGeneratorYield(cx, asyncGenObj, value);
 
-    // 6.4.3.2 step 5.d-g.
+    // 11.4.3.2 step 5.d-g.
     return AsyncGeneratorReturned(cx, asyncGenObj, value);
 }
 
@@ -565,14 +530,14 @@ GlobalObject::initAsyncGenerators(JSContext* cx, Handle<GlobalObject*> global)
     if (global->getReservedSlot(ASYNC_ITERATOR_PROTO).isObject())
         return true;
 
-    // Async Iteration proposal 6.1.2 %AsyncIteratorPrototype%.
+    // Async Iteration proposal 11.1.2 %AsyncIteratorPrototype%.
     RootedObject asyncIterProto(cx, GlobalObject::createBlankPrototype<PlainObject>(cx, global));
     if (!asyncIterProto)
         return false;
     if (!DefinePropertiesAndFunctions(cx, asyncIterProto, nullptr, async_iterator_proto_methods))
         return false;
 
-    // Async Iteration proposal 6.1.3.2 %AsyncFromSyncIteratorPrototype%.
+    // Async Iteration proposal 11.1.3.2 %AsyncFromSyncIteratorPrototype%.
     RootedObject asyncFromSyncIterProto(
         cx, GlobalObject::createBlankPrototypeInheriting(cx, global, &PlainObject::class_,
                                                          asyncIterProto));
@@ -585,7 +550,7 @@ GlobalObject::initAsyncGenerators(JSContext* cx, Handle<GlobalObject*> global)
         return false;
     }
 
-    // Async Iteration proposal 6.4.1 %AsyncGeneratorPrototype%.
+    // Async Iteration proposal 11.4.1 %AsyncGeneratorPrototype%.
     RootedObject asyncGenProto(
         cx, GlobalObject::createBlankPrototypeInheriting(cx, global, &PlainObject::class_,
                                                          asyncIterProto));
@@ -597,7 +562,7 @@ GlobalObject::initAsyncGenerators(JSContext* cx, Handle<GlobalObject*> global)
         return false;
     }
 
-    // Async Iteration proposal 6.3.3 %AsyncGenerator%.
+    // Async Iteration proposal 11.3.3 %AsyncGenerator%.
     RootedObject asyncGenerator(cx, NewSingletonObjectWithFunctionPrototype(cx, global));
     if (!asyncGenerator)
         return false;
@@ -616,7 +581,7 @@ GlobalObject::initAsyncGenerators(JSContext* cx, Handle<GlobalObject*> global)
     RootedObject proto(cx, &function.toObject());
     RootedAtom name(cx, cx->names().AsyncGeneratorFunction);
 
-    // Async Iteration proposal 6.3.2 %AsyncGeneratorFunction%.
+    // Async Iteration proposal 11.3.2 %AsyncGeneratorFunction%.
     RootedObject asyncGenFunction(
         cx, NewFunctionWithProto(cx, AsyncGeneratorConstructor, 1, JSFunction::NATIVE_CTOR,
                                  nullptr, name, proto, gc::AllocKind::FUNCTION, SingletonObject));
diff --git a/js/src/vm/AsyncIteration.h b/js/src/vm/AsyncIteration.h
index 974c209a01..58c43131b4 100644
--- a/js/src/vm/AsyncIteration.h
+++ b/js/src/vm/AsyncIteration.h
@@ -38,11 +38,18 @@ GetUnwrappedAsyncGenerator(JSFunction* wrapped);
 
 MOZ_MUST_USE bool
 AsyncGeneratorAwaitedFulfilled(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
-                              HandleValue value);
-
+                               HandleValue value);
 MOZ_MUST_USE bool
 AsyncGeneratorAwaitedRejected(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
-                             HandleValue reason);
+                              HandleValue reason);
+MOZ_MUST_USE bool
+AsyncGeneratorYieldReturnAwaitedFulfilled(JSContext* cx,
+                                          Handle<AsyncGeneratorObject*> asyncGenObj,
+                                          HandleValue value);
+MOZ_MUST_USE bool
+AsyncGeneratorYieldReturnAwaitedRejected(JSContext* cx,
+                                         Handle<AsyncGeneratorObject*> asyncGenObj,
+                                         HandleValue reason);
 
 class AsyncGeneratorRequest : public NativeObject
 {
@@ -97,6 +104,12 @@ class AsyncGeneratorObject : public NativeObject
         State_SuspendedStart,
         State_SuspendedYield,
         State_Executing,
+        // State_AwaitingYieldReturn corresponds to the case that
+        // AsyncGenerator#return is called while State_Executing,
+        // just like the case that AsyncGenerator#return is called
+        // while State_Completed.
+        State_AwaitingYieldReturn,
+        State_AwaitingReturn,
         State_Completed
     };
 
@@ -155,6 +168,12 @@ class AsyncGeneratorObject : public NativeObject
     bool isExecuting() const {
         return state() == State_Executing;
     }
+    bool isAwaitingYieldReturn() const {
+        return state() == State_AwaitingYieldReturn;
+    }
+    bool isAwaitingReturn() const {
+        return state() == State_AwaitingReturn;
+    }
     bool isCompleted() const {
         return state() == State_Completed;
     }
@@ -168,6 +187,12 @@ class AsyncGeneratorObject : public NativeObject
     void setExecuting() {
         setState(State_Executing);
     }
+    void setAwaitingYieldReturn() {
+        setState(State_AwaitingYieldReturn);
+    }
+    void setAwaitingReturn() {
+        setState(State_AwaitingReturn);
+    }
     void setCompleted() {
         setState(State_Completed);
     }
@@ -223,7 +248,8 @@ class AsyncFromSyncIteratorObject : public NativeObject
 };
 
 MOZ_MUST_USE bool
-AsyncGeneratorResumeNext(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj);
+AsyncGeneratorResume(JSContext* cx, Handle<AsyncGeneratorObject*> asyncGenObj,
+                     CompletionKind completionKind, HandleValue argument);
 
 } // namespace js