Implement Async-from-Sync Iterator Objects (#2234)

This Pull Request changes the following:

- Implement [Async-from-Sync Iterator Objects](https://tc39.es/ecma262/#sec-async-from-sync-iterator-objects)
- Give the proper `async` hint to `GetIterator` when executing a delegate yield expression in an async generator function

boa_engine/src/builtins/iterable/async_from_sync_iterator.rs

@@ -0,0 +1,440 @@
+use crate::{
+    builtins::{
+        iterable::{create_iter_result_object, IteratorRecord, IteratorResult},
+        promise::{if_abrupt_reject_promise, PromiseCapability},
+        JsArgs, Promise,
+    },
+    object::{FunctionBuilder, JsObject, ObjectData},
+    property::PropertyDescriptor,
+    Context, JsResult, JsValue,
+};
+use boa_gc::{Finalize, Trace};
+use boa_profiler::Profiler;
+
+/// Create the `%AsyncFromSyncIteratorPrototype%` object.
+///
+/// More information:
+///  - [ECMA reference][spec]
+///
+/// [spec]: https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%-object
+pub(crate) fn create_async_from_sync_iterator_prototype(context: &mut Context) -> JsObject {
+    let _timer = Profiler::global().start_event("AsyncFromSyncIteratorPrototype", "init");
+
+    let prototype = JsObject::from_proto_and_data(
+        context
+            .intrinsics()
+            .objects()
+            .iterator_prototypes()
+            .async_iterator_prototype(),
+        ObjectData::ordinary(),
+    );
+
+    let next_function = FunctionBuilder::native(context, AsyncFromSyncIterator::next)
+        .name("next")
+        .length(1)
+        .build();
+    let return_function = FunctionBuilder::native(context, AsyncFromSyncIterator::r#return)
+        .name("return")
+        .length(1)
+        .build();
+    let throw_function = FunctionBuilder::native(context, AsyncFromSyncIterator::throw)
+        .name("throw")
+        .length(1)
+        .build();
+
+    {
+        let mut prototype_mut = prototype.borrow_mut();
+
+        prototype_mut.insert(
+            "next",
+            PropertyDescriptor::builder()
+                .value(next_function)
+                .writable(true)
+                .enumerable(false)
+                .configurable(true),
+        );
+        prototype_mut.insert(
+            "return",
+            PropertyDescriptor::builder()
+                .value(return_function)
+                .writable(true)
+                .enumerable(false)
+                .configurable(true),
+        );
+        prototype_mut.insert(
+            "throw",
+            PropertyDescriptor::builder()
+                .value(throw_function)
+                .writable(true)
+                .enumerable(false)
+                .configurable(true),
+        );
+    }
+
+    prototype
+}
+
+/// The internal data for `%AsyncFromSyncIterator%` objects.
+///
+/// More information:
+///  - [ECMA reference][spec]
+///
+/// [spec]: https://tc39.es/ecma262/#sec-properties-of-async-from-sync-iterator-instances
+#[derive(Clone, Debug, Finalize, Trace)]
+pub struct AsyncFromSyncIterator {
+    // The [[SyncIteratorRecord]] internal slot.
+    sync_iterator_record: IteratorRecord,
+}
+
+impl AsyncFromSyncIterator {
+    /// `CreateAsyncFromSyncIterator ( syncIteratorRecord )`
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-createasyncfromsynciterator
+    pub(crate) fn create(
+        sync_iterator_record: IteratorRecord,
+        context: &mut Context,
+    ) -> IteratorRecord {
+        // 1. Let asyncIterator be OrdinaryObjectCreate(%AsyncFromSyncIteratorPrototype%, « [[SyncIteratorRecord]] »).
+        // 2. Set asyncIterator.[[SyncIteratorRecord]] to syncIteratorRecord.
+        let async_iterator = JsObject::from_proto_and_data(
+            context
+                .intrinsics()
+                .objects()
+                .iterator_prototypes()
+                .async_from_sync_iterator_prototype(),
+            ObjectData::async_from_sync_iterator(Self {
+                sync_iterator_record,
+            }),
+        );
+
+        // 3. Let nextMethod be ! Get(asyncIterator, "next").
+        let next_method = async_iterator
+            .get("next", context)
+            .expect("async from sync iterator prototype must have next method");
+
+        // 4. Let iteratorRecord be the Iterator Record { [[Iterator]]: asyncIterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
+        // 5. Return iteratorRecord.
+        IteratorRecord::new(async_iterator, next_method, false)
+    }
+
+    /// `%AsyncFromSyncIteratorPrototype%.next ( [ value ] )`
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%.next
+    fn next(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
+        // 1. Let O be the this value.
+        // 2. Assert: O is an Object that has a [[SyncIteratorRecord]] internal slot.
+        // 4. Let syncIteratorRecord be O.[[SyncIteratorRecord]].
+        let sync_iterator_record = this
+            .as_object()
+            .expect("async from sync iterator prototype must be object")
+            .borrow()
+            .as_async_from_sync_iterator()
+            .expect("async from sync iterator prototype must be object")
+            .sync_iterator_record
+            .clone();
+
+        // 3. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+        let promise_capability = PromiseCapability::new(
+            &context
+                .intrinsics()
+                .constructors()
+                .promise()
+                .constructor()
+                .into(),
+            context,
+        )
+        .expect("cannot fail with promise constructor");
+
+        // 5. If value is present, then
+        // a. Let result be Completion(IteratorNext(syncIteratorRecord, value)).
+        // 6. Else,
+        // a. Let result be Completion(IteratorNext(syncIteratorRecord)).
+        let result = sync_iterator_record.next(args.get(0).cloned(), context);
+
+        // 7. IfAbruptRejectPromise(result, promiseCapability).
+        if_abrupt_reject_promise!(result, promise_capability, context);
+
+        // 8. Return AsyncFromSyncIteratorContinuation(result, promiseCapability).
+        Self::continuation(&result, &promise_capability, context)
+    }
+
+    /// `%AsyncFromSyncIteratorPrototype%.return ( [ value ] )`
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%.return
+    fn r#return(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
+        // 1. Let O be the this value.
+        // 2. Assert: O is an Object that has a [[SyncIteratorRecord]] internal slot.
+        // 4. Let syncIterator be O.[[SyncIteratorRecord]].[[Iterator]].
+        let sync_iterator = this
+            .as_object()
+            .expect("async from sync iterator prototype must be object")
+            .borrow()
+            .as_async_from_sync_iterator()
+            .expect("async from sync iterator prototype must be object")
+            .sync_iterator_record
+            .iterator()
+            .clone();
+
+        // 3. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+        let promise_capability = PromiseCapability::new(
+            &context
+                .intrinsics()
+                .constructors()
+                .promise()
+                .constructor()
+                .into(),
+            context,
+        )
+        .expect("cannot fail with promise constructor");
+
+        // 5. Let return be Completion(GetMethod(syncIterator, "return")).
+        let r#return = sync_iterator.get_method("return", context);
+
+        // 6. IfAbruptRejectPromise(return, promiseCapability).
+        if_abrupt_reject_promise!(r#return, promise_capability, context);
+
+        let result = match (r#return, args.get(0)) {
+            // 7. If return is undefined, then
+            (None, _) => {
+                // a. Let iterResult be CreateIterResultObject(value, true).
+                let iter_result =
+                    create_iter_result_object(args.get_or_undefined(0).clone(), true, context);
+
+                // b. Perform ! Call(promiseCapability.[[Resolve]], undefined, « iterResult »).
+                promise_capability
+                    .resolve()
+                    .call(&JsValue::Undefined, &[iter_result], context)
+                    .expect("cannot fail according to spec");
+
+                // c. Return promiseCapability.[[Promise]].
+                return Ok(promise_capability.promise().clone().into());
+            }
+            // 8. If value is present, then
+            (Some(r#return), Some(value)) => {
+                // a. Let result be Completion(Call(return, syncIterator, « value »)).
+                r#return.call(&sync_iterator.clone().into(), &[value.clone()], context)
+            }
+            // 9. Else,
+            (Some(r#return), None) => {
+                // a. Let result be Completion(Call(return, syncIterator)).
+                r#return.call(&sync_iterator.clone().into(), &[], context)
+            }
+        };
+
+        // 10. IfAbruptRejectPromise(result, promiseCapability).
+        if_abrupt_reject_promise!(result, promise_capability, context);
+
+        // 11. If Type(result) is not Object, then
+        let result =
+            if let Some(result) = result.as_object() {
+                result
+            } else {
+                // a. Perform ! Call(promiseCapability.[[Reject]], undefined, « a newly created TypeError object »).
+                promise_capability
+                    .reject()
+                    .call(
+                        &JsValue::Undefined,
+                        &[context
+                            .construct_type_error("iterator return function returned non-object")],
+                        context,
+                    )
+                    .expect("cannot fail according to spec");
+
+                // b. Return promiseCapability.[[Promise]].
+                return Ok(promise_capability.promise().clone().into());
+            };
+
+        // 12. Return AsyncFromSyncIteratorContinuation(result, promiseCapability).
+        Self::continuation(
+            &IteratorResult {
+                object: result.clone(),
+            },
+            &promise_capability,
+            context,
+        )
+    }
+
+    /// `%AsyncFromSyncIteratorPrototype%.throw ( [ value ] )`
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%.throw
+    fn throw(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
+        // 1. Let O be the this value.
+        // 2. Assert: O is an Object that has a [[SyncIteratorRecord]] internal slot.
+        // 4. Let syncIterator be O.[[SyncIteratorRecord]].[[Iterator]].
+        let sync_iterator = this
+            .as_object()
+            .expect("async from sync iterator prototype must be object")
+            .borrow()
+            .as_async_from_sync_iterator()
+            .expect("async from sync iterator prototype must be object")
+            .sync_iterator_record
+            .iterator()
+            .clone();
+
+        // 3. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+        let promise_capability = PromiseCapability::new(
+            &context
+                .intrinsics()
+                .constructors()
+                .promise()
+                .constructor()
+                .into(),
+            context,
+        )
+        .expect("cannot fail with promise constructor");
+
+        // 5. Let throw be Completion(GetMethod(syncIterator, "throw")).
+        let throw = sync_iterator.get_method("throw", context);
+
+        // 6. IfAbruptRejectPromise(throw, promiseCapability).
+        if_abrupt_reject_promise!(throw, promise_capability, context);
+
+        let result = match (throw, args.get(0)) {
+            // 7. If throw is undefined, then
+            (None, _) => {
+                // a. Perform ! Call(promiseCapability.[[Reject]], undefined, « value »).
+                promise_capability
+                    .reject()
+                    .call(
+                        &JsValue::Undefined,
+                        &[args.get_or_undefined(0).clone()],
+                        context,
+                    )
+                    .expect("cannot fail according to spec");
+
+                // b. Return promiseCapability.[[Promise]].
+                return Ok(promise_capability.promise().clone().into());
+            }
+            // 8. If value is present, then
+            (Some(throw), Some(value)) => {
+                // a. Let result be Completion(Call(throw, syncIterator, « value »)).
+                throw.call(&sync_iterator.clone().into(), &[value.clone()], context)
+            }
+            // 9. Else,
+            (Some(throw), None) => {
+                // a. Let result be Completion(Call(throw, syncIterator)).
+                throw.call(&sync_iterator.clone().into(), &[], context)
+            }
+        };
+
+        // 10. IfAbruptRejectPromise(result, promiseCapability).
+        if_abrupt_reject_promise!(result, promise_capability, context);
+
+        // 11. If Type(result) is not Object, then
+        let result = if let Some(result) = result.as_object() {
+            result
+        } else {
+            // a. Perform ! Call(promiseCapability.[[Reject]], undefined, « a newly created TypeError object »).
+            promise_capability
+                .reject()
+                .call(
+                    &JsValue::Undefined,
+                    &[context.construct_type_error("iterator throw function returned non-object")],
+                    context,
+                )
+                .expect("cannot fail according to spec");
+
+            // b. Return promiseCapability.[[Promise]].
+            return Ok(promise_capability.promise().clone().into());
+        };
+
+        // 12. Return AsyncFromSyncIteratorContinuation(result, promiseCapability).
+        Self::continuation(
+            &IteratorResult {
+                object: result.clone(),
+            },
+            &promise_capability,
+            context,
+        )
+    }
+
+    /// `AsyncFromSyncIteratorContinuation ( result, promiseCapability )`
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-asyncfromsynciteratorcontinuation
+    fn continuation(
+        result: &IteratorResult,
+        promise_capability: &PromiseCapability,
+        context: &mut Context,
+    ) -> JsResult<JsValue> {
+        // 1. NOTE: Because promiseCapability is derived from the intrinsic %Promise%,
+        // the calls to promiseCapability.[[Reject]] entailed by the
+        // use IfAbruptRejectPromise below are guaranteed not to throw.
+
+        // 2. Let done be Completion(IteratorComplete(result)).
+        let done = result.complete(context);
+
+        // 3. IfAbruptRejectPromise(done, promiseCapability).
+        if_abrupt_reject_promise!(done, promise_capability, context);
+
+        // 4. Let value be Completion(IteratorValue(result)).
+        let value = result.value(context);
+
+        // 5. IfAbruptRejectPromise(value, promiseCapability).
+        if_abrupt_reject_promise!(value, promise_capability, context);
+
+        // 6. Let valueWrapper be Completion(PromiseResolve(%Promise%, value)).
+        let value_wrapper = Promise::promise_resolve(
+            context.intrinsics().constructors().promise().constructor(),
+            value,
+            context,
+        );
+
+        // 7. IfAbruptRejectPromise(valueWrapper, promiseCapability).
+        if_abrupt_reject_promise!(value_wrapper, promise_capability, context);
+
+        // 8. Let unwrap be a new Abstract Closure with parameters (value)
+        // that captures done and performs the following steps when called:
+        // 9. Let onFulfilled be CreateBuiltinFunction(unwrap, 1, "", « »).
+        let on_fulfilled = FunctionBuilder::closure_with_captures(
+            context,
+            |_this, args, done, context| {
+                // a. Return CreateIterResultObject(value, done).
+                Ok(create_iter_result_object(
+                    args.get_or_undefined(0).clone(),
+                    *done,
+                    context,
+                ))
+            },
+            done,
+        )
+        .name("")
+        .length(1)
+        .build();
+
+        // 10. NOTE: onFulfilled is used when processing the "value" property of an
+        // IteratorResult object in order to wait for its value if it is a promise and
+        // re-package the result in a new "unwrapped" IteratorResult object.
+
+        // 11. Perform PerformPromiseThen(valueWrapper, onFulfilled, undefined, promiseCapability).
+        value_wrapper
+            .as_object()
+            .expect("result of promise resolve must be promise")
+            .borrow_mut()
+            .as_promise_mut()
+            .expect("constructed promise must be a promise")
+            .perform_promise_then(
+                &on_fulfilled.into(),
+                &JsValue::Undefined,
+                Some(promise_capability.clone()),
+                context,
+            );
+
+        // 12. Return promiseCapability.[[Promise]].
+        Ok(promise_capability.promise().clone().into())
+    }
+}

boa_engine/src/builtins/iterable/mod.rs

@@ -1,3 +1,5 @@
+mod async_from_sync_iterator;
+
 use crate::{
     builtins::{
         regexp::regexp_string_iterator::RegExpStringIterator,
@@ -8,14 +10,20 @@ use crate::{
     symbol::WellKnownSymbols,
     Context, JsResult, JsValue,
 };
+use async_from_sync_iterator::create_async_from_sync_iterator_prototype;
+use boa_gc::{Finalize, Trace};
 use boa_profiler::Profiler;
 
+pub(crate) use async_from_sync_iterator::AsyncFromSyncIterator;
+
 #[derive(Debug, Default)]
 pub struct IteratorPrototypes {
     /// %IteratorPrototype%
     iterator_prototype: JsObject,
     /// %AsyncIteratorPrototype%
     async_iterator_prototype: JsObject,
+    /// %AsyncFromSyncIteratorPrototype%
+    async_from_sync_iterator_prototype: JsObject,
     /// %MapIteratorPrototype%
     array_iterator: JsObject,
     /// %SetIteratorPrototype%
@@ -36,6 +44,7 @@ impl IteratorPrototypes {
 
         let iterator_prototype = create_iterator_prototype(context);
         let async_iterator_prototype = create_async_iterator_prototype(context);
+        let async_from_sync_iterator_prototype = create_async_from_sync_iterator_prototype(context);
         Self {
             array_iterator: ArrayIterator::create_prototype(iterator_prototype.clone(), context),
             set_iterator: SetIterator::create_prototype(iterator_prototype.clone(), context),
@@ -48,6 +57,7 @@ impl IteratorPrototypes {
             for_in_iterator: ForInIterator::create_prototype(iterator_prototype.clone(), context),
             iterator_prototype,
             async_iterator_prototype,
+            async_from_sync_iterator_prototype,
         }
     }
 
@@ -66,6 +76,11 @@ impl IteratorPrototypes {
         self.async_iterator_prototype.clone()
     }
 
+    #[inline]
+    pub fn async_from_sync_iterator_prototype(&self) -> JsObject {
+        self.async_from_sync_iterator_prototype.clone()
+    }
+
     #[inline]
     pub fn set_iterator(&self) -> JsObject {
         self.set_iterator.clone()
@@ -154,11 +169,13 @@ impl JsValue {
                     let sync_method = self
                         .get_method(WellKnownSymbols::iterator(), context)?
                         .map_or(Self::Undefined, Self::from);
+
                     // 2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod).
-                    let _sync_iterator_record =
+                    let sync_iterator_record =
-                        self.get_iterator(context, Some(IteratorHint::Sync), Some(sync_method));
+                        self.get_iterator(context, Some(IteratorHint::Sync), Some(sync_method))?;
+
                     // 3. Return ! CreateAsyncFromSyncIterator(syncIteratorRecord).
-                    todo!("CreateAsyncFromSyncIterator");
+                    return Ok(AsyncFromSyncIterator::create(sync_iterator_record, context));
                 }
             } else {
                 // b. Otherwise, set method to ? GetMethod(obj, @@iterator).
@@ -257,7 +274,7 @@ impl IteratorResult {
 ///  - [ECMA reference][spec]
 ///
 /// [spec]: https://tc39.es/ecma262/#sec-iterator-records
-#[derive(Debug)]
+#[derive(Clone, Debug, Finalize, Trace)]
 pub struct IteratorRecord {
     /// `[[Iterator]]`
     ///

boa_engine/src/bytecompiler/mod.rs

@@ -1153,7 +1153,11 @@ impl<'b> ByteCompiler<'b> {
                 }
 
                 if r#yield.delegate() {
+                    if self.in_async_generator {
+                        self.emit_opcode(Opcode::InitIteratorAsync);
+                    } else {
                         self.emit_opcode(Opcode::InitIterator);
+                    }
                     self.emit_opcode(Opcode::PushUndefined);
                     let start_address = self.next_opcode_location();
                     let start = self.emit_opcode_with_operand(Opcode::GeneratorNextDelegate);

boa_engine/src/object/mod.rs

@@ -33,6 +33,7 @@ use crate::{
             NativeFunctionSignature,
         },
         generator::Generator,
+        iterable::AsyncFromSyncIterator,
         map::map_iterator::MapIterator,
         map::ordered_map::OrderedMap,
         object::for_in_iterator::ForInIterator,
@@ -165,6 +166,7 @@ pub struct ObjectData {
 /// Defines the different types of objects.
 #[derive(Debug, Finalize)]
 pub enum ObjectKind {
+    AsyncFromSyncIterator(AsyncFromSyncIterator),
     AsyncGenerator(AsyncGenerator),
     AsyncGeneratorFunction(Function),
     Array,
@@ -204,6 +206,7 @@ pub enum ObjectKind {
 unsafe impl Trace for ObjectKind {
     custom_trace! {this, {
         match this {
+            Self::AsyncFromSyncIterator(a) => mark(a),
             Self::ArrayIterator(i) => mark(i),
             Self::ArrayBuffer(b) => mark(b),
             Self::Map(m) => mark(m),
@@ -241,6 +244,14 @@ unsafe impl Trace for ObjectKind {
 }
 
 impl ObjectData {
+    /// Create the `AsyncFromSyncIterator` object data
+    pub fn async_from_sync_iterator(async_from_sync_iterator: AsyncFromSyncIterator) -> Self {
+        Self {
+            kind: ObjectKind::AsyncFromSyncIterator(async_from_sync_iterator),
+            internal_methods: &ORDINARY_INTERNAL_METHODS,
+        }
+    }
+
     /// Create the `AsyncGenerator` object data
     pub fn async_generator(async_generator: AsyncGenerator) -> Self {
         Self {
@@ -536,6 +547,7 @@ impl ObjectData {
 impl Display for ObjectKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(match self {
+            Self::AsyncFromSyncIterator(_) => "AsyncFromSyncIterator",
             Self::AsyncGenerator(_) => "AsyncGenerator",
             Self::AsyncGeneratorFunction(_) => "AsyncGeneratorFunction",
             Self::Array => "Array",
@@ -603,6 +615,30 @@ impl Object {
         &self.data.kind
     }
 
+    /// Checks if it's an `AsyncFromSyncIterator` object.
+    #[inline]
+    pub fn is_async_from_sync_iterator(&self) -> bool {
+        matches!(
+            self.data,
+            ObjectData {
+                kind: ObjectKind::AsyncFromSyncIterator(_),
+                ..
+            }
+        )
+    }
+
+    /// Returns a reference to the `AsyncFromSyncIterator` data on the object.
+    #[inline]
+    pub fn as_async_from_sync_iterator(&self) -> Option<&AsyncFromSyncIterator> {
+        match self.data {
+            ObjectData {
+                kind: ObjectKind::AsyncFromSyncIterator(ref async_from_sync_iterator),
+                ..
+            } => Some(async_from_sync_iterator),
+            _ => None,
+        }
+    }
+
     /// Checks if it's an `AsyncGenerator` object.
     #[inline]
     pub fn is_async_generator(&self) -> bool {

boa_engine/src/vm/code_block.rs

@@ -350,6 +350,7 @@ impl CodeBlock {
             | Opcode::LoopContinue
             | Opcode::LoopEnd
             | Opcode::InitIterator
+            | Opcode::InitIteratorAsync
             | Opcode::IteratorNext
             | Opcode::IteratorClose
             | Opcode::IteratorToArray

boa_engine/src/vm/mod.rs

@@ -6,7 +6,7 @@ use crate::{
     builtins::{
         async_generator::{AsyncGenerator, AsyncGeneratorState},
         function::{ConstructorKind, Function},
-        iterable::IteratorRecord,
+        iterable::{IteratorHint, IteratorRecord},
         Array, ForInIterator, JsArgs, Number, Promise,
     },
     environments::EnvironmentSlots,
@@ -2028,6 +2028,13 @@ impl Context {
                 self.vm.push(iterator.next_method().clone());
                 self.vm.push(iterator.done());
             }
+            Opcode::InitIteratorAsync => {
+                let object = self.vm.pop();
+                let iterator = object.get_iterator(self, Some(IteratorHint::Async), None)?;
+                self.vm.push(iterator.iterator().clone());
+                self.vm.push(iterator.next_method().clone());
+                self.vm.push(iterator.done());
+            }
             Opcode::IteratorNext => {
                 let done = self
                     .vm

boa_engine/src/vm/opcode.rs

@@ -1048,6 +1048,13 @@ pub enum Opcode {
     /// Stack: object **=>** iterator, next_method, done
     InitIterator,
 
+    /// Initialize an async iterator.
+    ///
+    /// Operands:
+    ///
+    /// Stack: object **=>** iterator, next_method, done
+    InitIteratorAsync,
+
     /// Advance the iterator by one and put the value on the stack.
     ///
     /// Operands:
@@ -1325,6 +1332,7 @@ impl Opcode {
             Self::LoopEnd => "LoopEnd",
             Self::ForInLoopInitIterator => "ForInLoopInitIterator",
             Self::InitIterator => "InitIterator",
+            Self::InitIteratorAsync => "InitIteratorAsync",
             Self::IteratorNext => "IteratorNext",
             Self::IteratorClose => "IteratorClose",
             Self::IteratorToArray => "IteratorToArray",
@@ -1468,6 +1476,7 @@ impl Opcode {
             Self::LoopEnd => "INST - LoopEnd",
             Self::ForInLoopInitIterator => "INST - ForInLoopInitIterator",
             Self::InitIterator => "INST - InitIterator",
+            Self::InitIteratorAsync => "INST - InitIteratorAsync",
             Self::IteratorNext => "INST - IteratorNext",
             Self::IteratorClose => "INST - IteratorClose",
             Self::IteratorToArray => "INST - IteratorToArray",