LibJS: Convert GetIterator AO to ThrowCompletionOr

Userland/Libraries/LibJS/Bytecode/Op.cpp

@@ -478,7 +478,10 @@ void PutByValue::execute_impl(Bytecode::Interpreter& interpreter) const
 
 void GetIterator::execute_impl(Bytecode::Interpreter& interpreter) const
 {
-    interpreter.accumulator() = get_iterator(interpreter.global_object(), interpreter.accumulator());
+    auto iterator_or_error = get_iterator(interpreter.global_object(), interpreter.accumulator());
+    if (iterator_or_error.is_error())
+        return;
+    interpreter.accumulator() = iterator_or_error.release_value();
 }
 
 void IteratorNext::execute_impl(Bytecode::Interpreter& interpreter) const

Userland/Libraries/LibJS/Runtime/ArrayConstructor.cpp

@@ -116,10 +116,8 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(ArrayConstructor::from)
         } else {
             array = Array::create(global_object, 0);
         }
-        auto iterator = get_iterator(global_object, items, IteratorHint::Sync, using_iterator);
-        if (vm.exception())
-            return {};
 
+        auto iterator = TRY_OR_DISCARD(get_iterator(global_object, items, IteratorHint::Sync, using_iterator));
         auto& array_object = array.as_object();
 
         size_t k = 0;

Userland/Libraries/LibJS/Runtime/Intl/ListFormat.cpp

@@ -276,9 +276,7 @@ ThrowCompletionOr<Vector<String>> string_list_from_iterable(GlobalObject& global
     }
 
     // 2. Let iteratorRecord be ? GetIterator(iterable).
-    auto* iterator_record = get_iterator(global_object, iterable);
+    auto* iterator_record = TRY(get_iterator(global_object, iterable));
-    if (auto* exception = vm.exception())
-        return throw_completion(exception->value());
 
     // 3. Let list be a new empty List.
     Vector<String> list;

Userland/Libraries/LibJS/Runtime/IteratorOperations.cpp

@@ -12,24 +12,23 @@
 namespace JS {
 
 // 7.4.1 GetIterator ( obj [ , hint [ , method ] ] ), https://tc39.es/ecma262/#sec-getiterator
-Object* get_iterator(GlobalObject& global_object, Value value, IteratorHint hint, Value method)
+ThrowCompletionOr<Object*> get_iterator(GlobalObject& global_object, Value value, IteratorHint hint, Value method)
 {
     auto& vm = global_object.vm();
     if (method.is_empty()) {
         if (hint == IteratorHint::Async)
             TODO();
-        auto object = TRY_OR_DISCARD(value.to_object(global_object));
+        auto object = TRY(value.to_object(global_object));
-        method = TRY_OR_DISCARD(object->get(*vm.well_known_symbol_iterator()));
+        method = TRY(object->get(*vm.well_known_symbol_iterator()));
-    }
-    if (!method.is_function()) {
-        vm.throw_exception<TypeError>(global_object, ErrorType::NotIterable, value.to_string_without_side_effects());
-        return nullptr;
-    }
-    auto iterator = TRY_OR_DISCARD(vm.call(method.as_function(), value));
-    if (!iterator.is_object()) {
-        vm.throw_exception<TypeError>(global_object, ErrorType::NotIterable, value.to_string_without_side_effects());
-        return nullptr;
     }
+
+    if (!method.is_function())
+        return vm.throw_completion<TypeError>(global_object, ErrorType::NotIterable, value.to_string_without_side_effects());
+
+    auto iterator = TRY(vm.call(method.as_function(), value));
+    if (!iterator.is_object())
+        return vm.throw_completion<TypeError>(global_object, ErrorType::NotIterable, value.to_string_without_side_effects());
+
     return &iterator.as_object();
 }
 
@@ -170,9 +169,10 @@ void get_iterator_values(GlobalObject& global_object, Value value, Function<Iter
 {
     auto& vm = global_object.vm();
 
-    auto iterator = get_iterator(global_object, value, IteratorHint::Sync, method);
+    auto iterator_or_error = get_iterator(global_object, value, IteratorHint::Sync, method);
-    if (!iterator)
+    if (iterator_or_error.is_error())
         return;
+    auto* iterator = iterator_or_error.release_value();
 
     while (true) {
         auto next_object = iterator_next(*iterator);

Userland/Libraries/LibJS/Runtime/IteratorOperations.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/Function.h>
+#include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/Object.h>
 
 namespace JS {
@@ -18,7 +19,7 @@ enum class IteratorHint {
     Async,
 };
 
-Object* get_iterator(GlobalObject&, Value value, IteratorHint hint = IteratorHint::Sync, Value method = {});
+ThrowCompletionOr<Object*> get_iterator(GlobalObject&, Value value, IteratorHint hint = IteratorHint::Sync, Value method = {});
 Object* iterator_next(Object& iterator, Value value = {});
 Object* iterator_step(GlobalObject&, Object& iterator);
 bool iterator_complete(GlobalObject&, Object& iterator_result);

Userland/Libraries/LibJS/Runtime/PromiseConstructor.cpp

@@ -37,10 +37,22 @@ static Value get_promise_resolve(GlobalObject& global_object, Value constructor)
 }
 
 // 27.2.1.1.1 IfAbruptRejectPromise ( value, capability ), https://tc39.es/ecma262/#sec-ifabruptrejectpromise
-static Optional<Value> if_abrupt_reject_promise(GlobalObject& global_object, Value, PromiseCapability capability)
+template<typename ValueType>
+static Optional<Value> if_abrupt_reject_promise(GlobalObject& global_object, ValueType const& value_or_error, PromiseCapability capability)
 {
     auto& vm = global_object.vm();
 
+    // FIXME: This is temporary multi-type support. When all callers to this method are transformed
+    //        to use ThrowCompletionOr, the 'else' clause (and template) can be dropped.
+    if constexpr (requires { value_or_error.is_throw_completion(); }) {
+        if (value_or_error.is_throw_completion()) {
+            vm.clear_exception();
+            vm.stop_unwind();
+
+            (void)vm.call(*capability.reject, js_undefined(), value_or_error.throw_completion().value());
+            return capability.promise;
+        }
+    } else {
         if (auto* exception = vm.exception()) {
             vm.clear_exception();
             vm.stop_unwind();
@@ -48,6 +60,7 @@ static Optional<Value> if_abrupt_reject_promise(GlobalObject& global_object, Val
             (void)vm.call(*capability.reject, js_undefined(), exception->value());
             return capability.promise;
         }
+    }
 
     return {};
 }
@@ -281,9 +294,10 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::all)
     if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve, promise_capability); abrupt.has_value())
         return abrupt.value();
 
-    auto iterator_record = get_iterator(global_object, vm.argument(0));
+    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record, promise_capability); abrupt.has_value())
+    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
         return abrupt.value();
+    auto* iterator_record = iterator_record_or_error.release_value();
 
     auto result = perform_promise_all(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (vm.exception()) {
@@ -310,9 +324,10 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::all_settled)
     if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve, promise_capability); abrupt.has_value())
         return abrupt.value();
 
-    auto iterator_record = get_iterator(global_object, vm.argument(0));
+    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record, promise_capability); abrupt.has_value())
+    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
         return abrupt.value();
+    auto* iterator_record = iterator_record_or_error.release_value();
 
     auto result = perform_promise_all_settled(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (vm.exception()) {
@@ -339,9 +354,10 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::any)
     if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve, promise_capability); abrupt.has_value())
         return abrupt.value();
 
-    auto iterator_record = get_iterator(global_object, vm.argument(0));
+    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record, promise_capability); abrupt.has_value())
+    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
         return abrupt.value();
+    auto* iterator_record = iterator_record_or_error.release_value();
 
     auto result = perform_promise_any(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (vm.exception()) {
@@ -368,9 +384,10 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::race)
     if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve, promise_capability); abrupt.has_value())
         return abrupt.value();
 
-    auto iterator_record = get_iterator(global_object, vm.argument(0));
+    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record, promise_capability); abrupt.has_value())
+    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
         return abrupt.value();
+    auto* iterator_record = iterator_record_or_error.release_value();
 
     auto result = perform_promise_race(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (vm.exception()) {

Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp

@@ -41,9 +41,7 @@ ThrowCompletionOr<MarkedValueList> iterable_to_list_of_type(GlobalObject& global
     auto& heap = global_object.heap();
 
     // 1. Let iteratorRecord be ? GetIterator(items, sync).
-    auto iterator_record = get_iterator(global_object, items, IteratorHint::Sync);
+    auto iterator_record = TRY(get_iterator(global_object, items, IteratorHint::Sync));
-    if (auto* exception = vm.exception())
-        return throw_completion(exception->value());
 
     // 2. Let values be a new empty List.
     MarkedValueList values(heap);

Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp

@@ -492,9 +492,7 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(CalendarPrototype::fields)
     VERIFY(calendar->identifier() == "iso8601"sv);
 
     // 4. Let iteratorRecord be ? Getiterator(fields, sync).
-    auto* iterator_record = get_iterator(global_object, fields, IteratorHint::Sync);
+    auto* iterator_record = TRY_OR_DISCARD(get_iterator(global_object, fields, IteratorHint::Sync));
-    if (vm.exception())
-        return {};
 
     // 5. Let fieldNames be a new empty List.
     auto field_names = MarkedValueList { vm.heap() };

Userland/Libraries/LibJS/Runtime/VM.cpp

@@ -196,12 +196,7 @@ ThrowCompletionOr<void> VM::binding_initialization(NonnullRefPtr<BindingPattern>
         TRY(property_binding_initialization(*target, value, environment, global_object));
         return {};
     } else {
-        auto* iterator = get_iterator(global_object, value);
+        auto* iterator = TRY(get_iterator(global_object, value));
-        if (!iterator) {
-            VERIFY(exception());
-            return JS::throw_completion(exception()->value());
-        }
-
         auto iterator_done = false;
 
         auto result = iterator_binding_initialization(*target, iterator, iterator_done, environment, global_object);