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LibJS: Don't crash on broken promises in AsyncGenerator#return

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See: https://github.com/tc39/ecma262/pull/2683
This commit is contained in:
Luke Wilde 2023-07-14 22:23:43 +01:00 • committed by Linus Groh
parent d1cb78c411
commit e86d7cab06
4 changed files with 58 additions and 15 deletions
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46
Userland/Libraries/LibJS/Runtime/AsyncGenerator.cpp
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@ -342,7 +342,8 @@ ThrowCompletionOr<void> AsyncGenerator::resume(VM& vm, Completion completion)
}
// 27.6.3.9 AsyncGeneratorAwaitReturn ( generator ), https://tc39.es/ecma262/#sec-asyncgeneratorawaitreturn
ThrowCompletionOr<void> AsyncGenerator::await_return()
// With unmerged broken promise fixup from https://github.com/tc39/ecma262/pull/2683
void AsyncGenerator::await_return()
{
auto& vm = this->vm();
auto& realm = *vm.current_realm();
@ -362,10 +363,31 @@ ThrowCompletionOr<void> AsyncGenerator::await_return()
// 5. Assert: completion.[[Type]] is return.
VERIFY(completion.type() == Completion::Type::Return);
// 6. Let promise be ? PromiseResolve(%Promise%, completion.[[Value]]).
auto* promise = TRY(promise_resolve(vm, realm.intrinsics().promise_constructor(), completion.value().value()));
// 6. Let promiseCompletion be Completion(PromiseResolve(%Promise%, _completion_.[[Value]])).
auto promise_completion = promise_resolve(vm, realm.intrinsics().promise_constructor(), completion.value().value());
// 7. Let fulfilledClosure be a new Abstract Closure with parameters (value) that captures generator and performs
// 7. If promiseCompletion is an abrupt completion, then
if (promise_completion.is_throw_completion()) {
// a. Set generator.[[AsyncGeneratorState]] to completed.
m_async_generator_state = State::Completed;
// b. Perform AsyncGeneratorCompleteStep(generator, promiseCompletion, true).
complete_step(promise_completion.release_error(), true);
// c. Perform AsyncGeneratorDrainQueue(generator).
drain_queue();
// d. Return unused.
return;
}
// 8. Assert: promiseCompletion.[[Type]] is normal.
VERIFY(!promise_completion.is_throw_completion());
// 9. Let promise be promiseCompletion.[[Value]].
auto* promise = promise_completion.release_value();
// 10. Let fulfilledClosure be a new Abstract Closure with parameters (value) that captures generator and performs
// the following steps when called:
auto fulfilled_closure = [this](VM& vm) -> ThrowCompletionOr<Value> {
// a. Set generator.[[AsyncGeneratorState]] to completed.
@ -384,10 +406,10 @@ ThrowCompletionOr<void> AsyncGenerator::await_return()
return js_undefined();
};
// 8. Let onFulfilled be CreateBuiltinFunction(fulfilledClosure, 1, "", « »).
// 11. Let onFulfilled be CreateBuiltinFunction(fulfilledClosure, 1, "", « »).
auto on_fulfilled = NativeFunction::create(realm, move(fulfilled_closure), 1, "");
// 9. Let rejectedClosure be a new Abstract Closure with parameters (reason) that captures generator and performs
// 12. Let rejectedClosure be a new Abstract Closure with parameters (reason) that captures generator and performs
// the following steps when called:
auto rejected_closure = [this](VM& vm) -> ThrowCompletionOr<Value> {
// a. Set generator.[[AsyncGeneratorState]] to completed.
@ -406,17 +428,17 @@ ThrowCompletionOr<void> AsyncGenerator::await_return()
return js_undefined();
};
// 10. Let onRejected be CreateBuiltinFunction(rejectedClosure, 1, "", « »).
// 13. Let onRejected be CreateBuiltinFunction(rejectedClosure, 1, "", « »).
auto on_rejected = NativeFunction::create(realm, move(rejected_closure), 1, "");
// 11. Perform PerformPromiseThen(promise, onFulfilled, onRejected).
// 14. Perform PerformPromiseThen(promise, onFulfilled, onRejected).
// NOTE: await_return should only be called when the generator is in SuspendedStart or Completed state,
// so an await shouldn't be running currently, so it should be safe to overwrite m_current_promise.
m_current_promise = verify_cast<Promise>(promise);
m_current_promise->perform_then(on_fulfilled, on_rejected, {});
// 12. Return unused.
return {};
// 15. Return unused.
return;
}
// 27.6.3.5 AsyncGeneratorCompleteStep ( generator, completion, done [ , realm ] ), https://tc39.es/ecma262/#sec-asyncgeneratorcompletestep
@ -507,8 +529,8 @@ void AsyncGenerator::drain_queue()
// i. Set generator.[[AsyncGeneratorState]] to awaiting-return.
m_async_generator_state = State::AwaitingReturn;
// ii. Perform ! AsyncGeneratorAwaitReturn(generator).
MUST(await_return());
// ii. Perform AsyncGeneratorAwaitReturn(generator).
await_return();
// iii. Set done to true.
done = true;