SWC has a tick too much in transpiled for await resulting in different output after transpiling

[danieltroger]

Describe the bug

This exact bug: babel/babel#13490 but for SWC.

See this, output after transpiling and before transpiling should be the same:

daniel@Daniels-MacBook-Pro swc-for-await % node dist/ie11.js 
0
daniel@Daniels-MacBook-Pro swc-for-await % node src/main.ts 
0
1

Input code

let resolve;
let promise = new Promise((r) => (resolve = r));
let iterable = {
  [Symbol.asyncIterator]() {
    return {
      next() {
        return promise;
      },
    };
  },
};

(async () => {
  for await (let value of iterable) {
    console.log(value);
  }
})();

(async function () {
  resolve({ value: 0, done: false });
  promise = new Promise((r) => (resolve = r));

  await null;
  resolve({ value: 1, done: false });
  promise = new Promise((r) => (resolve = r));

  resolve({ value: undefined, done: true });
})();

Config

{
  "env": {
    "shippedProposals": true
  }
}

Expected behavior
Expected behavior is for the code above to output

0
1

like it does untranspiled.

Version

@swc/cli: 0.1.46
@swc/core: 1.2.63

Additional context
I use SWC with parcel

Simple reproduction repository with SWC (kudos to @mischnic):
swc-for-await-repro.zip

Reproduction with parcel using SWC:
swc-for-await.zip

[kdy1]

I was aware of such bug as you mentioned in the babel issue, but I prefer waiting for the babel team because I want to align the helper scripts.

[danieltroger]

@kdy1 could you please review this pull request then for them? babel/babel#13491 they're just waiting for a review so they can merge

[kdy1]

I'm not a babel expert, so I expect my review to be helpless.
(I barely looked at the babel source code while building swc)

[danieltroger]

You know how async transpilation works and I therefore think you're one of the few people that even understand what the changes are. I think they're not merging because there's like one more person on the planet that knows what it's about and they're on vacation.

[kdy1]

But I don't want to do it.
It does not seem to be an interesting task.

[danieltroger]

I see, that's fair

[sachinraja]

Update: that PR has now been merged

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.