Native await keyword is not used in async generator even after es2017

[falsandtru]

TypeScript Version: master

Search Terms:

Code

async function f() {
  await 0;
}
async function* g() {
  await 0;
  yield await 0;
}

$ node built/local/tsc.js index.ts -t es2017 --lib esnext

Expected behavior:

async function f() {
    await 0;
}
function g() {
    return __asyncGenerator(this, arguments, function* g_1() {
        await 0;
        yield await 0;
    });
}

Actual behavior:

async function f() {
    await 0;
}
function g() {
    return __asyncGenerator(this, arguments, function* g_1() {
        yield __await(0);
        yield yield __await(0);
    });
}

Playground Link:

Related Issues:

[mhegazy]

Should be covered by #20463.

A PR for #20463 is welcomed.

[falsandtru]

@mhegazy This issue targets es2017 but #20463 targets es2018. That issue really covers this?

[mhegazy]

you are correct. it is part of es2017. PRs welcomed.

[weswigham]

It's not part of es2017. Async functions are part of es2017, but asynchronous generators (and async for loops) are still just a stage-3 proposal.

[falsandtru]

I think you can fix this issue without touching part of async generator.

[Jessidhia]

The generated code looks correct. Your example of "correct" code would be a syntax error even in ES2018 engines because you are using the await keyword outside of an async function.

[falsandtru]

Right, I can't think of a solution to that issue for now.

[mhegazy]

We can do it as part of es2018.