Add support for using and await using

[lahma]

Here to show some progress, might need some help to finalize but hopefully this is more than nothing. Branch pushed directly to this repo for easier checkout if you want to.

[adams85]

Here to show some progress, might need some help to finalize but hopefully this is more than nothing.

I could just take a quick look now but I can say it's promising! Please allow me some more time to dig into it properly.

Branch pushed directly to this repo for easier checkout if you want to.

👍

[lahma]

I've completed the work on Jint side and all tests are passing there too now.

[adams85]

Thank you for taking your time! I revised your work and made some corrections/improvements.

Unfortunately, there are still some rough edges to polish off:

• The double lookahead in isUsingKeyword is buggy in the original implementation. Acorn incorrectly accepts nonsense like async () => { await using\u0065 a = b } at the moment. I'll need to look into this, maybe discuss it with the acorn guys.
• Error reporting doesn't follow V8 in all cases (e.g. in bare switch cases). I'll set this straight too.
• Would be nice to port tests from acorn. Working on it. Plus, we should add some tests for the new AllowTopLevelUsing option.

To be continued.

[lahma]

Thanks, much appreciated. I know I create extra burden but hopefully at least something to build upon 😅

[adams85]

Come on, this has to be done anyway - the sooner, the better! :)

[adams85]

Okay, I think this is complete now. @lahma Could you take a final look?

[lahma]

Quite a lot of changed files, but checking the commits seems really good, thanks for pushing the final 90% 😄 All tests passing on Jint side so I think it's good to go 🚀

[lahma]

I'm also totally fine if you want to credit this to yourself in commit log instead of me, you did the actual work 💪🏻

[adams85]

Nope, this was a full-blown co-production. :D I wouldn't even have started implementing this if you hadn't taken the first steps...

I'm going to release this soon, along with some additional upstream improvements plus some minor performance-related tweaks.