certain bug: Illegal async arrow function parameter list

[nchanged]

version: 1.4.8
Snippet:

async function test(){
  const someVar = null;
  const done = async foo => {}
}

Throws Illegal async arrow function parameter list (also reproducible in the REPL)

Observations: commenting out const someVar = null; fixes the problem.

Can be found in the npm package electron-updater right here node_modules/electron-updater/out/AppUpdater.js

Related issue: fuse-box/fuse-box#1570

Being parsed without any issues with typescript or babel or esprima
https://astexplorer.net/#/gist/3e1e685684c77a841dd4452b677654f9/6e25a2a530fc046e1dc55f5f3285fa7d5acd20d0

[leeoniya]

@KFlash have you considered doing something like https://github.com/rust-lang/crater#crater- against large/popular NPM or github repos? i think it would quickly uncover more "edge" cases.

[nchanged]

@leeoniya the best way to test it is to run against as many libraries as possible. That I can provide, FuseBox' users started adapting the new version based on meriyah.

[KFlash]

@leeoniya I will try to validate against as some libraries soon as I get time. ATM. What @nchanged mentioned is the best solution.

Beside that I'm stress testing the code entire time, and run 3x different fuzzers and so on.

But to be honest. It's a known issue for me that async and async arrows are troublesome because I'm parsing this in a different way than what the specs says to avoid tons of known issues from other parsers and V8 with async arrow + call expr. This so I can avoid performance bottlenecks.

And sometimes I suddenly find more "edge cases" because one of my previous students did some code changes without knowing what he was doing as what happened with v. 1.4.5.

[nchanged]

const a = {
  foo: () => {
  },
  bar: async event => {
  }
);

This bug hasn't been fixed. Which makes me think there are more similar cases. @KFlash please take a look at all possible variations.

[KFlash]

@nchanged Are you sure about this? Btw. Your example is invalid. Missing a right brace.

If I modify your example into this, it pass for me

const a = {
        foo: () => {
        },
        bar: async event => {
        }
      }

[KFlash]

@nchanged FYI. This bug was caused because of a mutual parser flag and validation against it. This flag have been replaced with a func arg assignable and validations against that arg instead. You can find it here. This means that this bug will never happen again, and everything related to it can't happen either. So permanently solved :)

[KFlash]

@leeoniya @nchanged Parsed a lot of libraries now but couldn't find any issues or "edge cases".
I added a bunch of new tests just to be sure. Even the Chinese language is very well supported :)