[BUG] New js parser fails to parse some js that old parser supported

[phated]

Describe the bug
I tried upgrading Grain's binaryen.ml bindings to jsoo 5.1 and it crashes with failure to parse the binaryen.js file. I still need to create a reproduction that doesn't have the whole (large) js file to comb through but I wanted to preemptively open this issue.

Expected behavior
Should be able to parse es5 code that was supported by 5.0

Versions
Ocaml 4.14
Jsoo 5.1

[hhugo]

Where is the binaryen.js file you're talking about ? Looking at https://github.com/AssemblyScript/binaryen.js/blob/main/index.js, there are some fat arrows that were not supported by the previous parser.

[phated]

We actually have a custom es5 build at https://github.com/grain-lang/libbinaryen/blob/main/binaryen.es5.js

[hhugo]

Are you able to give more information ? Do you know what construct makes the parser unhappy ? Can jsoo successfully parse the es6 version of the file ?

[vouillon]

The issue is that of is not accepted as a label (nor are get, set, from, async).

of:{
break of
}

[hhugo]

Thanks @vouillon, should be easy to fix. Probably just a one-liner in js_parser.mly

[hhugo]

@phated, would you be interested by fixing this yourself and send a PR ?

[phated]

I'm not sure when I'll have time for awhile. We are pushing hard for the next 3 weeks to finish a grain release and we might just have to stay on the older jsoo