Wrong return value of puni-region-balance-p in js2-mode

[DamienCassou]

Given this content

values
    .filter((a) => a)
    .filter((a) => a);

in a js2-mode buffer, if I mark the second line and type M-: (puni-region-balance-p (region-beginning) (region-end)) RET, I get nil but I expect a non-nil value because .filter((a) => a) seems balanced to me.

forward-sexp seems to work fine but backward-sexp goes back to the beginning of the first line when invoked with point at the end of second line. forward-sexp-function is nil.

[AmaiKinono]

forward-sexp-function is nil.

Could you double check this? It's js2-mode-forward-sexp on my side, and if I set it to nil, I can't reproduce.

This is because a problem in the js2-mode-forward-sexp:

v.f|((a) => a);
// forward-sexp
v.f((a) => a);|
// backward-sexp
|v.f((a) => a);
// forward-sexp
v|.f((a) => a);

It treat this line as an sexp when going backward (using ; as a clue), but doesn't when going forward.

Let me think about how to fix this. I also noticed several other problems in js2-mode.

[DamienCassou]

forward-sexp-function is nil.
Could you double check this? It's js2-mode-forward-sexp on my side, and if I set it to nil, I can't reproduce.

you are perfectly right. I don't know what happened but forward-sexp-function is indeed equal to js2-mode-forward-sexp.

Let me think about how to fix this. I also noticed several other problems in js2-mode.

thank you very much. Is it something we could fix in js2-mode directly so you don't need to add a workaround in puni?

[AmaiKinono]

Is it something we could fix in js2-mode directly so you don't need to add a workaround in puni?

I think it is. But to fix improper (in Puni's opinion) handling of sexps is the goal of Puni. If we patch js2-mode, we fix this one case. But if we patch Puni, we fix similar problems of other major modes too.

[DamienCassou]

I agree with you that a general-purpose workaround in Puni can help for other modes. I opened an issue on the js2-mode project anyway because they might still want to fix the problem on their side.

[AmaiKinono]

Should be fixed. Please test.

[DamienCassou]

Thank you very much