bug#45717: 27.1; Error with apostrophe in JSX comment

[Jackson Ray Hamilton <jackson@jacksonrayhamilton.com>]

Hi, thanks for bringing this to our attention.

This code seems to throw js-jsx--syntax-propertize-extend-region into an 
infinite loop.  M-x toggle-debug-on-error and M-x eval-expression 
(js-jsx--syntax-propertize-extend-region 69 240) shows the stack trace; 
(backward-sexp) ultimately causes (syntax-propertize), thus the loop.

Using M-x edebug-defun to debug js-jsx--syntax-propertize-extend-region, 
after pressing space a bunch of times to step through it, I see it’s 
trying to jump from “)}” to the “{” in “className={”.  The presence of 
the apostrophe somehow interrupts the intended logic.

I tried adding parse-sexp-ignore-comments to the let and it suppressed 
the infinite loop but caused a scan-error (which is immediately caught) 
which seems wrong to me.

I tried adding (parse-sexp-ignore-comments t) to the let and encountered 
another infinite loop.

Tricky.  For now, I’ll leave the mailing list with my notes.

On 11/2/21 6:34 PM, Dmitry Gutov wrote:
> On 31.10.2021 05:41, Stefan Kangas wrote:
>> tags 45717 + confirmed
>> thanks
>>
>> Jakobsson Mattias<mattias.jakobsson@smhi.se>  writes:
>>
>>> I get the errors in the Recent messages further below if I edit 
>>> (e.g., by inserting a newline)
>>> a JSX file with the content between the ``` below. If I remove the 
>>> apostrophe from
>>> "don't" in the comment the errors goes away.
>>>
>>> ```
>>> import React from "react";
>>>
>>> const MyComponent = ({ someList }) => (
>>>    <div
>>>      className={someList.filter(
>>>        // don't include an apostrophe in this comment
>>>        (cls) => cls !== "someclass"
>>>      )}
>>>    />
>>> );
>>>
>>> export default MyComponent;
>>> ```
>> I tried reproducing this on current master, but I don't see any message.
>> However, I do see incorrect highlighting after the comment with the
>> apostrophe, so something is clearly still not working as it should.
>
> I do see errors in this scenario, especially after trying to edit or 
> move around. Like:
>
> js-jsx--syntax-propertize-extend-region: Lisp nesting exceeds 
> ‘max-lisp-eval-depth’Error during redisplay: (jit-lock-function 1) 
> signaled (error "Lisp nesting exceeds ‘max-lisp-eval-depth’")
>
> Adding Jackson to Cc, perhaps he'll have time and inclination to 
> investigate this.