bug#62333: 30.0.50; Issue with tree-sitter syntax tree during certain changes

[Dmitry Gutov]

On 24/03/2023 09:34, Yuan Fu wrote:
> Well, this is a bit embarrassing, there is even a comment warning 
this mistake, but anyway, I pushed a fix, once it gets merged into 
master, the problem should go away.

Excellent, thanks.

> As things stands right now, every time blink-match-open blinks the matching 
> parenthesis, tree-sitter would reparse the buffer twice, that’s not exactly 
> ideal. Blink-match-open’s use of narrowing is legit, and we can’t just 
> automatically widen in tree-sitter functions.

Not ideal indeed.

Aside from the performance impact, we could also see cases where the 
"narrowed" parse tree contains errors (due to incomplete code) which 
make the tree itself less useful. Especially when the narrowing's end is 
closer to the current position than in blink-matching-open's usage.

Not sure how to solve that, but suppose we had a way to convey to 
treesit.c that it shouldn't change the visibility bounds for the parser 
in this particular instance? Though that would raise the issue of code 
trying to use node positions beyond the current accessible range.