bug#67990: 30.0.50; tree-sitter: treesit-node-field-name-for-child seems to be broken after recent changes

[Eli Zaretskii]

> From: Denis Zubarev <dvzubarev@yandex.ru>
> Date: Sat, 23 Dec 2023 17:37:54 +0300
> 
> 
> libtree-sitter is compiled from sources (latest version) 
> 
> Steps to reproduce:
> 1. emacs -Q
> 2. M-x find-file /tmp/t.py
> 3. Paste there
> if (v is not None and #comment
>     v > 0):
>    pass
> 4. M-x python-ts-mode
> 5. M-x treesit-explore-mode
>     python
> 
> Parse tree:
> (module
>  (if_statement if
>   (parenthesized_expression (
>    (boolean_operator
>     left: (comparison_operator (identifier) operators: is not operators: is 
> not operators: (none))
>     operator: and operator: (comment)
>     operator: (comparison_operator (identifier) operators: > operators: 
> (integer)))
>    ))
>   condition: :
>   condition:
>    (block
>     (pass_statement pass))))
> 
> 
> Parse tree from the playground:
> module [0, 0] - [4, 0]
>   if_statement [0, 0] - [2, 7]
>     condition: parenthesized_expression [0, 3] - [1, 10]
>       boolean_operator [0, 4] - [1, 9]
>         left: comparison_operator [0, 4] - [0, 17]
>           identifier [0, 4] - [0, 5]
>           none [0, 13] - [0, 17]
>         comment [0, 22] - [0, 30]
>         right: comparison_operator [1, 4] - [1, 9]
>           identifier [1, 4] - [1, 5]
>           integer [1, 8] - [1, 9]
>     consequence: block [2, 3] - [2, 7]
>       pass_statement [2, 3] - [2, 7]
> 
> 
> Version from the playground has correctly assigned fields:
> parenthesized_expression - condition:, block is labeled as
> consequence:, the second comparison_operator - right:
> 
> I noticed this regression after 9874561f39e62c1c9fada6c2e013f93d9ea65729.
> Quote from this commit "So turns out ts_node_field_name_for_child takes a 
> named node index,"
> It seems that was a bug in the libtree-sitter and they fixed it in
> https://github.com/tree-sitter/tree-sitter/pull/2104
> Unfortunately, there is no release with this fix yet.
> 
> I have tested various combinations of libtree-sitter and fix from 9874561f39:
> With commit 9874561f39
> libtree-sitter v0.20.8 - condition: and consequence: fields are wrongly 
> assigned
> libtree-sitter version with the fix* - most fields are broken
> 
> When reverting commit 9874561f39
> libtree-sitter v0.20.8 - only right: field is wrong (points to the comment 
> node)
> libtree-sitter version with the fix* - ok

Yuan, any comments?