bug#59498: 29.0.50; c++-ts-mode get wrong-type-argument error when enabled

[Yuan Fu]

> On Nov 26, 2022, at 11:24 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Stefan Monnier <monnier@iro.umontreal.ca>
>> Cc: Yuan Fu <casouri@gmail.com>,  dev@rjt.dev,  aqua0210@foxmail.com,
>>  59498@debbugs.gnu.org,  mardani29@yahoo.es
>> Date: Sun, 27 Nov 2022 02:18:06 -0500
>> 
>>>> I added treesit-comment-start/end to help indenting comments. So this is
>>>> the correct way to use them. The following comment explains why I created
>>>> new variables:
>>>> 
>>>> ;; `comment-start' and `comment-end' assume there is only one type of
>>>> ;; comment, and that the comment spans only one line.  So they are not
>>>> ;; sufficient for our purpose.
>>> 
>>> ??? This is surprisingly unclean, IMO.  For starters, the names of the
>>> variables are confusing.  The need to define two sets of comment-start and
>>> comment-end regexps is also a nuisance and a source of errors.
>>> 
>>> How do non-treesit modes handle this issue?  Why do the treesit-based modes
>>> need something special here?
>>> 
>>> Stefan, any ideas?
>> 
>> `comment-start` and `comment-end` do not describe the set of possible
>> comment delimiters.  They describe the comment delimiters that should be
>> *inserted* when we do things like `comment-dwim`.
>> 
>> To find/match comment delimiters we have `comment-start-skip` and
>> `comment-end-skip`.  They're not ideal, but they've been good enough so far.
>> They don't say which comment starter matches which comment-ender (that
>> was done by the syntax-tables), but tree-sitter should be able to tell
>> us that when we need it.
>> 
>> It would be nice if we could avoid the need to set/use
>> `comment-start-skip` and `comment-end-skip` when using tree-sitter.
>> Maybe we can compute their values from the tree-sitter grammar.
>> But getting rid of uses of those vars will take a fair bit more work,
>> I think.
> 
> OK, but do you agree that adding yet another pair of variables,
> treesit-comment-start/end, is the opposite of what we want?

Yes. I removed them in d5dc1dbf7cb.

Yuan